WOOD SKEG for US box - process+pics


A friend of mine, called Nando, came to the conclussion that his flat is too clean, so he has been thinking of filling it with some foam or glass dust. Since he has no spare room for shaping a board and her wife would say “something” if he’d do it at the kitchen, I finally convice him about starting with a fin instead of builing a whole board.

Objective: US box wood skeg.

First of all: choose the outline, add the box foot and scale teh whole thing to fit a 250mm long USbox.

This is what Nando chose:

This is the result after I outlined and scaled it using CAD (240mm to fit into 250mm box):

This is what I sent to him for printing (he lives 150km from where I do):

That guy is a kind of “pain in the ass” and he thought a plain wood skeg would be too easy for a first experience. So he decided to buy some 1mm thick veneer sheets and build a “banzai sunrise” over it.

A 5mm thick pine sheet was chosen for the base and cut along the inner outline.

1mm thick sheets were cut and glued to the base with some kind of glue for wood (that white paste).

The result after veneer was glued.

The “hi-tech” tools: wood board, 10 sheets of glass, poly resin, pot, wax paper and a wood mould (320mmx240mmx10mm)

Skeg at in the mould after being glassed. Note the waxpaper at the bottom of the mould and over the mould edges. Note also the “Iguana Club VIP card” for squeegee.

Waxpaper+5 layers of glass with poly sanding resin+wood panel+5 layers of glass with poly sanding resin

Dude, that poly resin is quite clear!!!

Wait til tomorrow for mould release.

News fron Nando:

Top 5 glass layers seem to be “floated” out from the resin, since they are quite dry now (they were completely wet and covered with resin until reach de 10mm thick).

Since resin has set but it’s still tacky, I think it’s better to add NOW a new hotcoat.

BTW: “el canto guay”=“the edge [became] OK”

What the hell!:that resin is very clear!!

BTW2: This is Nando “que pasa neng!”, at CostaRica

Those “marcas” are from off-gassing due to the oils in the wood reacting with the polyester resin. Next time seal the fin with UV resin, just use a gloved hand or a brush.

Once sealed, the part can be laid up without any flaws.

Hope this helps,

You will have a lot better luck with epoxy resin on oily wood. If you choose to use epoxy for a sealer coat make a trial piece to make sure the polyester and epoxy a compatible. Polyester will not cure properly over some epoxy, System Three epoxy does not work well will polyester.

thanks heaps for this sequence on how to do the “sunburst” fins , Neira !!

…Most informative !!

…were you able to get rid of the dry spots / any shots of the finished fin , please ?

cheers mate !


the classic poly and wood problem… i would agree that the pre seal with uv can help a lot, but not 100% of the time… sometimes it happens after a few weeks… give the fin a good scrub down with acatone, pre seal, and good luck… it “never” happens with a good epoxy…

very nice fin anyhow, have you got to use it yet? how does it work?

I have made six wood core fins , all glassed with polyester resin . As long as I coated the wood with the resin BEFORE I glassed them , no problems !


It happens with epoxy too…

Even pre sealing it…

Resinous woods like cedar are un-predictable…

Live and Learn