bottom contours for thruster/quad convertibles?

General Discussion
1

i've got a 6'0" x 19" squashtail lowish rocker shortboard that i'm working on. i plan on setting it up with 5 boxes for a quad/thruster convertible...

what kind of bottom contours will work with both setups? how does single to double straight off the tail sound?

2

I think it sounds fine. 19" is a nice width for getting a fair bit of planing area and housing a single concave for responsiveness, but not so wide that stability becomes a problem when it starts to get heavy and choppy/textured. IMHO those dimensions are in the it all works category. Double to single, double to single with the double set inside a single concave (this is a good one) and straight single will also be fine. If you can’t make up your mind between single to double or straight single then the way I would look at it is if the tail is wide then go for a single to double, otherwise the straight single. But there is the question of how wide is a wide tail.

I’ve tried to give an opinion based purely from a responsiveness vs stability point of view. I don’t actually know if one design or the other is suitable for quads.

3

thanks for the input Mr. J...

straight single sounds good too. this will be my 2nd attempt at bottom concaves so, the simpler the better...

my first attempt went horribly wrong. learned a lesson though: "don't operate power tools after being up for 30 hours."

my next 2 boards after that were flat... i feel like i'm ready to try again.

4

I built a step up thumbtail covertible for a friend last week, single concave w/FCS Fusions.

 

a bunch of build pics here-

http://www.808surfer.com/forum/viewtopic.php?f=7&t=1067&start=390#p29232

for me, a proper single concave is more difficult to pull off. not even sure if I’ve ever really nailed it

5

right on Bud... did it fade to flat or does the concave go right off the tail?

6

mild single running off the tail

7

Always impeccable work Bud. Do you find that all the boxes there ake the board tail heavy? Especially when you start putting fiberglass fins in? That’s my main complaint with five fin boxes. How does it compare, weight wise, to that green twin you posted up?

Hey Chris, over at the erBB there are a couple of threads about single to double concaves with pretty good info.