Hi, I’ve just been thinking how board weight effects botton contours.
For example could a heavier board be made to feel lighter by having more extream concaves?
Also Would be the effect of a single concave running right out of the tail?
I don't necessarily think that concaves of any type would make a board feel "lighter."
A lighter board feels more lively and responsive. I don't think that you could achieve the same feeling by putting concaves on a heavy board.
Yes it would cause more lift, but not necessaily give that same feeling. A single concave would give off lift in the tail, but too much of it could cause a board to feel tracky and lead to an assortment of other problems. I have surfed quite a few boards with single in the tail, and it seems like more tail rocker needs to be added when the depth of your single concave increases.
A heavier board is already at a speed deficit. Any concaves though will loosen it up, but also cut into trim speed. More concaves equals more cavitation. good for turns, bad for down the line speed. Depends on how you want to surf and kind of waves.
I was thinking for a small wave board but with extra weight to help in windy conditions which is so typical here.
I’m thinking a wide template thruster board a bit like Al’s ‘gravy’ template or the JS ‘king pin’, and from your comments flattening the entry rocker and increasing the tail rocker a little to run the single out of.
Is there any advantage or disadvantage of the water being directed towards the trailer fin with the single concave running right out of the tail. I’m imagining a ‘lifty light responsive’ feeling, but if the water is being directed to and exiting the tail would make the trailer fin more effective giving the board a stiffer feeling, slow the board down on down the line speed but make it more effective for pivoty re entry turns… am I on the right track or have I got things a bit wrong here?
I’m guessing again the fins size could be adjusted with bigger side fins and a smaller trailer.
Would this make the board, light in the tail, loose responsive, small wave board that would still go well in say off short windy conditions.
Thanks for your help guys:)
Okay. A couple of things...
Single concaves, especially ones that run the entire length of a board, are a no go for me in widy conditions. The chop on the wave face makes it feel bouncy, skippy, an overall it doesn't work well. I'd say that extra weight should not be an issue in small surf. go with a normal weight, maybe a deck patch for extra durability. As for the bottom contour, a wide board will work better with some vee in the tail. how wide is your tail? if it is wide, a single will be hard to get over on edge. the width combined with the stringer line being above the rail line makes rail to rail transitions very difficult. also, vee in the bottom will help to "cut" through the chop too. In the end, i'd probably go with flat under the front foot to vee out the tail. If you want to add slight double concave in your vee it would be good too.
As for the single concave question, i've surfed a few with the single. going ALL the way to the end of the tail. they have a lot of "pop" when you hit the lip, but on turns under the lip in the pocket, there is too much lift back there and it is hard to sink your tail when vertical. it would be slow in chop but fast in clean peeling waves. the fin setup(rails are big, center small) is a twinner that you described. it is looser than a thruster setup but more controlled than a twin.
Hey, that all makes good sense, the tail width I’m planning is around 15 1/2’’ going to round pin.
V with double concave sounds like a good formula, and I think that is the bottom contours of Al Merricks ‘gravy’ board.
I have seen some pretty wide fish boards with a single concave that starts early and runs through the board, I’m guessing this works because of the different way you surf a fish, much more skatey slidy and less rail to rail, so the difficulty of burring a rail is less of an issue??
So just to recap on the single concave out of the tail, best in clean waves, and moves when you can really get some weight onto the back foot, so not best for the type of board I’m planning.
I’m also sort of guessing with a single out of the tail, a narrower tail and thinner rails will also help getting on a rail easier