over the last week i have been reading and looking through many build blogs, to get my mind set for my build.( waiting for plans to arrive :'(). i have seen some differing styles to seal the bottom of the keel. so my question is which would be the way to go for better protection.
1. standard epoxy/glassfiber
2. kevlar. what are the advantages of this and possible cost
3. carbon fiber.  i have seen this tape at the local boat store but know nothing about it.
just wanting to know for the future, when i get to that stage in the build.
An alternate solution that I and a few other builders have done is some sort of metal strip. I used steel (a pain to put counter-sunk screw holes in) but others have used other metals or a sacraficial wood strip.
I often joke with people that if they ever saw me sail they'd understand the need for a steel grounding strip :
The important thing do do though if you take that route is to make sure that it's properly bedded to prevent water getting trapped between the strip and the keel.
You're looking for a keel "shoe" which serves to protect the bottom of the keel.
Carbon fiber cloth or in tape form is useless as a keel shoe.
Kevlar is an effective shoe, though quite expensive, requires special tools just to cut it, will fuzz up as soon as you attempt to sand it and is difficult to work with. This is a material best suited for million dollar yachts, not back yard building projects.
'Glass cloth or tape is effective, but it has issues and there are better choices. Among the fabrics, Xynole and Dynel are much superior to regular 'glass fabrics at abrasion resistance, which is the primary job of a keel shoe.
Lastly, The best thing you can do is literally put a "shoe" on the bottom of the keel. This could be a sacrificial piece of wood, mettle strips (half oval), plastic strips, even rubber strips. That's right, not 'glass at all, but a strip of material, preferably with good abrasion resistance (like HDPE, or stainless steel). In the golden age of sail they would have used an oak strip, bedded to the deadwood assembly. Now, we can use bronze or stainless half oval or we can mill up some sort of plastic, of course all bedded and screwed to the deadwood assembly. When they get torn up or wear out, you pull it off and replace it with a new piece(s).
paul i never thought of a long rubber strip that you can change out from time to time...interesting...
Hi
I have used aluminium battens in my boats. In weekender it can be fastened without srews to keel. If aluminium is not anodized it had to be sanded lightly and primered with proper primer. Then glued with sikaflex 291 or 292.
In my weekender it has lasted 4 years.
I used similar batten in my kayak - the kayak was painted with one compaund paint and batter get loosed ( the paint was too weak and it left from kayaks bottom )
In weekender bottom I have painted it with 2 compaung paint and it has done great.
I first glued plasitk moulding with double sided tape - tape holded on boat, but not in plastic.
Perttu