The SKA is slowly coming along and Im after some input as to the dimensions for a cedar kingplank for a deck that is being built out of ply. I realise the main issue here is to provide a strong enough point to attach the jib tack.
Im thinking 12 * 6 mm with some sort of reinforcement locally for the tack can anyone give me feedback both on the kingplank dimensions and how best to reinforce the tack points. I believe a sp[ectra line is taken down through a tube to the hull bottom om glass boats and am thinking how I can do something similar.
Finally,having never set eyes on a real life boat,nor sailed one, will 3 deck tack chainplates be enough or will I need more for fine tuning?
Thanks for the help! Attached is a pic showing the current thinking on framing, being 2 ply ringframes. Id happily ditch these and save a few grams if I can.
If you are using a plywood deck the king plank doesn’t need to be that robust. You could go a little smaller than 6x12 although it’s not going to gain you(or lose you) that much weight. I use 3mm bamboo skewers for a lot of stuff and one of them is tyeing the deck to the hull. Just glue a 12x12mm patch to the hull and drill a 3mm hole in it. Drill a 3mm hole in the kingplank and glue the skewer in. I would use a strip of your deck plywood to reinforce the bottom of the kingplank. Just where the attachments go through. If you have a single mast position you can just have 3 jib attachments. If you have more mast positions then it gets more complex. You have to measure out each combination and see where things end up. I don’t use any bulkheads at all. The compound curves of a hull are strong. Think monocoque (SP?) race cars. I do use diagonal struts from the chain plates to the bottom of the mast tube so you could leave the center bulkhead in. I might add a couple more lightening holes though. The actual sailing loads on these thing isn’t that high. The real loads happen in collisions or when you try to carry the boat though a door(don’t ask).