Repair and Maintenance of a Drascombe Lugger

Removing and re-installing the centreplate-case mounted Bilge Pump
Making a new Mounting Board

The Mounting Board

The pump mounting board was originally made out of 0.75" thick marine plywood. This is not a good choice as it has to be secured in the centreplate casing by four large screws driven into the end grain of the plywood. This creates a weak fastening and can cause the plywood to split. A better choice is to use 0.75" thick hardwood with the grain running vertically when screwed in place within the centreboard casing. I used an offcut of teak left over from the construction of a replacement centreplate capping but a piece of mahogany would do as equally well. The process of making a new mounting board is illustrated below:

Sketch showing dimensions of bilge pump mounting board Sketch showing the dimensions of the mounting board

This sketch shows the dimensions of the wooden mounting board. The board is tapered to follow the cross sectional shape of the inside of the centreplate casing

(Click on image for larger view)

Photograph of new mounting board The new mounting board

Photograph showing the new mounting board. Note the outline of the pump base drawn on the board. This helped to establish the position of the four holes for bolting the pump to the board. The four wood screws are in the correct position for securing the mounting board within the GRP centreplate casing. For obvious reasons it is crucially important that the bolt holes and the wood screw holes do not coincide.

(Click on image for larger view)

Making the new Mounting Board

The best way of making the new mounting board is to use the old one as a template. Place it on top of the new wood and use a pencil to draw round it. The new board can then be cut out using a jig saw.

The next step is to place the board in position within the centreplate casing to try it for size. The bottom of the board rests on the 'tongue' of GRP near the bottom of the casing (See sketch diagram above). If it fits OK then manouvre the pump into the cavity as well and place in position on the board. The pump should be positioned as low down as possible within the GRP casing to allow room for the outlet pipe at the top. When positioned correctly, draw round the base of the pump (as far as possible), onto the mounting board.

Remove the pump and board from the casing and place both on a flat surface. Carefully position the pump so that it coincides with the outline drawn on the board. Insert a bradawl into each of the fixing holes on the pump base to pierce the underlying wood. Use these marks to drill four 5 mm diameter holes through the mounting board. These will take the four M5 stainless bolts securing the pump to the board.

Place the mounting board back in position within the centreplate casing and insert the bradawl through each of the four screw holes (two on each side of the GRP centreplate casing) used to secure the mounting board in position. It is vitally important that these holes do not coincide in position with the holes drilled in the mounting board to take the pump fixing bolts. Drill new holes through the casing if necessary.

Using the holes made by the bradawl, drill the pilot holes, 2 on each edge of the mounting board, to take the securing screws. Finally I gave the board several coats of Burgess Woodsealer. For wood other than teak, coat with varnish or Epoxy.

continued

[Back to page 2, Removing the Bilge Pump] [Forward to page 4, Re-installation of the pump]