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Traditional Maritime Skills :: Making Frame-Timbers for a Smack

Making Frame-Timbers for a Smack

Introduction

It is often necessary to replace the frame-timbers of a boat if the boat to be restored is in a very poor condition. This was the case with the smack ‘Vabel’. The collapsed boat was first returned to shape using heavy tensioning bars. The keel was then replaced and the first seven strakes from the keel upwards were replaced. These strakes were secured temporarily to the old frame-timbers using screws. Now that the bottom of the boat, the bilges, provided the hull with sufficient stiffening the bad frame-timbers could be replaced one by one.

Replacing the frame-timbers, the ribs of the boat, starts with the floor timbers, which are also known as the beams. These are the transverse frame-timbers that are fitted in the bilge. The knees are then made and fitted, followed by the futtocks.

Procedure

For marking, cutting to size, finishing and fitting the frame-timbers the pieces of timber required have to be lifted many times between the boat and the workbench. This is a strenuous job so it is a good idea to have several people ready to help with this. Proceed as follows:

  • Firstly, make a template of the floor timber that you want to replace (image 1). Never use the old floor timber as reference because this can be too deformed. Only use the old floor timber for determining the correct length of the template. To do this, screw a sheet of plywood against the old floor timber and mark the length onto the plywood sheet. Determine the correct curvature for the template on the basis of the strakes and the height on the basis of the adjacent frame-timbers (image 2). Saw out the plywood template and plane the template to fit using the hand plane.

  • Now find the correct piece of timber for making this floor timber. To do this, place the template onto one of the thick, large planks that have been pre-selected for the frame-timbers (image 3). Make sure that this piece of timber has the correct curvature and sufficient length. Make sure there are no large knots or splits in the area of the timber that you want to use. Make sure there is no sapwood in the piece of timber under the template. If necessary choose a more appropriate piece of timber.

  • Place the selected piece of timber onto the workbench and transfer the shape of the template onto the plank. The piece of timber can now be rough sawn to size using the band saw (image 4). The band saw should always be operated by two people. Cut off the first surplus pieces of timber so that it is easier to handle the timber. Now saw out the required shape carefully, oversized by approximately 2mm. Make sure that you always saw outside of the template shape so that there is no timber shortage. The surplus timber is removed by planing until the floor timber has the precise and correct shape.

  • Now place the rough sawn floor timber on the surface planing table. The surface planing table should also always be operated by two people. Level the raised edges of the floor timber using the surface planing table. This is done by passing the floor timber over the surface planing table a number of times.

  • On the bottom of the floor timber saw out a notch for the keel (image 5). On each side of the keel notch also saw out a limber hole. This serves to drain water collected in the bilges to the pumps. The floor timber is now ready to be fitted ‘in situ’. To do this the old, bad floor timber has to be removed first.

  • Remove the old floor timber by first removing the screws that are currently holding the new strakes temporarily in position. Using a crowbar and a heavy mallet the old floor timber can now be carefully loosened. Take into account that the floor timber can be well attached. For this reason, carefully tap a number of wooden wedges into the space created by the crowbar. Do not force anything otherwise the new timber strakes may become damaged. The new floor timber can be placed into position once the old floor timber has been removed (image 7).

  • When the new floor timber is in position you can mark off the bottom of the floor timber. To do this clamp the floor timber into the correct position first. Do this by placing two small timber blocks against the floor timber and screwing these securely to the bottom strakes (image 8). Now take a block of wood and a pencil and mark off the entire length of the floor timber on both sides of the floor timber. It is necessary to mark off both sides because the floor timber can be ‘warped’, in other words it may have a twist. Now remove the floor timber again and take it to the workbench.

  • The bottom of the floor timber can now be planed into the correct shape. To do this, clearly draw a flowing line on both sides of the floor timber along the pencil line that was marked off ‘in situ’ using the wooden block and pencil. Now plane the bottom of the floor timber using the electric plane until you are precisely on both pencil lines. Now check that the floor timber fits perfectly into the boat. Attention: do not mix up ‘starboard’ and ‘port’!

  • The top of the floor timber can now be made to fit. You do this using a marking gauge. This is a hand tool whereby two pieces of wood containing a pin can slide in respect of each other. This allows you to mark and transfer a specific distance between two points. Set the marking gauge to the correct distance. Now guide the marking gauge along the bottom of the floor timber and scratch a line at the required height. Do this on both sides of the floor timber. Make the scratch line clearer using a pencil. Saw the top of the floor timber to fit using a band saw.

  • The top corners of the floor timber can now be rounded off (image 6) (depending on the construction method of the boat the floor timbers are cut off straight or rounded off using a plane). To do this place the floor timber on its side and secure it to the workbench using a gluing clamp. Use something rounded (for example a dish or a cup) to draw a radius on the two top corners of the floor timber. Use an electric plane to remove the excess timber. Finish off the top and the rounded corners of the floor timber using a hand plane and smooth the timber. This is best done using a belt sander but can also be done by hand using a sanding block.

  • Before the floor timber can be fitted a countersunk square (image 9) first has to be created in the top centre, into which the thick bolt will drop that fastens the floor timber to the keel. To do this, place the floor timber back into position in the boat. Draw a square the size of the iron washer, through which the bolt drops, precisely in the centre of the floor timber. Use a hammer and chisel to chisel out the square in the floor timber, approximately 1 cm deep.

  • The floor timber is now almost ready for fitting. Draw the lines of the floor timber onto the inside of the strakes using a pencil. Place the floor timber to one side again. Drill two holes per strake from the inside to the outside, perpendicular to the strake. Offset the two holes from each other and make sure that the holes are always at a distance of a few centimetres from the edge of the floor timber.

  • On the outside of the strakes make the holes wider to a depth of half of the strake depth. This is done by countersinking the holes with a countersinking drill (image 10). Attention: do not drill too deep; sufficient timber must remain to be able to fasten the strake to the frame-timbers securely using screws. Only drill to a depth that allows the head of the screw to be fully countersunk into the timber and covered by a 0.5 to 1 cm deep wood plug. The countersunk holes will be filled with wooden plugs later.

  • The floor timber can now be fitted. The easiest way of doing this is with several people helping to hold and screw the floor timber into position. Coat the bottom of the floor timber first with an anti-wood rot treatment and then place the floor timber precisely into position. Gently fix the ends of the floor timber using two screws then use a (battery-powered) drill with bit holder to screw in all of the screws (but do not run them up tightly yet).

  • Now tighten the bolt that connects the keel with the floor timber.

  • Finally, tighten the screws that fasten the strakes to the floor timber. Start from the centre, from the keel, and work from the inside to the outside, alternating on both sides of the boat.

  • The finishing touch is to fill the countersunk holes with wooden plugs, which are then sanded flat so that the outside is completely smooth.
 
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Tools Required

  • Folding ruler
  • Pencil
  • Jigsaw
  • Band saw
  • Surface planing table
  • Electric plane
  • Hand plane
  • Crowbar
  • Mallet
  • Wood wedges
  • Screwdriver
  • Short chipboard screws
  • Marking gauge
  • Belt sander
  • Hand chisel(s)
  • (battery-powered) Drill with wood bits and countersinking bits
  • (battery-powered) Drill with bit holder
  • Woodscrews

Materials Required

  • Thick and large plank
  • Plywood sheets
  • Small blocks of timber

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