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Extraction Repairing the Casing Re-fitting Evaluation Back to Home page

Repair and Maintenance of a Drascombe Lugger

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Fixing a loose centreplate axle
Identifying the problem and deciding on method of repair
(page 1 of 5)

These pages describe a method of dealing with the potentially serious problem of a loose centreplate axle. Consultation with the experts confirmed that the way to deal with this is to completely remove the axle, repair and reinforce both sides of the centreplate casing in the damaged area, and lastly replace the original axle with a longer one, taking advantage of the additional reinforcement.

It's amazing how often that dealing with one problem reveals another more serious one!! After slackening off the centreplate uphaul/downhaul, I was pulling up on the extended arm of the centreplate whilst musing on its weight and how it might be extracted for re-galvanising. To my surprise I found that I could lift the arm by several inches. I repeated the operation whilst looking down through the slot of the casing so I could see the axle and, to my consternation and horror, saw that it was lifting with the plate and was extremely loose. Twenty years of wear and tear had obviously caused the axle to break it's bond with the surrounding GRP. This is potentially a serious problem as, whilst sailing, every time the plate is hoisted or lowered the axle will move with 31 Kg (70 pounds) of steel centreplate behind it; gouging into and wearing away the surrounding GRP. The ultimate conclusion is the loss of the axle and a centreplate held in the boat only by the uphaul/downhaul.

To visualise this problem some diagrams are required:

Figure. 1 Diagrammatic cross section of Lugger centreplate casing The casing is entirely constructed of GRP with a teak capping. It is quite a complex construction consisting of an outer GRP shell cemented by epoxy putty plus self-tapping screws through the teak capping, to an inner GRP shell at the top, the sides of which gently converge downwards towards the slot in the keel. The stainless steel axle is sealed into the base of the casing towards the front and a slot in the centreplate hooks over this to give a firm pivot point about which it can be swivelled up or down. (Click picture for larger view)

Figure. 2 Diagrams illustrating the effects of a loose axle. The loose axle moves every time the centreplate is raised and lowered. This gouges away the surrounding GRP and, over time, the axle migrates downwards driven by the weight of the centreplate. (Click picture for larger view)

This problem on Sospiri was tackled as follows:

• Locate the position of the existing axle at the base of the outside of the centreplate casing.
• Cut a small hole in the casing to expose and remove the existing axle.
• Make good the damage to the casing.

There are then several options:

• Build up the GRP reinforcement on each side of the case using Epoxy resin and glass fibre matting. Note that some owners have simply glued on a piece of hardwood or marine ply to effect the reinforcement and this has proved to be equally as effective.
• Replace the original axle with a longer one (e.g. part of the smooth shank of a 12 mm diameter bolt cut to size).
• Insert the new axle and cement it in place as per the original configuration but using Epoxy resin and glassfibre (Unlike polyester resin, Epoxy makes an excellent bond with stainless steel).
• Seal in the ends of the axle with Epoxy and glassfibre to make a waterproof seal on both sides of the casing.

OR

• Build up the GRP reinforcement on each side of the case using Epoxy resin and glass fibre matting (or by gluing on hardwood/marine ply reinforcement) - as above.
• Replace the axle with a 12 mm stainless nut and bolt passing right through the casing using rubber washers to prevent leaking.

The through bolt method was my preferred option as the bolt/axle is supported by the full thickness of the casing sides providing improved support. It also makes subsequent removal and replacement of the centreplate much easier. The only down side is the risk of leaks through the bolt holes. However, past experience with a Wayfarer and a GP14, where the centreboards were bolted through the centreboard casing, suggests that there is no problem with leaking as long as the rubber washers are backed up with a stainless steel washer against the head of the bolt on one side and the nut on the other.

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