The Tesla Catamaran!

hi today I'm going to talk to you about boats [Music] [Applause] if you came here because of the thumbnail don't worry we're gonna get to the the big model and a little bit but if you're an unfamiliar with the channel one of the things we try to do here is not just use the videos as a way to highlight projects that we've completed but to go through some of the underlying principles behind the design as well as explain some of the techniques we've used and admit some of the mistakes that we've made in order to allow you to either reproduce our results or to use some of the ideas on similar projects that you may be involved in now I've owned sail'd bought and built a variety of boats over the years and I have to say even though it's kind of fun sitting around on the deck of a luxury etched drinking a martini it's generally more fun the smaller the boat is you know it's a lot of fun paddling around on a little kayak and secluded waterway or hanging your rear end out over the side of a holy Cadiz you know the one hull starting to lift up in the air and one of the other advantages about small boats is because they are small they're less expensive they're easier to transport to store they're easier to construct you don't have a lot of the expense associated with insurance you don't have a dock space that you have to rent or a mooring and in addition to that if you do decide that you want to build a boat it's just a more approachable project now one of the difficulties though with a small boat is it's small and therefore usually has a limited capacity you've got maybe one maybe two people that you can carry a limited cargo and they tend to be unstable you know there isn't many people I think that heaven to either fallen out of or nearly fallen out of a canoe and so what I want to do today is I want to go through the method that we can use to build what's probably considered a moderate sized boat but take advantage of a lot of the the features of a little boat by constructing a boat that is modular with a half a dozen to a dozen major components that can be snapped together and snapped apart we can either bring this to a site that we want to launch it out or we can store it in individual pieces which makes it a lot more approachable now in addition the design of the boat to maximize the the flexibility with a modular design takes advantage of using a multi hull versus a monohull and part of the reason is is that when you divide the holes up you've obviously got lighter components in addition a multihull not only looks pretty sexy but it also has a higher stability than a monohull now the reason that the multi Hall is more hydrodynamic or will move more quickly for the same amount of power has to do with understanding a little bit about the physics of drag now there are three major areas where drag will occur relative to the movement of a displacement type of hull through the water in all of these discussions we're not talking about this sort of skittering activity as a planing boat skidders off across the top but when a boat is pushing its way or floating through the water the first source of drag is skin the surface dragged obviously a smooth surface will travel more easily through the water than a rough surface and you can finish whether it's a single hull a multi monohull or a multi halter the same level of smoothness depending on how much work or money you want to spend and actually a monohull will have higher drag for a given amount of speed then a multihull again simply because of geometry when you divide the hull into multiple components you're going to reduce the volume more quickly than you do the area and so the drag will actually be higher with a multihull an easy way to visualize that is with say a canoe if you were to split up anew longitudinally and then cover the exposed surfaces with a piece of plywood if you load the structure that multihull canoe versus the monohull pre-cut canoe to the same amount of displacement you're obviously going to have more water in contact with the surface and the drag will increase the drag with with friction increases as a square of the velocity but it tends to be only dominant at the extreme low end of the speed scale couple three knots and it is the dominant form of drag but once you move above that point the two higher speeds two other components come into play that become more important one is due to potential energy when the boat moves through the water say one hull length to the next hull length in a unit of time it has to displace an amount of water equal to its its its weight or its mass and when that water is displaced because water doesn't compress it has to lift that water out of the hole that it is drilling through the water and elevate the water around it so the sea level or the lake actually has to elevate slightly in an area around the boat and so therefore you have to invest potential energy to lift that water out of the hole now that drag will increase linearly with velocity and that makes sense simply because in if you're moving twice as fast you have to move two masses of water out of the air at way in the same amount of time that you had to move one if you were moving half as quickly and that drag is going to be the same for the monopole and for the multi hull but the real dominant factor has to do with kinetic energy there is an equation that represents the amount of energy that you have to impart in something when you move it and that equation is one-half mass times the quantity velocity squared or one-half MV squared when you move the boat through the water obviously you have to not only lift the water out of the way but you've got to get it over there you've got to move it so you have to impart a velocity to it and the faster you have to move the water the more energy you need now when you move a given quantity of water out of the way the multihull will have to move the water less distance simply because it tends to be narrower and so this velocity of this this energy goes up very quickly because if you double the speed of the boat you double the mass that's the M if you double the speed of the boat the water has half as much time for any given shape to get out of the way and so therefore you double the velocity and you square it so doubling the speed of a boat through the water increases the amount of drag associated with one-half MV squared eight fold it cubes it and so that becomes the dominant factor and that's the real advantage of the multi hulls because the hulls are thinner now couple things about the shape of a hole because of the fact that you want that velocity to be as low as possible that's why you want the front end of a boat to be tapered unlike grandpa's pontoon boat with its blunt end by making it smoothly tapered and slowly tapered you give the water more time to get out of the way the velocity is less and that's important for any kind of a boat in addition and a little bit more subtle is the reason you taper the rear end of the boat is that when that water eventually flows into the void that's left behind the boat when it moves to its