How to measure inside hull contour for templates.

Capt. Clueless

Capt. Clueless

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Very soon I shall be starting to gut the insides of my Guy Thompson right back to square one so to speak, as much is rotten. Can anyone tell me , as to how I can make a template of the inside hull contour to cut the ply to shape please? I've done a search on here, but to no real avail, and you tube was extremely helpful, showing the templates already made!!:D Many thanks.
 
roughly cut hardboard to shape
offer up, then either scribe to fit or add masking tape near the edge of the hb then measure & mark on the tape + x inch`s / mm all along the template.
transfer hb to ply & transfer measurements to ply,join the marks & cut ply
 
Thin lathes of wood and hot melt glue was another suggestion I have seen.
You could do similar with hardboard and offcuts of hardboard and thin lathes.
We had marble kitchen worktops fitted, the fitter used some stuff thin corrugated (I believe) plastic sheet. If I was doing something like that I would want something that was relatively light, stiff and resilient that I could cut with a nice or strong scissors.

Stiff card would be another option. I have a pair of small tough electricians scissors that would probably be good for detail.
 
Make a joggle stick from a bit of batten. Put a point in one end. Find a bit a scrap ply or hardboard that vaguely fits the space you want to put the bulkhead and clamp the ply or hardboard in exactly the right postition. (I know it doesn't fit and there are gaps all round.). Now put the point of your joggle stick against all the key fitting points round the edge of where you want the new bulkhead to go and hold it flat against the ply/hardboard and draw round it on the ply. Number the points if you want but be methodical.

When you've finished clamp the plywood/hardboard to the sheet you want to cut your new bulkhead out of and carefully place the joggle stick inside each of the outlines and mark a dot on the workpiece with your pencil. Once you've finished remove the scrap bit of ply/hardboard and join up the dots If its a curve use a flexible batten.

Tips.

Practice makes perfect.
Don't try and fudge things. If the joggle stick says that's where it goes, then trust it.
Care and accuracy is everything but after one of two attempts you can get very good.
Make sure your joggle stick is the same way up every time!

Good luck.
 
It's called 'flagging off' or 'tick boarding'.

This video shows one way of doing it.

http://www.boat-building.org/learn-skills/index.php/en/wood/generating-the-shape-of-a-bulkhead-flagging-off/

In the video he's got an in situ bulkhead to hold his pattern, but you achieve the same thing with a roughly shaped piece of ply/hardboard and some braces to hold it in the exact position of the bulkhead you plan to make.

He also has a notch on the spiling stick, but I use a tick mark. In fact I often use two tick marks (A and B) so you can reach a greater variety of distances with the same stick. As long as you record which you used on the pattern it's fine. Some people use to lengths of sticks in fiddly corners, but again just record which one you used to make the marks.
 
Many thanks all. I now have somewhere to start instead of scratching my head and wondering how the best way would be. The work will start in earnest as soon as we get back from Thailand for our two week jollies. I've seen a floating dinghy for 20 quid on facebook. I reckon I'll get it and use it as a waste/materials carrier and tow it behind my tender.
 
Another vote for Joggle Stick/Tick Stick. Dead easy to do & your original vertical sheet need only be approx 25% of the bulkhead size. Quick, simple & economical.

I have 2, one largish for large area measurement & one small with very detailed joggell s to allow more accurate detail around complex areas.
 
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