What is the BULBOUS BOW for?

have you noticed how a lot of ships have this strange protrusion at the forward end it's a big lump of metal sticking out below the water and we call it the bulbous bowel but it serves a specific purpose in this video I'm going to tell you what it is for and why they are fitted looking at these different pictures you can see the ships are all different sizes and just like the ship's the bulbous bowels are also all different sizes they're all designed specifically for the ship in which they are fitted and they're all designed to serve one main function to understand a bulb let's first consider this vessel which does not have a bulb fitted as it moves through the water a pressure wave builds up at the front of the ship this increases the height of the water the ship is pushing it ahead but that water has to go somewhere so what happens it flows back down the side of the hull it will keep flowing back down forming this wave all the way along the side of the hull now the problem with this is it increases the drag of the vessel it's in contact with a larger surface area of water it's coming higher up the hull the water is moving at an inconsistent speed because it's going up and down as well as along this increases the fuel consumption of the vessel we need to find a way to mitigate this wave we can model this wave mathematically on this graph I've plotted a curve of y equals sine X if we think back to mathematics we also know if we plot another curve that is 180 degrees out of phase with our initial curve and they will actually cancel each other out all you do is you add up each of the points along the curve and the resultant is this line straight through the middle if we could generate the same thing on a ship we would be able to mitigate that wave that's causing all that drag let's now return to our original ship diagram I've now taken her out of the water so you can see the shape of the hull underneath we on the bow area because that's the area we're interested in I can do a quick redesign and add a bulb and change the underwater shape this is going to affect the way the water moves around the hull if we think back to the original waveform I can overlay it here in blue this is the effect that the hull itself has on the water flowing around it but we've now got this additional bulb at the front so what I can do is I can overlay the waves generated by that bulb alone and I'm going to put them here in red now you'll notice that these two waves are out of phase with each other and what we went just went through with the maths we know that those waves can cancel each other out if they're out of phase the correct amount in this case they are and what that does is that flattens out the waterline along the full length of the hull it does mean you still get that slight up rise here at the bow but along the majority of the length the water is now flat this is reduced the drag and it's reduced the fuel consumption and this is the main reason for fitting a bulb if we remember back to the start of the video we saw the old bulbs are different they're designed specifically to produce that wave 180 degrees out of phase to reduce the fuel consumption on their designed vessel anything outside of the design parameters we're talking speed loading conditions hull size the bulb will no longer work and it would actually increase fuel consumption because it's an extra lump of metal that the ship is having to carry around if it doesn't produce that useful wave it's no longer any good and that brings us to the end of today's video hopefully you found the information useful until next time thank you for watching and good bye

Channel: Casual Navigation

Views: 4,699,586

Keywords: bulbous bow, what is a bulbous bow for?, bow of a boat, bulbous, nautical terms, sailing terms, front of a ship, bow wave, parts of s ship, bulbous nose, why do ships have a bulbous bow, bulbous bow explained, bulbous bow how it works, bulbous bow effect, ship bulbous bow, bulbous bow design

Id: 6FrCusDG41U

Length: 4min 8sec (248 seconds)

Published: Fri May 11 2018