Hull Deck Joint Repair

[the_alpine]

On my shoebox style hull deck joint I've been getting some leaks at the through bolts. Water was seeping in from the outside to the interior. A glassed in firring strip soaked up much of that water. I've cut out that wood around the nuts to allow for replacement of the thru bolts and nuts directly agains the fiberglass hull.

My question is: should I attempt to scrape out the old sealant on the outside of the joint? This joint is downward facing so recaluking with 5200 would be a sloppy runny exercise in futility I think. I was thinking maybe butyl rolled into a "rope" and pushed up into the joint might be a good idea? Or just leave the old sealant and only seal the thru bolt holes?

Thanks for the help.


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[Cheechako]

I would take it out , get it very clean and squeeze the joint full of something. Something that doesn't "run" that bad unless you are in quite warm weather. On a cool day 5200 would work. I don't think you can be successful with butyl without opening the joint. Although not sure anything will be totally successful without doing that either.
You need to force something into every small crevice and a butyl rope just isn't going to do that... squeezing something in might.

[SVTatia]

Are the deck bolts the same as the aluminium toe-rails or are they under the toe-rail?
Is it leaking when underway, closed hauled, just sitting (rain) or both?
In any case, I would start with the thru bolts. It could be that the hull-deck sealant is still good and the bolts were not properly sealed and leaked into the wood.
Remove the wood from underneath and use fender washers or something large to spread the load and take the compression.
Remove some that you can see the leaks, and re-bed them with Sika 241 or butyl rolled up like a joint around the bolts head and tighten the nut without turning the bolt head. I would prefer to use Sika as with butyl you will need a second pass to re-tighten the bolts.
Do a few and check if the leaks persist, if not, do the rest.
You will not be able to do anything with the hull-deck joint unless you open it, in fact - lift the deck off the shelf. To do that you will need to remove the bulkhead tabbings, liner, etc everything glassed to the deck - needless to say a huge job. I am sure by fixing the bolts you'll fix the issue.

[the_alpine]

The bolts are seperate from the toe rail attachments.

I bit the bullet and used wood shims to pry the joint apart and scrape it clean. I'm glad I did as the sealant in there was broken down in some places and non-existant in other places.

With the joint wedged apart I've got about 1/4 -1/2 inches of clearance to work with. Im thinking judicious use of painters tape to mask off the area and then squeeze as much 5200 up in there as possible. Then get the bolts back in to pull it tight. Maybe another strip of tape directly across the now closed seam to keep it from weeping out too much?


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[US1Fountain]

I did the same thing on my hull/deck joint. Looked to been nothing more than silicone on mine, and when the deck was lowered into position, a lot of the sealant got scraped off proving to be worthless. Working on some lengths at a time working around the full perimeter, removed all the thru bolts and screws and spread the joint apart in order to clean all the old silicone out. Cleaned surfaces with acetone, then filled the joint with 5200. Tape below the joint made cleanup easier. Reinstalled the bolts and tightened it up and cleaned off the access that squeezed out. Now its not only sealed permanently, the hull is more solid.

What I also noticed was during the reassembly, on the self tapping screws that were used every 9-12" or so to hold the joint together, before the thru bolting was done between each of those screws, the manufacture drilled thru both the hull and deck with the same size drill, then installed the screws. No way the joint could be pulled tight with that method, resulting in joint gaps at those screw locations. In order for 2 panels to be pulled tight,one has to be drilled for screw clearance size. I drilled all the deck screw holes for clearance, before doing the reseal. Made a huge difference and better fit by doing so. Nice and straight joint, no longer in and out at each screw

[the_alpine]

I'm wondering if 5200 is the thing to use? Something that stays more flexible would be more ideal perhaps?

US1 - how's your joint holding up? How long ago did you do the repair?


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[US1Fountain]

5 yrs ago. As far as I know it's still sealed and bonded. No signs suggestion otherwise. Between all the thru bolts and screws, (every 6" or so alternating between the 2) I can't imagine flexing is either possible or the original intent . I like the 5200 as a bonding agent to help prevent flexing at those bolt/screw locations putting undo stress on the gel there. As said before, the solidness was very noticeable after the reseal.

[UNCIVILIZED]

On some models of (aging) Cal's, the Hull to Deck joint becomes a leak problem. And on them, it seems that the most common fix is to pull the bolts, clean out the joint, & lay some glass both into & overtop of the joint (some guys do it inside & out).

Odds are there's info about it on some of the Cal groups on Yahoo. It's also described to some degree at www.SwellVoyage.com - look at the section titled "About", in the subsection "Swell".
Also, here's another example of a heavy duty fix - Wilkie's Sailboat Page
And I can't imagine that some Googlefu on the topic would hurt either.

[Cheechako]

Originally Posted by the_alpine

The bolts are seperate from the toe rail attachments.

I bit the bullet and used wood shims to pry the joint apart and scrape it clean. I'm glad I did as the sealant in there was broken down in some places and non-existant in other places.

With the joint wedged apart I've got about 1/4 -1/2 inches of clearance to work with. Im thinking judicious use of painters tape to mask off the area and then squeeze as much 5200 up in there as possible. Then get the bolts back in to pull it tight. Maybe another strip of tape directly across the now closed seam to keep it from weeping out too much?


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I wouldn't put tape over the 5200, but a masked edge with it is good. Spend the money for blue or green tape.... much easier than trying to remove dried on tape! It's amazing how soon regular masking tape will setup in places like Florida!
A lot of bolted on deck joints are done at the factory with 5200, maybe there is something better but it will likely last as long as you own the boat.
I find if you mask the edge, squeeze the 5200 in and then just use your finger to create a smooth fillet and to push the 5200 into the joint it works best.. Then pull the tape off before it cures. Don't skimp on 5200... put a lot in there, the excess will come off with the tape.
You are going to have a sore hand from pumping the 5200!
I agree with SVTatia though... often it's the bolts or screws that cause the deck joint leaks...

[the_alpine]

Say hello to my leetle friend..




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[Cheechako]

Originally Posted by the_alpine

Say hello to my leetle friend..

Attachment 94527


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Yep, if that's air operated that's what you need!

[shipleft]

Sikaflex makes some pretty awesome adhesive/sealants too you know, the 292 is heavy bodied and will stay where you put it. The stuff stays flexible forever as long as no UV gets at it, in the open it only lasts several lifetimes! The only draw back is, it is extremely difficult to dis-assemble anything once it sets up completely. It can be cut with a razor knife or ground away with a coarse sanding disc or abrasive disc, and on metal, if you can heat the metal up just above 140*F, it softens so you can pry things apart .

[ozskipper]

Side note. Ensure that as you take the bolts out for resealing, there are no loads on the deck. eg no nearby cleats or winches under load.

[Boatyarddog]

Pull the rail, glass the joint, and Rebedded with 4200, all hardware, use Nyloc nuts on the thru bolts with washers.
Sorry it's a tough job.


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