Deck joint-Who, What and When

Some time ago in one of these threads the topic of the deck to hull seam was tossed about. I tried to scroll back to the begining of the tech threads and dig for the information but all I got was a couple of mentions and fuzzy vision. Not everything I remembered it to be! Usually when I sit in the cabin or lay inside one of the cockpit lockers invisioning possibilities my eyes inevitably drift to one of two things:1) my beverage sitting just out of reach or 2) that pesky seam. It has held up for fourty years but it just doesn't look that strong. Besides, maybe it was only supposed to last fourty-one years. The cloth doesn't even appear to have been saturated and looks to be as weak as the cloth that was tabbed to the mast support beam(cut that with a dull standard screwdriver). Granted I haven't even started sanding in that area yet but it is definitely on the list of things to address. I've thought about filling it with epoxy, fileting the underside of the then flush deck/toerail with the inside of the hull and over lay that assembly with cloth and epoxy compatable matting. The primary goal is to strenghten the joint with secondary intentions of providing a strong attachment for a caprail. The one stumbling block for me is it would probably amount to twenty-some pounds of epoxy before we're done and a couple of scorched areas from the exothermic curing. The thought of rolling glass up inside the toerail doesn't thrill me one bit so I'd like to fill that void with something( however, I did get two glass rollers for Christmas this year even though it should have been an ab-roller:( )
What has worked for others out there? Tell us your stories of how you cured this feable joint. Any ideas of a good approach to take?

Do it on the outside ! Then cap it with wood .

I would remove the metal rubrail on the outside and take a look at the seam. If water has gotten trapped behind the rubrail, it can soften the seam.

Grind out any soft spots and fill the gap with thickened epoxy or 5200.

I also thought that the hull/deck joint was not as robust as might be expected. I decided to add some layers from the inside.

First I ground off all the old paint and scroungy bits of fiberglass underneath the toerail and back a few inches down the hull and underneath the deck.

That was a nasty, miserable job.

The only reason I got started on this job is because one or two of the partial bulkheads had started to seperate from the shelf below and I wanted to glass them back again. The project just kinda escalated. I decided to do all of the bulkheads and corners and the hull/deck joint too.

I used layers of fibeglass tape (regular and biaxial) overlapping 2 inch, 4 inch, 6 inch and finally 8 inch.

The fiberglass tape will stick upside down, provided you keep the lengths less than about 2 feet.

I did the hull/deck joint in the whole cabin area. I thought I might do the rest of the boat in the future. But, I'm not so sure.

I think its important to make sure all the structural bulkheads are securely attached to the hull and deck.

Beefing up the hull/deck joint was probably unecessary overkill.

Trying to fill the whole underside of the toerail with epoxy and matt is possible. But, you would still need to grind off the paint (the hard part). You would probably need more like 200 pounds of epoxy.

Glad to be done with that job

Mike, I don't have enough confidence in my glassing abilities to lay from the out side. We're looking at Flag Blue or Black hull colors. My dad had a body shop and I understand the principle of building up and sanding down to arrive at a new fair line but I don't think there is enough wood out there to cover it up! Maybe after retabbing the interior I'd be more comfortable with that tack. We like the inside approach because it doesn't have to look that pretty, just has to be strong.
Yeah, the stainless half round is destined for our Ensign and the remaining scars will be dug out, ground and filled. Good point, CPete, about keeping the tape lenghts short, I had forgot all about the 'under the cockpit nightmare' of our O'Day 22 when I epoxied my hair :mad:
What sort of grinder set-up did you use for sanding the inside of your hull and under the toe rail? Maybe I'll get to but a new powe tool! So far I've been lucky and have been able to get away with a minimal amount of hand sanding but things are about to change here.

My vote -- since it's what I did -- is to fill the seam from the outside. I was addressing the problem of leaks rather than trying to reinforce the joint, and may have accomplished both. The leaks are gone.
My Ariel has a teak caprail bolted through the toerail. I simply removed, bent up and threw away the stainless rubrail; scraped and ground out the silicone goo and dry cloth in the joint; and pressed epoxy thickened with West Systems 406 into the joint and faired it out. Will paint the hull next summer.
Since I can't see the joint from the inside, it may be that somebody already reinforced it - but it all looks original to me.
For what it's worth.
--Dave Gillespie

I had the same concern about the junction (I could see daylight through spots), coupled with the knowledge that the joint leaked, and I could never figure out where the leak was. The fix I made is easy and only takes a few hours.

