Hi
I have just spent the last few days reading some of the topics on constructing methods and glassfiber, now I would like to pass
on a method of constructing complex shapes for one off builds.
I have used the method described to make outboard motor casings and boat hulls that you would normally need a split mould for
I.E a boat hull with tumble home.
What you need.
Building board (mdf or ply) Stiff card board or foamboard old newspaper Finishing plaster ( the stuff you plaster walls with) Glass cloth NOT CSM, resin & Hardener.
1) We need to make External Templates:...... Take a piece of card/foamboard about 6" longer and wider than half hull plan,at deck
level and transfer the shape from your plan to the card and cut it out, KEEP the outside bit this is your template.
2) You now need to make external frame templates as above I find about 4 frame sections is adequate 1 been the transom the other 3 divided over the hull length.
3) You need to mark a C/L and the positions of the frame templates on your building board, using the hull template and working off the C/L you can mark the shape of the hull onto your building board.
CONSTRUCTION
1) Take a bucket of water and put some torn up newspaper in to soak after a couple of minutes remove from water and wring it out, screw it up and place it on your board carry on doing this until you have a rough hull shape approx 1~1/2" smaller than the finished hull size all around, use your frame templates to gauge the shape.
2) mix up some plaster and start to build up your mould it is best to use several layers for this and if the weather is hot you shroud
flick or spray water on to the plaster to prevent it from cracking, use your frame templates and build the plaster up until it is
slightly larger than your template.
3) Leave it to dry for a couple of days at this stage it Will look a bit rough but don't worry, To finish your mould use a razor plane, rasp and coarse sand paper to give a smooth finish.
If you have any dips just mix and add some more plaster, I know the above method may sound complicated and difficult but with a bit of practice it is very easy and the plaster is nice to work with.
4) I use woven glass cloth cut into strips to make the hull with the cloth weight is approx 130 gm you can lay the strip along the
hull mould or my preferred method is diagonally across the mould Butt the cloth together do not overlap it as this will leave bumps.
When you have finished the first layer you place the second layer approx 45 degrees to the first, I normally use 3 to 4 layers on a hull length 30 to 40".
When dry you simply remove the paper and break out the plaster from inside the finished hull you can then use a stiff brush and water to clean the inside with.
I hope this method is some use to you.
Regards
Bob
