Dear Editor

I was interested to read Cliff Laycock’s letter in the Winter Bulletin, since in completing my 15 foot dinghy last year I also encountered the problem of adding substantial weight to a relatively small centreboard. I wanted to make my boat self-righting, and considered that this would require a weight on the end of the centreboard comparable to the weight of a crew member righting a racing dinghy. With a 2” thick centreboard, this weight could be achieved by making the lower 2 feet of lead and the rest of wood, but how was the lead to be attached to the wood?

I sketched various arrangements of steel bars cast into the lead and built into the wood, but this seemed awkward, so I decided to make the joint with glass fibre only.

Over an area of about four inches either side of the joint, the wood and lead are both tapered down to zero thickness, so that at the plane of the joint the board is solid fibreglass. The fibreglass is extended over the whole board to form a sheath maybe ⅛” thick, but thicker at the leading edge and tip which abrade against the seabed. The lead would have been best made as a casting, possibly using a wood pattern and concrete mould, but to save time I brought scrap sheet lead and cut out layers which were riveted together to form roughly the required streamlined section, then shaped by hammering. This was fairly satisfactory, but it was difficult to minimise voids between the layers. The lump of lead and the wooden board were then propped up on edge and carefully aligned, before plastering with low resin-content glassfibre, then turning onto the other edge to complete the glassfibreing. Final finishing was by filler paste and paint-on gel coat. The hole for the centreboard pivot was made much oversize, filled with glassfibre and then drilled the required size.

The centreboard was in use all last summer, and proved to be quite strong enough. It shows less sign of abrasion than would be expected of a normal wooden centreboard. The only problem was the failure of one of the pulley blocks in the hoist tackle, which resulted in my being unable to get ashore until I reached a marina with deep water berths.

The centreboard case in my boat is 2¼” wide, and there is a violent splashing of water in the case when sailing at full speed. Had the centreboard been made of wood with lead encapsulated within it, as suggested, it would either have resulted in far too wide a centreboard case, or would have been too light to make the boat self righting. However, even a relatively small amount of external ballast should help the crew to right the boat, especially if combined with suitably positioned buoyancy.