Why My Plywood Joints Look Wrong
I explain why the plywood joints marked on my plans do not line up with the actual sheet edges, thanks to some unexpectedly non-standard sheet dimensions. The layout matters for both the beam-through joint and aligning the stern and bow sections of the hull.
You may be slightly confused when you look closer at these drawings - why your ply joints are not aligned with actual PLY JOINTS??
Well, let’s start from the beginning (it is apparently a very good place to start) - standards. And a standard sheet size for plywood is a bit strange 2440x1220 mm. It is stopping being strange when you use normal (meaning imperial ;) ) measurements (no judgement here- it was normal measurement for this standard to appear!). Suddenly you realise that these strange numbers mean 8 by 4 ft. And that’s pretty much standard measurement for sheet materials ANYWHERE in the world.
But to make things more complicated, my plywood was definitely bought in the UK, so theoretically it should adhere to a British standard sizes - which for plywood would be simple 8 by 4 ft. Or 2440x1220 mm. But no. My plywood was actually made in Greece and despite it being made for a British company and certified by yet another British institution (Lloyd’s) the bloody thing is actually made to “simplified” standard by someone thinking rounding the number (in decimal!) will be easier for customer :) (who obviously is an idiot unable to use a tape measure!)
Simplifying it went only one way- probably because width of the machine is much more complicated to change than the length of the piece cut by it.
So the length of the sheets I have is nice, round 2500mm (or much less round 8ft 2in and just over 1/3 of an inch!).
As I said, it went only one way - so they are not, as logic would suggest, 1.25m (or 1250mm) - which would keep proportion of the sheet. No, width of the machine is not easy to change, so they are still 1220mm wide 😂
So why do I bother marking ply joints from plans made for 8ft long sheets? Well, glad you asked! You see, one of these joints is supposed to land exactly in the middle of the beam through. So to keep this, I need to know where this particular ply joint comes. Yes, I could get it doubled and just laminate the joint but here comes another reason - my table fits only three out of five sheets. This ply joint allows me to align sheets from the stern to sheets from the bowpart of the hull.
#tiki38 #theseanation #buildingwharram #allelectricboat
