Adjustable Fin System

Just in! Just got some -- 4 Way Fin System -- fins and round fin boxes. www.4wfs.com

The system allows several adjustments:

1 - allow you to move the fins forward or backward about 1/2 inch.

2 - adjust "toe in" (the angle the fin points towards the nose of the board (or not)).

3 - play with the "cant" or "splay" (angling the fins towards the rail a certain number of degrees).

I'm excited to get these in some boards and try them out!

Hey Matt, I'm really interested to see how they work. Be sure to give us a step-by-step on the install and also, please, on the adjust on the water.

OK - so finally got around to doing the install on these.

Here's some pics of the process...

Everything laid out


visualizing the layout...



Measuring some horiz lines for reference


tracing out the jigs -- they come with PSA (pressure sensitive adhesive) to stay in place, but outlining helps when laying them on the board

on the foam jigs you can remove the whole wax paper or just four little pieces around the circle. removing all the wax paper means you have to peel it ALL off later, so I decided just to remove the four little pieces around the circle.


placing them on the board -- (this is on a glassed, hotcoated, and gloss coated board)


Since I didn't want to spend another $60 on the official 4WFS jig - they said I could do it with a 2 1/8 hole saw. Just had to tape off at about 1 inch to make sure I didn't saw all the way through to the deck


i cut a small piece from an old plastic squeegee to reduce the length of the drill bit that would extend beyond the yellow hole saw itself to make sure that it didn't go through to the deck as well.... (in retrospect maybe I should have just bought the jig and router bit, etc...)

the work of the hole saw is done, now time to pop out the glass and router out the rest of the foam


the routering was a little nerve wracking without a jig to ensure i didn't go over the edge of the hole saw cuts... but with a lot of patient cuts and remaneuvering so I could see the router bit as it was cutting, i think they came out OK.


4Way Fin Systems recommend if doing this method that you use a nail or a dremel tool to remove about 1/16th inch of the foam under the glass about 1/4 inch from the edge of the cut to allow the resin to bond under the glass for strength. i also put an additional 6oz layer of S glass patches in the fin box area when lamming up the board.

holes are cut and ready. now reapply the foam jigs that now become 'resin catchers' -- (i'm glad i only removed the 4 little pieces before because if I hadn't they would have been a major pain to remove)

also have 4 more patches of fiberglass to go in the holes with the resin


making sure things are level


now, don't laugh -- ok laugh if you want, but because i didn't order the whole jig kit (which comes with specific weights that are quite expensive) i found that a small piece of PVC stringer material and a couple of cans of Campbell's chunky would suffice to make sure the boxes stay level and don't float up during the gelling process. (cheap level from Harbor Freight - i know)


resin gelled -- time to remove the foam jigs -- i cut into them a bit with a utility knife to make them easier to pull off...

peeling off the foam


ready to grind down the resin dams -- 40 grit sand paper on a fairly hard backing plate


getting close -- at this point i switched to 80 grit to not make any huge gouges into the fiberglass.


testing fit -- the blue circles are 0 degree cant. the yellows are 4 degree -- it looked like the fins came with about a 2degree cant in them. so in the yellow boxes they would be 6deg and in the blue at 2deg

the 4wfs key and screwing in the splay adjustment



the great thing about this system is the ability to adjust your toe-in on the fly on the water - just take out your allen key - turn the two screws a bit, twist the fin with your hand, screw back down tight and feel the difference. immediate feedback!!!


ready to ride - didn't bother to buff / polish yet, just wanted to get on the water...


(Message edited by smedman on April 09, 2008)

(Message edited by smedman on April 09, 2008)

got out on the water a little bit on monday.
it was really fast with the quad set up, but a bit tight on the carving... since time was limited i removed the back fins and just played a bit with the toe-in on the front fins.

in the few runs i had, with just the twin set up, I found that i liked them with more of a 0 degree splay (parallel to the stringer) rather than the farthest splay setting (which would probably be about 1/4 inch though I didn't measure. but i'll have to get back out and play around with different settings.

i also just got in the mail from 4WFS in Australia some brand new -fresh for 2008 - mini twinzer fins (i'll post up pics later) that i'm excited to test out hopefully this weekend...

great post Matt

Thanks