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Finally finished the compresion post repair. Took the better part of a day. I loosened the turn buckles, and jacked the mast up.The compresion post came out of the floor easily (no rot at all). I epoxied two aluminum plates under it like a pyramid. Very clean and works well. I appreciate all the advise given.
Sailho
 

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I am close to purchasing 78 Islander 28. My surveyor found rotting plywood in the bilge at the lower end of the baffles that become structure for the floor and one which the mast compression post bears on. Have you found similar issues in your boats? My surveyor thought it wasn't super major b/c there was plenty of solid wood where it was needed, but it needs to be fixed. The owner offered to make it right and cut out the rotting wood and glass in new.

Have any insights or thoughts?

Thanks!
 

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I am a new owner of a 1978 Islander 28 and have a compression post issue as well. The other threads indicate removing the existing post and replacing/shimming the bottom end to restore the correct height. Looking in the head, there appears to be a post in the corner of the bulkhead and inner cabin wall. Is that what has to be removed? When lifting the floor bilge boards I can see a plywood plate on top of the stringers but do not see any distortion or collapsing. The oak shelf above the table has cracked and distorted due to the compression loads and I would like to restore it if not too difficult. Any suggestions?
 

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I changed out the plywood with 3/4" of AL plate. The material needs to be large enough to cover both of the floors which are (basically) located under the compression post built in to the corner of the head enclosure. I built the plate wide enough to spread the load to within a few inches of the hull. Not to close, you don't want to build in hard points....

I had the cabin sole out from the middle of the head door aft to the companionway steps to permit other repairs so I had full access. If you carefully cut the sole out aft of the head, about a foot, you should have enough room to do a similar repair and then cut to fit and reinstall the original plywood.

One change I would make is provide either a slick bearing surface for the post to "work" on of perhaps add provisions to shim the bottom of the post. Under a hard sail the bulkhead sometimes growls as the boat hull flexes under load. Need pictures?
Paul Comte
Milwaukee, WI
Islander 28
 

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Thanks for the prompt response. I can see a piece of ply across 2 stringers which I am assuming is the plywood to be replaced. How is the post attached to the bulkhead between the cabin and the head itself? I would assume the lightening ground runs through the post?


Pics would be great as thery are usually worth a thousand words (or so).
 

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Well "Sundayflyer32", I don't know why those other folks are ripping that post assembly apart. Unless the post is rotten, I can't see any reason to replace it. (even if split I'd install carriage bolts through it...) Also, I can't see how replacing it will address the source of the problem, i.e., the poorly supported, under-strength, doomed to be crushed plywood cabin sole.

BTW, that is not Bob Perry's problem but is Islander's engineering interpretation of his design.

Paul Comte
Milwaukee, WI
Islander 28

PS, On our boat, the Ground cable and mast electrical leads run down the starboard side of the post covered by a piece of wood trim. pc
 

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Paul Comte pretty much nailed it. The problem results from placing two pieces of plywood under compression. As most of us understand, resisting compression isn't something plywood is supposed to do, especially in a damp environment. Apparently the engineers who actually built the boat didn't know or didn't care. Because of deck leaks around the mast, our '79 Islander 28 had both the 3/4" plywood sole and the 3/4" plywood countertop rot and collapse which resulted in the mast dropping well over 1". The wooden post you mention is firmly attached to the bulkhead so unless it is rotted I would leave it alone. When you jack up the mast, gaps will appear above and below the wooden post as the weight comes off and you can chisel out the old plywood. Replacing the teak veneer countertop was a major proposition which involved removing all those beautiful teak plugs covering the wood screws on the counter rail, jacking up the mast and pulling out the remains of the countertop to use as a template. When we replaced the countertop, we left a circular hole in it the size of the bottom of the steel compression post and cut an aluminum disk to fit between the steel post and the wooden post that you see in the head. Be sure to leave a slot in the disk for the mast wiring. On the bottom, we cut away the sole and placed more aluminum plates bridging the two stringers in the bilge. Because we were replacing 3/4" plywood we backfilled with 3/4" aluminum sheet stock. If you are going to replace the countertop, I would also recommend treating the sole as well even if it doesn't look bad right now. You don't ever want to tear things up again. We did all this in our marina berth with the mast stepped using a 2 ton hydraulic jack but it requires nerves of steel to listen to all the cracking and creaking as the mast comes up. My wife had to leave - I had to have a ration of grog. It would be much easier to do it on the hard with the mast removed. Sorry for the long reply. I suppose I should have just sent some pictures. Please let me know if you have any other questions.
 

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"and cut an aluminum disk to fit between the steel post and the wooden post that you see in the head. "
Aluminum plate, or unknown alloy, next to steel? If you don't insulate the two (i.e. put in a piece of UHDPE) you are likely to get galvanic corrosion there in a mainre environment.

