H49 Selden Furling Mast Base Plate replacement

[CliveCollett]

Hi All
Has anyone had the mast base plate replaced on their H49?
Ours has developed a crack on the side.
Trying to figure out how its all put together and if access under the deck is required.

It looks like a plate is attached to the deck and then the mast base plate is attached to that.
Any information welcome.

 

[kloudie1]

Strange, looks like "corrosion jacking" from a piece of iron or steel between the two plates.. the corrosion product is many times more volume than the base metal, so if someone used a shim between the plates and it corrodes, it swells up and cracks the weakest point.. I don't have experience with that step, but most likely will need to have mast removed and the base plate welded by a competent aluminum welder.. The base is under compression against the lower plate so the mast itself is not in danger.. The only thing I see is that the base pulley block at the crack may break out if loaded heavily..

 

[Rick486]

I suggest making contact with Selden and bring them on board this discussion.

 

[CliveCollett]

So....No one has any information about how this is fitted to the H49??
Selden not required as I have a yard with a replacement part ready to go.

 

[artboas]

So....No one has any information about how this is fitted to the H49??
Selden not required as I have a yard with a replacement part ready to go.

First step is to pull the rig. It will likely become more apparent at that point

 

[CliveCollett]

I have that scheduled for this week. The yard seems to think its through bolted and will need access to the underside. This will mean pulling down the headlining. I was hoping to find a definitive description of how this is attached. As Hunter often fitted plates in key areas that are glassed in as part of the hull it would make sense in this case.

 

[artboas]

Contact SBO, and pay for a consult with Mr. Kerr. He will have the answer. No need to guess

 

[CliveCollett]

So as a follow up. Once the mast was removed the 4 Phillips set screws (one in each corner) needed to be removed.
It transpires that these are M10 countersunk, 120mm long and go through the mast base plate, through a stainless steel plate on top of the deck (we will circle back to that) into the deck and go into a threaded plate encapsulated in the deck (As I had hoped). They are NOT bolted through with nuts on the end so no headlining removal required.
They were very difficult to remove and required a powerful air wrench. Where they go through the mast base plate, the different materials cause corrosion which swells around the set screws. 2 came out ok after allot of persuasion, the last 2 had the heads drilled off and then the plate was removed. After that, they came out by hand.
The stainless plate that sat under this mast base plate is actually the top of the compression post and a ring was evident where it was welded on. THIS was the cause of the corrosion swelling that cracked the plate. Once moisture got under the plate, it was only a matter of time before the dissimilar metals reacted.
A Teflon sheet was used as a barrier for the new plate along with new 100mm set screws.

Plate with mast removed

Close up of crack

Underside of plate once removed

120mm long M10 countersunk set screws. These did not need to be this long. 100mm was fine.

Stainless plate on top of the deck. The ring is where the compression post is welded on.