2016.09.29 - Not thinking Three-Dimensionally
There was a bit of a problem today. It started well as I rounded the lower edges of the cockpit coaming and then drilled a series of 26 holes in each cabin side using the template as a guide. However, when I screwed the cabin sides in place temporarily I found that I had made a bit of an error. The cabin sides need to slope in a bit and certainly with respect to the sloped side decks but in order to do this along the curved decks the front and back parts of the cabin side have to slope down more than they do right now otherwise they slope outwards. This 3D thing is very hard to visualise if you're not used to it.
After some consideration I decided to cut off the forward ends of the cabin sides and to fit them separately and fill the gap with epoxy.
Lots of photos of today's work and more explanations as usual.
The lower edge of both cockpit coamings now rounded off. There will be space behind these coamings so I'll be reaching in and out, hence the rounding.
Small piles of wood shavings where the holes have been drilled through the template and the cabin sides.
Having clambered in and out of the boat a few times I decided that since I have the correct bit in the router there was nothing stopping me from rounding off the rubbing strake. In fact, it was a very good idea as that square corner scrapes the skin.
Here you can just about see the curvature problem. The starboard cabin side is vertical...
But in order to do that, the forward part of the cabin side is now too low down.
Similarly on the port side. Here the cabin side is vertical but the forward part is too low...
But put the forward part in the correct place and now the cabin side slopes outward.
I can pull the sides of the main cabin in using the sash cramps like this but the front parts remain too low.
So I cut them off.
Now the front part can be put in at an angle.
It is easy to fit, the holes were already drilled.
And the remainder of the cabin side is also in place. You can see the gap. This will close up at the top when the tops of the two pieces are pulled inwards. The gap is too narrow to fit in a graving piece, I doubt that I could accurately cut a piece of plywood that thin so it will have to be thickened epoxy.
Both sides are refitted, the new cut clamped together and the tops of the cabin sides adjusted using sash cramps. Parallax makes the sides look wonky but they are upright or inward sloping. The final shape will be determined when the sides are screwed and epoxied in place before the epoxy has cured. I'll have battens all over the place pushing things around. Probably string as well, anything to pull the cabin side into the shape I want them until the epoxy is hard.
I'll not be able to set the correct slope on the deck batten either, it's too irregular to do a good job, or for me to do a good job. Looks like I'll be mixing up quite a lot of epoxy tomorrow!
You can't see it from the photo above but one thing that is encouraging is that the three sash cramps, which are resting on the top of the cabin sides, are all in a line to within about 1mm. You can sight along the top of the cramps from the bows and they all line up. This means that the cabins sides are parallel to each other, always a good thing.
One of the things I was certain of was the need to have the bottom of the cabin side parallel to the top and the holes for the port lights and stowage all parallel to both as well. You can see the line of screws rising up towards the front of the cabin and if everything followed this line the entire cabin would look like it sloped. Not good!