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Old 09-04-2013, 13:18   #1
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Compression post repair part deux

I tried to fix this already as you can see. I cut the old part of the beam out as the wood was wet and not holding up as it was designed to. I had the aluminum block machined to take its place and thought I was done with this. Well, you can see the block was about .25 inches too big and the sides of the beam were not supported and this caused the cracking that you see in the pictures.

I've dropped the mast and removed the compression post and I'm attempting to fix this for the final time. I'm planning on doing a sail to Mexico from Seattle and cant be worrying about this damn beam.

I have an idea of how to fix it but I'd like to hear from you guys first on how I should fix this.

as a side note I have no idea how to remove this block. I put some 4200 on it and then it took the pressure of the full rig and is stuck there pretty good. I'm thinking I may have to remove some more of the beam around it to get a better angle at the block to try and bust it off.


Thanks in advance!
-Jared
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Old 09-04-2013, 22:44   #2
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Re: Compression post repair part deux

Hi Jared, say hi to James for me!


That doesn't look good. Particularly in the last pic, it looks like there are substantial stress fractures in the beam. Try to take some better pics and post em. Where's the boat live?
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Old 10-04-2013, 10:45   #3
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Re: Compression post repair part deux

Fingers crossed that it is just the fibreglass that is cracked due to the point loading created from your mod to the mast compression post.........but your comment on the beam being wet and needing partial removal before does not sound promising - could well be that the problem is the beam and not the post........

In any event, I would be getting out the angle grinder for a bit of investigative surgery (and removal of that aluminium block)......with the remedy depending very much on what you find (dry or soggy - if lots of soggy then the beam will always compress / move up and down and therefore the Fibreglass will always crack.....hopefully only a partial cut out, replace and re-fibreglass - maybe with an additional strengthener on the underside of the beam......if dry then I would be looking to spread the load at the top of the post - I would go with a wood strengther (under the beam) that extends say 6 inches either side of the post, 1/2 inch? and butt the post up to that.

But more photos would be useful - especially after investigative surgery........
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Old 10-04-2013, 13:23   #4
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Re: Compression post repair part deux

Can you just cut the post and replace it? I used stainless square tube for mine after removing the douglas fir 4x4.
kind regards,
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Old 10-04-2013, 13:53   #5
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Re: Compression post repair part deux

If I'm seeing it right it looks like you need to spread the load more. You got a crack right where the point loading is. A wider teak or solid wood plank comes to mind...... is that fiberglass "beam" hollow?
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Old 10-04-2013, 13:53   #6
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Re: Compression post repair part deux

Will say hi to James for ya! Boats at Salmon Bay marina, right across the street from SeaMar...

I was lucky enough to find a powerpoint slide of a guy who replaced his on a Hunter 34 with steel square tubing and replaced the beam with a wide aluminum block (2x4x15). That looks like the "right" way to fix this thing once and for all.

I've cut into the beam and the wood was dry which was a surprise considering the first time I cut into the beam it was wet and soggy. I attribute this to the gap the block made that let it air out. Non the less it needs a wider support than just the block

I'll post some pictures as I go. I should have the beam and block out tonight.

I'm trying to find a metal worker though to create a new post from square tubing (within the old compression post so it looks factory) and new beam. Any estimates on costs for such work? I'm a little broke at the second as I'm replacing the standing rigging also at the moment.


Thanks!
-Jared
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Old 10-04-2013, 17:36   #7
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Re: Compression post repair part deux

Quote:
Originally Posted by jared1048 View Post
Will say hi to James for ya! Boats at Salmon Bay marina, right across the street from SeaMar...

I was lucky enough to find a powerpoint slide of a guy who replaced his on a Hunter 34 with steel square tubing and replaced the beam with a wide aluminum block (2x4x15). That looks like the "right" way to fix this thing once and for all.

I've cut into the beam and the wood was dry which was a surprise considering the first time I cut into the beam it was wet and soggy. I attribute this to the gap the block made that let it air out. Non the less it needs a wider support than just the block

I'll post some pictures as I go. I should have the beam and block out tonight.

I'm trying to find a metal worker though to create a new post from square tubing (within the old compression post so it looks factory) and new beam. Any estimates on costs for such work? I'm a little broke at the second as I'm replacing the standing rigging also at the moment.


