Fitting a Frame
An important part of boatbuilding is fitting frames. Frames and floor timbers form the strength of the boat.
First we will look at the equipment that the shipwright uses for this and in the second part the operations are described step-by-step:
Tools and equipment required for fitting a frame:
The pencil is used to mark the correct position where the frame is to be fitted.
Drill with thin drill bit for pre-drilling.
Fitting bolt to hold the frame temporarily in position.
Drill with wider drill for drilling the correct sized holes.
The tape is wrapped around the drill bit to indicate the depth that should / can be drilled.
Sealant is applied between the hull and the frame to be fitted.
Gluing clamps and wedges or cotters
Both are used to clamp the frame against the hull when it is being secured.
Lump hammer, metal pins and punch
The punch is used to countersink the pins deep into the hull. Later the end of the pins will be hidden behind plugs.
Step-by-step operations for securing a frame into the correct position:
- Preparation: The frame is brought on board. Move the frame roughly into position. Where necessary use wedges to hold the frame in the correct position. Mark off the contours of the frame on the hull.
- Drill the fixing holes: After removing the frame a sufficient number of holes are drilled from the inside out. Fitting bolts will be placed in a number of these.
- On the outside the holes are reamed to create holes for the plugs that will hide the heads of the pins.
- The hull is coated with sealant at the location where the frame is to be fitted. The sealant prevents dampness getting between the frame and the hull.
- The frame is put back into position.
- Permanently fix the frame: After the frame is placed in its exact position the top of the frame is secured using a gluing clamp. Temporary fitting bolts are evenly fitted at three locations over the length of the frame which, together with the gluing clamp ensure that the frame remains exactly in position during fitting. The pre-drilled holes are reamed to the required diameter.
- The metal pins are hammered into the pre-drilled holes using a lump hammer and are driven in deeper using the punch. To make it easier to hammer in the pins they are coated in grease. The holes for the pins are drilled using a drill bit that is slightly thinner than the actual pin. For example: an 11.5 mm hole is drilled and 12 mm pins are hammered in. In this way the pins are tight and the joint is exceptionally strong.
- The pin is countersunk into the strake and now has to be finished off with a plug.
- A plug is inserted over the head of the pin.
- A chisel is used to chisel off the protruding part of the plug so that the plugs and the hull are level.
1. Fitting bolts
2. Pins already countersunk into the hull
3. Pin to be hammered into a drilled hole
4. Pins already covered by plugs