So I have a 9.5" Rainbow Fin Co. Wingnut longrake single fin fiberglass with wood core that is warped. Its not just at the tip, its actually deviated to the left begining about half way down the fin. I can actually notice it when I’m surfing, especially when I knee paddle the board wants to turn to the right and its pretty annoying. Is there anything I can do to straighten the fin out? I already tried heating it up with boiling water and attempting to flatten it with no results. I’m thinking it might be a lost cause and I might need to get a new fin. I’d appreciate any suggestions.
Love the site by the way. It was a great resource when I built my first board last summer (a 5’ 6" keel fish). Lookin forward to my next shaping attempt soon. Thanks for the help
I have NO experience in this as it's never happened to me but I did buy a bunch of Rainbox flex fins some years ago and the uk distributor di warn me that they may be susceptable to warping...can't remember the reason he said it could happen but he did suggest it could be fixed by leaving the fin on a household radiator for a few days and it should return to it's original form - I guess it's sort of plastics memory???
You'll need to bend it past the vertical the same amount of degrees that it's currently warped at.
Stabilise the base where it's not warped and heat the section that is. Slowly bend it past vertical and support it in that position, let it cool release the support and it should retract to normal.
But as you said, wood and glass has a memory so it's a bit of hit and miss.
Hot cars, prolonged direct sunlight, and stuff to that nature can do it. Especially to a "flexy" type glass fin. Greg liddle advises his customers to avoid having his volan flex fins in a hot car for long periods of time on his website if i remember correctly. It makes sense. I think I remember hearing or reading that pe resin softens at 120 or 130 degrees F. could be wrong, and someone here probably has the answer. Maybe try the oven and clamp it into its original state once it is heated up. Can't hurt to try it. good luck with your problem
I've been using Greg's fins for years and years and yes they will warp if mistreated. They are also fixable. But wood core fins a lot of time are not, due to the disparity of materials. If the wood had any moisture, or growth rings oriented incorrectly could be a factor. One reason I'm not a wood fin fan. Plus when dinged they suck water.