new position that water flowing into that area will actually cause a small amount of force in the direction of motion just like when you take a slippery pumpkin seed and you squeeze it between your fingers and it pops out laterally the same thing is happening with the rear end of the boat you're recovering some of that potential and some of that kinetic energy with the flow into this space and that is why a swordfish or a tuna fish or a boat tends to be tapered at the rear end so these things tend to define the shape of a boat now Multi hulls not only having the advantage of being easily modular or breaking them apart also have the advantage of being a little easier to construct because there's just a less smaller scale with everything that you build one of the things that I have discovered in building a number of boats by a number of different techniques is that a lot of the work can be spent on jigging and aligning and creating the fixtures that are going to build the boat and the other one is fabricating some of the precision components and so the design that I'm going to show you today is gonna allow you to produce a boat of extraordinarily high hydrodynamic efficiency but also incredibly easy to build at the same time and what we're gonna do is we're going to use two techniques one is called stressed plywood and the other one is called stitch and glue and by combining those techniques we can build a full-sized hull like the one that you're gonna see a little bit later in the video with a couple of guys with average carpentry skills and average tools in a long weekend now in order to design specifically the shape of the boat we're going to take advantage of the fact that there are a lot of similarities between air foils and hydrofoil and there is a very good website we'll put the description or put the link in the description below this video to airfoil tools it provides thousands of different types of air foils it gives you calculators and design programs that allow you to produce a variety of different types of air foils we're gonna use a symmetrical airfoil called an NACA or National Advisory Committee on aeronautics four digit airfoil now don't get intimidated by all the words in the letters it's actually very similar it's a symmetrical airfoil and so when they specify NACA air foils there will be four digits that follow them the first two of the four digits represent a non symmetrical airfoil and so in our case these digits are going to be zero and zero not and not we're not even going to pay attention to them the last two digits in the four digit designator are zero to 100% of with versus length so if you build an airfoil that's one-tenth as wide as it is long it'll be a in NACA zero zero one zero or ten percent we're going to be building a zero zero zero nine percent symmetrical NACA airfoil and take advantage of the plywood and the stitch and glue technique to build this thing very quickly now I'm going to open this up and kind of show you what's involved this system is going to take advantage of the fact that when you take monolithic pieces of plywood in this case we're just using a thin fiber board because it's inexpensive and easy to work with but in the case of building the boat you're going to use sheets of plywood to do this and we're going to take advantage of the fact that when you take sheets that are very homogeneous and you support them at a couple of points they will inherently bend to form what's called a fair curve in boat design fair means my fair lady pretty it also tends to mean no discontinuities and generally very smoothly changing curvatures which serendipitously tend to be hydrodynamic the water flows around them very F efficiently and the other part of the technique that we're going to use is called stitch and glue and what that originally was designed to do is to allow you to take pieces of plywood and connect them at one point to provide stability in sliding but allow them to hinge in order to allow them to form the smooth curves that we want to form so what I'm gonna do is I'm gonna put together a few parts here on the table and literally this design is so simple I'm going to build this boat in front of you in real time - the three or four minutes it takes between steps for the five minute epoxy to harden up alright this is about all we need to do the initial build now typically with the old stitching glue technique what would happen is you would take a couple of very identical panel panels that you've cut out of plywood and you would drill a series of holes on one end and literally use wire to stitch together the end in order to provide that security from movement this way and movement this way but allow hinging of the two panels away from each other to allow them to form the nice fair curves that we're going to produce nowadays we have a better technique available and that is to use very high strength fiberglass reinforced packing tape this tape has an extraordinary strength it's about 300 pounds of tear strength on this and there's enough stickiness that if we give enough surface to the wood we won't damage the wood when we take it off it's faster to put on and it will provide all the same advantages without having to do a bunch of drilling and then eventual removal of the wire so the first thing to do is to take the two panels that we're going to be working with here and make sure that we've not only cut them very symmetrically but we want to get the ends perfectly at the same point we don't want to have any kind of misalignment because that's gonna determine how successfully we get a very even symmetrical curve so when we've assumed we've gotten everything is about as perfect as we can then we're going to put the tape on and the tape in this case is overkill we're not going to be producing anything like the amount of force that a full sized boat would produce but this tape is sufficient that the model that we built that you'll see later was using the exact same tape applied the same way just more pieces of it and roughly I would say you can you really can't overdo the length if you look it up the sheer strength on the glue is 30 or 40 kilograms per centimeter of length so you're gonna exceed the strength of the plywood after you get a couple of inches or maybe five to ten centimeters on each side it's important when you put this on not only do you assure that you're putting it on symmetrically and these things are lined up but it's important to make sure that you squeeze the two parts together so you don't form a gap between the two panels as you're putting the tape on and the reason I'm going to put on three pieces on each end is because I want to totally seal the front of the boat there's a reason for that later I'll explain to you this really isn't necessary for additional strength once this has been taped turn this around and we keep the process on the stern of the boat okay now what we're gonna do is we're gonna set this thing laterally like this on top of another surface you want to get this pretty flat so if you're gonna use sawhorses or something to put this on you want to make sure that