securing bolts along the hull to deck joint

[marc]

Hi,
I need some of your expertise.
I started to repair a leak I have in my hull to deck joint. I took off the rub rail and cleaned up the old goop. I found about half a dozen cracks and voids in what I assume was 5200 that was bedded into the joint. Crack size is less than the thickness of a quarter. I widened some of the cracks a hair by running a dremel cut-off wheel along them. I plan to push in more 5200 into the cracks and then put a skim coat of 5200  over the whole length of the joint. Here is a photo of a cleaned out crack.



The biggest surprise to me was finding that the joint was bolted at 6 inch intervals but the nuts were all loose. No lock washers or lock nuts. No fender washers or bedding either. The bolts themselves were shortened after being installed to a length of about 9/16 inch. In fact, what kept most of the nuts on was the bur that was formed on the bolt when it was shortened. I want to more securely fasten the nuts. One option is to put a dab of caulk on the end of the threads. Not sure what caulk I'll be using but I was planning to use something other than 5200 to bed the fasteners so I could get them off if needed.

Another option is to use lock nuts - but then I'd have to buy and subsequently shorten about 100 bolts. The new bolt length would be about 3/16 inch longer for a total length of about  3/4". My concern with with approach is that I'll struggle to get the rub rail back in place since I'll have to slip it over longer bolts. I guess my preference is to go with the caulk at the end of the threads but I'm looking to see what you all would do.

Thanks for your help. Marc

[nies]

The deck joint on my CP16 is pop-riveted and has held since 1978 when the parts were joined.....do not know if they would work rather than bolts, but do not see why not.................nies

[wes]

Marc - i would not sweat this too much. That 5200 is an amazingly strong adhesive. Once it cures, you could probably remove the bolts without any serious danger of the joint coming apart. I have always suspected the factory mainly used the bolts to keep the joint aligned while the goop was drying.

I also think it would have been impossible for the bolts not to get some 5200 on the threads when they were inserted, and that stuff is better than Lok-Tite. I'll wager none of your nuts have fallen off.

When I redid my joint, I just used a dab of 5200 to bed each bolt and reassembled them just like the factory did.

Wes

[Allure2sail]

Hi:
Can you at least get a flat washer under the nut and tighten it back up after sealing all the voids and cracks? Would the thickness off the washer stop the rub rail from going back in place? I have read that some people actually found duck tape under the rub rail. I haven't figured that one out yet, perhaps to keep the 5200 in place while it dried.
Good Luck
Bruce

[MacGyver]

Marc,
Thanks for posting this, I found this to be my issue as well today!
What I did end up doing is just leave them all ALONE!!
I tried a number of things, take them off, reinstall with sealer, and when I went to put the test few back together!!!! YIKES!!! what a bear!

So my end result? Well, I tightened them, but not too tight, just snugged up good. Then maybe a drop of 5200 on each nut to hull spot and allow to dry thouroughly.....

My plan is to use interlux 2000 to help hold em in place due to a overall paint job I am doing right now.

Leave them in place.... you will thank me later!

if you do use 5200 to seal over them or what not, DEFINITELY ALLOW IT TO DRY ALL THE WAY before putting that rubrail back on!!

5200 is a beast..........

OH! and dont take the bolts out without putting them back in same spots.... turns out now I have some longer ones to cut off to smooth it back out....... dont need bumpy rubrail with a nice paint job...

Mac

[marc]

Think I'll use 4200 to bed the bolts.
Mac - I already found out that the bolts vary in length depending on where they are located. I took out 40 bolts - individually - on the starboard side. Cleaned them up by screwing the nuts on & off, then temporarily reinstalled them. It is a PITA to get the nuts started back onto the bolts but I was successful on all but 3 bolts. On my boat there was no bedding used on the bolts, so the bolt holes themselves may be a source of water intrusion. So I'm going to go the route of taking the bolts out and reinstalling with caulk under the head of each one.

Bruce - I may be able to get a flat washer on most of the bolts.  Most of them extend about 2 thread lengths beyond the nut when the nut is snugged up. My 1st inclination was to use a washer but it's probably not a good idea. It is already a trial to get the nut started on the bolt since the end threads were somewhat damaged when cutting the bolt to size. Also with caulk oozing here & there I'd probably create a nightmare getting the nuts back on.
Thanks for your comments.
Marc

[skip1930]

Were the original fasteners aluminum rivets? So if you have bolts, other then at the corners, someone was in there before you?

skip.

[marc]

Doubt someone was there before me. The duct tape over the bedded 5200 was still in place. The last owner didn't have the where with all to do maintenance. I was told the one owner before him used the boat for 1 summer and then just had it parked in his driveway. But who knows?

