I tried to contact a designer but no response. I would even buy a set of plans for reference but nothing modern seems available eg Blade or Viper era. I took some measurements from a Viper because I plan to use Viper sailplan and mast. Chainplate distance from main beam = 68 cm, main beam to rear beam 2m.
Questions
1. please critique my layup plan. Using 200 gm per m carbon cloth over Divinycell H80 overall, with 30g /m glass over that for a better finish. 0/90 deg orientation on th eoutside , -45/+45 inside of the hull.
Doubler of 200 g carbon starting 2m from tip of bow to 1m from transom 0/90deg orientation .
Deck doubler of 200g carbon starting 1.5m from bow tip to transom 0/90 deg orientation.
Local reinforcement of 200g /sq m cloth under beams and chainplate area -45/+45 deg oreintation. Local reinforcement of 300g/ kevlar under beams, chainplate and forestay anchor point to insulate metal from carbon and provide protection.
2. Should I have a sheer clamp to attach the deck? Timber? or Divinycell foam?
3. Bulkheads under Main Beam and Rear beam. Should I use plywood ( 10mm? ) or 200g carbon/H160 foam/carbon sandwich ?
4. Deck hardpoint under the beams - should I have 10mm plywood replacing the H80 foam or can I use H160 to replace the H80 foam?
5. Thinking of a 10mm diameter solid carbon extrusion covered in kevlar for a sidestay anchor instead of a 2,5mm stainless chainplate. More for the 'cool' factor but also to avoid crevice corrosion in the stainless steel. Worth the trouble for the cool points?
6. Broad centreboard like the Taipan or High Aspect ratio like the Viper? Asymetrical or sysmtrical foils?
7. Should there be a bulkhead at the chainplate position?
8. Do I need diagonal stringers between bulkheads as a hull stiffener and to give torsional strength?
Thanks in advance
6.
1. Wouldn't bother with the glass for wear, except maybe right down the keel say 50mm each side. Consider 45/45 inside and out for torsional stiffness. 200gsm carbon should be enough all-round although maybe consider some carbon unis from bridle to cb case along the inboard and outboard sheers (check out CST's new carbon flat bar pultrusions). You'll likely not need the extra layers of carbon. Don't forget to take the cb case opening to single skin, probably 3-5mm thick will be enough.
Depending how quickly you are doing the hull laminates, the epoxy filler screed can be laminated straight over before it cures. Less sanding (the most painful task in boat building) and a better (chemical) bond between the foam and skins.
You haven't mentioned the core thickness? This will ofcourse impact some answers.
2. Yes for sheer clamp, at the very least for locating the deck and controlling the glue while laminating the sheer. As said above, an "L" of carbon is probably the best, can kill two birds with one stone and avoid the sheer stiffener step above.
3. Use a sandwich laminate for framing. See the frames from my home build for what I consider a neat idea (ring frame with a diagonal brace of carbon unis in tension when on one hull). Think the photos are on the F16 website.
4. I prefer a resin soaked plywood and single skin laminate for hardpoints but only because I've never bothered to buy really dense foam for the small number of areas. Either should work in theory.
5. Plenty of ways to do chainplates. May I also suggest carbon plate (c-plate) as an option, but make it very thick.
6. High-ish aspect ratio cb. Buy some off the shelf if you've got the dollars, much easier to get right first time.
7. There should be a bulkhead at the forward or aft end of the cb case which should be close enough to the chainplate to provide enough support. If it is too far away then consider a ring frame that has plenty of depth at the chainplate, and thinner depth elsewhere. As said above, add a frame at the bridle too.
8. I'm not sure what you mean by diagonal stringers, but anyway, you shouldn't need any stringers. Firstly you are using a cored laminate which does the job that stringers typically do, and secondly with a 45/45 skin or two it won't need to be diagonal, you'll get plenty of torsional stiffness from the skins. Only reason you'd need a stringer is if you're core is very thin, and then only to cut the hull panel sizes down.
Just read the other responses and I agree with them too. Love that F22 chainplate, brother has something similar on 12' skiff, but it straddles a frame.
