Hull/Deck joint re-sealing

[vizwhiz]

Okay, here's an idea I've seen comments on, and wondering if anyone can give some real-life experience on their boats...
Background:
I have recently, due to major work, separated the hull/deck joint (removed all 14,278 bolts!). The rub rail was bad, beat up, and falling off...to be replaced...so I just pulled it off and found that the PO's had goobered goopy stuff in various places under the rub rail on the joint, I'm assuming to stop leaks. So once I started looking, I thought it might be a good idea to check the whole thing out, and that's how I ended up taking all the bolts out...

Found that the oldest-looking bead of sealant in areas with no obvious goopy-goop nearby, which I'm assuming was the original from the factory, was just that, a small single bead of sealant between the deck joint, and a ball of sealant at each bolt. It did not look substantial to me, and it was dirty, dry, and I would like to replace it with something more substantial, but am not convinced (yet) that trying to put a bead of anything in there is the best way.

In my head, I'm thinking that it needs to be flexible (because the hull does flex), and thick enough that when the two flanges are pulled together it will fill up any bumps and surface irregularities (and the surfaces ARE irregular). I also think it should go for about the whole width of the two joint flanges (about 3/4" to 1" wide) so it has enough chance to seal against most of the surface.

Someone mentioned that they had found a "strip" type of seal, like weatherstripping, in that joint. The more I have thought about it, that doesn't sound like a bad way to go, and might be easier to be sure it seals. Any experience with this you can share please?

 

[Hollyweirdos]

I did this to my boat too, you know, just to see what was in there. I had all the same symptoms as you. Heres what I did to fix mine.
1. Remove old rub rail and all hardware and order new Taco rub rail kit
2. Clean up joint (I repainted mine)
3. Fill the gap with white 5200 and used self tapping screws to hold it together while glue dries. About a week. Seal the old bolt holes now as well
4. Remove screws and put a drop of 5200 in the holes to seal
5. Now you have two halves joined with the 5200 and it is basically one unit now
6. Install the rub rail kit with 2 helpers, 1 stays inside to hold the socket on the bolts, one stretches the rail on, one runs the screws in. The new rail comes with predrilled holes for the bolts, I used these to keep the spacing correct.
7. No more leaks and I have a nice new rub rail.
8. Take two helpers out for a nice dinner

 

[finding41]

I'm the guy with the foam tape between the joints. I don't think it is original factory type of job. I'm pretty sure my boat has been taken apart... Here are some pictures of the foam sticking out from in between the joint.
The 2nd picture doesn't show the foam but it shows ware the motor well was repaired for some reason.
Oh NOTE the foam isin't painted like the rest of the aft storage area...? Installed after it was painted...? While it was split apart? It's 2 different colors...
I say hmm allot when I'm looking around the boat.

 

[vizwhiz]

yeah, I remembered it being someone on here, but couldn't remember who...thanks.
But it's not the first time I'd heard about it either...I just never had a boat I had to think about doing it to! Now it matters... LOL.

Anyway, is that repair on the port side of your motor well between the well and the hull/transom, or is that between the motor well and the cabin bulkhead in the laz?

 

[finding41]

1st pic is Starboard in laz.
2nd pic is Port between the motor well and the hull in laz.

Here is a few pic of the "trim" used around the motor well and the stern. Stair nose aluminum trim... Nothing but class.

 

[vizwhiz]

Okay - time to revive this thread.
CLEAR!! (beeeeeep - Thump!)

So after a long holiday season of entertaining family, traveling, working, and generally being otherwise distracted, I finally got back to working on the boat. I've reached the point on the major fiberglass repairs where "I'm done for now!". I have yet to finish some small tasks in the fiberglass dept, such as cutting the hole for the shroud chain plate, fixing some damaged spots on the hull/deck joint flange, and removing a light and antenna and plugging those holes...but no more big repairs for now.

In the very near future, I will be at the point where I need to seal the hull/deck joint and put on a new rub rail. I have had many months to think about it now, and the more I think about it, the more I just can't see the value of spending $25 a tube on 4200, or pursuing any of the other options I was thinking about...I just want to get it finished so I can sail it.

