I managed another few hours work today to make up for the lack of work yesterday and I stood bulkheads 3 and 4 today. I will be away until Friday so I wanted to have bulkhead 4 stood today as it is the first of the traversing bulkheads and I wanted an idea of how far the bulkhead return stretched to the other hull. I was worried I may not have enough room to get between the 2 hulls but it worked out ok.
One of the methods I use to save time on attaching the legs to each bulkhead is that I have marked out a template on a sheet of 3mm packing mdf. On the sheet I have marked a centre line and a DWL line, WL1200 line and also a line at 2 meters or WL2000. This is the height that I had set up the bulkheads at DWL to on the first hull. So the bottom of the foot crossbeam on each leg is at the 2000mm line.
You may recall that I was in 2 minds about whether this was a good height for the hull as it seemed a little high, however the upside is you can easily get in and under the hull to get inside without too much trouble, the lower it is the harder it is to get inside, so in retrospect this outweighed the perceived disadvantage of the hull being higher up. So I have gone with the same height this time. The deciding factor was going to be the difficulty turning the hull and it turned out not to be too much of a problem so I have stuck with it, besides it saves me having to make any adjustments to the legs or the setup process.
With the template I have I place the bulkhead on the template and line up all of the lines marked then I set the legs on the 2 meter line and centred on the centre line and then I clamp the legs to the bulkhead, then I stand the bulkhead and clamp it to the strongback and start the measuring and plumbing process. I already know where the legs should be stood as I am using the same position they were in for the port hull (I still measure against BH0 to be sure). I then ensure the bulkhead is attached (still clamped at this stage) to the legs so that it sits at the right height using a tape measure, the DWL line and stringlines either side. I also check it is centred using the centre stringlines over and under the bulkhead.
Then I ensure the bulkhead is the same distance from the bulkhead behind (not twisted) and square to the WL1200 stringline and that all lines are level (centreline is level vertically and WL1200 line is level horizontally). The only plane left is to ensure the bulkhead is not leaning forward or back using a level against the face and then bracing the legs in the correct position to plumb it. If all of this lines up to another round of measuring and plumbing to ensure that nothing has moved (often correcting one plane or angle disturbs another) I then screw it all down before removing the clamps and then one final round of measuring and levelling and re adjusting where needed.
Now that I have got to bulkhead 4, the next bulkhead is the first of the MDF temps. These things are heavy and usually take a little longer to get into position. I should get this done on Friday and then get the rest done on the weekend. It took me about 40 hours work over 10 days to get them all stood last time. I think it will take about half that this time around.
One final note. I spent a lot of time trimming peel ply last time as I wanted to remove as little as needed each time thinking it would protect the panels from drips and save grinding and sanding time. But in the end I spent more time trimming peel ply than sanding drips so I have just opted to remove most of the peel ply in one go. Having done that Murphy’s Law would suggest I will get resin drips all over now!