Reinforcing the deck joint

[MILD THUNDER]

On my old Formula, the deck joint is crap. They glued the deck to the hull, and although there are some thru bolts, its still not a strong enough joint for a 40' offshore in my opinion. The old glue is not doing its job anymore, and too much deck flexing. Last season there were areas of the hullsides under the rubrail where i can push in the hullsides by hand almost 3/4", as the glue and screws were not holding.

I was thinking of glassing in some strips of wood on the insides of the joint, then using new glue inside the joint, then adding more thru bolts, and then the rubrail screws would have something to go into instead of just thin Fiberglass that they pull out of.

Anyone have any good ideas on this topic??

[MOBILEMERCMAN]

I have noticed on their newer boats they have some extruded type metal backing strips. Sorry I haven't paid close enough attention to describe it better.

Glassing it would work well but may not be realistic because of everything involved.

[Wahoo 214]

Glass it solid from the inside. If you cant get to it try injecting epoxy or 5200 from the outside. On the rub rail, you may want it to pull off if you hit something. It will do less damage to the hull.

[MILD THUNDER]

I can access most of the joint from the inside fairly easily. Should i clean the old joint out from the outside, to remove all the old glue, then reglue, and use the screws/bolts to draw everything up tight, then glass the joint from the inside after the glue has cured?

[MOBILEMERCMAN]

I agree glassing it is best.

The glass job will be better if you are not working around screws or over them. The glue method you mentioned may work. I think waiting for something like 5200 to dry will take to long. Maybe a two step process will give you the best results. Bolt it together, glass while not going over any bolts. Then remove the bolts, prep and glass remaining sections. Seal outside at the end after you drill the necessary holes.

There are many ways to go about it and since the boat is assembled there is likely to be a compromise somewhere.

[Chris]

Whatever repair you do is only going to be as good as the bond with the original hull. Secondary bonding with fiberglass is never as strong as the initial layup. By secondary bond, I mean laying fresh plys over fully cured material. You need to layer your plys, making each one wider as you go out. The base glass needs to be ground smooth and cleaned well. Soaking it down with MEK right before applying your plys will soften the old resin slightly and give you better bite.

I would 5200 it where you can, screw it together as tight as possible, then strt laying plys around that junction from the inside. I'd lay in 1708 and do at least 3 plys if not more. I would certainly do it the heaviest in the middle third of the boat- that's where your greatest twist is going to be.

While in there, I'd check your bulkhead tabbing. If the shoebox wasn't carying the load, something was. The bulkheads are next in line.

[tommymonza]

I think the way to do it would to clean the joint between the deck and hull real good and possibly rough it up a bit. Than fill it full of 52000 and draw up the deck and hull with thru bolts drilled in a new fresh area between where the old ones pulled thru.

After a couple days of letting the 5200 set up go and grind the area between the bolts with a little angle grinder and than cut 6 by 6 inch strips of 1708 and lay these strips in with some west system epoxy.

Its not perfect but it would make the boat 3 stronger than it was.

To go one step further you could remove the thru bolts than and put them back thru the newly glassed area and than lay strips of glass and epoxy in between the new strips you just laid.

Double layering the is way overkill and would really have no benifit as the secondary bonds going to the hull and deck would be the primary failure in a catastophic hull deck failure.

Grind it good and clean it up and use West System Epoxy and i guarantee your bond will not fail.

[MILD THUNDER]

From what I have read about flexing in the old Formula 357 SR1's, the deck joint was the culprit, and those who reinforced the joint enjoyed a much more rattle free and flexy ride in rough water. I can only imagine the way my joint is, and being that the 402 has a much larger deck, this joint is crucial in keeping the old bird stiff.

Lots of good input, keep em coming! happy NY btw

[Offshore Ginger]

Just curious before i get into this and from the looks of things and what you are saying is that you are ready to tear into the cabin area to bond the hull to the deck . YES ?

[MILD THUNDER]

Just curious before i get into this and from the looks of things and what you are saying is that you are ready to tear into the cabin area to bond the hull to the deck . YES ?

Good thing about my boat is that area is fairly easy to get at to glass ...they ran like 6x6 square boxing which has the a/c vents, speakers, and lighting along the deck joint in the cabin on both sides, which come down pretty easily. same in the enclosed head. Vberth area is pretty much just carpeted walls going up to the joint, which should peel back pretty easily. As for the cockpit area, there are storage lockers along the sides that allow access to most of that area too. There are a couple small areas where i wouldnt be able to get to without major disassembly, but thinking at least if i can access 80% or more of the joint, it would have to be better than what i have now. Plus from the outside id be regluing everything around 100% of the joint?

[Offshore Ginger]

Hey guy , at this point if you are going to bond the hull to the deck , forget the 3M 5200 because it is only a waste of time. I have to say that i have bonded more then my share of hulls to decks Skater's , Fountains , ext ext and might i recomend using a material other then 1708 with epoxy ? I was just wondering , after removing the rub rail do you have a flush surface other then pop rivits holding the deck to the hull ? HAPPY NEW YEAR untill tommorow .

[mbam]

What about using Plexus? It produces a secondary bond that is stronger than the glass. At least that's what they say. I used it on a recent job to attach some reinforcing ribs to the bottom of the cockpit deck panels on my boat. Being somewhat skeptical we did a narrow test panel and jumped on it until it broke. It delaminated before the bond let go. It’s a little pricey and you need a special dispenser gun but I bet it would do the job.

Cleaning the old stuff would be most important. Pry it open a little, get in there with a die grinder to rough it up. Squirt the stuff in, pull it tight with some screws and work your way around. I like the MEK idea also.

PS – it stinks, a respirator is a must !!

http://www.itwplexus.co.uk/index.php?/plexus/marine/marine/

[open72]

+1 on the Plexus , superior bond

[tommymonza]

Is Plexus kinda like VetteBond? If it is i think the short working time would make it a little tough.