TOPIC: 3M 5200 question

3M 5200 appears to be the first choice among many boat restorers. The top and bottom of the Playmaster is a "butt" fit. No edge to perch on. To glue this back together would I put a bead of 5200 around entire perimeter of the bottom than simply rest the top on top? Can I cover 5200 with fiberglass? Also why do I get boat motivated when it is fricken 20 degrees?!! Dave

Dave,
I would say yes to the bead. As far as the glass sticking to it, if you do a thin bead, just enough to "glue" the top to the hull then I don't think it will really matter since the glass will stick to the deck and the hull, however don't forget the 5200 doesn't get real hard. It gives even after it's dry, that's why the wood boat guys use it for a "dry hull" because it gives so the wood can shrink and expand and not leave a gap between the planks so water can get in. That's why I say a very small bead between the deck and hull. Either that or mix up a bit of epoxy peanut butter and use that as your adhesive. That will glue them together and you won't have to worry about any give, plus the glass will adhere to that.

Bob

As Bob says, it never gets real hard... also to note, it takes forever to set. You will find it takes several days to setup even in a cozy-warm workspace. I love the stuff and use it in a lot of places, but see it as sealant/adhesive... not so much a structural adhesive like epoxy or some of the acrylic-based adhesives.

Dean

Keep in mind that the 5200 is a PERMANENT bond even under water. I would call it an adhesive for sure. Directions and years of experiance back this up. It takes seven days to cure so there is no need to hurry your work. I've moved boards into position two days after initial setting and haven't had any issues.

Thanks for input. Have a great Christmas. Dave

Dave,

I believe the rub rail extrusion follows the deck to hull joint and is screwed in place over it - does it not?

If it were my boat, I wouldn't use 5200 as you describe. It would be best to bond the two parts back together with fiberglass. The glass being bonded will need to be clean for this to work well. Depending on how much room there is to work with, most old boats with a butt joint have a 4" to 6" strip of fiberglass that "tapes" the two together. This is actually a pretty easy job to do, excepting parts of the boat where access is very tight. Just to be clear - this work takes place on the inside of the hull.

Carefully clean the adjacent areas of the hull and deck fiberglass - sandblasting, grinding, sanding will prep it just fine. Don't get carried away - it just needs to be clean - NOT smooth.

I like polyester resin, but in this case, epoxy would be a really great way to go. You can purchase fiberglass "tape" in a range of widths. 4" wide tape would work fine. The tape is just straight cloth - no adhesive on it. Mix up a batch of epoxy paste by using milled fiberglass, silica, whatever you like. Use a plastic spreader to smear the paste onto the joint – being sure to completely cover the area where the tape will be placed. Apply the fiberglass cloth tape to the goop by lightly pushing it into position. A small-serrated roll will help to work out any bubbled up areas in the cloth. Once this is in position, saturate the tape by applying straight epoxy – using a chip brush and a “stippling” motion. A couple layers or more of tape & the boat will be solid as can be. Keep in mind that the taped joint will help reduce the chances of the hull distorting and cracking if it hits a dock, or other object along the joint line.

There's an old saying: "Either bend with the wind or break." 5200 bends with the wind, so to speak. It may have a very little "give" to it but breaking free is something I have never seen. I'll take slight undetectable movement over splitting apart under stress any day.

I once stuck a 1x6x6 mahogany block to the inside bulkhead of a boat with a heavy bead of 5200 along the 1" edge. I wanted to make sure I could add wooden ribs in order to plank the gunwhales. I forgot about it for a couple weeks. It wiggled slightly under pressure but I couldn't break it away from the side by hand and needed a 2 lb hammer to free it. It took fiberglass threads with it! That's holding power with "forgiveness" built in...best of all possible worlds in boating situations.

Of course, it's just my opinion but then again, I've never been wrong about anything in my entire life.

Please post a pic of the joint, is it a shoebox fit where the deck fits along the outside of the hull?
Or by butt do you mean the thin edge of the deck meets the thin edge of the hull?
Shoebox joints are often done with Plexus or 5200 or 4200 for the joint itself, but will wait to see what you post.
www.jordanyachts.com/wp-content/uploads/2010/01/hull-deck-joints.jpg

yes, but you wouldn't need to.