everything is pretty flat because if you're doing the construction of any kind of a boat if you have a nice solid predictable surface from which to work everything tends to line up a lot easier than if you just sort of put this down on a garage floor that's bumpy or your your surface isn't clean now what you're going to do is you're gonna take advantage of the fact that when you spread the hull like this you can see that you form something similar to the design that we're gonna eventually build and so in this particular design with a 9% thickness hull we're gonna move all the way back to about 40 to 45 I've got this little mark here at 43% of the way back and we're going to put a spreader in here that's going to produce approximately 8% not quite the maximum spread that we're going to want and we're going to place this spreader or otherwise called a bulkhead at two marks that we've placed on here to make sure that we don't put this in crooked like this and then once we have position this correctly it's kind of a nice idea to get a square something that you can use as a reference to make sure that your surfaces are plumb with the sides so we don't end up with a boat that tends to taper or taper once you've done that and you've lined this up in this position then you're going to need to secure this particular bulkhead at the forty three-percent point with a little bit of epoxy now ultimately what I'm doing is just a tack joint we don't need to put this in to provide a great deal of rigidity or our strength because we're just tacking this into a position ultimately later on when you're getting near the end of the construction you can reinforce these joints that we're creating here with additional epoxy and what's called a fill it joint where you take epoxy and you mix it with a thickener to provide additional strength to this zone but this is just simply to keep everything from sliding around and repositioning itself during the initial construction so it doesn't have to be neat and it doesn't have to be strong looks good and now let's give it about five minutes to stiffen up alright it's been about five minutes and this glue is it's gotten pretty solid so we're gonna go ahead and we're going to actually form the airfoil and then we're gonna do this is we're gonna take a dowel rod in this case this is a nine millimeter or 3/8 inch diameter dowel rod in the full-scale boat we ended up using a five centimeter or two inch diameter rod and it's convenient to use this because it slips nicely between the surfaces and so what we're gonna do you're going to put a little glue on this we're gonna place this into the bow of the boat and then using a clamp we're going to draw this in toward the bow and you can see what happens when I just do this with my finger this tends to have more curvature up front than this this almost looks symmetrical from bow to stern but if I put this dowel rod in here and I press it back watch what happens to the width here and the width here you see how the back end of the boat tends to narrow in over here a little ruler up here just to make it a little bit easier to see what's happening but you can see as I push this in what happens to the back end it narrows in like that and the front end tends to fatten up which is exactly what we need for the airfoil so what we're going to do is at this point here which represents 25% of the way back we're going to end up having to bring this out to approximately 11 centimeters but the point is it will be at the nine percent or the maximum thickness of the hull so once this gets to that point after compressing this we've basically created the hull shape this can get a little messy I'm not using gloves but I'll try to stay reasonably clean I just put a little bit bit of this on here this self mixing epoxy from the big-box stores this is Loctite tends to be very expensive per gram but it's so convenient with the self mixing that for this tacking operations is a good time saver we're gonna put this in here with the sticky sides toward the walls and then we're gonna Snug it in about as far as I can with my fingers and then we're gonna take the clamp I'm gonna place this on here and start drawing it in and you'll see what starts to happen here this will be a little hard to see on the camera but over time you're going to see that this is going to begin to broaden out and this is going to narrow in now in the big boat what I ended up doing is I ended up drilling three holes in here putting some threaded rods through the nose and with nuts was able to clamp this in because it's hard to get clamps that are you know this tall but it works fine then you just cut the rods off when you're done stainless steel now see what's happening here if you watch very carefully I'll try not to shake the boat you'll slowly see that it's getting narrower this is where the maximum load is also occurring at the ends so if something's gonna go pear-shaped it's gonna do it now now where am I in terms of width and I'm getting there about 10 centimeters right now yeah that's it as you can tell it's no longer that's perfectly symmetrical shape but we've drawn this in and we broaden this out now we're gonna give this about 10 minutes to dry and then once this is hard we'll go ahead and put in the bulkheads that will reinforce this shape and it's very important these are done just right see in just a bit it's been about another eight nine minutes and now what I'm going to do is relieve this clamp and hopefully if the epoxy sticks the dowel will stay where it's supposed to looks good now I'm going to confirm that nothing slipped in the meantime I have about 11 centimeters perfect and this is 25% of the way back from the bow the maximum thickness is 9% the length of the boat we have the form now one of the things that you'll notice obviously is that this is extremely weak and so it has to be reinforced and the way we're going to do that is we're going to use bulkheads what you do in this design which is kind of a little different than you might do in most votes is you usually design the boat you do the drawings and then you cut the wood to fit the drawings and then you fit the pieces together in this case what we're gonna do is we're gonna place the bulkheads pretty close to equally spaced in order to provide reinforcement but the important point here is we're going to provide reinforcement to maintain the shape of the hole that we have we don't want to rien it with these bulkheads so for example if I take this bulkhead right here and it's designed to go at a point that I marked here at about the same distance from this primary bulkhead as the width of the boat and each one of these individual pieces is going to be going into a space that has been measured and then cut it's important that if you make a mistake and you cut the the piece the wrong width so that it doesn't fit don't think I'd better just force it in because what's going to happen you'll redefine the shape so if your cut is not precise don't worry about it just fit the bulkhead in to where it just kisses the surface but does not distort the surface and change