Thanks!
-Jared

You want Dave White, I'll get his number for ya. All the yards use him. I did this for CB aboard Palarran (Hans 38) at Shilshole last fall, rebuilt the step too. Lemme know if you need help, anything for a fellow mariner you know. Dave is reasonable for what you get.
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Old 11-04-2013, 13:37   #8
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Re: Compression post repair part deux

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Originally Posted by minaret View Post
You want Dave White, I'll get his number for ya. All the yards use him. I did this for CB aboard Palarran (Hans 38) at Shilshole last fall, rebuilt the step too. Lemme know if you need help, anything for a fellow mariner you know. Dave is reasonable for what you get.
I might just do that. More resources the better


I cut into the beam and got one side out. Broke the tool while cutting the other side out.
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Old 11-04-2013, 15:15   #9
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Re: Compression post repair part deux

probably a goood time to rebuild or replace the mast step....or whatever about it that is leaking into your deck core.....you also appear to be suffering a sagging deck--your bulkhead is not a happy camper either----maybe a replacement or rebuilding of the compression post..feather in replacement wood when you remove all the rot...
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Old 11-04-2013, 17:48   #10
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Re: Compression post repair part deux

Thanks for the reply ZeeHag.

Yup. That's what I'm going to do. That area I cut out of the beam is going to be replaced with a solid aluminum block.

The post is going to be replaced by a 2x2 stainless steel square tubing. Which brings up the question of what size and type of steel. .25 inch walled 2x2 tubing sound strong enough? Sure looks a lot stronger than the 4x4 teak post. What grade stainless steel? Something like this (Order Stainless 316 Square Tube in Small Quantities at OnlineMetals.com)


Once the post is made I'm going to epoxy the block up pushing up on it with a bottle jack to raise the cabin a little. I'm not sure how much but I figure I'll keep raising it until the water on the roof wants to run away? Hard to say. a 0.25 inch is my guess.

I'll cut out the old teak post and put the steel tubing in it so it looks factory
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Old 11-04-2013, 18:02   #11
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Re: Compression post repair part deux

mmm . . . when you put that aluminum block in, tapper/scarf the edges into the wood, otherwise you will get a big stress riser at the edges of the block.

And make sure you insulate between the steel post and the aluminum.
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Old 11-04-2013, 18:39   #12
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Re: Compression post repair part deux

That SS post is going to be very heavy compared with a good 4 x 4 wood..... not a good combo with aluminum either. 1/8 wall is adequate in compression. The bigger the tube, the lighter the wall thickness could be and the better the result. I havent run the numbers but my gut says go with a little larger tube even if the wall thickness goes down to .080 or so. Are you going to have the stainless polished? that will cost more than the tube probably. If you are going to paint just do all aluminum. A nice clear vertical grain fir 4 x 4 would be cheap and look great!
How thick will the aluminum be? You're adding up the weight above the Center of gravity.
Scarf the block to fit the contour as good as possilbe, then put a pile of 5200 in wich will harden and fill the void with a little elasticity geting rid of those stress spots.
With one fir, oak or spruce 4 x 4 x 8ft piece you could make both parts.
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Old 12-04-2013, 06:36   #13
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Re: Compression post repair part deux

i would use woood for the post, tho....is prettier--
only raise the coachhouse to the level of the top of the bulkhead you see glitched from sagging deck....

you will have a big discussion on 304 vs 316 stainless now. 304 is good.
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Old 12-04-2013, 13:54   #14
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Re: Compression post repair part deux

I have to say that this project worries me.

Aluminum does not like to be buried in wood (the aluminum can slowly turn to mush), stainless and aluminum do not like each other (corrosion), and wood/glass beams don't like having huge stiff pieces of metal (especially with square untapered edges) stuck in their middle (stress cracks).

I normally am all for DIY, but this is a real critical part of this boat.

It might be worthwhile getting a little person-to-person help/advice from a boat builder.
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Old 12-04-2013, 14:23   #15
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Re: Compression post repair part deux

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I have to say that this project worries me.

Aluminum does not like to be buried in wood (the aluminum can slowly turn to mush), stainless and aluminum do not like each other (corrosion), and wood/glass beams don't like having huge stiff pieces of metal (especially with square untapered edges) stuck in their middle (stress cracks).

I normally am all for DIY, but this is a real critical part of this boat.

It might be worthwhile getting a little person-to-person help/advice from a boat builder.

Lol-you mean like me?
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