I'm a fan of glassing hull/deck seams for structural rigidity. I would rather have that joint stiff than flexible, but each to their own.

Best of luck to you. Enjoy that balmy weather!

Frank

Nautilus wrote:

There's an old saying: "Either bend with the wind or break." 5200 bends with the wind, so to speak. It may have a very little "give" to it but breaking free is something I have never seen. I'll take slight undetectable movement over splitting apart under stress any day.

I once stuck a 1x6x6 mahogany block to the inside bulkhead of a boat with a heavy bead of 5200 along the 1" edge. I wanted to make sure I could add wooden ribs in order to plank the gunwhales. I forgot about it for a couple weeks. It wiggled slightly under pressure but I couldn't break it away from the side by hand and needed a 2 lb hammer to free it. It took fiberglass threads with it! That's holding power with "forgiveness" built in...best of all possible worlds in boating situations.

Of course, it's just my opinion but then again, I've never been wrong about anything in my entire life.

I noticed you used it on your transom on the CC. Any issues with fiberglass sticking over it?

I've always glassed my wood in place with mat and resin, but have wondered how effective 5200 or some of the other urethane adhesives would be for this.

We laminated marine plywood on the Custom Craft to build-up to a thickness of 1-3/8". The last sheet was 3/8" meranti and that was glassed-over with the traditional method of glass matting and resin.

There are two typical deck to hull mating schemes. One is Shoebox where deck is "lid" hull is box. Then there is the but fit where hull and deck are exact same profile.
If it's a shoebox the rub rail fasteners generally go through both the hull and deck at overlap tying everyting together, a low strength sealant like silicone would be fine to keep stray splash out.
5200 used instead would be stronger and provide sealing but would be overkill and near impossible to take apart but now sure with a proper restoration you'd ever need to again. Glasspars have an extruded rubrail that is what I'd call modified shoebox, the deck fits into a groove as does the hull and then the fasteners pull all this together.
If it is a true butt joint, skip the 5200 and glass them together on the inside of the joint using maybe 4 inch wide Biaxial tape, the fibers are at 45 degrees rather than 90 as on typical tape. This gives many more strands overlapping the joint. This in my opinion is the strongest construction scheme and is not seen as often as tooling demands are more exacting and assembly is a bit more labor intensive. On the butt fit I use machine screws, nuts and two fender washers, one on inside and one on outside to help align the seam all the way around. Then I glass tape
short pieces to hold deck and hull together. Once cured remove the washers screws and nuts. The put your final continuous glass tape layer across the joint.Add second layer if you want. Rubrail is added to outside to hide joint seam. Just my opinion, hope it helps I've done all three styles, butt, shoebox and special glasspar rub rail joint. All work.
Good luck,
Randy

Dave,
For this application I would use (3M 4200 Quick Cure) it cures in 3 hours and the bond is super strong and the product is paintable. I use it all the time.Go to James Town Distributing web site and read all about it. Be sure to clean up as you go, once this stuff sets if is not easy to remove, keep several rags close at hand with a can of paint pre clean handy to place on the rag and wipe with as you go, if you don't clean as you go you will not be a happy camper trying to get the stuff off after it sets. Pic attached
JAG

There is a third way the two halves are put together. On the Shell Lake project I am currently working on the upper and lower were sandwhiched with a 1"lip and then stapled and that covered up with one ugly thick bummp rail. In order to accomplish what I have for my project I trimmed the lip off essentially making it a butt joint, glassed the seam from the inside and then used 5200 slow cure on the outside mahogany and that whole configuration is through bolted (and plugged) with fender washers on the inside.

This is the sandwhich seam before trimming.

Here are pics of the inside and outside after trimming the lip off and glassing the inside butt and adding the through bolts and fender washers.

I'm finding this thread great reading. Your never too old to learn.

robert-lorigan wrote:

I'm finding this thread great reading. Your never too old to learn.

X2! I whole-heartedly agree, Robert.

Looks like as long as I do something.......LOL
My first thoughts were to use some sort of a backing, glue top and bottom. Than fiberglass on inside. The World Famous "Coolest Boat Ever" has a smooth outside fiberglass hull over a much rougher internal hull. I like the idea of using a bead of adhesive and using fender washers. Than a couple of rounds of tape and glass. Thanks for all of the extra input.