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bellyboard fins

Posted: Thu May 29, 2014 12:36 am
by flojo
Hi, I have an old kneeboard that I want to re-shape into a bellyboard. It has a quad fin set up and I intend to cannibalize parts to put two fins on the new bellyboard.
The front two fins are larger and are only foiled on the outside surfaces of the fins, the inside surface is flat. The rear fins are smaller and foiled on both sides.
I also notice that the toe in of the front fins is more severe than the toe in of the back fins. So I am looking for info on the better fin to use as a twin fin set up and also which toe in I should mimic when placing the new fins..any info would be appreciated

thanks, flojo

Re: bellyboard fins

Posted: Thu May 29, 2014 7:06 am
by bgreen
Flojo,

I'm hopeless at fin placement.

You might find this of some use: http://www.swaylocks.com/forums/twin-fi ... tance-rail

Bob

Re: bellyboard fins

Posted: Thu May 29, 2014 8:24 am
by rodndtube
Toe-In, Canting, distance from the rail, distance from the tail, type and size of fins... it is a lot more complicated than back in the good ol' 1940s and 1950s ;) In part, it depends upon bottom contour, tail width, and your style of surfriding. I do suggest you read up on the benefits and penalties of canted fins and having toe-in of various degrees. Like Bob, I am no expert on these things! But I do love my fins and figured out what works for me on my Austin designs!!!

A couple of quick references:
http://mypaipoboards.org/skegs/FinGuideByAustin.pdf
and
http://www.waveridersfingallery.com/

Re: bellyboard fins

Posted: Thu May 29, 2014 12:39 pm
by jbw4600
Here is what I use to determine toe in. FCS fin plugs come three different angles of cant (0, 5, 7). Probox fins boxes can be adjusted after installation to several angles. Swaylocks.com has several threads about toe in and cant. http://www.greenlightsurfsupply.com/sha ... quare.aspx Mark Richards says you need toe in and cant or the board will track too much. That is what I do. But am no expert. My first board had little cant or toe in and it does seem slower to initiate turns. http://www.surfscience.com/topics/surfi ... uper-twins

Re: bellyboard fins

Posted: Fri May 30, 2014 11:27 pm
by Poobah
If you haven't stripped off the glass yet, then you might try the Lazarus method. In this case it would involve cutting off about 10 inches of the nose with a circular saw, and then giving it a wood noseblock. Kneeboards usually have too much nose rocker for a bellyboard anyway. Minimal glass itch and fewer chemicals than a complete reshape. You can even do it without fiberglass. Glue on the noseblock with epoxy, and then seal it with epoxy after it's shaped. Maybe a little varnish after that.

Lazarus boards were someithing Mr. Mike and I collaborated on about six years ago. Mostly I did the heavy pontification, and Mr. Mike did everything else. There's some photos in the old forum. I still have the tail end of the Firewire. Cool board. Floats better than you might think. The tailblock was glued and sealed with epoxy. Some minimal glass was used to fix minor dings. Leash plug is in the right spot when you make a surfboard tail into a bellyboard.

http://rodndtube.com/paipo/forum/viewtopic.php?t=508

Re: bellyboard fins

Posted: Fri May 30, 2014 11:50 pm
by flojo
Poobah, that is a great idea!!!! Having stripped a lot of boards in my misspent youth, I wasn't looking forward to that part of it. thanks for the input on the nose rocker--I had no idea.

thanks!

flojo

Re: bellyboard fins

Posted: Sun Jun 01, 2014 6:54 am
by krusher74
One simple thing you can do is try prone riding that board with just the front fins, and then just the back fins in. Will give your brain food for though.