Graham_U wrote:With the Jez nob in place, it seems to be the "side swipe that does the damage, and the foam protection is unlikely to stop those hits, unless I fit it on the rails?
Unless you have a very
odd shaped mast, it just isn't possible for it to strike the rails whilst still plugged-in to the board. It will
strike the deck just above the rails, which can crack all the way down the rails as well as the decking. Depending upon the height of your boom, there's a very remote possibility of your boom clamp striking the rail. As a test, set up your rig as normal on the Techno, lay the rig down & see if the boom clears the nose/rails. If it doesn't, then use a boom bra when sailing.
The only sensible solution is to pad the area around the nose & the upper rails with foam, as Ian suggests. As dense a foam as poss (something like bedroll from a camping shop is good & inexpensive) to absorb an impact.
As for the repair - you're not worried about cosmetics, so dig out as much of the damaged skin as poss. A large hole is much easier to repair than a small one. Use a really sharp Stanley blade to leave a straight edge of skin a few inches back from the nose. Try to leave the foam core intact. Feather/bevel the edge of the skin.
Epoxy resin by itself has no great strength, but when applied to woven carbon fibre or even fibreglass, it produces enormous strength. I'd guess there were originally only one, max two, layers of glass around your nose. If you were to lay up 2 layers of carbon fibre interleaved with 2 layers of fiberglass, you'll probably never break it again, though it may crack at the join with the old skin. Better still would be Kevlar, but it's v. expensive & impossible to cut. Simply lay each layer of the top of the previous layer. Don't need to wait for each layer to cure.
If you want to make really strong join with the old skin, the rub down a strip about 1" wide along the edge of the existing skin, before
laying-up the cloth. Lay-up the cloth as described. When cured, rub down a 1" width of the new repair. Then lay down 2 layers of 2" wide glass or carbon fibre to span the join.
If you're worried about longevity, then you'll need to cover the repair - epoxy resin is sensitive to UV light & will become brittle over time. Acrylic car spray cans are good enough for what you want, but rub the repaired surface down with 120grit wet & dry first to give a good key for the paint, else it'll flake off.
Graham_U wrote:I think this could empact the sailing? I guess it starts to question if the Jez has any real purpose.
Jez's knobs do 2 things: They crush masts & rip mast tracks out. The forces involved during a catapult so low down on the mast are huge. A ripped out masttrack is a very serious repair - if possible at all. A crushed mast is very expensive to replace. But a multiply-damaged Techno nose has little intrinsic value & is relatively easy to repair.
Graham_U wrote:But then if I ever get good enought to sail with you guys, ...
Stop running yourself down. You are
good enough to sail with "us guys", & it would benefit you no end from the amount of help & assistance you'd get. NeilB is right - inland water, particularly Cotswold Water Park, is gusty as hell. And you know what happens in really gusty conditions? You tend to get catapulted a lot
It's an ill wind that never blows at all.