Fitting a Strake
The strakes of a clinker-built mussel boat are made from broad, thick planks that are carefully hot-formed into the correct curvature before being fitted. The joint of the strake with the adjacent strake is determined with care. The strake has already been cut to the correct shape.
Proceed as follows to fit a strake:
- Before the preparations for fitting the strake are undertaken, the strake is once again placed in the precise correct location in order to verify whether the strake uniformly abuts the strake in line with it and the strake underneath it. If necessary you can place a saw between the strakes and then saw along them in order to achieve a good fit. Additional wood can be removed with care using a hand plane if required, so that the strake abuts the strake in line with it as well as the strake underneath it in the best possible way. Mark the position of the strake using a pencil and possibly fit a few temporary chocks to the strake below. Remove the strake for the next step.
- Before fitting the strake, coat the faces of the timber frames that will mate up with the strake using bitumen sealant (image 2). This ensures that the faces of the timber frame and the strake meet completely and that no moisture and dirt is able to penetrate between both parts. In this way you will prevent the timber from rotting where the parts meet. Apply the bitumen sealant using a sealant gun or palette knife if you are using a large tin of sealant. Smooth out the applied sealant using a filler knife so that the entire surface of the timber frame is covered with bitumen sealant (image 5). Coat all of the timber frames against which the strake will be fitted (image 6).
- Before fitting the strake, put a number of large gluing clamps and small planks of wood ready. The strake is now placed onto the chocks and then carefully moved into the correct position. You need at least two, preferably three people to do this. Clamp the strake to the timber frames using the gluing clamps. The outer foot should be on the side of the timber frame (image 1), the foot on the side of the clamping handle should be on the side of the strake. Before tightening the gluing clamps, slide a small plank of wood between the foot and the strake in order to prevent damage to the strake during clamping (indentations). It is best if two people work on placing the small plank of wood under the foot. Slightly tighten the gluing clamps such that the stake can still slide a little. Check the strake abuts the best it can and if necessary hit the plank with a hammer and small plank of wood or a wedge so that it ends up in the best position. Attention: because of the soft sealant it is possible that the strake starts 'floating' and can slide without being noticed! Only tighten the gluing clamps once the position of the strake is correct and only tighten them sufficiently to just keep the strake precisely in the correct position.
- The forward end of the strake, which has not been sawn to length and which therefore has a bit protruding, can be pulled towards the timber frame. Do that using a strong piece of rope and a stick. Tie the rope to the frame on the opposite side, make a loop around the end of the strake and secure the other end also to the frame on the opposite side. Now insert a strong stick through the loop and turn the loop until it gets tighter and tighter. The strake will now be pulled towards the frame. Once the strake is tight against the frame, secure the stick against the frame so that it cannot unwind.
- Using a drill, now drill a few large holes into the strake, above each other, aligned with the centre of the frame. Drill the holes until they are approximately halfway through the thickness of the strake. Later, these holes will be filled with a wooden plug. Now, using a longer and thinner drill, drill a smaller hole in the centre of the large holes until the drill enters a few centimetres into the frame (image 7) – this will depend on the length of the wire nails to be used.
- Using a hammer (image 9) hammer a wire nail into these holes (image 16), through the strake (image 8) and into the frame. The wire nails in this photograph have been forged by the boat builder himself, as has the hook in the photograph. The wire nails have been forged to match old nails (image 13). Once the wire nail has been hammered into the timber, with the head almost touching the strake, hammer the nail further into the timber using the correct size of punch (image 15). To prevent hitting your fingers with the hammer you can make a tool for holding the punch (image 10). In this case, the boat builder has made a tool using a piece of round steel wire into which the punch fits so that a helper can keep the punch securely in position without the impact of the hammer blows being transferred to the hands.
- If you want to secure a strake against another strake rather than against a timber frame then drill a hole about 2mm deep for the head and then drill a hole of appropriate diameter through both strakes and hammer through a copper rivet: a nail with a head of sufficient size (image 14). On the inside you slide on a tapered washer (roundel) and cut off the excess length of the rivet. Once the washer has been hammered into position, a small ball-peen hammer is used to hammer the copper until a head is formed, which secures the wash and, therefore, the rivet.
- Once the strake is fastened securely to all timber frames you saw off the forward-most protruding part and smooth the end using a wood shave (image 11).
- The strake is now fitted and ready for further finishing (image 12).
Bracket on the inside of the timber frame
Smooth the sealant on the face
Timber frames with sealant applied
Pre-drill hole for wire nail
Place punch into hole
Hammer wire nail into timber
Tool for holding the punch
Shave the edge of the strake smooth
The end result
Old wire nails
Rivet-shaped wire nails with roundel
Various punch sizes
Newly forged wire nails