Fin Blanks

Is G10 the stuff I am after? The stuff I found in the archives is not that comprehensive. Also does anyone know of a fin designing program?

dean, i am by no means an authority on this, but i can recall several instances of people here on sways using g10 for fins.


I bought a sheet of 1/4" thick G10 material recently. Haven’t used it yet, but it’s nice laminate. Well worth the $60+ dollars I spent on the 1’x3’ sheet. It’s pretty easy to find on the internet. If I saved the site on my other comp, I’ll post up the link where I bought mine.

hey dean

in the ‘quad fin ideas’ thread further down the page, probox larry mentioned the use of g10 for fins. his comment leads me to believe that this is not a good choice of material for fins, but does confirm that there are people doing so.


He mentions it being heavy, not that it won’t work for making fins.
Seems like that’s all Greg Griffin uses for his boards and people love

The sheet I bought doesn’t feel particularly heavy. As
soon as I get a chance, I’ll make a set of fins and weigh 'em against
other fins for comparison.

It’s an excellent material to make fins, the best IMO. No they are not light but heavy fins dont affect swing weight. G10 is the strongest non-carbon based plastic material money can buy. Warning: lots of dust, wear good lung protection.

What are you cutting it with, scroll, band, or jigsaw? How many teeth per inch?

Greg Griffin uses G10… check this:

btw, G10 is just fiberglass/epoxy but cured under (a lot) of heat and pressure. Not your typical room temp epoxy and E-glass cloth.

Cheap bandsaw with metal cutting blade. Teeth wear out fast but I just keep using it. Some guys r using jiggys with good expensive blades. Hands smell like plastic skunk that lasts.

There used to be a fin cad program but it never worked on my Mac so I never used it. Swansea university or something like that. yea, g10 is kinda sick stuff. It is heavy but not too bad. you can use marine ply too and after foiling put a few layers of glass too if you are really worried about weight. how many fins are you planning to cut? I cut about 6 bonzer fins on my scroll saw out of some g10 I had to use one wood blade pretty much per fin. If you can band saw with a metal blade is better and the best are the abrasive bands with grit. in terms of designing a fin, my advice is draw out a template you like on graph paper, and trace the outline onto the fin blank. the thickest part of the foil should be between 25% and 45% of the way back, I forget which gives more drive and which gives tighter turn radius. mark the thickest part of the foil near the base and start foiling. Counting the layers is key.

Thanks for the tip. Any suggestions on how many layers of glass to use?


I vaguely remember ProBox Larry saying somewhere around 30 layers or so of 6oz.

Did a quick search, read this post by blakestah, he says .01" per layer 6oz

on top of wood or in the g10? I think I used double six on both sides of my wood fins in order to preserve the foil then stick them on the board as you would normal fins and hotcoat after they have been glassed onto the board. In the g10 I would use a 1/4 in thick panel, however many layers that takes, I do not know, but I would guess in the 30-40 range, If you are making your own panel, George Greenough used to jack a car up onto of the panel to get a higher fiber to resin ratio.

I just rough foiled a pair of twin fin sized G10’s for an FCS setup. I weighed the fiberglass fins I used for the template post foiling and the G10’s came in at a whopping 1/2 oz. heavier. I think I can live with that!

Hi dean,

Just did a set of FCS tabbed fins, Hand layup of 35 layers of 5 OZ (all those offcuts that lay around the place) worked out perfect thickness.

Its alot of dusty itchy work. $30 for a set of plastics suddenly seems like a good deal.

Hope that helps

where do you buy the g10 sheets from? they seem to be used in pcb construction, but where would you get sheets of it from that arnt copper coated on one side?

Here’s where I got mine:

“George Greenough used to jack a car up onto of the panel to get a higher fiber to resin ratio.”

In the past, to make high pressure fin panels, I’ve layed up the panels, put a visqueen sheet over it, then a piece of plywood, then a hydraulic pump jack, then placed it under my garage door header and cut a 2x4 to span between the jack and the header…A few stokes of the 20 ton jack compress the glass/resin nicely…

cheers for the reply, i should have added that i am in New Zealand.

So what would you say that the material cost for one set of thruster fins is?around $10usd, if a 36" x 48" sheet that is 6mm thick is around $200usd.

I bought a 1x3 piece of 1/4" thick G10. It fits perfect in FCS, no filling or sanding to make it fit. I reckon the $70 I spent (after shipping) means I could net any number of fins that come out and still be ahead. I cut out two fins of four for a quad fish, and I’ve got enough for probably 10 more (just a guess) of the same size fins (front fins about the size of a smaller sized twinfin). So yeah, your guess of a 10 dollar thruster set is pretty good. Of course, you still have to cut and foil 'em, so factor the labor (of love?) cost into it!