Take the stainless steel rub rail off the outside. Use a Dremel Tool with a 1/8" router bit and grind a 1/8" gap in the existing deck/hull seam all around the boat (with the possible exception of the transom). You will generally pierce the skin and go through into the hull. That really is what you want to do, except where the seam is really good and deep. When you are finished, clean the gap with MEK, acetone or something like that. You now have a clean surface for 3M 5200 to adhere to.

Get a gun and a tube of 5200 and force it into the 1/8" gap. If it goes through the gap a bit into the hull all the better. Use a putty knife to smooth the outer surface of the 5200 so it protrudes just a bit outside of the gap. On the outside surface, it might be a half inch wide (covering the gap) and perhaps 1/16" thick.

When dry, the stainless steel strips are replaced (using 5200 on the self tap screws), and you have a perfect seal, one that is flexible and will not crack when you hit a dock or encounter other stresses (such as a boat alongside), one that is as strong or stronger than an epoxy seal. Don't worry if your bead over the gap is not particularly smooth or extends beyond that covered by the rub strips (although you want to do your best in this regard because there is a lot of work if you make a real mess). The 5200 can be cut away with a razor or drywall knife after it has cured. 5200 is used commercially to bond decks to hulls. 5200 comes in black, I believe. 5200 adheres to glass better than the gel coat. (If you try to pull the stuff off, the gel coat comes off. That is how well it adheres.)

7 years ago, Tom reiforced our deck-hull joint from the outside, sanded the joint down, filled in the gaps with ???, faired it out, and replaced the stainless steal rubrail (with a sealant for both rail and screws. It needed no fiberglass reinforcement. We never had a problem with leaks from this area.

I had ALWAYS wanted to get rid of the stainless steal rubrail and the hundreds of screws, to me they were hundreds of ways water could get in, but Tom insisted on keeping that rail so it remains to this day on Wayward Star. I have no intentions of altering that, though I will inspect the area this haulout and see what he used as a filer and how its holding up. He had checked it two years ago, and it was fine.

To grind the paint from the underside of the toerail, I used an electric drill with various wire wheel and wire brush attachments.

No way to get any type of sander up there.

Have fun.

I read all of the hull/deck seam postings on this site and then I removed the leaking rub rail on my boat, hull #330. The seam was filled with some of the original stuff, by the summer of 2002, brittle and no longer functioning as a water barrier. However someone had at one point removed a mess of that stuff and pumped the seam full of silicon. I cleaned all of that out. Here are my log entries for July 2002 related to my solution to the problem of water intrusion:

04-Jul-02
Hull / deck seam:
Cleaned out hull deck seam with razor knife designed for cutting plastic.

08-Jul-02
Hull / deck seam:
Cleaned out hull-deck seam with razor knife designed for cutting plastic.

09-Jul-02
Hull / deck seam:
Cleaned hull deck seam and screw holes w/ acetone, filled screw holes w/ epoxy, filled seam with 3M 5200

11-Jul-02
Hull deck seam :
Sanded exterior of seam w/ 600grit sandpaper and cleaned with acetone, applied back half of rub rail with 3M 4200 and 1/2 inch #8 screws

12-Jul-02
Hull / deck seam:
Applied front half of portside rail with 3M 4200 and 1/2 inch screws, and back half of starboard rail. Applied front half of starboard rail with 3M 4200 and 1/2 inch screws.

I worked on other projects also on those five days. Many of the original ¾ inch screw holes went all of the way through the hull and through the glass tape that holds the hull onto the deck. That is why I filled the holes with epoxy.

I sealed the hull / deck seam with 5200 to give a permanent flexible waterproof bond, and used 4200 to reattach the rub rail so that if need be I can remove the rub rail again at some time in the future.

