Im thinking about getting a fin box put in my 14 ACE flat water board. Thinking of puttting it in the centre of the board , getting the biggest fin i can find and putting it in. Im hoping this would aid in the stability of the board for downwinding , without creating to much drag. As it is its great for flat water , but id have real trouble staying on it in the ocean. So would it work?

see the thread over on standup zone about ventral fins:

www.standupzone.com/forum/index.php?topic=18881.0

I have ventrals in both my 17' Naish and 14' WoW downwinder. A Larry Allison in the Naish and a smaller house-brand in the WoW. I was going to put one in my DC Makaru but I sold that board before doing it.

IME they improve 1) tracking and 2) stability (ACE tracking probably doesn't need improving but stability...maybe). Fin placement and size/shape are pretty important for the idea to work in the way you want. Place it too far back and it acts as a pivot point, like a centre board on a windsurfer (you don't want this), too far forward and the board won't turn at all. The happy place seems to be to set the rear of the fin box around 18"-20" forward of the board's balance point, which for most folks corresponds to the most powerful phase of their stroke, most of the time. Long base, low aspect ratio fins seem to be the go and there is a relationship between the ventral fin and tail fin...too big ventral vs to small tail fin and the board tends to get really drifty and want to spin out on a decent runner (trust me on this point ).

Happy to send you some pics of what I've done if you like, and Larry (while hard to catch sometimes) is pretty good about taking time on the phone to explain all this stuff.

HumanCartoon said...
see the thread over on standup zone about ventral fins:

www.standupzone.com/forum/index.php?topic=18881.0

I have ventrals in both my 17' Naish and 14' WoW downwinder. A Larry Allison in the Naish and a smaller house-brand in the WoW. I was going to put one in my DC Makaru but I sold that board before doing it.

IME they improve 1) tracking and 2) stability (ACE tracking probably doesn't need improving but stability...maybe). Fin placement and size/shape are pretty important for the idea to work in the way you want. Place it too far back and it acts as a pivot point, like acentre brad on a windsurfer (you don't want this), too far forward and the board won't turn at all. The happy place seems to be back of the fin box around 18"-20" forward of the balance point, which for most folks corresponds to the most powerful phase of their stroke. Long base, low aspect ratio fins seem to be the go and there is a relationship between the ventral fin and tail fin...too big ventral vs to small tail fin and the board tends to get really drifty and want to spin out on a decent runner.

Happy to send you some pics of what I've done if you like, and Larry (while hard to catch sometimes) is pretty good about taking time on the phone to explain all this stuff.

Pics would be great thanks.

Teatrea your the same guy who took a chain saw to the DC a while back

Go for it mate

DavidJohn said...
Bad idea IMO

DJ

Why...

PTWoody said...

DavidJohn said...
Bad idea IMO

DJ

Yeah I wonder about messing with the subtle concave on the Ace. There's some magic ju-ju going on under there especially on the plane on a downwind run and I would be hesitant to dick around with it.

I could be wrong, but I think teatrea's board is an ACE PRO?

PTWoody said...


Yeah I wonder about messing with the subtle concave on the Ace. There's some magic ju-ju going on under there especially on the plane on a downwind run and I would be hesitant to dick around with it.

Good point. Most of the boards it's been done to have flat or slightly rounded bottoms (Fanatics, Barks, etc) and mine are up front of broad single concaves, quite different to the ACE. While I use the WoW for DW I tend to use the 17 in that configuration for flat water distance runs (DJ you'll have to give it a try some time).

But yeah...if we're talking ACE PRO I reckon it'd be a candidate for a ventral. If I wasn't so fat and slow I'd think about picking up a cheap old 14'Jav and doctoring it for sprints...

Really the man to talk to about all this is Larry Allison. He and his test pilots have done the hard yards on it and I'd respectfully suggest know way more about the pros and cons and ways to make it work than anyone here. Friend him on FB and book a skype call with him.

Im thinking of going the other way and for flat water either getting the smallest fin I can for my 14footer or removing it all together. I think a tiny fin is all that is needed if I was doing a 5k time trial or I was downwinding on the lake.

Do it and see what happens !

You'll not know if you don't give it a go!

laceys lane said...
while this board is fast, i didn't feel it really pick up any bumps in the creek mouth when i paddled there.

i'm not sure it would dw

Conclusion, silly idea

Teatree I used a very small fin 1m+ forward of the rudder in the k15 in the tuttle box and it worked a treat.

I also tried a nose fin and it worked better.

The thing about a nose fin is it makes the board track dead straight. When you want to turn stomp on the tail lift the nose and it turns easily get of the tail and hay presto it tracks dead straight again. Go figure.

Not my idea Yoda (Dean Snow) did this 3 years ago in his home made customs and it worked hands down.

have fun

laceys lane said...
while this board is fast, i didn't feel it really pick up any bumps in the creek mouth when i paddled there.

i'm not sure it would dw

Yeah Ace Pro is definitely not a DW board no matter what you do to improve lateral stability. It just doesn't have the rocker for starters.