the shape of the boat again these are to maintain the shape not to define the shape and that's critical there's always a temptation to say well I marked it here I better put it there don't do that now the point with this is that once we've marked out these individual spaces we're then going to fix these bulkheads at these locations with some additional epoxy I've measured each one of these out to fit the location where they're supposed to go and once I place them in the right order then I'm going to adhere them with a little bit of epoxy make sure that I line them up so that everything is plumb with the sides of the boat and then once we've affixed these into the right position then what we're going to do is we're going to talk about the completion of the boat with the top surfaces and reinforcements ok now that this is hardened up what we're going to have to do is reinforce the bow and the stern because eventually we're going to want to take the tape off of here and we're going to run around this to a nice hydrodynamic shape and because we probably won't want a feather edge back here but we're going to want to cut this short so that we have a flat surface on which to mount hardware or like pintles force a rudder or an outboard engine we're going to want to fill the space here and here with a thickened mixture of epoxy I would recommend about a 50/50 mix by volume of wood flour and a very slow cure epoxy we're going to be potting in this case putting a volume of epoxy in and so you want to slow cure so that it doesn't build up so much internal heat that it damages the structure once that has hardened I want to just also mention actually to interrupt is that you notice that these are solid bulkheads you could for the ultimate lightweight structure actually place a hole in each one of these bulkheads that's about 50% of the outside dimension of the bulkhead to lower weight we elected not to do that because what we're essentially accomplishing here is we're building individual flotation cells so that if we get damaged the whole boat won't sink and we'll Titanic down to the bottom of the ocean so for a little additional weight and it's less work just keep the bulkheads solid at this point though what we're gonna have to do is we're going to have to decide how we're going to use the boat and part of the this the final finishing of the structure is going to involve covering this up with the top deck when we do that we're no longer going to be able to see the location of the bulkheads and so what you want to do is sort of cart before the horse we've built the boat now we want to draw the boat presumably you're building both hulls at the same time that'll help to ensure that whatever kind of variations you make in your original intention it's going to be similar between the hulls but nevertheless if it's not exactly according to the original design having the location of all the bulkheads available to you after the fact will allow you to know where you can cut through four hatches and where you can put Hardware before we go any further though I think it's going to be important for us to decide how we're going to use the boat and so that's what I'm going to show you next now let's assume that you're going to be putting fuel cells in this boat or you're going to be putting storage batteries in the boat or you want hatches that have a relatively strong insight so you can bang tools around inside of them this is the opportunity for you to draw and Mark a couple of extra pieces of plywood that you're going to use as doublers that you'll place into gaps in particular areas you'll put this down on the mark on the drawing so that you'll know where they are but you'll thicken up the floor because to keep this light the lower floor of this of this boat is quite thin and we want to distribute load so that we don't damage them as a battery is bumping around inside in addition to that we also want to think about where we're going to be putting Hardware for example if we're gonna put it cleat and we're gonna screw something down we may well not want to depend on the very thin material that's gonna form the top of the boat we may want to put additional material underneath to give some additional thickness so that screws have something to bite into again you want to think about how you're going to be building the boat that also brings up the whole idea of how we're going to actually connect the two hulls and there's a variety of options for doing that the simplest method would simply be to place a board across the two holes glue and screw it down and your but we lose the modularity there and so we probably want something that's going to be demountable now one option would be you could simply place a board across here a doubler underneath and a whole bunch of screws and take them off and put them on each time that you deploy it another method that you could use and it's a very neat method that was originally used by the Polynesians in their explorations across the Pacific for thousands of years and James Warren in his Tiki designs which are trans-pacific sailing craft used the same kind of design and it's pretty clever what they do is they take a element like this a wood channel that has been fabricated with a trough inside of it you could do this out of fiberglass or build this up from wood and you place it on the surface of the boat so it provides a support for a cross member like this and then what you do is using either a thickened piece of material inside to give it a little bit more strength or you could actually fabricate something where you bolt clips on here but a rod through this hole actually acts as a nice support and then what you do is you take a cross beam now this could be a piece of metal pipe it could be a piece of fiberglass or a wooden log piece of bamboo and you place it into the channel and then what you're gonna do is you're actually going to lash it down and the way to do that is you're gonna place a small piece of string here and we'll see if I can do this opposite I'm left-handed and we'll see if I can manage to do this anyway for the camera but you're gonna want to wrap a couple of wraps around here of the of the lashing and then once you've done that what you're going to do to give this some strength and some tightness is you'll pass the cord around here a few times to cause the entire circle to become tight here and when you do that it creates a very strong lashing and you'll do that on each side of the of the hull the advantage with this kind of design when you finish with this is that obviously you can take it off and you can put it on it's extremely strong because it distributes the load across a large area of the boat and it also retains a little bit of give and so what the hull to do and that's what made these boats so sea worthy is that the boats almost act like a vehicle with independent suspension as one hull rides over a wave the passengers in the middle don't feel all of the disturbances and the boat can sort of flow with the water and the irregularities in the surface it makes it tough it makes it more comfortable it's