Building Logs

Setting Out The Plot Sheets

Posted by Paul

Today I set out the full size plot sheets so as to mark the CL (centre line), DWL (design waterline) and 1200 WL (waterline + 1200 mm) onto the bulkheads in preparation for standing the bulkheads on the strongback.

Before marking the lines on each bulkhead I had to first remove all the tab overhangs I left when jigsawing the panels out of the sheets. When cutting out the panels I worked on the theory that it is easier to take the excess off than to add filler later so I was conservative with my cutting, erring on the side of safety. It is relatively easy to re jigsaw the tab if too much is left on, but usually it is just a case of running a rasp (course file) over the tab until the panel is straight (as if no tab was ever there). To finish you can use sandpaper on a long block (get used to that there will be a lot of that later!!).


I layed out the plot sheets the night before and put weights (a drill, a hammer, etc) on each corner overnight to ensure the sheets didn’t roll up as they come to you rolled up like wallpaper.

I then layed them out on the 3mm chipboard that came as a protector sheet on top of each pallet of Duflex (it pays to never throw anything away, you never know when it will come in handy) and sticky taped them in position, using a small tab of tape first until it is all correctly aligned then I fully taped each join and also taped the edges so that nothing could catch on them and tear. I will be laying heavy panels on and off so it needs to be robust. To line up the sheets you have arrows printed. You can cut the edge of one sheet to make it easier to line up but you can see the arrow through the sheet easily enough. When all sheets are in place you have a full size plot of each panel you have cut out, now it is just a matter of placing each bulkhead on the sheet and marking in the lines (CL, DWL, WL1200). I placed the 3mm chipboard with plots attached onto Duflex sheets (13mm furniture that I will glue later) as a sturdier base.


You can scribe a mark from the sheet to the panel and then finish the mark across the edge using a square, then around onto the face on each side. As you mark each bulkhead from the plot sheet you can mark its twin (other hull) using the one you have just marked as a stencil rather than setting it out on the plot sheet (I found it easier) and you can clamp them together to make this job easier, but be careful with the first marks as any mistake on the original will also go across to the twin (I checked each one by placing the twin on the plot sheet and doing a quick check that the marks line up). As well as the line marks (CL, DWL, WL1200) I also marked the number of each bulkhead (starting with 0), an arrow toward the in board of the hull and also the word “front” (I know, I should have marked forward, or even fo’ard if I was being nautical!) on the forward face of each panel so that setting out is easier. Be careful when sliding panels on and off because corners can tear the sheets. You can repair by taping over the tear.


Once all the bulkheads are marked (I marked 8 today, there are 18 bulkheads, 9 in each hull plus the mdf temporary bulkheads but they are already marked when they are made) they will be ready to be stood. I will need to make legs for them to stand on, which I plan to make out of the 19mm x 70mm pine but to make them strong enough to hold the bulkheads without moving I plan to make “T” joins in them (2 lengths for each leg).

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