H27 mast compression problems

[heritage]

The sliding door between the saloon and the head will not close all the way because the port side of the ceiling has dropped about 1/2" when compared to the starboard side. Not sure how to go about doing a permanent fix because I don't how the mast/compression post area is constructed on the 27. The compression area on the bottom of the post is a mystery also. I've seen some pics of the H30 where you can see an iron support plate under the post from the bilge. Can any shed some light on the H27 construction?

 

[David in Sandusky]

Here is a good discussion of this issue, including a detailed description of my solution:

https://forums.sailboatowners.com/i...compression-post-interface.34554/#post-163661

The mast step construction top down is:

1. Aluminum mast "boot." Ours was fastened down with 1/4 inch bolts running through all of the following layers, with nuts in the cabin near the compression post.
2. Fiberglass layer over the step structure.
3. T shaped plywood reinforcement of the mast step area.
4. Fiberglass top layer of the deck.
5. Balsa core of the deck. (Some have found plywood here.)
6. Fiberglass bottom layer of the deck.
7. (Detached) cabin liner.

Good luck! This is a doable repair, and it is time to do it! (Or have it done.)

 

[heritage]

Thanks David. The info in the link answered a lot of questions. I suppose that the balsa and plywood cores under the mast step are the primary supports for the mast. If they get soaked with water, they lose their connection to the fiberglass panel and can no longer add much support to the mast. In your link, one of the fixes was to remove some of the wood and epoxy in an aluminum plate. This would spread the load more evenly on both sides of the compression post. On my boat its the port side ceiling that has dropped.

 

[David in Sandusky]

When you pull your mast to have access to repair the step, the deck may recover something like it's original shape. Ours did.

You could replace the rotted deck core ( probably balsa) with balsa, a plastic substitute or aluminum. We liked the way the aluminum plate spreads the load, and prevents deformation of the deck. I would wait until you see how much deck core is rotted before deciding on an approach. You may want to combine an aluminum plate with balsa depending on the size and shape of the core you need to replace.

 

[dakno]

How does your floor under the compression post look? I bet you have a deflection, sinking floor there under the post. Hunter had the outer hull, then the inner liner. In between the 2, under the compression post Hunter laid 2 blocks of wood that look like 2x4's flat , one on top of the other. This was /is the support from outer hull to the inner liner. Over the years water in the bilge rots this 2 blocks. The repair is to remove the mast, compression post, cut the liner floor under the post, remove decayed material, install new spacer between outer hull and liner floor, patch liner, make a metal plate, wood block to cover the repaired area, and reinstall a compression post to get your cabin top where it belongs. Your bulkhead door should slide freely. On my 27 the cabin top was 100 percent intact, all the deflection was in the floor.

 

[heritage]

Thanks for the reply Dakno. I was curious about what was under the compression post. In the larger Cherubini Hunters a metal insert was used under the post and is visible from the bilge, but on the H27 the area under the post is completely sealed off except for the small hole that drains to the bilge. I didn't notice any deflection in the floor around the bottom of the post, actually I assumed that the post penetrated the pan floor and bedded on the keel stub.