Slot closure strips best way
to prevent centreboard jamming due to sand or stone.
Two years ago, the shore in front of our Wayfarer dinghy park at the Ho Bugt Sejlklub was damaged by a major storm, and the beach had to be built up with fresh sand that was especially sharp. Since our Wayfarers are placed on the beach during pre-sailing preparations, and they are landed directly on the sand after sailing, this caused a lot of trouble with jammed centreboards. Because of this, we have worked with our two club Wayfarers, to find a solution to the problem of jammed centreboards caused by sand or stones. Before our experiments, we often spent up to an hour removing sand and small stones from a jammed centreboard.
1. Our club Wayfarer (W 6300), was provided with a centreboard of the old-fashioned shape with a leading edge chamfered 64 mm (rule 17.4) in a V-shape. This moved the narrow point between centreboard and casing 50 – 60 mm's up into the casing, and resulted in no jamming, as we had often seen with a centreboard with the newer "cigar-nose-shaped" leading edge.
My conclusion is that the V-shaped leading edge will prevent sand and stones being washed so high into the centreboard casing that it sticks there, and jams the centreboard. ( Al's note: A V-shaped entry is not a very efficient leading edge and, in my opinion, an unacceptably high price to pay for jamming protection. My experience has been that there is only one solution - other than closure strips perhaps - to keeping sand from jamming the board, and that is to never park the boat such that the CB box (casing) is located where the waves are breaking onto the shore, d.v.s. either park the boat with the box completely in the water, or drag the boat up far enough that the CB box rests on dry land. This has always worked for me and others to whom I have suggested it, and it's logical because the breaking waves are what washes the sand up into the box where it gets stuck. If you are in tidal waters where the water's edge moves, you would need to get creative: rig and de-rig with the boat afloat in shallow water, or get closure strips.)
2. Our other club Wayfarer W 4907, was fitted with McNamara closure strips under the centreboard slot. This boat has a "cigar-nose-shaped" centreboard. Here, we have seen the same effect: no jamming, and there is no sign of damage to the closure strips.
My conclusion is that the closure strips prevent sand and stones being washed into the casing, and the resulting jamming.
Therefore I can recommend these two ways to jam-proof the centreboard:
Ø The V-shaped leading edge
Ø Installation of slot closure strips
W 1740 Jens Konge Rasmussen
PS. I have never seen the problem on my own W 1740. I have the "cigar nose", no closure strips, and I often place W 1740 on the beach while I move to help others to release their centerboard. Coming back to my own W, I just push it back into the water, and sail away without any CB troubles!