So help me out here...what's wrong with using good old-fashioned bathtub caulk? Not silicone, mind you, but the old fashioned acrylic stuff. Here's my list of why I can't get my head past this...
1. $5 or less a big tube
2. can use as much of it as i want without risk of damage to f/g or gelcoat
3. not exposed to UV, thus won't break down (covered by the rub rail)
4. not exposed to water continuously (or shouldn't be!) - this isn't a thru-hull
5. boat will spend most of its time on a trailer (see #4)
6. i have no delusions of sailboat grandeur or snobbery - and nobody will know what i used anyway (but you)
7. bathtub caulk is made to seal against water - exactly the purpose i need
8. easy to remove and fix later, bonds well, and can be cleaned up easily
9. the joint won't be moving, other than very minimal flexing, and not carrying load (held in place by a buzillion bolts)
10. stays flexible over time so it won't take a set and stop sealing

Anyone have good reasons NOT to use standard (not silicone) acrylic bathtub caulk to seal the hull/deck joint? Am I just missing something???

 

[finding41]

Doesn't your hull bolt together in a kind of sandwich way? (1995 S) Then the rubber goes over the lip and bolts? If so I would use a foam strip. Sticky on one side to help hold it in place. Or add a bit of spray adhesive to one side of the foam strip. (Do that away from the boat... maybe on the lawn before you cut it for the week...)
The foam is all my 26D has. But my hull joint is a lap joint with a aluminium rail attached by the bolts then a rubber insert n the middle.
As for an adhesive to hold your rubber bumper on I would go with the marine grade $25/ tube stuff. You should only need one tube if you don't make a huge bead of calk. I think most calk says how long a bead at a certain width you can get from a tube. I would only put the adhesive on the top of the joint in a continual bead and do spots allong the bottom untill I ran out of calk.
Here is a quick drawing of what yours (26S) looks like and what mine (26D) looks like....
Note: I added foam and adhesive to the drawing of the 26S

 

[Doc_holiday]

I have a 26s and without looking, mine seems to look like your D. Maybe cause its a 1990?

 

[MrBill_FLL]

Okay - time to revive this thread.
CLEAR!! (beeeeeep - Thump!)

So after a long holiday season of entertaining family, traveling, working, and generally being otherwise distracted, I finally got back to working on the boat. I've reached the point on the major fiberglass repairs where "I'm done for now!". I have yet to finish some small tasks in the fiberglass dept, such as cutting the hole for the shroud chain plate, fixing some damaged spots on the hull/deck joint flange, and removing a light and antenna and plugging those holes...but no more big repairs for now.

In the very near future, I will be at the point where I need to seal the hull/deck joint and put on a new rub rail. I have had many months to think about it now, and the more I think about it, the more I just can't see the value of spending $25 a tube on 4200, or pursuing any of the other options I was thinking about...I just want to get it finished so I can sail it.

So help me out here...what's wrong with using good old-fashioned bathtub caulk? Not silicone, mind you, but the old fashioned acrylic stuff. Here's my list of why I can't get my head past this...
1. $5 or less a big tube
2. can use as much of it as i want without risk of damage to f/g or gelcoat
3. not exposed to UV, thus won't break down (covered by the rub rail)
4. not exposed to water continuously (or shouldn't be!) - this isn't a thru-hull
5. boat will spend most of its time on a trailer (see #4)
6. i have no delusions of sailboat grandeur or snobbery - and nobody will know what i used anyway (but you)
7. bathtub caulk is made to seal against water - exactly the purpose i need
8. easy to remove and fix later, bonds well, and can be cleaned up easily
9. the joint won't be moving, other than very minimal flexing, and not carrying load (held in place by a buzillion bolts)
10. stays flexible over time so it won't take a set and stop sealing

Anyone have good reasons NOT to use standard (not silicone) acrylic bathtub caulk to seal the hull/deck joint? Am I just missing something???

the bounty capt used DAP window calk... below the waterline. -that didn't work out so well....

jamestown has it for about 16/tube. how many tubes are you talking about? 5?
at a minimum, I would use silicone 2.


how would you feel about saving a hundred $ if you have to go back in there... cause it didn't work out.... I would not use something that was water soluble. when its a PITA to fix it, if it didn't work out...
(cost savings not worth the hassle of failure).

 

[vizwhiz]

Yes f41, mine is the sandwich of two flanges, as you have shown, and which is the standard on the X/M as well. The older overlapping joint was phased out somewhere between doc's boat (1990) and mine (1995) which are the very early and last years of production (the two extremes).