As far as the integrity of the hull/deck seam, I am for sticking with Mr. Alberg's design. I suppose if I had pulled off the rub rail and looked at that seam before I decided to buy an Ariel, and realized that:

1.The screws do nothing but hold the rub rail onto the boat, and

2.The only thing holding the deck to the hull is that little strip of glass and resin applied as a cold-joint band-aid along the flush mounted hull deck seam when the hull was married to the deck,

I might have had second thoughts about buying the boat. But hey, my boat had been "rode hard and put away wet" for years before I bought it, and apparently even once survived a major collision with a metal can which sent radial cracks out about a foot across both the deck and hull near of the starboard sheet winch, and the hull deck seam, boltless and screwless survived all of that.

Personally I subscribe to the idea that the decks on blue water cruising boats should be through bolted (not screwed) to the hull along an overlapping flange and also sealed with a flexible bond like 3M 5200.

Of course the Ariel was probably not intended to be a blue water cruising boat. There is no such flange on Pearson Ariels through which bolts can be passed, and that mystifies me, but I wanted a Carl Alberg boat and I bought one. I figure that Mr. Alberg had a very good reason for designing the Ariel the way that he did. Those who choose to attempt to strengthen the seam will still be dependent on what amounts to a chemical bond, with no fasteners connecting the hull to the deck. Not to worry; many other successful boats use chemical bonds without fasteners.

The longitudinal cracks evident on my toe rail before I repaired them tell me that that area must have flexed considerably. I wonder if the rather strong "U" shaped but hollow toe rail was designed to flex to some degree to offload the stress on the hull deck seam. If the toe rail was designed to flex in order to offload stress, then filling the underside of the toe rail with epoxy would serve to reduce the ability of that area to flex, and necessarily shift stress to another area.

ole ebb went thru all this befor, you know, and it is appalling the assumptions people can make.
First off, Don't ever think you need a flexible seam in that deck/hull joint. NEVER, ok? This joint HAS to be the rock of Gibralter. 5200 IS fine because it is a real fine adhesive. But you could have done just as well with a 100% solids epoxy and X-mat or cloth or a mishmash of chopped strand.
You can evacuate the paint from the cove inside with an electric drill and carbide burrs of various rounded styles. There are many and they are effective. Even a Dremel tool can be used but the bits tend to be too small, tho the tool itself is light and easy to use.
On 338 we used a Milwaukee 80% angle drill that you hold by grasping the body of the tool. Heavy, but really gets in there. Good design.
I guess I don't know how serious you are about the hull/deck joint. So it's worth finding out what you CAN do - if you are going to do the job right.
The right way for most is the EdEkers/MikeGoodwin method. You have to keep in mind that the hull and the deck at the seam is quite thin. so you can't grind away with abandon for the strip of glass you are going to seal the seam with. I broke thru the inner mat factory layer in many places with a Dremel blade when I was cleaning the crack..NO PROBLEM

The other way is to scrape that inside cove clean of old paint and add a strip of Xmat and epoxy to what Pearson did. Sandvic makes two small scrappers, hand tools, with small staysharp blades that are perfect for the job. One blade is triangular at about 5/8" a side. The other is a 5/8" round.

The problem is: where do you start and where do you stop - if you opt for the inside route. 338, and I don't say this lightly because it took considerable effort, has no cove left at all inside. It was filled, stem to stern with xmat over the seam and then stuffed with triangular sectioned short pieces of mahogany embedded with epoxy and chopped glass and then smoothed on the last pass with e. and cabosil. 338 will never have a leak here. It will be finished off with wood outside rather than that REdiculous 1/2" s.s cove. (which could now be held on with two inch screws!)

If you are not going to tear the whole boat apart like crazy ebb, IMCO the only way to go is the Ekers gambit with a nice mahogany or teak rail that you have tapered gradually and sweetly just a little smaller at both ends. Look SO fine! .......................whatever..............
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[later EDIT] THERE IS A COMPANION THREAD ON THIS SUBJECT HERE IN THE TECH FORUM TITLED............hulldeck joint/and a story

They should somehow be combined or crossreferenced....

The two pro's with whom I have spoken, both recommend cleaning the joint, repairing where the fasteners fail to hold and then bedding with 5200 and fastening back on the ss moulding. Time is money and they quoted $400 to $600. Work guarnteed. Should last about 30 years . . .