336 compression post dropping

[amystic]

The compression post on my 1995 336 seems to be sinking into the cabin floor. As result my floor is sagging a little and the top deck by my mast step is depressed a little and holds a little bit of rainwater. I see from other posts that it may be wood rot beneath the compression post. I removed my floor boards and I see the post sitting on 2 - 5 inch by 7 inch stainless steel plates. these plates are held in place by 4 lag screws one at each corner. They are screwed into a fiberglass mass underneath. I do not see any rotten wood only fiberglass. I plan to repair this problem this winter and would like advice on doing this repair. Some posts have said that there is a piece of wood within this fiberglass that needs to be cut out and replaced. I would like to know just how much needs to be removed before I start cutting. If anyone has done this repair job I would appreciate some advice.

 

[robertsapp]

There's no wood under the post. It sits on a stainless fitting that is bolted into a fiberglass stringer that's part of the hull liner. That in turns sits on the hull forward of the keel stub. I've asked Hunter about this in the past, and they've said if the post base is sinking, drill holes into the stringer under the post and inject epoxy into it. That should stabilize it and keep the post from sinking any further. You can then use a fiberglass shim under the post base to restore it to the original height. This won't cure any sag in the cabin sole around the post base, but it will fix the problem up on deck with the base of the mast becoming depressed. Naturally, you'll have to take the rig down to do it right.

 

[amystic]

Robert thank-you for the insight. Since I now know that there is no rot in that fiberglass the base is sitting on I am going to try to slip a couple more aluminum plates between or under the existing plates. I will make them the exact size and drill holes to match in the 4 corners and the get some lag screws that are just a bit longer. Now here is my idea. I am going to have a welding shop make me a shaft with a tab/hook on the top that will fit into the slot near the top of my compression pole. I will design this shaft with a larger flat surface on the bottom to allow a bottle jack to be placed under it. I will make this shaft out of angle iron or iron pipe. I will remove the table temporarily. I will have to leave the adjustable cylinder that holds the table but I see that if the cylinder is turned properly it will allow room for a shaft to be positioned parallel close to the compression post. I will then chain or heavily strap this shaft I made to the pole and then place some 4x4 lumber across the floor and place a bottle jack under the shaft. I will loosen all standing rigging and then jack the pole up just enough to slip a couple of additional plates under the post. I figure a couple hundred bucks to get the shaft fabricated. I may try this this winter. If it works I will let everyone know. My problem may not be that big of a deal but I just dont like the puddle on top of my boat. I also suspect that the settling of the fiberglass base has just happened over time and may have now settled all its going to settle.

 

[Mcksailor]

Are you sure the post is sagging and not just the deck compressing from rot? Suggest not using epoxy injections but cutting out the rot and replacing it with foam board, rot resistant and stronger then wood. Local boat builders and fiberglass companies will give you good advice. Take lots of pictures and ask around. Befriend an old ship builder and pick their brain, they may seem crazy but know what they are talking about.

 

[Ray Bowles]

Amystic, I am not knowedgable of your set-up but I did a simular job on a Catalina. I like the use of metal rather than fiberglass. One thing I would say is to use all SS rather than mixing the aluminum and SS. There are electrolysis issues if these are mixed.
Ray

 

[robertsapp]

Robert thank-you for the insight. Since I now know that there is no rot in that fiberglass the base is sitting on I am going to try to slip a couple more aluminum plates between or under the existing plates. I will make them the exact size and drill holes to match in the 4 corners and the get some lag screws that are just a bit longer. Now here is my idea. I am going to have a welding shop make me a shaft with a tab/hook on the top that will fit into the slot near the top of my compression pole. I will design this shaft with a larger flat surface on the bottom to allow a bottle jack to be placed under it. I will make this shaft out of angle iron or iron pipe. I will remove the table temporarily. I will have to leave the adjustable cylinder that holds the table but I see that if the cylinder is turned properly it will allow room for a shaft to be positioned parallel close to the compression post. I will then chain or heavily strap this shaft I made to the pole and then place some 4x4 lumber across the floor and place a bottle jack under the shaft. I will loosen all standing rigging and then jack the pole up just enough to slip a couple of additional plates under the post. I figure a couple hundred bucks to get the shaft fabricated. I may try this this winter. If it works I will let everyone know. My problem may not be that big of a deal but I just dont like the puddle on top of my boat. I also suspect that the settling of the fiberglass base has just happened over time and may have now settled all its going to settle.

Why not just take the mast down? You can then check all your rigging aloft, wiring, maybe add a TV or WiFi antenna or some spreader lights, upgrade your anchor light to LED, AND fix your compression post problem without having to work around the compresion post and mast.

As for the potential for future settling, I would think that once started, the process of plastic deformation doesn't usually just stop. Fiberglass doesn't work-harden as metal does.

