A damaged slot gasket slows you down by making the inside of your centreboard case into a washing machine. Normally you can examine yours next time you capsize,
and fix it later if it's coming adrift. However, if water comes into your boat through the top of the centreboard case, or if the existing item is coming up the case with the centreboard and jamming it,
then you may need to replace it
There are two materials, Sailcloth and Mylar. You can use either if you have the metal or plastic strip going down each side of the case. If not, you need mylar.
This will come as two strips, each of which is a wider piece folded over. Just screw it on under the metal/plastic strips so that there is a 5-10mm overlap.
Make sure the folded edges are towards the centre.
If you are using mylar, try to buy it as two narrow strips. It is also available as one wide strip which you cut in half yourself, but why would you want to
? The overlap should be 3-4mm, and the shiny side should be exposed. If you are gluing it on, you want a proper old impact adhesive of the variety favoured by glue sniffers, not the new style
rubbish. Leave about 10mm of the width of the gasket unglued (beyond the bit which extends over the slot) to allow it to flex more easily with the movement of the centreboard. Don't fix the gasket to the
boat directly at the leading edge of the slot, it needs to flex here too, but DO glue it or fix it down somehow at the leading edge of the gasket (allow at least 30mm excess gasket at the front of the
The quickest way to mess up a slot gasket is to have a rough or badly chipped trailing edge on your centreboard. The chips etc catch on the gasket as the board
goes up into the slot and take the gasket with them. Once mangled, the gasket can become useless. However, if you have a mylar gasket which is merely deformed, give it a blow over with a hot air gun.
Done carefully this will cause the material to regain it's former flatness. Done badly, you'll cook the surrounding gel-coat or paint and regret ever trying it.