been around for a long time and it's extremely inexpensive one disadvantage of this technique as well as putting a board across here is what's called free board that's the distance between the deck that you eventually put it on the top of the boat and the level of the water when it's immersed and loaded and in this kind of an application unless you have a very tall hole you're gonna have a rather low free board and therefore you're more likely to get water on your feet and get spray depending on the weather and so what we elected to do is to use a technique where we actually created a bridge using pipes effectively what we did for the main sized boat is we used some schedule 42 and a half inch OD aluminum pipe it comes up to 7 meter 24 foot lengths and we had them professionally bent into curves so that what happened was we were able to support the boat or the deck arbitrarily high above the hulls so that we could keep the holes relatively small and light but we can get whatever free board we want it's inexpensive if it's extremely light its deployable we can take it off and put it on and in order to fabricate the support that we're gonna use for this I'll show you the trick that we used and it's kind of neat inside of the hull we anticipated that we're going to put it in this section here so we put a doubler here that's gonna represent produce a little bit more load capability of the thin material up here and then what we did is we took a bunch of pieces of plywood glued them together into a thicker component and then drilled partway through them so that when we insert this in here we have both a reinforcement for the floor is also also including a receiver for a larger diameter tube that the support can fit through so when we put the top on this boat like this and we insert the receiver into the cup down there we have an oversized hole to allow us a little bit of misalignment and freedom when we put this thing together so it's not too rigid and then we just fabricated a reinforcement ring that goes on the top here maintains a perfect position so this is plumb and also distributes the load with some screw holes around here to provide a very strong structure this not only ties the two surfaces together and produces again a very strong piece of material this prevents hogging that this thing would eventually do if it was constantly banging against the side when this thing is on the water and also because this is glued at the bottom here and glued around here this is waterproof so if water pours in here it doesn't fill the chamber inside of here so that's the method that we ended up using and I think it's probably the best because it is very flexible if you look over here in our test model we built a little cheaper version of this to allow us to play around with dimensions and you can see that it obviously prevents provides a lot of strength this way and it prevents a lot of strength from bending like this but it does not provide any resistance from scissoring because obviously these can rotate so finally on the final boat and as you can see in this model what we did is we simply mounted some cables with some clips and these screws that allow us to pull in the cable and essentially tighten up the hull in order to provide a structurally rigid structure to whatever level of amount of flexibility we want in addition if we didn't fabricate this thing perfectly by adjusting the tighten tightness on these two we can kind of take out any kind of errors we have in the structure so we get a nice square support for our deck this is this is excellent I'd highly recommend doing this because it worked out very well now this model that we tested on the lake is so efficient it was difficult to test it we found that when we were testing this for drag and alignment and buoyancy points we found that it was so-so hydrodynamic that every time the little tow cable would get a little tense behind the tow boat the boat would spring forward and ram into the back of the boat it just wouldn't run out of speed before it caught up to the it was it was incredible in addition it tracks very well even if we pull this at about a 45-degree angle to the angle that it's aiming it still continues to track straight forward so for sailing applications we don't need any additional keel or anything else to keep this thing a line that has to do with the fact that these are air foils they're hydrofoils and they want to go straight once you fabricated this you'll notice a couple things we don't use up the entire length and that has to do with the fact that unlike grandpa's pontoon boat these boats do not have a lot of buoyancy at their ends because obviously we've gotten a taper here and so even though this is extremely stable laterally it is not very stable longitudinally so one of the things that we decided to do when we built the final boat is that once this has been glued down the inside sealed the top has been glued down and everything is ready to be sort of fabricated to the final shape we only trimmed the Bott the top to form the shape of the hull the bottom we left hole we trimmed it and round it a little bit but basically the bottom in the back was left intact to act as a thin so that what happens is when the boat wants to do this tip you know when a wave hits it and it wants to go up like this by having the fin at the other end it changes the angle of attack on the fin and so instead of the boat going like this with waves it goes like this with waves and it becomes much more stable and it's easy to do because it's inherently part of the structure we don't have to add anything it actually saves work doesn't cost us any money and was a good modification to the simple holes that we used on the original test model the other thing you'll notice too is because the buoyancy still is somewhat limited at the ends the deck is limited somewhat to the center portion of the of the hull this helps to maintain balance even if people move around because they don't have the ability to move all the way to the bottom of the stern another thing to keep in mind too is that the balance point of your hull is going to depend on the shape of your hull for a reference on our hull it turns out that the center of buoyancy is approximately 40% of the way back from the bow as this becomes fatter and this becomes narrower it's obviously going to move forward and you'd have to accept with each one of the shapes or you could do a measurement of the area of the hull if you're if you're willing to go to the airfoil tool site and look at their calculators but for our purposes about 40% of the way back and so we centered our deck about that point so when people move around this thing shouldn't tip that much from a flat orientation in the water when it's floating next thing is the deck we want this thing to playable and we don't want to produce a permanent deck and we don't want things anything too big that you couldn't put it easily in the back of a truck or a trailer and so what we did is we fabricated these planks that have a longer upper edge than the bottom so that what can be done is these simply can be