Repair and Maintenance of a Drascombe Lugger

Fixing a loose centreplate axle (page 4 of 5)
Strengthening the centreplate casing and refitting the centreplate.

This page describes the third stage in fixing the problem of the loose centreplate axle. Having removed the centreplate and the old axle and repaired the enlarged holes and associated cracked GRP in the centreplate casing, the next step is to strengthen the centreplate casing in the area of the axle. Finally the centreplate is replaced in its casing and the new axle (bolt) passed through the case sides and the plate slot to hold it in position.

In summary this was tackled as follows:

Making the Reinforcement pads (GRP method)

The first step is to make the GRP reinforcement pads. Two polythene milk containers make ideal moulds for these.

Cutting the bottom out of a plastic milk container Making the 'moulds' for the reinforcing pads

The reinforcement pads need to be about 70 mm square and about 10 mm deep. The bottom of a polyethylene (polythene) 500 ml container of milk makes an ideal mould as the shape and size is right and the Epoxy or polyester resin does not bond to the plastic. The photograph shows the bottom being cut off the container using a scalpel

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Preparing to make a GRP pad
Making a reinforcing pad

The pad can be made out of about 6-7 pieces of chopped strand mat cut roughly to the same size as the polythene mould. NOTE that if you are using Epoxy resin, the Chopped Strand Mat MUST be powder rather than emulsion bound. Powder bound mat can be used with Epoxy or Polyester resins. Mix up 5 ml of hardner with 25 ml of Epoxy resin in a drinking cup Click here for instructions on measuring out resin and hardner. (Polyester resin with MEK hardner can be used instead of Epoxy if preferred). Use a brush to wet out the bottom of the polythene mould and then place one of the pieces of cut fibreglass matting on top. Add more resin using the brush until the matting is completely wetted out (i.e. there are no pale areas of matting). Place the next piece of matting above the first and add more resin using the brush. Use the brush with a stippling action to press the matting down and again wet out completely. Make up more resin plus hardner if required. Continue until all the cut pieces of fibreglass matting have been added making sure that the last one has been completely wetted out. Allow to cure (24 hours if Epoxy has been used).

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The GRP pad in its polythene mould The cured pad

This photo shows the appearance of the pad in the mould after the resin has cured.

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The GRP pad extracted from the mould Extracting the GRP pad from the mould

It should be very easy to peel away the mould from the GRP pad. The top surface of each of the two pads should then be sanded using a sanding block with 60 or 80 grade Aluminium Oxide paper, until the top (rough) surface has been completely abraded. The curved sides should also be abraded. The area around the axle holes on the casing should also be abraded to ensure a good key when the pads are glued into place. Next, a 12 mm diameter hole is drilled through the centre of each pad.

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Fitting the Reinforcement pads

After the pads have been made, drilled and abraded they are ready to be glued to the sides of the centreplate casing.

Diagram showing how the pads are held in place whilst the glue cures The port GRP pad ready for gluing on the casing
Step 7. Gluing the pads in place on the case

Another tube of parcel tape is made round the bolt and inserted through one of the pads. The bolt is passed through this tube and the pad as shown in the photograph. The purpose of the tube is again to protect the steel from the glue. Mix up 5 mls of hardner to 25 mls of Epoxy resin in a plastic drinking cup. Use a brush to wet out with unthickened Epoxy the inner surface of each pad and the centrecase sides where the pads will be glued. Stir in 404 filler powder to the remaining epoxy filler until it has reached a mayonnaise like consistency and use a wooden or plastic spatula to apply it to ALL the surfaces being glued. Push the pad with the bolt up against the centreplate casing so that the bolt passes through the casing. Slip another plastic tube on the end of the bolt protruding from the other side and push the other pad on the bolt and up against casing. Apply the nut and washers and lightly tighten so that both pads are held in place against the centreplate casing. Smooth excess glue that has squeezed out of the joints using the spatula. Allow to cure for 6 hours.

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Diagram of completed repair The completed repair on the starboard side of the casing
Step 8. Removal of the bolt

The bolt should be removed after the glue has had about 6 hours to cure. This is just in case some of the Epoxy glue has bonded between the glued joins of the pad and the stainless steel bolt. After 6 hours although the glue has hardened it has not achieved its full strength and a bond with the bolt can be easily broken. The photograph shows the completed repair, with the bolt removed, on the starboard side of the casing.

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Refitting the centreplate Refitting the centreplate

Using a wooden frame with block and tackle to re-fit the centreplate - great entertainment for the neighbours! Note that in some instances the plate can only be re-fitted by careening the boat (lying it on its side).

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Diagram of completed repair with centreplate refitted The completed repair with centreplate re-fitted
Step 9. Project completed!

The final stage is the replacement of the centreplate which is held in place by the 12 mm stainless steel bolt. The photograph shows the refitted plate with the securing bolt in place.

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Project started February 2002 and completed, July 2002

Follow this link for a retrospective review of this project


[Back to page 3, repairing the centreplate casing] [Forward to page 5, In retrospect]