Sealing chainplates

[Billyo]

My chainplates penetrate the deck and are bolted through the knees below. On deck I have a cover piece made of fibreglass that goes round the chain plate and has been stuck to the deck with some sort of mastic (probably silicone). The PO restuck the covers with down and they are now leaking after 2 years. I'm going to remove the mast to rerig and am wondering what to use on the chainplate covers to re stick them? I'd rather not use silicone as it failed already so was thinking butyl tape, but have 2 worries, the covers aren't, can cant be, screwed down so will butyl hold them, and the boat is in the Tropics so will the tape essentially melt when too hot?

Any thoughts or ideas would be appreciated!

 

[vyv_cox]

Sounds like you need an adhesive sealant, polyurethane or a hybrid. Sikaflex 291, Puraflex 40, CT1, OB1. Butyl certainly creeps under load and temperature.

 

[geem]

Use Geocell Works. Mine are sealed down with that.
Also, those cover plates are a secondary device. Thr main thing is to ensure there is no leaks where the chainplates go through the deck.
Since you have cover plates, you can excavate around the chainplate a little as the cover plates will cover the enlarged hole. If you can excavate, say 5mm around the chainplates using a Dremel and a vacuum cleaner to suck out the bits, you can fill the void around the chainplate with epoxy and some chopped up glass strands. This will ensure there are no leaks down the chainplate. With the chainplate covers glued in place on top using Geocel Works ( a MS Polymer with excellent UV resistance) you will have a leak free set up. We did ours a few years back after struggling to cure chainplates leaks. They have been leak free and done a couple of Atlantic crossings since.
As a side note, all our deck fittings are sealed with Geocell Works. Excellent stuff for bedding deck fittings in my experience

 

[Minchsailor]

I had leaky chainplates on my Rustler. Dug out all the failing multiples gunge tried by the previous owner. Used old fashioned black bitumastic gutter sealant, which is non-setting and sticks like the proverbial s***t. Cheap as chips, and problem solved.

 

[vyv_cox]

If, as geem suggests, there are cover plates attached to the chainplates you may find this useful Sadler 34 lower and cap chainplates As with just about every sealing job aboard I used Sikaflex or Puraflex. This was done a few years ago, no sign of leaks since.

 

[ColinR]

My chainplates penetrate the deck and are bolted through the knees below. On deck I have a cover piece made of fibreglass that goes round the chain plate and has been stuck to the deck with some sort of mastic (probably silicone). The PO restuck the covers with down and they are now leaking after 2 years. I'm going to remove the mast to rerig and am wondering what to use on the chainplate covers to re stick them? I'd rather not use silicone as it failed already so was thinking butyl tape, but have 2 worries, the covers aren't, can cant be, screwed down so will butyl hold them, and the boat is in the Tropics so will the tape essentially melt when too hot?

Any thoughts or ideas would be appreciated!

When I had a new deck fitted a few years ago the shipwright used grey mastic (butyl?) on the chainplates that he swore by as it never hardens. Leaked like sieve. I cleaned it all out and resealed with sikaflex. Much better. As previously said, you need a good seal in the hole through the deck rather than on the pads above and below deck. Make sure it wets the inside of the hole and the thread on the through deck fitting, and put enough so it squeezes out when you tighten. And if necessary you can remove it later if you need to with a bit of perseverance.

 

[geem]

I had leaky chainplates on my Rustler. Dug out all the failing multiples gunge tried by the previous owner. Used old fashioned black bitumastic gutter sealant, which is non-setting and sticks like the proverbial s***t. Cheap as chips, and problem solved.

We tried a multitude of sealants. We had no success. Digging out the core and filling with epoxy and glass strands cured it for us. I think you need to be careful to get full adhesion between the sealant and the surrounding core/grp. This means drying the void thoroughly before filling it. A hair drier or hot air gun will speed up the process.

 

[Billyo]

Thanks all, been looking at sika 291 and have read that it can't be used over the top of silicone as the 291 won't bond.

Has anyone tried it? I will obviously remove all visible silicone before applying and could give the area a light sand and wipe with acetone?

 

[ColinR]

Thanks all, been looking at sika 291 and have read that it can't be used over the top of silicone as the 291 won't bond.

Has anyone tried it? I will obviously remove all visible silicone before applying and could give the area a light sand and wipe with acetone?

clean out the silicone as best you can then drill it with a bit as close to the size of the hole as you can, you don't want to enlarge the hole. Then wrap sandpaper round something round and clean out. Make sure its dry. You should be okay.

 

[Daydream believer]

As a side note, all our deck fittings are sealed with Geocell Works.

I just looked this up & if I am not mistaken, there are a couple of different types of "the works"
Which one are you suggesting please?

 

[KAM]

On my previous boat I made hemispherical covers with slots in the top the covers were permanently epoxied to the deck. Flexible sealant was then used in the slots. This ensured water did not pool near the sealant and I've never had leaks since. I used small rice bowls as moulds. Just make sure you use plenty of release agent. My wife is still looking for the bowls.

 

[Paul1962]

My chainplates penetrate the deck and are bolted through the knees below. On deck I have a cover piece made of fibreglass that goes round the chain plate and has been stuck to the deck with some sort of mastic (probably silicone). The PO restuck the covers with down and they are now leaking after 2 years. I'm going to remove the mast to rerig and am wondering what to use on the chainplate covers to re stick them? I'd rather not use silicone as it failed already so was thinking butyl tape, but have 2 worries, the covers aren't, can cant be, screwed down so will butyl hold them, and the boat is in the Tropics so will the tape essentially melt when too hot?

Any thoughts or ideas would be appreciated!

Personally - I would use Arbomast BR - it stays flexible - Do not be sparing on application.