Deck fittings

[nicknick109]

I have seen an idea on how to fit or replace my deck fittings this uses a washer to stop the sealant being fully squeezed out when tightening the screws/bolts etc.The article was from fitting boat windows. Point was they did not say where to place said washer. Have tried without and they still leak although I did as advised not fully tightened left for a few days then nipped up.
My question is where best to put the washer, against the hull with sealant on top or sealant first then washer then fitting ?
Will leave thanks for any help in case I miss any replies.
Nick

 

[rob2]

I don't see that it makes much difference as the washer is only being used as a spacer. I guess it depends on the fitting and the orientation when fitting. All the fittings I've stripped which weren't leaking had non-setting, oil based mastic under them. I find that modern mastics are good to start with, but lose adhesion to the faces after a few years.

Rob.

 

[VicS]

I have seen an idea on how to fit or replace my deck fittings this uses a washer to stop the sealant being fully squeezed out when tightening the screws/bolts etc.The article was from fitting boat windows. Point was they did not say where to place said washer. Have tried without and they still leak although I did as advised not fully tightened left for a few days then nipped up.
My question is where best to put the washer, against the hull with sealant on top or sealant first then washer then fitting ?
Will leave thanks for any help in case I miss any replies.
Nick

Isn't the idea to just slip a washer under the edge of the fitting so that you dont squeeze out all the sealant.
Ive seen little wedges made from matchsticks suggested in the past.

When its cured remove the washer and tighten the fastenings.

It might be nice to just fill the little gap left by the washer first.

Holding the screw/ bolt and only tightening the nut will avoid breaking the seal between fitting and screw

 

[JSYmartini]

When I assemble stuff with sikaflex, I tighten down slightly, just enough that the sikaflex is oozing out all the way round. Then leave for a couple/few days before tightening fully. This way the sikaflex has gone off and you're compressing it to get a nice waterproof joint.

 

[Rossynant]

I find that modern mastics are good to start with, but lose adhesion to the faces after a few years.

There are adhesive type sealants on the market, Sikaflex has one - or so I heard - 29something. No idea how long it will hold adhered, but is said to be same kind as one I used - 3m 5200 (USA). Like a tar, you will spend whole life scrubbing it off after 30 years.

 

[nicknick109]

From Nick,
many thanks to rob2, VicS, JSYmartini and Rossynant for all ideas and suggestions.
Nick

 

[Deleted member 36384]

I don't know about the washer method in the article you describe. However, I have read about making a slight countersink to allow sealant to form an 'O' Ring in, in particular with using non setting mastics but I can see the principe being the same on setting type sealants. I am not sure how it works but the countersunk hole probably retains a thick enough mastic such that it resists tearing / shearing after it has set; a thin film obviously tearing easier and introducing a leak path.