My chain plates come up through the ply deck , as of most chain plates they are a source of leaks .
one chain plate has rot around it which I knew of before buying the boat the others all showing signs of rot .
first job I did was to seal the plate with sika flex which seemed to work laying liberal amounts of sika around the plate, but I am finding the movement of the plate is breaking the seal while sailing
can the brain trust share their ideas on a better fix thanks .
First thing to do is re-seat the chain plates bolts preferably in epoxy to stop movement there.
Next cut some say 25 mm tufnol or alloy or hardwoood discs about 60mm round or oval if you like (Depending on chain plate size)
Cut the inside to fit the chain plates leaving a say 20mm gap around chain plate.
Place these over the chain plate (even screw it there to the deck)
You should then have a 25mm deep recess around the chain plate as it come through the deck.
Fill with a soft sealant that does not fully harden (not all silkaflex in the same)
The added thickness of the sealant allows more movement before cracking and leaking.
Problem solved!
Select to expand quotelydia said..
First thing to do is re-seat the chain plates bolts preferably in epoxy to stop movement there.
Next cut some say 25 mm tufnol or alloy or hardwoood discs about 60mm round or oval if you like (Depending on chain plate size)
Cut the inside to fit the chain plates leaving a say 20mm gap around chain plate.
Place these over the chain plate (even screw it there to the deck)
You should then have a 25mm deep recess around the chain plate as it come through the deck.
Fill with a soft sealant that does not fully harden (not all silkaflex in the same)
The added thickness of the sealant allows more movement before cracking and leaking.
Problem solved!
Thanks Lydia I knew you would have the answer do you have the name of the sealant a number of it ?
Also make sure use the primer on the Stainless steel.
As to which product from memory 3M 5200 does not set hard and i think 291 is the sika product but you need to check.
Select to expand quoteMAGNESIUM said..lydia said..
First thing to do is re-seat the chain plates bolts preferably in epoxy to stop movement there.
Next cut some say 25 mm tufnol or alloy or hardwoood discs about 60mm round or oval if you like (Depending on chain plate size)
Cut the inside to fit the chain plates leaving a say 20mm gap around chain plate.
Place these over the chain plate (even screw it there to the deck)
You should then have a 25mm deep recess around the chain plate as it come through the deck.
Fill with a soft sealant that does not fully harden (not all silkaflex in the same)
The added thickness of the sealant allows more movement before cracking and leaking.
Problem solved!
Thanks Lydia I knew you would have the answer do you have the name of the sealant a number of it ?
Butyl mastic.
www.theboatwarehouse.com.au/tapes/butyl-sealing-tape-white-10m-x-20mm-roll/?gad_source=1&gclid=Cj0KCQiAoae5BhCNARIsADVLzZe5XuWoGWfeY7pRbtxcnlQ0fFXrVtwAiDY4JtY6YGDF25NvDmKeF3oaArkmEALw_wcB
I would use Butyl Mastic as well but in a cartridge.
www.gluesaustralia.com.au/selleys-butyl-mastic-rubber-caulking-compound-for?srsltid=AfmBOoqzXhm3Q4Rla7SweScSSMeRnZvUhHhc2zLJW5PSHJpayA8zPa-U
I had a similar issue with through deck penetrations for rigging attachments allowing water to get into the ply core, cause rot and delamination of the deck. I ended up cutting out a section of upper side of the deck, digging out the rotten ply, glassing in a new core and laminating a new top section. Then I built new bulkheads and through deck chain plates to strengthen everything. I also made sure that when I did this, I cut the ply back from where the chainplates would pass through and back filled with epoxy. Any water leaking around the chainplates will not be in contact with the ply core.
I have gone down the road of building up a fillet of butyl mastic around the chainplates and that seems to help, but is not 100% effective. The only way to stop the leaks is to put chainplate covers on the deck with sealant underneath. (www.rigrite.com/Hardware/Chainplates_&_Stemheads/Chainplate_Covers.php)
I have the covers, but haven't installed them yet as it will need me to pull the mast down and disconnect all the rigging.
Select to expand quoteMicrobe said..
I had a similar issue with through deck penetrations for rigging attachments allowing water to get into the ply core, cause rot and delamination of the deck. I ended up cutting out a section of upper side of the deck, digging out the rotten ply, glassing in a new core and laminating a new top section. Then I built new bulkheads and through deck chain plates to strengthen everything. I also made sure that when I did this, I cut the ply back from where the chainplates would pass through and back filled with epoxy. Any water leaking around the chainplates will not be in contact with the ply core.
I have gone down the road of building up a fillet of butyl mastic around the chainplates and that seems to help, but is not 100% effective. The only way to stop the leaks is to put chainplate covers on the deck with sealant underneath. (www.rigrite.com/Hardware/Chainplates_&_Stemheads/Chainplate_Covers.php)
I have the covers, but haven't installed them yet as it will need me to pull the mast down and disconnect all the rigging.
Can you not just do one at a time, if necessary using a halyard to provide extra mast support??
It's only a 22 ft boat, so pulling the mast down is not too difficult really. It's something we do regularly to get under the bridges at Freo.
Plus I need to run a new topping lift and replace the masthead windex, so dropping the mast is required.
I made it sound like a difficult job to try and hide the fact that I just need to pull my finger out and do it. 
