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