Was replacing the hoses and waste tank hoping to rid the boat from some unpleasant smells. Had to cut the tabbing off the plywood holding the tank in. Tank came right out after cutting.
Ordered the tank from Ronco, they have the dimensions on file and are just super. Sent them some pictures of the ports so they know where to put them. Left off the port that went to the overboard discharge as we are on the Great Lakes and would never have a place to dump overboard. While the tank was out was looking at the thur-hull and decided would never be more room than now to replace (going to use in future for a/c).
On the flip side of the hull and water system decided to replace all the hoses and valves on the fresh water side along with the hot water tank. Again when all the stuff was removed decided to do the two thru-hulls on that side. Again access was great at this time.
So the question is what is the sealer of choice for the new seacocks, yes installing true seacocks with backing plates.
Also putting in a Bosch under cabinet mount hot water tank. I know i will not be able to make hot water under way but after a conference with the Admiral she is fine with that. This removes the two long hoses from the engine and the problems they bring.
The guru, MaineSail, recommends Sikaflex 291. He is strongly against 3M 5200 as being too strongly adhesive, but says 3M 4200 is okay. Remember, you will not get a lot of differential motion once it is tightened, so super strong adhesion is not critical.
I recommend reading his excellent two articles on the topic:
https://marinehowto.com/replacing-thru-hulls-and-seacocks/
and
https://marinehowto.com/seacock-thru-hull-primer/
His other articles are great reading too.
Jeremy
Thank you for the links missed those :?