I have a wood glass-on on my 10’ balsa, 10" base / 7" depth that I need to extend in depth and add some more rake as it releases too quickly on a high line, for obvious reasons. I don’t want to go the side-bite route as I save the multi-fin setups for my thrusters and fishes. Now, my question is: has anybody out there or is there a thread somewhere addressing this, that has increased the length/depth and rake of a wooden fin while glassed-on the board? My idea is to add an inch or so in depth and rake with a clear resin/glass extension, but need some practical advice on how to get started and of course some expert pointers from you guys that are smarter than me, before I screw something up. Thanks for any input.
How about making your extensions out of wood, sort of like a L shape, glass over them to seal them off, then glass them to the fins already on the board.
If you don’t like them, cut them off without damaging your glass ons…
hi moondog !
…are you able to instal a finbox into your board , or is it a chambered balsa ?
Because , ‘purism’ aside , it would be nice to be able to retain the original fin , with a base added [‘moulding fin bases’ thread] for certain waves , and also to be able to change over to other fins … eg : deeper , more raky , or more based fins for other conditions / days / waves.
…that’s just my .05 , anyway …
cheers ,
ben
I think Chip is on the right track. I can’t think of any way to extend your fin length without creating any weak areas in the fin that doesn’t involve surgery that would be just as radical as converting to a box system. Adding laminations to increase fin depth without a proportional increase in thickness seems very tricky, as does amputating part of the fin horizontally, drilling each section with at least 2 matching vertical borings to hold long reinforcing pins, then filling and fairing the “middle”, and those are the only techniques I can see. Are you really that philosophically opposed to sides (or a trailer closer to the tail - might that concept not work on a single, also?) on this board? I wonder if adding a horizontal plane of some sort near the tip would increase hold when you are tracking the lip? Similar to the “tunnel fin” concept without the tunnel? I can think of at least one reversible way to try that one, at least, and you could also provide for a pivot to adjust the horizontal angle.
-Samiam
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I think Chip is on the right track. I can't think of any way to extend your fin length without creating any weak areas in the fin that doesn't involve surgery that would be just as radical as converting to a box system. Adding laminations to increase fin depth without a proportional increase in thickness seems very tricky,...
If you were skilled with the angle grinder and at making fins…
you could grind the equivalent of 5 layers of 6 oz glass off each side. Then shape an extension, 5 layers too thin, and lam them together with about 5 layers of 6 ounce on each side, then finish sand and gloss it.
Of course, this is more work than installing a finbox and making a new fin from scratch, but what he doesn’t know won’t hurt him…there are still people out there that pull glass off boards to re-shape them…
moondog: i reckon it’s possible mate. what i’d do is build a 3/4" to 1" clear bead or ‘halo’ around the fin using rovings. it’d be fiddly, lots of little half-hour sticky resin sessions & itchy sanding, but definitely do-able.
“there are still people out there that pull glass off boards to re-shape them…”
ah yes …
thank god [or someone ] for the "lunatics’ , eh ?
“got to keep the loonies on the path”
[pink floyd 1973]
cheers ,
ben
Thanks for the reply oldy. That’s the idea I had. Don’t mind the work or tediousness. I think adding a 1" bead will accomplish what I want. The only waves I ride this board on are our Central Florida mushburgers up tp waste high. Over that and it’s the fish.
The most straight forward way to get the fin on the board that you want is to grind the old one off and glass a new one on.
If you want to make the one you have bigger you’ll have to grind either side of the fin down as Blakestah suggests. A good solution to getting the layers on nicely would be to just work the top 1/2 of the fin. So tape the bottom half off and grind several layers off the top half. Once you have the grinding work done tape a thin piece of plywood to one side of the fin extending beyond where you want the fin extension to go. Then take some plumbers putty and make a bed to set a piece of cardboard with a waxpaper skin on it that will fit around the tip of the fin. Then lay up on side of the extension with a sufficient number of layers to work with.
Once this goes off cut you fin outline turn the fin to the other side and laminate it with an identical number of layers. The rest is done with a careful touch and foiled to suit. A hot coat, fine - finish sanding and polishing will conclude the project. If it were mine I’d just grind the old on off, cause it’s always gonna look like a patch job no matter how careful you are.
No Worries, Rich
I’d go with the grind it off, make a new one, and glass it back on.
Quote:
Quote:I think Chip is on the right track. I can’t think of any way to extend your fin length without creating any weak areas in the fin that doesn’t involve surgery that would be just as radical as converting to a box system. Adding laminations to increase fin depth without a proportional increase in thickness seems very tricky,…
…Of course, this is more work than installing a finbox and making a new fin from scratch, but what he doesn’t know won’t hurt him…there are still people out there that pull glass off boards to re-shape them…
I’ve pulled glass off a production board to get a blank. To me, the grinding/fitting/fileting sounds more challenging. I remain skeptical that there won’t be a potential fracture line around the joint unless there is some structure added to distribute the flex forces, although I’ll defer to your experience on that one. I’d also be concerned about reference points/lines to make certain everything remains plumb. But it isn’t my time, so I say “gopher it!”
PS: I’m still curious about whether in theory a very small single fin trailer far to the rear would add some “lip trackability” without a tremendous penalty in maneuverability at other times. That’s one fin arrangement I don’t recall that I’ve ever seen…
-Samiam
The Fin
No room for a trailer there…