[skip1930]

Perhaps the factory did change the method of fastening two flanges together?

Starting the nut on threads with goop in the seam and a washer involved is ... well more ...  involved.

Screwing it down at 32 threads per inch and then cutting off the tail is more work and more time then a air driven rivet gun to pull flanges together.

When the rivet pops, all the toque is the same along the hull.

What ever, it is what it is. My rub rail is taped on with double sticky sided tape. I can peel it off and back on at will.

It's always about spreading out the forces and weight over the greatest distances, especially when fiberglass is involved. But you know that.

skip.

[Allure2sail]

Think I'll use 4200 to bed the bolts.
Mac - I already found out that the bolts vary in length depending on where they are located. I took out 40 bolts - individually - on the starboard side. Cleaned them up by screwing the nuts on & off, then temporarily reinstalled them. It is a PITA to get the nuts started back onto the bolts but I was successful on all but 3 bolts. On my boat there was no bedding used on the bolts, so the bolt holes themselves may be a source of water intrusion. So I'm going to go the route of taking the bolts out and reinstalling with caulk under the head of each one.

Bruce - I may be able to get a flat washer on most of the bolts.  Most of them extend about 2 thread lengths beyond the nut when the nut is snugged up. My 1st inclination was to use a washer but it's probably not a good idea. It is already a trial to get the nut started on the bolt since the end threads were somewhat damaged when cutting the bolt to size. Also with caulk oozing here & there I'd probably create a nightmare getting the nuts back on.
Thanks for your comments.
Marc

If the bolt was cut to length (with a cut off wheel or a bolt cutter) on the boat after the nut was installed the very last thread on the bolt most likely has a small burr on it. If the bolt is out and you look very closely at the very beginning of the tread you will see the small burr made by cutting the bolt. You could file it off or very lightly put a very small chamfer on the end with a bench grinder....notice I said small, very small. The last thing you want to do is shorten the bolt, just lightly chamfer the last half or three quarters of thread. That should improve immensely the starting of the nut on the bolt. Perhaps the duct tape on the outside seam isn't such a bad idea after all, at least it would give the sealent a chance to set somewhat. I also do what your going to do which is put sealant down into the hole as well. I then take a small Phillipp's screw driver and use it to spread the sealent around the walls of the hole as well, that way it doesn't all get pushed out the other end when you push the screw through.
Good luck..
Bruce

[Shawn]

Bruce,

"Perhaps the duct tape on the outside seam isn't such a bad idea after all, at least it would give the sealent a chance to set somewhat."

When I redid the joint I used 5200 in the joint and then used a layer of gorilla glue over top of that. Figured it was an extra layer of sealing, helps to keep the nuts from loosening, and it also allowed me to get the rub rail back on quicker.

Shawn

[marc]

I've removed all the nuts & bolts, 1 at a time, and put them all back in. I used a dremel to dress the ends of the threads where I had burrs. Even so, I had to replace 5 bolts. Now I'm ready to fill cracks and bed the fasteners. Before I do that, I've been eyeing the chain plates. Looks pretty simple to unscrew 3 bolts and then pull the chain plates up through the hull/deck joint flange. Am I missing anything? Looks too easy. Are they glued to the side of the hull?
Marc

[DougN]

,Marc, removed my chain plates last fall,and yes it's that easy.I found the hard part was removing the old bedding,what I found that worked(a lot of trial and error)was interlux 202 fiberglass solvent cleaner,it also removed silicone,the glue from the old stripes and the soles on my flip-flops,nasty stuff.Jason or some of the others with more experience might know of a something better to use.My flange was riveted with 3/16 aluminum pop rivets,still look good after 30 years.I took a dolly bar and hammer to tighten them up but probably didn't need to.Depending on the size of the bolts you could drill out the holes and replace with rivets,a #11 drill is the size to use for 3/16 rivets.Whats up the duct tape,I had it too?

[marc]

Doug,
I take it that you used the solvent only to clean up the bedding after you removed the chainplates and that the solvent was not needed to get the chainplates out in the 1st place. Have I got that right? As far as the duct tape goes, my understanding from other postings was that it was used to facilitate the quick assembly of the boat. By covering the 5200, it was not necessary to wait for it to dry before mounting the rub rail or doing other work on the boat.
Marc

[DougN]

Yeah Marc,the chain plates came right off.The only problem I had was that I was by myself so it was a lot of trips in and out,get someone to help you.I made new ones out of 1x1/4,my old ones were really twisted up bad.Just waiting for a break in the weather to install them.Sounds like the mystery of the duct tape has been solved.