I've seen Bob Perry's drawings for the I28 and they show several differences from the production boat. One of them is what appears to be a sensible keel-stepped mast instead of the offset kludge that actually got built. But, of course, if they'd built it with a simple mast they couldn't have shown the pictures of the "huge" open interior, which probably sold more boats for them than anyone asking about how well plywood would age. But at least for the deck and cabin top core, they did use Bruneel plywood, which ages like iron.
 

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Thanks "Hellosailor". You are absolutely correct about the need to isolate two dissimilar metals and anyone else unfortunate enough to attempt this repair should heed your good advice. Even more galling is the fact that I had a sheet of UHDPE laying around at the time. On the other hand, here's how I can avoid not sitting bolt upright in the middle of the night in a cold sweat and immediately jacking up the mast to insert said dielectric material. As you know, the rate of galvanic corrosion is dependant upon the amount moisture and the duration of it's presence. Obviousy, the more moisture for a longer period, the better the "battery" so to speak. What caused my problem in the first place was a leaky deck around the mast which I hope I have a least slowed down. "Dry" is impossible on a boat for a lot of reasons but at least water no longer constantly drips onto the counter and compression post. I have achieved "pretty dry" in that area. So although galvanic corrosion is doubtless occuring even through the thick layers of factory black paint on the steel compression post, it's the rate of corrosion I'm considering late at night. At the magical age of 64, I'm willing to bet that my personal rate of decline (and probably that of my 30-something boat) will exceed that of my repaired compression post. Thanks again for your astute observation.
 

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Re: water intrusion from deck stepped mast. I made a plastic (cheap cutting board) template to locate the wire location under the mast. Use the bolts as an index. Then after removing the mast step casting, I cut an opening around the mast wires at the cabin top. I slid a sleeve of bicycle inner tube over the wires and then a threaded bronze nipple over that. (use the largest one you can make fit) I made gummy ball of thickened epoxy to plug the bottom of the hole I'd carved in the cabin top and then filled in around the threaded part of the nipple with a more wet thicked epoxy mix. The template comes into play locating the nipple so the mast step casting is not interfered with... I have a piece of hose over the wires and onto the nipple. The hose is folded inside the mast so water cannot enter the boat in this area - period! I didn't need the nipple and a thinner stainless tube could work as well - but I had the nipple already...

The following year I addressed the dimple which had been driven into the cabin top by the previously unsupported mast loads. I floated a mast step turning plate on a bed of thickened epoxy (used nylon washers to shim it properly, a dab of five minute epoxy would hold them in place.) The trick there was to make sure the step wound up perpendicular to the where the mast should point... You get one easy chance at this so get those shims glued and mask the area around plate on the cabin top (doing it again, I might use a bead of silicone caulk as a dam to control the epoxy flow.) I've got a dry boat, and with the plate and turning blocks, am taking more loads and leaks off of the cabin top...
Paul Comte
Milwaukee Wi
Islander 28
 

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Quite a project. I'm glad it worked. My approach was no less complicated and started with the observation that the 1979 mast base casting had small divots in the vertical flange on both sides which were apparently to provide a pathway for water to exit the casting. Unfortunately, there were no corresponding divots on the bottom of the factory mast itself. While the mast was off, it was a matter of 5 minutes with a chain saw file to open up divots in the bottom edge of the mast to match up with the holes in the base. As for the wiring, I ran everything down 6" of garden hose which fit quite nicely into the existing hole in the mast base and stuck up 6". There was another smaller hole which I simply threaded and plugged with a matching threaded PVC plug. I fastened the hose in with a good dollop of 3M 5200 caulk. The mast base itself was bedded with 3M 4200 after the usual prep (drilled out epoxy through-deck holes after drying the core, etc.) while it was removed. I filled the garden hose with expanding foam around the wires which could end up too permanent if I ever have to pull the mast again but we're sick of drips. So I figure that unless we forget to check the weep holes occasionally the water will never get 6" deep in the mast. So far, so good but nothing is forever. I figure my point of failure will eventually be the 5200 caulk seal between the hose and the base but if water can't pool up in the base I'll still stay "pretty dry". Our cabin top dimple was not too bad (< 1/8") so we decided to live with it. This can only mean that the entire cabin top deflected down which is probably a bad sign and explains the creaks and cracking sounds as we lifted the mast. As "Hellosailor" pointed out, it also speaks to the stiffness and quality of the deck and cabin top core in the Islander 28. The PO had sadly neglected to maintain his deck fittings so I have had ample occasion to examine the effects of leakage into the core and its durability is absolutely remarkable with nary a soft spot (yet) responding to tapping and discreet drilling.
 