dropped between the bars the horizontals to form a deck that is lightweight in its individual components but is also arbitrarily wide and arbitrarily long depending on how this ends up being built so once you built all this you then cut these to fit now one of the limitations here is that these individual boards because they are individual are not working together they're just sort of laying next to each other and so if you got a big heavy guy bouncing around on the boat unless you build these things very strong they're gonna tend to do this so in the final model when we built the box structure what we ended up doing is allowing some of the verticals to be proud and some of the verticals to be recessed so that when the boat is put together and these things are hung on the front of the bars they key together like this they become a single entity and then when we put tie rods between here and tie rods between here we form a very rigid deck that's nice to walk around on without having to over build the structure that's about it for the design in here and so what I want to do now is I want to go outside and what we're going to do is we're going to cover some of the differences between this and the full scale so let's go outside and take a look at the real boat [Music] [Music] [Music] [Music] [Applause] [Music] all right this is the real thing this is four times the scale of the model that we showed you inside so its overall length is 16 feet or 5 meters its overall beam is 3 meters or 10 feet each of the hulls is half a meter high or 21 inches they're fabricated from quarter-inch Okuma plywood for the stressed component and 3/8 inch or 9 millimeter sapele which is a stiffer a little more expensive plywood for the deck and the floor the surfaces were sanded they were glassed and then each of them were covered is covered with two coats of a two-part polyurethane paint from inter luxe called perfection paint it's a very high gloss and very hard marine paint and the overall structure is extremely strong it's probably over built the weight of the boat are empty as it is right now is about 110 kilograms or about a 240 pounds so it's not that heavy as you can see these are the aluminum spreaders or load spreaders that we placed at the penetration point for the schedule 40 pipes that enter the hall into those receiving tubes that I showed you inside in addition to providing a load spreading up application or a load spreading service what they also do is they provide a hard point where we have placed some eyelets some little eye rings and then we take clips and we place them through holes in those pipes and can retain the pins down so this prevents the pipe from coming out depending on what kind of conditions you're sailing through in addition you can see here the cross cables that we put in order to resist the scissoring action of the structure they have quick disconnect pins over here and then turnbuckles it allow us to tighten them up and adjust them when we're on site because of the fact that we were we designed this and we put the drawings down before we closed everything up we knew where we could put penetrations through into the deck and so we put a hatch waterproof hatch that allows us to store items so we can put tools and extra line supplies and fall weather gear now if you look here you'll see a cross member which wasn't part of the design and I'll explain what this is used for but it's simply a square box channel of aluminum that's retained on some hard points that has applications we'll get into that in just a little bit but this isn't structurally necessary it's just added for future purposes the poles are identical here and they attach or support the deck which rides between the two poles here and is secured by these seven millimeter or 5/16 inch diameter stainless steel tie rods that extend all the way through at these two points laterally and then when we go around to the front you'll see that I have two similar tie rods that run longitudinally and these things apply force to lock the deck into a single monolithic structure which makes the whole boat a lot stiffer okay so as you can see here we have a cleat that we mounted on the front in order to be able to support line we added a couple of extra layers of plywood under the deck here to give the screws more purchase in order to give this some strength and it's something you might also want to think about if you're going to be using this boat as for in a sailing application having some additional plywood up here to support a forced day or other hardware that we're going to want to screw down to the deck think ahead now something else I didn't talk about in the model inside is that in order to retain the deck onto the pipes and keep it from riding up we have an aluminum sea channel that is squeezing the deck down onto the pipe and is pushed in and held secure by the two longitudinal tie rods that we have here on nuts that allow us to squeeze its mate against the pole from the other side so we can essentially force the deck into one unit and then is if you can see these little rings over here and over here where I have these temporary knobs this is simply to allow us to retract the sea channel from this structure because when the wood swells up and this gets really tight it can be difficult to remove so these are just a convenience factor now I think it's time that we talk about propulsion now originally we were going to use an outboard engine to power this and one of the considerations you have when you've got a boat with this type of design is that it has a very high freeboard it's almost it's almost a meter above the water and so it would be rather difficult to mount a typical outboard on top of the deck and have the shaft still in the water there's another problem that you have with this type of a boat with a rather limited deck and that is that a typical tiller steering type of outboard produces its ability to turn because it's creating a force or a lateral force at the rear of the boat so that allows you to to to maneuver but when the force is being applied near the buoyant center of buoyancy what happens is if you try to use a tiller in order to steer the boat what you're really doing is producing a lateral force kind of amidships and the whole thing is wanting to just slide sideways as opposed to turn so it wouldn't really be very practical to use a typical outboard and because of the fact that we wanted to experiment with different types of drive systems what we did is we went ahead and got what's called a mud motor or a Thai long tail swamp motor what's neat about these things is they're used all over Southeast Asia they're used in South America they use inexpensive typical for stroke to stroke outboard engines I mean internal combustion engines and then simply mount a very very long shaft onto the end of the engine to allow you to produce fairly lateral force by just slightly inclining the drive relative to the surface of the water so that eventually the water the propeller is in the water even though this is up on a transom the reason we decided to use this kind of a motor