As for the foam, I'm not opposed to it, as I had alluded to earlier, but I never fully separated the deck from the hull, so the best I'll probably be able to do will be to separate small sections of it at a time with wedges/blocks. I am thinking that it will be too difficult to put a foam strip in-between when I only have a foot or two apart at a time, with the wedges getting in the way of the foam strip as well...that's why I abandoned that idea.

the bounty capt used DAP window calk... below the waterline. -that didn't work out so well....

LOL, yeah...not below the waterline...but this joint is very much clear of the water most of the time, or should be, and even when heeling, water might splash up there, but it won't be submerged for any length of time (or better not be!).

how would you feel about saving a hundred $ if you have to go back in there... cause it didn't work out.... I would not use something that was water soluble. when its a PITA to fix it, if it didn't work out...
(cost savings not worth the hassle of failure).

I agree, but that's kinda the whole point...is it really going to be that much at risk once I bolt it all back together? The difference between a couple bucks a tube and $16 is certainly better than at the pricing I was finding, so I'll look again. But I guess my thought was just that I could have just as many issues putting on 4200 as with regular caulk, except for the possibility of trouble with the caulk itself...and that's the part that has me shrugging my shoulders. If I'm going to miss a spot or have bonding issues, and ultimately have a leak, it could happen just as easily with the 4200 as with bathtub caulk.

Now if there is a material problem with the caulk itself, something that could make it very short-lived, or could cause it to break down or something, then that's different...but is there an issue with it that way?

 

[finding41]

Viz wiz make sure you clean the surfaces you Want to seal very well.
That is the most common mistake with people using any type of calk.
If its not perfectly clean it won't work.
As for DAP. DON'T!
It is crap I'm my opinion. My guys even joke that there urin is thicker than that stuff!
At $16/ tube.... Go with the right stuff. Your not going to need more than 3 tubes if you apply the correct amount.
Hey I just found a good use for DAP.... Ust it as a practice calk on an old piece of cardbourd. Cut the tip at 1/8" and see how many perfect lines you can get out of a tube. When your done count the lines and multiply that by the length of the lines and you will get a aproxament length measurement for how far you can go with the $16 stuff! That's about all Dap is good for.
In the end you will k ow how to make a perfect bead of calk.

 

[fdnynapes]

April/May boat US has a detailed article on what sealant to use. Butyl tape is probably the material for this job.

 

[Chris & Lenore]

I had a flange leakage issue on our 26s. I just worked 4200 into the cracks and "skinned over" the outside surface of the flange. The bolts were tightened "lightly" (many were completely loose).

Eight years later it looks the same... Much easier than taking out 100+ screws.

Also, the rub rail on this type of joint does not require any adhesive. It snaps over the bolts, which retain it.

A question I have - does anyone know where I could get replacement rub rail material? I mean for a reasonable price?
On our last boat (Matilda 20) I needed gasketing for the windows. Local boat supply was $18 per foot. Apple auto glass had the exact same rubber extrusion for $3 a foot. They used it around the windows of construction equipment. So I figure MacGregor simply sourced material used for another purpose. I have yet to locate it though...

Chris

 

[nosnebjim]

I haven't had to do this to my 25. However, I am a supplier to the auto body and industrial market. I can tell you that the BEST product to use to seal it as well as glue it AND stay flexible would be a urethane sealant. I used this on my chain plates and it worked very well. It won't dry out and will stay flexible for the life of the boat.

 

[vizwhiz]

Well thanks to everyone again.

Chris, BWYachts has the 50' of rubrail for less than $100, and is where I plan to get mine.

I also was pretty successful separating almost the whole hull/deck today. the motor well is a big deal so I won't take that apart. I still used wedges to hold it apart, but I've taken all the connecting points inside apart and could essentially lift the top off right now if i could grab it somehow (but don't own a crane).

Anyway, i have to leave it alone for a couple more weekends due to family visits and work and such, but the next available weekend will be spent attempting to prop the top up from the inside so I don't have to keep wedges in between the two flanges. Will report back in a couple weeks.

 

[vizwhiz]

Update on this... After much consideration, and many conversations, and personally going over and cleaning out the hull-deck joint, and finally looking at the cost of several options and the relative ease/difficulty of the options, I have decided that I will use Bed-it butyl rubber tape for this job. I bought two rolls of 50' each (and yes, i know my boat is only 26' long)
I plan to roll it or crunch it to make it taller and rounder and not so flat when i put it in the gap so it will squish to fill the space as needed. (Squish is a nautical engineering term, in case anyone was wondering.)
I haven't made the final decision about whether to actually try to bed all 160 bolts that go around it individually, or to rely on what fills the crack and squishes up into the bolt holes naturally.

