Replacing maststep core rot. Step shape

[gramparuve]

I am planning on replacing my rotten mast step and the core in the deck around it on a 78 Hunter 30'. Does anyone know if the rounded "T" shape of the raised step has structural importance? Could the deck be smooth here? It would loose about .5 of height, adding slack to my stays.

I am also replacing the section of rusting "I" beam that is beneath the compression post with some aluminum or stainless steel.

(Also any suggestions on the best core material for largis sections of deck with a slight curve? I don't think Coosa is very flexible- This could be another forum question)
Thannnnkkkkss!!!!

 

[David in Sandusky]

I suspect the rounded "T" shaped base was a way of beefing up the cabin roof to spread the load of the mast. When we did this repair on our h27, we retained the shape. We replaced our rotted core wood with a 1" aluminum plate bedded in epoxy to fit the curved shape of the step area, and the irregular shape of the rotted wood we pulled out once we got it open. I had a fiberglass expert do the repair, and it has lasted 14 years now with no hint of a problem.

 

[gramparuve]

Thanks David!

 

[Ben Jammin]

My boat has the same issue with the rusted I beam, apparently like almost all Cherubini Hunter 30s used in saltwater. My mast step also appears to be sagging, so I may have problems there as well. I haven't repaired mine yet, but noticed that there is a wealth of info in this forum about both the compression post and the mast step area. I found one repair that as a mechanical engineer, I thought looked particularly structurally sound to me, and noticed that the owner was in my area. So I contacted him and he showed me what he did. I plan on doing what he did for the most part, but I may use G10 in the bilge and tie it into the sides as well as having it set on the keel. I'm thinking a 1" plate flat on the bottom and on the top with a vertical longitudinal 1" plate to basically replace the I-beam. Plus I plan on adding a lateral vertical plate to tie into the hull and reinforce the forward keel mounting area. Tying into the hull was recommended by the forum member that goes by Diana of Burlington. He has experience with these boats from an early age, so I take his recommendations seriously.

Here's the thread by H30Gary on replacing the compression post (also addresses fixing the mast step area).
https://forums.sailboatowners.com/index.php?threads/h30-replacing-the-compression-post.160382/

 

[DianaOfBurlington]

Please search the archives for the post I wrote about replacing core material in the mast-step area. A (very strong) caveat: cutting out a section of deck skin and stuffing in a block (of any size) of rigid core material and patching it back over is NOT sufficient for a deck-stepped mast step. The proper way to do this is with poured-in-place epoxy-- unless you want to re-'glass a substantial area of the whole deck structure. This is NOT a place where you can snip out the core stratum and put in a patch. I've seen people say that for this they can/should/will/did use blocks or pads of koosa, plywood, solid fiberglass, metal, even StarBoard (the very worst) and, with respect, none of them are professional boatbuilders and few of them understand what bad choices these all are.

I've preached on this several times but if you search by my user ID you can probably find the one post I'm recollecting. Take care.

 

[DianaOfBurlington]

BTW I also answered the question of the H30's aluminum I-beam. That one's posted in my blog (Diana's Blog on Blogger).

 

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[GorillaToast]

For those that are interested, this is a pic of a 1/2" hole as viewed from inside the cabin next to the compression post on a h27.



It appears the glass is 1/2" - 3/4" thick in the area under the t-shaped platform. Above the glass is an 1/8" aluminum plate and a thin wood core above that.