I have a great prone board but I want the tail to be narrower. Is it doable to cut a board into the desired (Kalama tail) shape and finish it. I don't need it to be pretty. If I sell my current and buy a new board I'd spend a fortune. Is this easy for a shaper and/or DIY

Not a thing..you'd have to relaminate such a large area you'd never get a great bond with the existing carbon. I feel like you'd have to skin the whole thing and start from scratch(which I just did - reusing a fancy $$$ blank)

I think the operative word here is "great" prone board. Once you change the shape, it may not be so great. But, sure, it's very doable if you have the tools and know how, and especially, if you really don't care if it all goes wrong. Most boards have a carbon layer with e-glass over the carbon to protect it from impact and sanding. The carbon is providing the stiffness and strength in the eggshell, so if the board is carbon, you need to repair with carbon similar to original for a large repair like re-shaping. Lap the carbon a good 2" onto the sanded laminate (wear a respirator) and then one or two 4 oz glass patches an additional 2" and you should be good to go. You can do both layers in one lamination with a 2 part epoxy made for that use. Then you can spread a cabosil and microballon paste filler for fairing after the lam has mostly cured. Then sand, paint and seal with a clear uv stable acylic finish. Read up on how to laminate so you don't get out gassing that bubbles under your repair. You may have to seal the foam with a cabosil and micro ballon fairing, but if you are using a slow cure epoxy and steady temperatures, you should be ok. If you want a clear finish with the carbon showing, then just sand the first lam reasonbly smooth without buring into the carbon and most of the glass, do a second epoxy coat and sand smooth without burning into any of the glass layers. And cleat coat.

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IanInca said..
I have a great prone board but I want the tail to be narrower. Is it doable to cut a board into the desired (Kalama tail) shape and finish it. I don't need it to be pretty. If I sell my current and buy a new board I'd spend a fortune. Is this easy for a shaper and/or DIY

It is definitely doable, no worries about the bond, it will hold.

If you have never shaped a board before, the shaping part may be quite tricky however. Just keeping things symmetrical and not too ugly will be harder than it seems, especially if you want curved surfaces. But easy for a shaper.
The Gong shaper learnt his craft this way when young: each night he would reshape slightly windsurfing boards of a racing team to tweak their performance.

But if you take your time ("measure twice, cut once"), has some experience repairing dings, use good tools and materials, and plan to do mostly straight cuts, it should be OK to DIY.

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colas said..

IanInca said..
I have a great prone board but I want the tail to be narrower. Is it doable to cut a board into the desired (Kalama tail) shape and finish it. I don't need it to be pretty. If I sell my current and buy a new board I'd spend a fortune. Is this easy for a shaper and/or DIY

It is definitely doable, no worries about the bond, it will hold.

If you have never shaped a board before, the shaping part may be quite tricky however. Just keeping things symmetrical and not too ugly will be harder than it seems, especially if you want curved surfaces. But easy for a shaper.
The Gong shaper learnt his craft this way when young: each night he would reshape slightly windsurfing boards of a racing team to tweak their performance.

But if you take your time ("measure twice, cut once"), has some experience repairing dings, use good tools and materials, and plan to do mostly straight cuts, it should be OK to DIY.

Actually Colas it's a gong board fsp construction ??

It's full sandwich then, so the board structural strength should help.

Hwy1North advice is quite good, will just add:
- use nitrile gloves, as they do not stick to tape. Having your gloves (latex, vinyl,...) stick to tape is hell.
- make a "scarf" at the edge of the board laminate to have a good surface to anchor the repair by overlapping on it
- you can also build a "step" under the edge of the repair by injecting/inserting some epoxy + miscrospheres + carbosil just under it to continue the scarf
- if you cut too much and want to re-build foam, I disintegrate EPS foam into beads by hand, and the just wetting then a bit with epoxy makes a ultralight filler. Or use foaming epoxy, or gorilla glue mixed with drops of water.
- I found it much easier to impregnate the cloth on a cardboard and then put it in place rather than put the cloth in place then wet it with resin
- covering the repair with airtight tape for curing will help avoid most bubble holes. Do not be afraid to tape directly over the resin (PVC tape, but any stretchable plastic tape will do), it will come off easily.
- filling the holes after curing is easy by drilling a bit to widen then, then use UV resins (Solarez, DuraRezn) + clear tape stretched tight on it + an UV lamp of the proper wavelength to fill the holes in seconds, without leaving time to the bubbles to find their way again through it.

Thanks Colas and others input, much appreciated! I'll do a before and after unless I make a complete mess of it.