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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?
 

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I'll have a shot at some answers but "experienced" is probably an overstatement of my qualifications. First, even if the fix gets nasty, stick with it because the boat is worth the effort. The Islander 28 is a sound and sweet-sailing boat. What year is your hull because your pictures show something a little different from what I see? For example, the 5/16" difference between the two cross-members doesn't exist on my hull. If I were to do things over again (besides using dielectic materials) I would have pulled the mast rather than jacking it up. We pulled the mast later anyway and I was impressed with how much easier and less nerve-wracking it was not having the jacking system in the way and the mast poised above my head when I repaired the mast base. In my opinion, the plywood-under -compression has got to disappear no matter what - it's just trouble waiting to happen. The all-steel post is a good way to go but it may obliterate the corner of the head bulkheads. The infamous 4"x4" post seems to be in the way so a lot of cabinet work may be needed to put things right. I wasn't worried about keeping everything plumb because the 4"x4" post seemed very firmly attached to the bulkheads, one of which is tabbed to the hull and I had also bolted it to the steel post. I think the entire assembly needs to flex and move a little under heavy conditions and I'm not so certain that everything rigid and firmly attached is the best idea. However, I must admit that the thought of my mast slipping off the compression post and shooting like an arrow through the bottom of the hull is a bit terrifying. My fix seems to be working even after we have been bounced around so I guess it's still better to be lucky than good. I'll try and keep my promise of pictures. Off-topic but how do you intend to deal with the missing vinyl headliner? Maybe on another thread?
 

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Datsun, at this point it is anyone's guess whether those two "beams" were ever supposed to be the same height. "I still have several issues with the current compression post design," But I have seen Bob Perry's original drawings for the boat, and it was designed to have the mast either supported by a simple vertical compression post, or keel-stepped.

Apparently someone at Islander "had a better idea" and used this zany scheme to open up the interior and give the boat a palatial cabin. One might seriously consider throwing out some scrap wood and metal, and installing a simple vertical post, and just telling folks to exhale and squeeze by if they want to go forward of it.
 

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Amen to that! You shouldn't expect to be able to tango in the cabin of a 28' boat. Anyway, it's not that much of a squeeze and that's what I would do if I was starting over with the mast. The boat as built (and properly maintained) is not unseaworthy at all but it would be more seaworthy with this modification. Great design but there are few points where you have to wonder what they were thinking on the production boats.
 

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Datsun,
Go to the 2nd page of the thread titled I-28 Keel Stub Construction, I posted some pictures there of my I28 during the mast step rebuild. I replaced everything below the timber post with solid fiberglass; I made my own ¾ inch fiberglass plate material to replace sole and to build up a new mast step support beam.
 

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Datsun, I have come to the conclusion that these boats are more "plastic" than we think. Everything seems to be moving a bit and maybe that is a survival strategy! I'll try to attach some images of our repair but I noticed our boat is not identical to yours. We have a "sold in" 1979 version...
PC
 

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Ok, Thanks for you replies all!

I have a 1976, I-28, hull #23, I recently removed the tile floor with a drain in to the bilge, a rare shower/head option. Ya, a shower in the head, sure would like to witness that task. I'm lucky to sit on the throne and read a paperback, forget the newspaper.

I have decide to replace the cabin sole with the GPO3 fiberglass, replace the piece between the cabin sole and 4x4 with GPO3 fiberglass, cut a hole in the counter top the size of the flange, and replace the counter portion between the 4x4 and metal post with the GPO3 fiberglass too. I can epoxy the fiberglass to the 4x4 at both ends.

I decided to go that route because it would all be doable by jacking up the mast and kind of a retro-fit, modifying what is already there. I will take pictures of my fix and post them up after I finish the project. It may be a while before I get it done, but I promise to post it up to help I-28 owners having to deal with this issue.

I really like my I-28, and get compliments on it every time I'm out on the water, got one just today!

As for the headliner, I was going to post up a thread on my idea for that fix. So, look for it soon.
 

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In case you are wondering about what GPO3 is, I used it as a spacer when I did my thru-hulls. I used kitty hair, polyester resin with glass fiber, to bond the spacer to my hull. I tapped the spacer and bolted a thru-hull spacer to it. Here is a picture of the GPO3 fiberglass, the red material.

You can see the blue tile floor, too.
 

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510, a lot of the plywood on the I28 is "Bruneel" plywood, which is damned strong stuff. I don't recall ever looking at what that little countertop section is made from, but if that's also Bruneel, it is already as strong as fiberglass. Unless you're planning to refinish the whole strip, it might not pay to bother changing just that bit under the post.

A tile floor...good lord, there's room for a whole new HGTV show, on renovating heads! (VBG)
 
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