viscosity of 3M 5200

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viscosity of 3M 5200

Postby bluesman » Sat Jun 21, 2014 8:10 pm

I am doing a repair at the seam between the hull and deck of my day sailer. The bondo that was used from the factory has failed in several spots. I have scraped out the bad stuff and will be replacing it. I am thinking of using 3m 5200 adhesive sealant which is reccomended for this repair. If I leave the boat on the trailer The gap I have to fill will be upside down ( under the rub rail ) and I am wondering if I use a caulking gun applicator if it will go up into the small gaps and if it will stay or leak out via gravity? How thick is this stuff? Will it sag or stay where it is put?
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Re: viscosity of 3M 5200

Postby GreenLake » Sun Jun 22, 2014 4:57 am

A couple of questions: which type of DS do you have, a DS 1 or a DS II. Can you access the joint from the inside (that would be the case with an early DS1, where the seats do not have seat backs connecting to the deck. For such a boat, I would use a layer of fiberglass to make the repair - the repair does not require a flexible connection like caulk would produce.

However, when you must fill a gap that's not easy to access, then laminating over it is not possible. It may still be possible to use epoxy - a thickened, paste-like epoxy like what is being used for "filleting" may be used in some cases. These can be bought ready made (SystemThree), or mixed on the fly with fillers (West System). Each manufacturer would have product literature on their site.

If the gap is very narrow (or, if it can be squeezed shut or partially shut by light clamping) then another type of epoxy can be used: non-sagging preparations intended for gluing. Both SystemThree (GelMagic or T-88) and West System (6-10) sell these glues in caulk gun cartridges with self-mixing tips. GelMagic flows really well (with a bit of pressure) but it is like good ketchup in that it doesn't run. Because it has no fillers, I wouldn't want to use it to bridge really wide gaps, but 1/8th inch or less should be fine. T-88 is similar, and it's formulated for "structural" use.

I would not hesitate to use any of the products I mentioned here for the kind of repair you have in mind.

The various caulks come into their own when you have rather wider gaps to fill - but as you can see from my reply so far, I'm not readily convinced that 5200 is "the recommended" goop to hold hull and deck together on a DS. On larger boats, a caulk is used in production, but it's not necessarily 5200. But what I'm thinking of there is the original join, where the lip of the hull would be liberally slathered with whatever join compound was selected and then the deck lowered. The compounds would be supported from below and they would flow with the pressure to create an even seal.

This is much different from squeezing anything sideways or even upside down into an existing gap. The danger there is that you have spots where you end up with a void (open gap) behind just a thin layer of caulk that was spread over the gap by the nozzle, instead of filling the gap fully. You are better off, in those cases, with something that is much more honey-like in consistency, like those non-sagging epoxies I mentioned. With those, it would be possible to fill the gap, then run a thin tool through to make sure the glue has gotten everywhere, then filling again, and finally, to clamp lightly to push any excess out. In my view, you are more likely to get a good bond with that approach. Because these glues are non-sagging, they usually don't run from gravity alone.

If you have a way to tilt the boat so that you can work at a better angle, I would go for it. It takes only 3-4 guys to manhandle a DS, either on its side or upside down. If you work outside and have the room, launch the boat onto the hard, raise the mast, and then you can tip it leisurely by yourself on its side (not upside down).
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Re: hull to deck adhesive choices

Postby bluesman » Sun Jun 22, 2014 6:14 am

Much respect Green Lake. Thank you for a very detailed and well thought out response. First of all you hit the nail on the head with several of your point. The construction is that if a single wall construction like DS 1. I will have access only from the outside. I will also not be clamping in any way. From the factory this connection has a gap of varying width by design that is filled by the filler/adhesive. Second you are exactly correct it appears that they simply placed the two halves on top of each other during manufacture with some filler sandwiched in between as glue.

The gaps that need to be filled are anywhere from 1/8" to as large as approx. 3/8" . As you stated a big concern is filling deeply the skinny gaps and keeping the adhesive from dripping out of the wide ones.

I like west products and researched west 610 and it seems like good stuff. Seems to be sag proof. From what I have read it will most likely dry to be like most other epoxys hard and amber like. I will want to sand and gel coat the finished edge so I would like a material that will sand at the same rate as the edge of the hull. This seems OK?