is because as long as we knew that we couldn't really steer with the motor itself and because this is a lot cheaper per horsepower than a regular outboard we thought we'd put this thing on that crossmember that I was talking to you about before that runs underneath the deck and just hinge it to allow it to drive the boat with a propeller located near the stern of the boat and then what we were going to do is to use a couple of rudders similar to what you would do on a sailboat and you would put these down on some pintles put them at the rear of the boat and then use an actuator to be able to steer the boat remotely and we elected to use electrical actuators similar to trim tab actuators that would allow us to drop the rudder onto the onto the pintles clip this onto the end of the the rudder and then just plug a 12-volt line into this to run it up to a joystick in order to be able to steer the boat by producing the force at the stern of the boat what that allows us to do is produce a much larger moment arm and give us a lot more maneuverability however we built this boat as a testbed for a variety of different types of propulsion systems both gasoline we were going to be using hybrid we might use a sail kite sail mast sail we might look at steam engines a Stirling engine and so with that in mind we thought maybe the most interesting way to start would be the electric drive electric outboard engines have become very popular however they are very very expensive and for this scale boat I would say torpedo is probably the most competitive model out there but still you're talking a couple of grand per motor and so what we decided to do instead is to use trolling motors now from my experience the very best trolling motor out there is made by MinnKota but it's also still pretty expensive and so what we decided to do is to get what I think is probably the best of the Chinese clones which is the new port trolling motor it's a 24 volt 86 pound static thrust motor on each side and the motor has a fiberglass shaft that would normally be attached to the controller and would obviously be very difficult for you to operate from this distance so what I did is I cut through carefully the fiberglass shaft and took a segment out so that I would have some bare wire to work with and connected the extended wires there are four of them into a very long much heavier gauge cable that then carries the control and the power all the way forward to the front of the boat where you saw the controlling end of this this outboard then place this on a claim that allows me to adjust this in height as well as rotation clamp this down and then placed it with a little hinge pin here that allows us to extract the motor from the boat when we're done using this or when we're getting ready to put this on the water in order to keep the motor in line what I've done is I fabricated a little tapered aluminum channel here that acts as a support as well as a fairing to provide much better hydrodynamic flow around here than the nasty flow you get around a circular structure inside of a water flow and then at the bottom as you can see we have a little pin that's been placed in this fairing and there is some sacrificial aluminum wire that we wrapped around the pin the purpose of this is that this wire is strong enough to resist the full reverse flow of the force of the motor but if we were to strike an item or a log or something on the bottom of the water this wire will snap and this thing can hinge up so that we don't damage the motor and we don't damage the boat it's also easy to remove and put this on we can just wrap that on in 30 seconds when we're on site now as you notice this doesn't look like you'd expect a normal trolling motor to look problem with trolling motors is that they're designed to keep very very heavy boats from moving or moves them at a very slow speed trolling motors and so in order to be able to move very quickly these things would have to rotate faster than the design of the of the motor and in order to be able to move faster than about five or six knots you can't use one of these propellers because basically at that speed the propeller is basically just keeping up with the speed of the boat no matter how light the boat it won't move any faster because you're just screwing through the water with the boat and it's a problem that some kayakers have found that when they take these rather powerful motors and lightweight batteries even a very light kayak begins to top out at around five to six knots because the propeller just simply can't keep up with a higher speed if you go online and try to find a coarser pitch trolling motor propeller you won't find them to begin with they're very poorly specified generally people say weedless or they say high-performance but they really don't give you a pitch typically the pitch is about two to three inches of of advance per rotation or you can figure out the metric equivalent and even though there are slight differences in performance and people swear by one kind of proper another but you really can't change the the overall ability to move fast through the water by staying with a trolling motor propeller so what we elected to do based on some success people have had with kayaks is go to an RC airplane propeller this is a master screw three bladed pusher propeller fifteen inch diameter seven inch pitch that's how it's specified it's in imperial so you have to do the conversion it only costs about sixteen dollars because it's pusher it allows it to rotate in the correct direction and produce thrust if you look into this you'll find that all gas propellers which would have been the other alternative need to go in the opposite direction and so that's a nice thing about these they come and pusher and tract or design in addition they have an extremely efficient a symmetrical airfoil which makes them very efficient in the water and if you decided that the only thing you want to take from this project is this idea and no matter how small or large or trolling motor I would get that particular propeller it's a glass glass fiber reinforced nylon it's waterproof and it's very tough and if your trolling motor is incapable of driving such a large propeller simply trim the diameter down so that you maintain the thick web and the three blades divide the load rather than getting some lightweight park flyer propeller that's gonna bend and twist under the load of driving them driving the boat this brings up the issue of power these motors are 24 volts and each one will draw about 1300 watts and so in order to be able to move this boat any kind of reasonable distance you're going to need two pretty good-sized deep cycle batteries per motor for batteries of that size are going to weigh as much as the entire boat and so thanks to Elon Musk we decided to do something a little different so here we have a single module from a Tesla s there are 16 of these in the the car and each one of these modules contains 444 of the 1 8 6 5 0 Panasonic sells a set up an array of 6 s 6 s meaning it's 24 volts which is convenient for our motors in addition to that it has