Re: Compression post repaired
Ok, I have some deformation at the top, cabin sole, and bulkhead self in the compression post area on my Islander 28. I came up with this thread when I searched my problem. Therefore, I am posting on this old thread to keep the subject matter together. No pictures of the issue were ever posted, and I have some, "pictures are worth a 1000 words".
On surveying the issue, I believe many Islander 28 owners will have experienced the problem, and looking for how the problem was corrected. I have a few ideas, but need some experienced advice.
First, I noticed under the cabin sole there are two cross supports under the compression post area, marked "A" and "B" in the third picture. These two cross supports ARE NOT the same height at original construction of the boat, which doesn't make since, because the 3/4 inch plywood floor would surely deform in this area with the pressure of the compression post. So, to fix this problem, I will have to add material to the lower one to meet the higher one. I plan to use epoxy glass reinforced, I have to make up about 5/16 or so. Doing this will make part of the head sole a different height, I will have to even out the floor by feathering the fiberglass material to meet the old floor.
Second, none of my wood is rotten, so removal of the 3/4 plywood cabin sole, the 3/4 plywood square under the wood 4x4, is going to be a tough job. I need to remove part of the sole and the 3/4 plywood piece under the wood 4x4 that forms the corner of the head in the bulkhead area. I plan to replace both pieces with GP03 Electric Grade fiberglass. I can buy it from McMaster Carr in many different sizes and thickness, and I can easily epoxy or resin it to the fiberglass floor and supports.
So, I'm going to loosen all of the rigging and jack up the cabin top at the metal compression post area, as mentioned earlier in this thread to perform the cabin sole repair.
I still have several issues with the current compression post design, the plywood counter is between the wood 4x4 and round metal flanged post. So, once again plywood is bearing the load, not good, and deforming at this location too. The deformation is actually recessing the counter top. So, I was planning to cut out the counter top the same diameter as the flange, remove it, and replace it with the fiberglass board or delrin, a high density plastic. If I cut a hole in the counter top, the two piece compression post would no longer have the counter bulkhead keeping the compression post plum to each other or the cabin top. My question here, would I need to attach the 4x4 wood portion of the compression post to the cabin sole to keep the post plumed to the cabin deck?
I was even thinking about removing the wood 4x4 and extending the metal post to the GPO3 fiberglass by making a matching metal post section to bolt to the current one and bolt it to the GPO3 fiberglass. I'm not sure if I should bolt it to the cabin sole if I go this route, the current set up is not fixed to the cabin sole.
I believe the total deflection at the cabin deck, picture one, is equal to the deflection of picture two plus the deformation of the counter top. You cant really see the actual deformation of the counter top in picture four because it is all around the metal flange, but it is around 3/16, it is NOT the deflection you can see of the counter top to the bulkhead wall, which you can see because of the different wood color.
So, do my ideas seem good or should I try something else?
What are your thoughts?
Last edited by 510datsun; 04-03-2012 at 02:13 AM.
Reason: change photo