 

[fdnynapes]

Butyl tape

Update on this... After much consideration, and many conversations, and personally going over and cleaning out the hull-deck joint, and finally looking at the cost of several options and the relative ease/difficulty of the options, I have decided that I will use Bed-it butyl rubber tape for this job. I bought two rolls of 50' each (and yes, i know my boat is only 26' long)
I plan to roll it or crunch it to make it taller and rounder and not so flat when i put it in the gap so it will squish to fill the space as needed. (Squish is a nautical engineering term, in case anyone was wondering.)
I haven't made the final decision about whether to actually try to bed all 160 bolts that go around it individually, or to rely on what fills the crack and squishes up into the bolt holes naturally.

Hi, check out the kind sold to install car windshields. It is the perfect material.

Rich

 

[Chris & Lenore]

There is a relatively easy way to do this properly and in a way that seals all those bolts. This is how it's done by builders and boat yards - for this type of joint.

Remove the bolts over a 6 to 8 foot section. Lever the joint apart with a heavy spatula (or similar) - just 1/4 or 1/2 inch - whatever opens up easily (do not force).

Clean out any remaining old sealant. A small spatula or razor knife works well for this. Don't worry about getting every last bit of the original caulk.

This may be easier with a helper but insert the stip of butyl tape so it's centred under the bolt holes (or if off centre, have more butyl towards the inside. Don't roll it or anything. You want to end up with a strip of tape along the entire joint that is centered under the bolt holes. If you noticed any areas that had larger than average gaps, you could double up on the tape in those places.

Use an awl or similar to pierce the bolt holes before inserting the bolts. A sharp point (like an awl) will ensure the tape is not distorted and the material from the hole is displaced into the joint (as opposed to being "punched out" by the bolt.

Be sure to gently tighten the bolts to a point that compresses the butyl no more than 75%.

This will provide a joint seal that also seals the bolt holes.

Do not add any external sealant to the bolts and nuts. In fact, if you do, it will interfere with the way the rub rail snaps on (it engages the bolt heads and nuts).

Don't seal the rub rail either. You want water to just leak past it (since it can't go though the joint anymore).

If you do this properly, you will only have to do it once.

Chris

 

[vizwhiz]

Thanks Chris. I was planning to do what you suggest, but the gaps between the two flanges are so uneven that i wasn't certain that a 1/16" thick tape would be thick enough to contact properly on some of the gaps... I was just going to squish the two sides of the tape in to make it stand up higher (like making a mountain ridge down the middle) because I knew it would flatten back down to the right thickness while filling the gaps.

Also, the two flanges don't meet flat-on-flat at all points around the boat, but in some cases are spread out (splayed) so that they are touching on the inside edge behind the bolts. I didn't want these areas to squish the tape out in the wrong direction before the area near the bolts even contacted the tape.

And thanks for the comment on the rub rail. After this exercise, I was not planning to seal it at all, just stretch it and attach it at the back.

You made the comment about not worrying about getting all the old sealant off...too late!? I was concerned that the butyl might not stick well due to so many different types of sealant from previous owners. A razor knife would not work well everywhere because of how rough the surfaces are, and how much stuff was there in various areas, so i took the time to scrape it off with a chisel and then wire-wheeled it gently to get more out of the fiberglass texture. Seemed to work pretty well where it could be reached.

The more I've been looking at it, the more I think I should paint the flanges, especially the edges and the inside of the gap before I seal the joint...the fiberglass is pretty exposed on the edges, and there are a lot of small patches along the side that appear cracked (layers separated) or frayed and crumbly, like there was water damage from the rub rail holding water, and the fiberglass delaminated. I don't want those areas to continue to decompose (for lack of a better word) and I'm thinking that a coat of paint might be enough to help keep some of the water from being in direct contact with the fiberglass surface. I was going to use the same type of topsides paint that I would use on the hull and deck. What do you think?

 

[BrokeNotBroken]

rub rail source

I would appreciate finding a less expensive source for the rub rail as well since I am going to tackle this project too. I'm tired of having a leaky boat.

I going to try prying the hull/deck seam apart and using butyl tape. I'll let you know how it goes.

-david