the ability to be charged by a typical standard RC charger that can charge 6 s the system comes with a battery management system that normally plugs into the computer system for a Tesla you can tear that off and simply pigtail the seven leads necessary to be able to remote that and therefore you can use a standard battery monitor system that is used for RC applications allows you to measure the voltage of the battery when we're operating it in addition this can then be unplugged and put into a typical RC battery charger in order to be able to chart balanced charge the battery each one of the cells in here has been wired into the apparatus into the system with very tiny lead wires that actually act as simultaneously as fuses so if any one of these individual cells were to go haywire blowout it would not destroy the entire battery it would simply blow out its tiny little fuse and you would lose a tiny bit of the capacity of the battery but the battery itself would be completely usable in addition at this end of the battery we had to blow out and clean out and seal up the cooling tubes that run through here that in a normal Tesla would allow this battery to be cooled and warm to keep within a normal temperature range or an optimal temperature range for the very gentle use that we're going to be putting this battery to we're not concerned about heating during charging or discharging this battery can charge it can produce up to 1500 amps continuously at most we would draw a hundred out of it as you can see at this end of the battery we have these very heavy 6 gauge cables that are then attached to the two leads that come out one for each of the motors through waterproof fittings and the entire thing has been placed in a water proof cell so that we can see what's going on in here but water can't get inside the top surface has been gasketed down held down this entire structure is not light but it is remarkably powerful this single battery here costs about a thousand dollars on eBay and that might sound high but for good quality deep-cycle lead-acid batteries are gonna probably cost you about $600 in addition the capacity of this single module is 5.3 kilowatt hours for lead acid batteries would not even be able to produce that much power it would take six lead acid batteries to be able to produce the same amount of total usable capacity as this one module and this module weighs less than a single battery it also has more cycle life's life and because of its compact nature it allows us to mount this thing underneath the deck as I'll show you in just a bit but it makes it also easier for us to get this in and out rather than having to dump this into the hulls so let me show you how this gets fits together and we'll run this thing up so forward reverse and left and right and so we because we can control the thrust on these motors forward and back left and right we don't have to articulate these motors in order to turn which keeps the operation a lot simpler now anybody familiar with boat design might realize that the speed of this boat which is a displacement boat typically is limited by a property called hull speed and it has to do with the density of water and gravity and effectively it is the speed limit beyond which the hull no longer efficiently travels through the water because the water is simply unable to fill the void left behind the boat and it starts to produce a bow wave that creates a great deal of acceleration because the water simply doesn't have time to move around the hull in a steady laminar flow that speed is often designated by an equation which is in knots 1.34 times the square root of the waterline length and feet or 2.4 times the square root of the waterline in metres this is a 16-foot hull square root of 16 is 4 1.3 4 times 4 is about 5.4 knots so you might be wondering why do we want a propeller that allows a boat like this to be able to travel at 3 or 4 times the hull speed and I'm going to answer that question in just a second I'd like to make a little appeal a short time ago we decided to take this channel from a few hundred subscribers and several videos for laser enthusiasts to cover a much broader range of technologies and the variety of projects that we have been involved with over the years and in less than two years we've expanded to nearly 300,000 subscribers because of that success and because it's so much fun doing these projects and even more fun it's a blast to share what we've been doing with all of you we've decided to take the next step and go from a part-time weekend and evening activity to a full-time project and that kind of commitment is gonna mean that we're gonna get better video with skills involved we're gonna get better video equipment and more importantly we're gonna expand the content we're going to cover big projects like this as well as more frequent videos that cover smaller useful topics like how do you glass a hull or how do you steam Bend oak how do you resin infusion how do you vacuum bad when do you use Kevlar when you use graphite even if you don't want to build one of these big projects you might find some of those technical videos very useful and kind of interesting and to justify that kind of commitment on our part we need your help and I don't mean direct financial if you like what we're doing here give us a thumbs up and if you spend a few more seconds if you can give us a comment even if it's something as simple as hey I like the video or hope you can swim that triggers the YouTube algorithms to promote us or to place us on the recommended list which expands our exposure to a much wider audience and helps us to grow even more importantly if you share what we're doing either with other content creators on forums that you visit on Facebook and Instagram on gab on reddit family picnics PTA meetings even graffiti at your favorite train station just kidding you don't want to be default facing any property but that kind of support that kind of exposure will helpfully expand this channel to the point that we can target several million subscribers in return we'll continue to try to provide better content and more frequent content and before I leave you I'd like to answer the question that I posed before why do we have high-speed propellers on a boat that shouldn't be able to go more than three or four maybe five knots this is a hydrofoil you see why you might just want to subscribe thanks a lot for watching you have a wonderful afternoon and we'll see you soon [Music] you

Channel: Tech Ingredients

Views: 881,208

Rating: 4.9204283 out of 5

Keywords: Boat, Tesla, Boat build, Tesla battery, Elon Musk, Lithium ion, Catamaran, Sailboat, DIY, DIY Boat, Multi-hull, Stitch and glue construction, Mud motor, Swamp motor, Trolling motor, Displacement hull

Id: 6BMskpsLiYA

Length: 60min 31sec (3631 seconds)

Published: Fri Oct 11 2019

Reddit Comments

[u/DukeOfMarshall]

That guy's always doing some awesome stuff.

[u/davewasthere]

Great cliffhanger.

I've really been enjoying this channel the past few months. Some exceptional videos. Think it was his modified swamp cooler that got me hooked.