Bottom

An open goal here – surely there is some ‘bottom’ joke to put in to liven up the blog? However, I think I’m too wrapped up in boat-building to think of one.

The bottom went on in two layers but, as with the sides, each layer was scarphed into a single piece before fitting. Probably not strictly necessary with the type of joints I am doing, but I offset them between the layers.

20141118_152506Joints being made on the CNC


20141118_162441One end or the other – probably aft


20141125_170504First bottom layer being glued up


20141125_170517Need some space to do it this way!


20141127_162333First layer in position above the hull. This is being held up with lines from the ceiling, using pulleys from a “Sheila Maid” scrounged from home.


20141128_141521The main weight is then taken by wooden props holding the bottom high enough so that we could pop up from inside the hull to apply glue to the floors and all around the centreboard cases.


20141128_141534In this shot you can clearly see the slots for the centreboard cases, which protrude through both layers. These proved very useful for locating the bottom in the right place


20141128_161733First layer nearly complete. It was held down by dozens of screws (as ever, all removed and filled afterwards).


20141202_142014Second layer ready to go on


20141202_142019Final preparations before second layer – glue rollers ready in the foreground.


20141202_164829All glued up. Again, mostly done with temporary screws, but with some clamping assistance. I had planned to vacuum bag it on, but I would have been using a sheet of polythene on the top only, relying on the first layer of ply to complete the vacuum. Unfortunately, a test showed that the ply is too porous to establish a decent vacuum, so to make it work I would have needed to seal the first layer from underneath – either with epoxy or polythene. The prospect of grovelling under the hull to do either did not appeal.


20141202_164839The second layer seemed to take gallons of glue. We coated both surfaces with unthickened epoxy first, then applied a generous amount of thickened to the installed layer. I thought it looked like too much glue at one point, but it proved to be just right – we had just enough squeeze-out (at the edges and the predrilled screwholes) to give confidence of a good join, but no more.

 


20141202_170657The completed bottom – just needs trimming now.

There was an article on the BBC website the other day about whether a bottom can constitute a work of art – well, I think I have proved the point! (Sorry – couldn’t resist it in the end.)

Topsides

20141118_142900As before when I’ve needed components larger than a single sheet, I have done these ‘lobed scarf’ joints.


20141118_152445With the sides, I decided to make each one up as a single piece. At first I thought this might be mad, but having calculated the weight, it seemed do-able.


20141118_162428Here are the sides gluing up using MDF cauls and curved bearers to spread the clamping pressure. Motivated by extreme laziness, they were both done simultaneously, to avoid setting the clamps twice.


20141119_152131First side going on.


20141119_152235Here is a shot of the forward apron during the dry run. When cutting the sides to shape, I had relied on Rhino (the CAD software I use) to convert the 3D part to a 2D shape, and then added an extra 50mm all round – or so I thought. Because the ply is somewhat tortured each end, I couldn’t treat the side as a developable surface and simply ask Rhino to unroll it – instead I had to use its ‘smash’ command. This is not a command I normally use, so you might have thought I would read the instructions. Perhaps if I had, I would have seen that this does not automatically result in a correct shape in all directions. In this case I lost the curvature at each end, so far from ending up with 50mm spare, I ended up with absolutely nothing at all! It was sheer dumb luck that it was not too short.


The second side followed without incident, though as with the first we had to get it very accurately placed to avoid running out of ply each end.