 

[amystic]

Thanks Everyone,
I don't believe it is the deck compressing because I assume that the compression post is in direct contact with the mast base via the mast step. I also see some sagging in my cabin sole which is about the equivalent to the sagging of the deck adjacent to the mast step. I will verify the metal involved and I will use matching metals. Thanks for the suggestion.

If after this fix I continue to see a problem developing I will have to look at the fiberglass material under the base plate.

Why not take the mast down? I am on an inland lake which is predominately power-boaters and finding someone with expertise is rare and expensive. I will consider the take down for the reasons you suggest but I may try my system for a quick fix. I will keep all advised of my project this winter.

 

[amystic]

here is my fix with pics

OK I finaly got around to implementing my theory and It worked. I did not have a metal bar fabricated. I used wood and it cost about 20 bucks for materials and worked well. I also cut some 5x7 spacer panels out of some composite type kitchen cutting boards you can find at walmart for a few bucks. I cut several panels with differeing thickness because I did not know how thick I would need so I knew I could use one or two of various thickness to be able to vary my final thickness adjustment. First I loosened the 4 standing rigging turnbuckles as loose as they would go. I kept count of the turns and made all equal turns and retightend equal turns after I added spacer plates so I knew the tuning would be the same. I removed the table from the height adjustment clamp that moves up and down the compression post.

I then cut some 4x4 posts to make 2 risers and one cross piece. I placed the risers and the cross piece just aft of the post base. The risers were placed on solid areas of the fiberglass substructure. This allowed a bridge I could work under. see pics. I then placed a small bottlejack on the cross piece. I cut a vertical support with a slight angle on one end. I lashed the vertical to the compression post with straps. The vertical ran from the jack on the bottom up to the table height adjustment clamp. It is very important to move the clamp all the way up and wedge somthing ( I used a big socket extension) into the little hole at the top of the post where the flat pannel of the clamp device is snug aginst the socket extension or hatever you use for this. This will keep the clamp device from sliding up when you crank up the pressure on the jack. see pics It is also important to cut the top of the vertical 4x4 with a slight angle at the top where the only contact that the vertical makes with the flat part of the support is very close to the compression post so you do not bend the flat support part of the height adjustment device that the table is screwed to. see pics

I then jacked up the compression post just enough to slide in 2 layers of spacers that I cut from common cutting boards. I replaced the existing lag screws with some a little longer to accommodate the additional thickness. see pics I then removed all the support wood and the jack and tightened the turnbuckles down to a point approximately above the point equal to the thickness of my spacers. Be carefull not to raise the base plate to much with to many spacers or the flooring will rest on the lag bolt heads and be uneven. If this happens you can drill some shallow counter holes in the underside of the flooring to allow extra room for the bolt heads.

This whole process took me less that 2 hours and I feel very good that my top deck just around my mast step now does not have the slight depression that held water. The total amount I raised the mast base was about 5/8 of an inch.

Of course this whole correction repair process is based on the fact that the compression post base has settled all its going to. I believe there will be no more settling and what settlement happened over the 20 year life of the boat.

Now on another note. The flooring around my compression post base has rotted because it stays moist from watter running down from the mast. I just wanted to report that I suspected there was dirt in the bottom of my mast. There is a dime sized hole in the front of my mast about 2 inches up from the bottom of the mast. I took a stiff piece of wire and disturbed the layer of dirt that was covering inside the bottom of my mast then took a piece of small tubing and attached it to the end of my shop vac and I actually sucked out about a pound and a half of fine dirt. It is no wander the weep hole was getting clogged. I hope this helps my moisture problem. I think the dirt came from dirt dobbers making nests inside my mast over the years.

 

[amystic]

OK I finaly got around to implementing my theory and It worked. I did not have a metal bar fabricated. I used wood and it cost about 20 bucks for materials and worked well. I also cut some 5x7 spacer panels out of some composite type kitchen cutting boards you can find at walmart for a few bucks. I cut several panels with differeing thickness because I did not know how thick I would need so I knew I could use one or two of various thickness to be able to vary my final thickness adjustment. First I loosened the 4 standing rigging turnbuckles as loose as they would go. I kept count of the turns and made all equal turns and retightend equal turns after I added spacer plates so I knew the tuning would be the same. I removed the table from the height adjustment clamp that moves up and down the compression post.

