Making the Frame-Timbers for a Scow
Four types of frame-timbers are required for the frames plan of a scow: floor timbers, standing knees (also known as knees), carlings and futtocks (image 1). The floor timbers are the straight athwartships frame-timbers in the floor and which keep the flat bottom /floor parts together. The standing knees are the strong curved athwartships connections between the floor, bilge and side, that connect the flat bottom/floor with the skin parts. The carlings are placed on top of the standing knees in order to support the wash strakes. The futtocks are on the ends of the floor timbers and 'extend' the floor timbers; the futtocks connect the skin parts together. The frames or frame-timbers are the athwartships bracing of the boat. For a clinker-built boat, such as the mussel boat “Nieuwe Zorg” the frames are fitted after the skin has been formed.
- Before starting to make the frames the flat bottom / keel has to be laid first. It is important that the flat bottom / keel is straight and level.
- In the boat to be restored a basic template was made of the main rib. The main rib is the largest frame, which determines the beam of the boat. This template acts as the starting point for all frame-timbers in the boat. The template shows the extremity dimensions.
- To mark a frame-timber onto a plank of timber you place the template flat on the flat bottom / keel and slide it to the side up against the wash strake (image 2).
- In the fore and aft part of the boat the frames not only run in a curve upwards, they also taper in a slope towards the fore section or aft section (image 3). This is called the ‘bevel’. The frame-timbers are therefore marked off as a bevel, whereby the frames at the forward and aft sections have an increasing amount of bevel (image 4). To check: in the cross-section of a frame you would see a diamond shape.
- When marking from the template onto the timber it is important that the frame runs as much as possible with the grain of the timber (image 5). For a floor timber you can use a piece of timber with a straight continuous grain. For a standing knee you select a piece of timber which has a curve in the grain, where a branch has grown from the trunk (image 7). The grain has to run with the curve in the frame (image 6). If necessary, if there is a shortage of suitable rough material the bottom corner of the standing knee can be fitted with a different piece of timber (image 8). The greatest force on the standing knee is in the curved section of the timber, at the location of the bend (image 9).
- Before the floor timbers are fitted you cut a notch in the underside of the timber, which is known as a ‘limber hole’. The limber holes are located on the starboard and port sides of the boat and are intended for draining water that gets into the bilge. This water is pumped overboard using a pump. The holes run parallel with the bilge line at precisely the same position so that in the event of a blockage it is possible to push the debris through the holes.
Frame plan with frame-timbers: floor timbers, standing knees, carlings en futtocks
Basic template for frame-timbers
Bevel: difference between the fore and aft side of the frame-timbers
Standing knees have more bevel as they go forward
Positioning the basic template onto a thick plank
Grain runs with the bend
Thick plank from a trunk with a branch growing out of the side
If necessary: filler in the bottom corner of the standing knee
Greatest force on the standing knee is in the bend