Rob, I found soft foam a bit annoying with it getting dislodged, or weed still getting stuck. My latest method is a sandwich of silastic and soft thin plastic (from an old bucket).put a bit of Vaseline on the board, then screw the fin in and let it set.
Yeah, I haven't tried the foam in thick weed. It's pretty dense stuff and I made sure it sits a fraction in front. The fine stuff might still get in there.
I'm not using anything yet but has anyone tried Stickaflex calking adhesives and sanding it when dry ?
Ok, so the leading edge of the high density rubber moved away and it started picking up weed. Next try Kneed It.
Select to expand quotekato said..
I'm not using anything yet but has anyone tried Stickaflex calking adhesives and sanding it when dry ?
Recommend you do Kato, this is what happened to my board not using a gasket
I tried caulk with no success. It fell apart
Select to expand quoteolskool said..
Anyone tried flat rubber sheet?
I prefer no gasket at all, and if I have to use one, I like to keep it as thin as possible. The rubber sheet idea sounds like a good compromise between compressibility and strength. What glue would you use Olskool?
I've used treadly inner tube rubber, and that didn't work real well, but my fins have a sharper point than fangy's, so it's hard to get a good firm glue fix, (I used contact cement)
Ive got some insertion rubber sheet. So Contact cement or Gorilla glue. Gorilla expands slightly, so will conform to whatever shape reqd. Easy to apply then activate with a spray of water. Can be cut sanded etc.
Kato ive tried sanding sikaflex, not so easy. Its easier to cut to finish. Or form it up perfectly with metho or saliva upon application. Amazing how this stuff gets everywhere!!! 
I cringe everytime i use it. You get it looking sweet, then go ' i will just tweak it there'. Hey presto youve now got a stringy black mess to clean off a perfect white surface! 
I only use the black 291. Ive had white deteriorate many times after only a few years on boat projects.
Yachties now use Butyl rubber tape to bed fittings these days. Seals as well as Sika,but can be removed for servicing. So that may be an option.
Whats everyones favourite to fill the void in fin?
Expanding foam?
I use lots of Slickaflex for wood projects and tend to sand it with no issues. Wasn't sure how it would go with Ally. Yes it does get on everything 
Select to expand quoteolskool said..
^ You talkin the Woodworking maxbond/liquid nails stuff? That stuff sands ok.
Nah, liquid nails is useless except when installing chipboard flooring on joists.
Sikaflex is pieceapiss to use
A release agent on you board, apply Sikaflex compound to fin flange then insert and tighten to desired thickness.
Leave for a day or two to set then trim.
Custom moulded to your board
Select to expand quoteelmo said..
Sikaflex is pieceapiss to use
A release agent on you board, apply Sikaflex compound to fin flange then insert and tighten to desired thickness.
Leave for a day or two to set then trim.
Custom moulded to your board
Agreed. It's my go-to method for thin gaskets, except, I use gladwrap as the 'release agent'.
Select to expand quoteolskool said..
Expanding foam for fin hollow?
I haven't ever tried it Olskool ( mainly because I don't bother filling the hollow these days.)
Ok. Oiled the box, glad wrapped the board and Stickaflexed the fin . I'll post the results in a few days
I ended up going with "Session Saver", which is probably just Kneed It, with Alfoil instead of Gladwrap. It looks pretty good, hopefully with last more than one sail.
Select to expand quotefangman said..olskool said..
Expanding foam for fin hollow?
I haven't ever tried it Olskool ( mainly because I don't bother filling the hollow these days.)
Why don't you cast a soft rubbery alloy 
The issue i have is i want the 1 fin to fit 2 different shaped boards. So im lookin for squishy but not too squishy.
The Sikaflex is a soft polyurethane so should have sufficient compression to handle both.
Do the moulding on the worst gapped board. then trim on the other board.
The trick is not to make it to thin initially as you want to be able to compress(~20%) the rubber later when you do up things properly
Select to expand quoteelmo said..
The Sikaflex is a soft polyurethane so should have sufficient compression to handle both.
Do the moulding on the worst gapped board. then trim on the other board.
The trick is not to make it to thin initially as you want to be able to compress(~20%) the rubber later when you do up things properly
+1 on what the muppet says Remember that you can reduce the width of the fillet by half at its widest point, which in turn makes your footprint substantially narrower and reduces the need for a greater compression range on the gasket material.
Hard to get a good pic of the gasket. Sort of happy with it, I wanted to clean up the water flow around the filet for more speed rather than weed Issues. Might cast it again later and make it thicker. Glad wrap worked well
Select to expand quotekato said..
Hard to get a good pic of the gasket. Sort of happy with it, I wanted to clean up the water flow around the filet for more speed rather than weed Issues. Might cast it again later and make it thicker. Glad wrap worked well
Don't worry about the gasket, it's high time you mowed the lawn instead Kato
Select to expand quotefangman said..kato said..
Hard to get a good pic of the gasket. Sort of happy with it, I wanted to clean up the water flow around the filet for more speed rather than weed Issues. Might cast it again later and make it thicker. Glad wrap worked well
Don't worry about the gasket, it's high time you mowed the lawn instead Kato
Mate..... I live in the bush ,very little lawn to keep me from water sports. Anyway the Roos mow the lawns
