Deck Collar

[swhfire21]

I knew I had a soft spot to be repaired at the base of the mast and started on it today (I chose to have the boat hauled to my yard and skip boating this summer to get things right ). It appears that the offending moisture was introduced by the through bolts that held the mast collar in place.

The mast collar consists of two pieces of aluminum as shown in the pictures with a rubber/plastic spacer (partner?). This thing seems have been built (or improperly installed?) to ensure water passed below as the two piece of aluminum have a channel (about 3/8" high X 3/4" wide) in the middle with no gasket/sealant. The only sealant was between the smooth face of the lower piece and the deck. The through bolts pass through both pieces then the deck.

Has anyone ever worked with a deck collar like this and know how it is supposed to be installed. I was planning on filling the channel with silicone sealant to make an O-ring (I was contemplating silicone as I'd guess there is a bit of movement between the two halves) then poly to the deck.

Thanks,

[mgphl52]

I would strongly suggest NOT using silicone! Instead, use plenty of rubber butyl tape. It will very well and allow ample movement without breaking the seal. When "sealing" is thr primary goal (vs adhesion) I always use rubber butyl tape.
After installation, it is very easy to remove the excess.

[swhfire21]

Someone got back to me and reported that the two pieces are intended to provide a groove around the perimeter of the collar. This groove was used for old tie-on mast boots.

When I re-core the deck and reinstall the collar I'm planning to pour epoxy plugs for the through bolt holes to prevent core intrusion should it ever leak again. Also, I plan to seat the collar on the deck with butyl rubber and to chamfer the bolt holes.

I'm still uncomfortable though with bolt passing through sealant without the bolt heads there to compress any sealant that squirts up through the holes. Just seems unnatural.