aren’t traditional longboards and all traditional surfboards technically displacement hulls? i mean the idea behind them was to displace water, just like a boat with a displacement hull. thast where the bottom shape for surfboards during the 60’s and prior came from, right?
so although they dont work with flex and all of the things a liddle does, traditional longboards and most surfboards made during that era, stiff or flexy fin, were displacement hulls of some sort.
then brewer said its my turn and invented plaining hulls. no?
Every waterborne craft displaces some water up to a point. Even a 70,000 ton ship would at some point ( velocity) come up on a plane… in theory. ( in practice i doubt there exists a powerfull enough engine to bring a supertanker that normally draws 50-60ft of water up on a plane)
my 99.9999999% of the surfboards i know of are all really planing hulls - even my now beloved Liddle smoothie. The name ‘hull’ only describes a type of board. Like a Fish ain’t really a fish – it’s a name. with hulls however, cuz the up rails, round bottom can give it a boat-like look - i guess the name ‘hull’ stuck.
I’ve thought about that same thing–it’s interesting to look at boards with any belly at all and think about how they are, as you say, displacement hulls at least some of the time.
that is precisely why liddle refers to his boards as “modified displacement hulls”…modified to give it the flexy funk that makes it do what it does so well.
i guess a better way to define ‘displacment hull’ in truly nautical terms would be, a vessel that moves through the water on it’s own bouyancy, travelling through the water as efficiently as it can by knifeing through the water. At a stop for instance a small displacment hull boat would draw 3 ft of water, and at it’s top speed of say 10 kts, it still draws about 3ft of water (more actually, as she ‘squats’ down)
whereas a planning hull displaces water while it is stopped ( as most waterborn craft do), but is designed to become so inefficient at slicing through the water, that it eventually is lifted on top of the water. The speed at which it lifts up is relatively low compared to speed at which it normally operates. a small planing hull vessel my sit 3 ft deep while at stop, but as you move forward to say 10 kts, she has enough HP to keep pushing harder, and then the water ‘lifts’ it up to the surface. ( at which point you can actually come down on the hp again)
i’m using small boat in about the 30-40ft length range as an example. and i know many/most know this theory, but somehow it doesn’t get too well explained, adn it gets confused… den it gets heated.
It’s actually a real interesting thing to checkout - like in basic naval architecture book and all that.
Sr. Pato: i know you tried to warn me/us – i just cain’t leave this one alone!
aren’t traditional longboards and all traditional surfboards technically displacement hulls? i mean the idea behind them was to displace water, just like a boat with a displacement hull. thast where the bottom shape for surfboards during the 60’s and prior came from, right?
so although they dont work with flex and all of the things a liddle does, traditional longboards and most surfboards made during that era, stiff or flexy fin, were displacement hulls of some sort.
then brewer said its my turn and invented plaining hulls. no?
Kind of. . . . I have a 17 foot pintail which surfs at ‘displacement’ speeds some of the time. . . but most surfboards, even longboards, are planing most of the time. . . although they do still displace water when planing.
Here are two clips with some sub planing (displacement) surfing . . . the transition between planing and displacement speeds is hard to pick, there’s no abrupt change, the board accelerates onto the plane without fuss, and there is no great change in handling between sub planing and planing speeds.
No problem Jason, I just love the fact that these discussions exist. It really provides insight from different perspectives.
BTW- wait until you see what I picked up this past weekend. It’s another variation on the hull theme. The board is a late 60’s to early 70’s Weber, serial #0187. It looks like a combo between the Feather Fastback and an Anderson style hull with a slight “S” deck from tail to nose. There was some nasty damage to the nose where it lost some foam but the guy that repaired it did a pretty decent job, including replacing the pinstriping. This looks like one helluva fun board to ride. I’ll try to get some pics of it tonight and post them tomorrow.
Roy- Your video link didn’t work. Could you repost it?
Those two videos are uploading right now, which on solar powered dial up will take about 3 hours ( sorry I thought that they were already loaded)… . . I have a new ‘potato peeler’. . . . 350 Mg hosting, so expect to be bombarded with clips for a day or two as we troll through old footage. . .
here’s one that IS currently loaded… . . not displacement surfing though, just a mild Cuppa surfing, the tail end of a cyclone swell !
i think its also important to note that boats made to ride through the water don’t need as much energy to get them at a crusing speed and keep them there, where boats with planing hulls can go a lot faster on top of the water, but also use a lot more energy…i think…?..?
but even though all hulls may be displacement hulls, technically speaking, or in my mind, a cruise ship, or tug boat is a displacement hull. a speedboat or center console is a planing hull. they bounce and dont slice, even with their deep v noses.
and boards with belly feel completely different than boards with flat bottoms.
and im gonna leave it at that and let people who know more about it chime in.
but even though all hulls may be displacement hulls, technically speaking, or in my mind, a cruise ship, or tug boat is a displacement hull. a speedboat or center console is a planing hull. they bounce and dont slice, even with their deep v noses.
and boards with belly feel completely different than boards with flat bottoms.
and im gonna leave it at that and let people who know more about it chime in.
That’s true, and another classic way to get a displacement hull is to go long and narrow, or long, narrow, and heavy, with a pintail. . . . plenty of boats around doing that.
i think its also important to note that boats made to ride through the water don’t need as much energy to get them at a crusing speed and keep them there, where boats with planing hulls can go a lot faster on top of the water, but also use a lot more energy
It must be the angle of the image, because that looks a little like a MP Camel circa early 70’s profile too - i.e. a hump. I not that familar with the Weber or Anderson boards of the time.
Anyway, I hope you get some fun out of it. If its got a hump (or is humpish) it will be interesting to hear your comments on any difference in feel, which might be difficult if you don’t have anything to compare it too. Still I’d enjoy hearing about how it rides, if you do get it back in the water.
