Sikaflex or silcone

[achjimmy]

Howdy all. 
 

I am well versed in using sika for most things , but I got thinking I am fitting a new bow spirt and as I just want to stop water seeping under and into the bolt holes would a neutral cure white silcone be as effective ? I know sika has adhesive qualities but I don’t need that just a sealant ? 
 

TIA 

[campr]

I don't think it would matter as long as it's a neutral cure compatible with your hull material.  Ron 

[zmk1962]

Sikaflex has many products. If you are referring to sikaflex silicon sealant then a quality silicon sealant would probably do the same job. 
However Sikaflex marine 291 is a completely different compound. It’s a polymer based adhesive, bedding agent and sealant. It’s tacky and sticky as sh*t when dispensed and you need to work it with mineral turps, but when it goes off - the polymer chains form a plastic type compound that is far superior (adhesion, longevity, robustness) to any silicon sealant in my experience. 
I have tried to cut corners/cost with silicon. It does an ok job for a while. But for permanent work, like bedding the plate glass windows, thru hull fittings or where I wanted an absolute water seal I have not found a better product than the 291. 
cheers Zoran 

[achjimmy]

Thanks guys , yeah I use 291 for sealing  it’s good but I find if used as “caulking “ and if  it’s exposed it goes “matt” and allows dirt to adhere unlike silicone that’s why in this case was thinking of using white silicon .  
 

on my transom I’ve drilled out most of the holes oversized and filled with epoxy before redrilling the screw holes  so the screws holding the fittings on need no sealant at all , but I still used 291 🙂

[dunc333]

291 for me .strength and seal. no brainer mate.i stuck down a bow roller 15 years ago with 291 +3 stainless nuts and bolts and it is still rock solid. cheers dunc333

Edited December 31, 2021 by dunc333

[dmck]

I've switched from Sika to SOUDAL T-Rex. Its worth checking it out.