I also revisited 3m 4200 / 5200 for its repair and remove ability and it seems like it could work as well considering the original material used in the boat construction is soft bondo like material. I like the fact that it does not have to be mixed and in the case of 4200 can be removed if for their rework is needed, but this would be unlikely. I am also not sure about the anti sag properties of this material.

Your idea of tipping the boat over with the mast is a great one I did not think of. I have restored a hobie cat 16 but never done any serious work on a mono hull so this never occurred to me

If you had to pick one material for the job that is readily available and easy to work with what would it be? I would like something that can be "injected" into the gaps and also sandable, but not harder than the fiberglass hull when dry so sanding at different rates could be a problem.

Thanks
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Re: viscosity of 3M 5200

Postby GreenLake » Sun Jun 22, 2014 3:40 pm

If you have 3/8" then that exceeds what you can bridge with epoxy, unless you mixed it with something to turn it into a composite. I've used 3M High Strength Marine Filler for some situations like that, it's essentially polyester resin mixed with chopped glass fibers. It's quite strong, but its sanding characteristics are good (just about the same as the hull, because chemically, it's the same stuff, really, so it gets just as hard as the hull). Polyester resin isn't as strong a glue as epoxy, especially in bonding to already cured material, but it should be effective in this case.

It's not sold in a cartridge, but if you feel that forcing it through a nozzle would make for better application, all is not lost. The method to use is what people used for decorating cake. A sheet of plastic with a nozzle fitted to the middle. You trowel the mix on the sheet, fold it over and squeeze.

Given your narrow gaps, I would use something like a tongue depressor to try to really pack it in, not relying on flow (because, like a caulk, this stuff is more of paste than a liquid).

My main concern with your repair is that the mechanics of stuffing goop in sideways is so different from how the joint was put together (bedding). If you were working from the inside, where you could squeeze caulk into the wedge formed by deck and hull, you would create a solid seal, even if the gap wasn't fully filled with caulk all the way to the outside. But starting at the narrow end, your job gets tougher.

If the gap can be spread with a wedge before application, that might help. And I don't see why, given the rather wide gaps you mention, you wouldn't want to apply some (moderate) clamping pressure - unless of course the voids in the existing joints are localized, rather than the linear gaps I'm picturing.

If you do end up using a caulk, I'd stay away from 5200, because I've read too many cautionary tales about it being "too permanent". Also, I don't know about how sandable either one would be. Because you haven't worked with 5200 before, if you end up deciding to use it or 4200, do yourself the favor of testing it on a sample. Better a wasted cartridge than a botched job.

Anyway, I'm largely using my imagination here - you have the advantage of seeing things directly. I'm sure you'll make the best decision.
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Re: viscosity of 3M 5200

Postby bluesman » Mon Jun 23, 2014 5:55 am

Gonna go with West Systems Six10 thickened premixed epoxy. Should be able to squeeze in the skinny spots and gap the big ones. I may try doing it with the boat on trailer using tools to insure the material gets deep inside the cavity.

Thanks for the ideas
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Re: viscosity of 3M 5200

Postby kokko » Mon Jun 23, 2014 11:19 am

The viscosity is about 100000 centipoise.
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Re: viscosity of 3M 5200

Postby GreenLake » Mon Jun 23, 2014 12:15 pm

kokko wrote:The viscosity is about 100000 centipoise.

To put that into perspective:
wikipedia wrote:When determining centipoise, all other fluids are calibrated to the viscosity of distilled water at STP. (in some practices, one can use the following approximation: water at approximately 70 °F (21 °C) is about one centipoise).

Thicker liquids, like honey, have higher viscosities. For example, while ethylene glycol has a viscosity of just 24 centipoise at 23 C, honey has a viscosity of 2 000 centipoise and molasses has a viscosity of 5 000 centipoise. Lard has a viscosity of 100 000 centipoise.[


But I think bluesman has come to a decision. Now all we can do is wait to hear whether it worked out the way he expected.
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Re: viscosity of 3M 5200

Postby SailinMick » Tue Jul 01, 2014 9:07 am

GreenLake wrote:
kokko wrote:The viscosity is about 100000 centipoise.

