Everyone in the team felt good that last night we were beginning to make parts for the actual boat, rather than just clearing and preparing our building space and doing preparations. We also now have behind us our first experience of using the MAS Epoxy resin and for some our first shot at using any version of this magic ingredient. What follows is a description of the process, which I hope will be useful beyond our own Skiff for Seil.
Procedure for laminating stems
The stems on the St Ayles Skiff involve fairly sharp bends and if the decision is taken to laminate them, rather than to cut them from solid timber, the strips must be very flexible.
Seil, in common with most teams, decided to laminate and we sourced some very clear Douglas Fir with a low enough moisture content to glue with epoxy. Most people will be familiar with the basic principles involved, but it may be helpful for us to record some points of detail from the process.
Machining the wood
To do this on a bandsaw would need a massive machine, as small domestic ones are no way up to the task and the blade will simply wander off. Using a commercial table saw gives perfect strips at the cost of quite a bit of wastage through the wider saw cut, but is clearly the way to go.
It’s essential to cut some test strips to prove that the results will take the curve without breaking. Watch the growth rings as you will find that the wood bends more happily along the grain. Our strips are just under 1/4 inch, meaning that we needed about forty to do the two inner and two outer pieces. These turned out just about right, taking the bends without complaint and showing no tendency to spring back once unclamped.
Before starting to cut John our expert thicknessed the planks to 2 3/16ths and trued the edges, to ensure that the finished pieces were uniform. This is worth doing as it greatly neatens the work later.
Mark the pieces, as you will want to reverse every second one, end to end and back to front, to equalise out any stresses in the wood.
Using a scrieve board
The traditional way to laminate a stem is to make a jig from solid timber to go round the inside of the curve and use large clamps to bring the strips in to it. This wastes a lot of time, as more effort goes into the jig than the actual work and only makes sense if several boats are being built.
We have a heavy chipboard base, painted white, on which the curve of the piece can be drawn from the pattern provided. Angle brackets are bolted to this, to which clamps will draw in the glued strips. It’s probably better to have the brackets along the inside, concave face of the pattern, as the clamps will be more effective, although some say this stresses the strips more during the process.
The board and the brackets must be protected from glue. It’s less messy to use plastic sheeting for this, rather than to cover everything with sticky tape, which will need to be removed later.
Sorting out the strips
Next the strips are selected, inspected, then double inverted as described above, then numbered and the gluing faces marked, for example A-A, B-B and so on, as it’s terribly easy during the excitement of the process to lose track.
Mark off a couple of inches at one end of each strip (the end that will be nearest to the floor) that will be kept clear of glue so that you can lift them. Also mark the outside faces of the end strips for no glue.
Stack the strips in order and drill a hole for a large nail to keep them in place.
If in any doubt try the whole thing out without glue.
Gluing the strips
Set the strips out in order on a level surface covered with plastic sheeting and give them a good drink of neat epoxy, followed by thickened stuff per the makers instructions. Our strips were quite dry and thirsty.
Once they’re all nice and sticky stack the strips on the nail and carry the bundle to the scrieve board.
Start clamping from the nail end, gently bringing the bundle together with a couple of clamps, then adding more as you work along the bundle. Protect the wood from the jaws of the clamps with little wooden pads.
Some strips may want to rise up from the board and must be pressed or battered down with a mallet.
Dispose of surplus plastic sheeting, gloves and any glue spills. Resist the temptation to poke the strips. Just go home and dream about the new stem cresting the waves.