Building the Eun Mara "Skerry"
Scarphing
I hadn't done any scarphing since my last boat (Grebe) a few years ago. At that time I joined the scarphed, but unshaped, planks together on the bench. However, as Eun Mara is much longer than Grebe, I decided to roughly shape each of the three planks needed to make the length, join them in-place on the boat, then mark the final shape with the joined planks laid out on the workshop floor.
The scarphs were planed 8cm back (9.5mm plywood) using a block plane. The glue lines help to achieve an even result. The surface was painted with slightly thinned epoxy.
(Both sides had been scarphed and dry-assembled sandwiched between two particle board strips - hence the screw holes.)
With epoxy still wet, the first plank was put into place. There is no epoxy on the keelson at this stage as only the plank join is being done. Hence the paper. (The building frame is effectively acting as a jig.)
The two end planks of the garboard planed and epoxied.
The centre part was also painted with thinned epoxy, and then a layer of thickened epoxy (Bote Cote's "High strength filler") was applied.
Then the joins were re-assembled between the particle board compression strips, with plenty of paper to prevent undesirable sticking.
(A note of caution. This clamping arrangement worked well on the garboard, where there is not much bend in the strake at the join. When I joined the planks for the third strake, where the curve was significant, I ended up with a slight kink at the join. The solution was simply to make the pads wider to force the two sides to follow a smooth curve.)
When the edge of the plank is bevelled the accuracy of the scarph becomes apparent through the glue lines. (There's a bit of optical illusion in this shot. The scarph angle really is 1:8, but the viewing angle, combined with the angle of the bevel, makes it appear too steep. Also, the plank is 7 ply, but the bevel only went down to the third layer.)
I was very happy with the one shown above. But less so with...
(Yuk!) It looks worse than it is. It's only 1/3 of a lamination out in a seven-ply plank, and so is structurally still OK. But I'll certainly be more careful next time!