Surface Prep for Thru Hull Sealant

[vandy]

I am planning to change most of my skin fittings and valves etc. I am planning to use Sika 291i so was wondering other than getting rid of the old sealant once I remove the old fittings, and gently sanding the area (keying) do I need to use any other product prior to using sealant? I have heard Sika Aktivator 205 but don't have any experience of using it. So was wondering what others use?

 

[LoneHort]

I just used CT1 much better than Sika £££ anything when installing my forespar ones last years . No need for anything else.

 

[thinwater]

Fittings don't leak because the sealant is bad (assuming quality product), they leak because they move. The hole is over size. The backing block is rotten. The inside and outside surfaces are not square. The skin is too thin and the threads have bottomed out. The top has too much leverage on it. The fitting is twisted during the curing process, breaking the seal. In other words, poor installation mechanics.

With a good mechanical assembly you have nothing to worry about.

 

[Ruffles]

It cures in moisture so not a lot to worry about. If you're enlarging a hole then a half round carpenters rasp is very (possibly too) effective.

I guess if there's an existing ply pad then any alterations to it will need to be sealed with epoxy?

Don't forget to get a packet of baby wipes from Boots. So you can clean it off your hands, arse, car door handle etc.

 

[rogerthebodger]

Ensure there is no grease or oil on any part of the joining surfaces.

 

[Poey50]

CT1 Multisolve for degreasing followed by CT1.

 

[Graham376]

291i is fine, I used it on TruDesign fittings and no sign of movement after several years. Just clean the area with acetone first and apply enough sealant so there's some squeezout when tightening.

 

[rogerthebodger]

Sikaflex 221 is the same as 291 but cheaper, 291 is marketed as a "marine" sealant