I then cut some 4x4 posts to make 2 risers and one cross piece. I placed the risers and the cross piece just aft of the post base. The risers were placed on solid areas of the fiberglass substructure. This allowed a bridge I could work under. see pics. I then placed a small bottlejack on the cross piece. I cut a vertical support with a slight angle on one end. I lashed the vertical to the compression post with straps. The vertical ran from the jack on the bottom up to the table height adjustment clamp. It is very important to move the clamp all the way up and wedge somthing ( I used a big socket extension) into the little hole at the top of the post where the flat pannel of the clamp device is snug aginst the socket extension or hatever you use for this. This will keep the clamp device from sliding up when you crank up the pressure on the jack. see pics It is also important to cut the top of the vertical 4x4 with a slight angle at the top where the only contact that the vertical makes with the flat part of the support is very close to the compression post so you do not bend the flat support part of the height adjustment device that the table is screwed to. see pics

I then jacked up the compression post just enough to slide in 2 layers of spacers that I cut from common cutting boards. I replaced the existing lag screws with some a little longer to accommodate the additional thickness. see pics I then removed all the support wood and the jack and tightened the turnbuckles down to a point approximately above the point equal to the thickness of my spacers. Be carefull not to raise the base plate to much with to many spacers or the flooring will rest on the lag bolt heads and be uneven. If this happens you can drill some shallow counter holes in the underside of the flooring to allow extra room for the bolt heads.

This whole process took me less that 2 hours and I feel very good that my top deck just around my mast step now does not have the slight depression that held water. The total amount I raised the mast base was about 5/8 of an inch.

Of course this whole correction repair process is based on the fact that the compression post base has settled all its going to. I believe there will be no more settling and what settlement happened over the 20 year life of the boat.

Now on another note. The flooring around my compression post base has rotted because it stays moist from watter running down from the mast. I just wanted to report that I suspected there was dirt in the bottom of my mast. There is a dime sized hole in the front of my mast about 2 inches up from the bottom of the mast. I took a stiff piece of wire and disturbed the layer of dirt that was covering inside the bottom of my mast then took a piece of small tubing and attached it to the end of my shop vac and I actually sucked out about a pound and a half of fine dirt. It is no wander the weep hole was getting clogged. I hope this helps my moisture problem. I think the dirt came from dirt dobbers making nests inside my mast over the years.

Just for everyones info here is some more discussion on the subject;

In reference to the cabin sole (teakwood floor) I dont really have a problem. You can see in one of the pictures that it seems that some of the narrow fiberglasss bridge that runs just behind the post base is sagging downward. I assume this was not like this when the boat was new. My sole around the post base does seem to lack some support due to this sagging but the floor boards remain straight. I plan to glue in some thin wood shims under the wood floor to create more support. My main concern was always the slight depression of my top deck near the bottom on the mast.
My biggest issue now is the rotting and delamination of the floor wood around the compression post base. It is as if water ran down the post and saturated the wood near the post. I have removed lots of dirt from inside the mast base and cleaned the weep holes and hopefullly this will help to keep the problem area dry. My rot was so bad that I have now cut it out causing a little bigger hole in the floor. I found a nice round peice of wood at my local lowes and it is the perfect coverup for this hole. I will post some pictures of what I am talking about tomorrow when I go to the boat. I can always rebuild some new floor pannels but as log as this big round peice of wood looks ok I will put that job off.

 

[amystic]

As I said I had a little rot around the base of my compression pole from water intrusion. I had to cut out a much bigger circle to remove the rot then I still had to re-laminate some of the areas. I did this by forcing carpenters glue in the loose layers of the floorboard and the clamped and allowed to dry. (see pic).

I then found this big round wood shape at Lowes and cut, stained and sealed it and use this to cover the ugly hole. My wife says it looks like crap but I say It beats replacing the floor boards for now. (see pics)

I also wanted to show the sophisticated piece of equipment I used to suck the dirt out of my mast base. ( flexible piece of tubing with my vacuum) I also wanted to show the dime sized hole in the front of my mast. This may be from the factory or some previous owner may have drilled this hole. (see pics)

I also attached a pic of the small wood shims I installed to support the floor where a slight sag has occured in the fiberglass bridge just aft of the compression post.

Finally I am happy to report that after all this effort the drain system on my mast, step and post seem to be working the last picture shows evidence of water and dirt flowing out of the weep hole at the bottom of my compression post. I also believe that the fact that the wood flooring has been cut away from the compression post base will allow any water that makes it down the post to run into the bilge and keep it from wicking into the wood flooring and causing further rot.

 

[heritage]

Looks nice, Amystic. Go easy when you re-tune your standing rigging. It doesn't take much over torquing of the turnbuckles to distort the shape of the boat. This will cause a depression of the deck at the base of the mast and a slightly narrower boat. It's not so apparent on keel stepped boats as the mast is able to move freely through the deck.

 

[amystic]

You know that's a good point. I purchased this boat last spring and I am no expert by far but the shrouds seemed extremely tight. I actually did not tighten them quite as much as they were prior to my rework for exactly that reason. Now that I think about it this may have contributed to the problem over the years.