Never use silicone sealant on a boat???

[PetiteFleur]

I always use Butyl tape - never sticks permanently and always flexible. If fitting windows etc always use a small ss washer where the fixing screws are so it doesn't get all squeezed out. Alternatively use the rubber adhesive 'P' or 'W' profile draught sealing strip where water tightness is not critical or if you need to remove items occasionally.

 

[Spirit (of Glenans)]

From what I can make out from the Sika website, the 291i seems to be an "adhesive sealant", at least that's what the experience of forumites seems to suggest, whereas the 295UV seems to be merely a "sealant" without the death-grip properties.
Sikaflex®-291i
Sikaflex®-295 UV

 

[PaulRainbow]

I find CT1 seals really well and can be removed without destroying the boat.

 

[Neeves]

To remove most of these adhesives/sealants do not use a knife, scraper, chisel etc. Make your self an acrylic scraper. A steel scraper, knife etc - being more robust than the gelcoat will damage the gelcoat.

Take a piece of scrap acrylic grind one edge at 45 degrees and then sharpen that edge. It will make an ideal scraper and will not damage the gel coat. You will find the sharp edge you make wears relatively quickly - so you either re-sharpen or make lots to start with. If you plan this you can 'recycle' scrap acrylic choosing pieces that when the edge is sharpened you have a sensible and comfortable handle. You make the width of the edge to suit the task.

The softness of the edge is a reflection of the simple fact that the acrylic wears - not the gelcoat. If you remove old acrylic windows and don't have access to scrap - chop up the old windows and or keep pieces of the windows you remove for future tasks.

Making the acrylic tool is as much about making it comfortable to hold as having a sharp edge. If its uncomfortable to hold - you will not be keen to load it up to remove the sealant (which will be tenacious). It helps if you have a bench grinder to make the edge.

Jonathan

 

[webcraft]

Another vote for CT1

- W

 

[HR352]

Hi, I appreciate this is a 2 year old thread, but ......

You have to read the manufacturer's spec and recommendations. Going to Sika's or 3M's (or other's ...) websites is essential to be sure you get the right sealant/ adhesive. Lots of subtly different properties strengths etc. 'Sikaflex' is not one product ...291i, 292i, 591 all have different design characteristics, some more for sealing, some adhesive focused. Look them up.

I've just been looking at installing a spinlock clutch - instructions specifically say don't use polyurethane or polysulphide sealant (which all of the above are) . The fitting instructions say USE SILICONE ...

I've only found Geocel marine silicone as appropriate, unless anyone knows anything different?

 

[Scubadoo]

Geocel marine sealant is a good choice, used it for many years and not experience any problems.

 

[webcraft]

I use CT1 for pretty much everything

 

[HR352]

I use CT1 for pretty much everything

Yes, it's awesome, good value stuff. It's 'trybrid' (brand name) a silane polymer, like one of the 3M products. Anyone know if that is a kind of polyurethane polymer ie can't use on those products that can't cope with polyurethane products?

 

[Hacker]

I use CT1 for pretty much everything

I wouldn’t

 

[webcraft]

I wouldn’t

Care to say why?

Many of us are fans.

CT1 anyone?

- W

 

[Hacker]

It’s fine where you need something to stick permanently (and indeed I use it for that at work). If you ever need to disassemble then there are better products.

 

[Snowgoose-1]

Arbomast seems to have an increasing following . Particularly above the waterline. Often favoured for new builds where locations on the boat may change due to owners preferences. Good price too.

 

[winch2]

Ugh, silicone. For me it doesnt like wood and salt air kind of delaminates it.. .. yet when u go to remove it, it just stretches and wont come off... awful stuff.

 

[vyv_cox]

I cannot understand the objection to polyurethane. I doubt very much that there is any adverse reaction between it and any normal plastics.

One thing is for sure - my Spinlock and Barton clutches have been sealed with it for years, no water gets in and I have removed one or two with minimal problem. The negative aspects of using silicones were all covered in the original post.

 

[justanothersailboat]

Polyurethane/hybrids if you want it stuck down, butyl mastic if you don't, silicone if you hate whoever owns the boat in a few years' time. Simple.

Clutch guidance about not using sika/poly types is probably because if you use too much it could be hard to remove for servicing. But doesn't have to be.

 

[Hoist]

Having made a mess with silcone, sikaflex, bathroom crap and everything expensive out of a tube I now keep a roll of butyl tape on the boat at all times.

Its basically like blue tack but softer. You just wrap it around whatever your needing sealed and it squidges in

Butyl Sealant Tape 8mm X 6 Meter High Performance Class A Certified by NFRC | eBay

easily removed and no mess. Can be reusable as well just like blue tack.