To put that into perspective:
wikipedia wrote:When determining centipoise, all other fluids are calibrated to the viscosity of distilled water at STP. (in some practices, one can use the following approximation: water at approximately 70 °F (21 °C) is about one centipoise).

Thicker liquids, like honey, have higher viscosities. For example, while ethylene glycol has a viscosity of just 24 centipoise at 23 C, honey has a viscosity of 2 000 centipoise and molasses has a viscosity of 5 000 centipoise. Lard has a viscosity of 100 000 centipoise.[


But I think bluesman has come to a decision. Now all we can do is wait to hear whether it worked out the way he expected.


Bluesman,
Just in case You Haven't Executed this/these repairs yet, and While Green Lake had definitely good tips for getting the vessel on it's side (via mast for leverage)...a couple things to contemplate:
A-Use Scotch blue tape over the opposing side from that where any joints are where You're applying the adhesive (minimizes mess and cleanup in a major way, stops 'leakage' completely if properly applied...ergo You don't waste any material and the tape is exponentially cheaper than the adhesive, which ever was decided on)
B-I'm in a similar dilemma with several cracks in the integral reinforcing stringers either side of the, and thereby part of, the 'backbone' of the hull where 2 glassed in stringers running either side of the very bottom have cracks in their tops causing flex in the hull.
Point being that, like Your repair I'm going to have to "SHIM" the hull so that it retains it's original shape (VERSUS Sitting on a trailer or On it's Side in Your case; 1 side for 1 batch of repairs, then the other side for other repairs), because IF You attempt the repair[s] With a "Mis-shaped" Hull (caused by Gravity, Ground, Your "on it's side" dilemma, (because the ground in Your case, just ike the trailer bunks in my case...isn't remotely Like the WATER which applies pressure to the Whole Hull equally) And established weakness in the hull based on this damaged hull to deck joint), You may be worse off than not repairing at all(!)

See, IF the hull is 'out of shape' when You repair one side (especially using an epoxy system for repair that's dramatically less flexible than 5200 or the like), then You roll it over and repair the opposing side, when THAT Side is ALSO "out of shape"...well brother You may wind up with a boat like A FG Dinghy I ran in to this problem with decades ago...it wound up much 'squarer' than it's original design and while more seaworthy, much less water dynamic. Me thinks Your desire isn't a 'boxy' boat when completed.

One of the cures/preventatives for the potential dilemma (that actually defies gravity) is to take the cinch/tie down moving straps used for hauling everything from motorcycles to Refrigerators (about 4 will be required, like the 4packs that are sold at HD/Lowes, etc.) and run them all the way around the hull, PRIOR rolling on it's side, just below the Hull to Deck joint, and tighten Just enough to retain the shape while noting measurements from bow to stern, amidships across cockpit, and double checking same after You have on it's side. final tightening/adjusting should be done across the transom and don't over-tighten.
Good Luck in Your mission,
HTH,
-Mick
Only posting here because the weather must stink for messing about boats today!
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West systems Six-10 Thickened epoxy

Postby bluesman » Wed Jul 16, 2014 2:57 pm

Well I went with the West systems Six-10 Thickened epoxy. Just to be clear the areas of repair were a max of 2 feet long and the overall intengrety of the hull to deck on 90 % of the boat was fine. I scraped out the bad and cracked stuff using a putty knife and utility blade knife and squirted the self mixing 2 part thickened goo into a plastic syringe and injected it into the gaps. Man this stuff is fantastic! It is a workout squeezeing it out using the caulking gun but man it stays put. the majority of the injection were done upside down. I chose not to flip the boat over since the epoxy was supposed to not run and indeed it does not run at all.

I am totally impressed by this material and the ease of use. at around $22 a tube (only half a tube really) it is worth every penny in my opinion. I have also used G-Flex thickened epoxy that required mixing to effect a mast repair on my hobie and this is far easier and more consistent due to the pre mix nozzle (totally different application but my only comparison). G-FLex is great stuff also by the way.

Long working time, and when hardened, sands like a champ.
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