how strong is 3m 5200?

[~~~J~~~]

How strong an adhesive is 3m 5200?

Is 3m 5200 strong enough to mount a rule bilge pump to the hull without using screws?

My fiberlgass boat was built with the bilge pump 4 feet forward of the transom screwed to a wood pad which was fiberglassed in for this. What I don't like is that the boat sits somewhat stern heavy and the bilge pump is already 3/4" above the hull bottom on this mounting pad, so I always have this wedge of water along for the ride. I'd like to mount an auxiliary pump aft, but due to the sterndrives can't figure out how to mount it to the transom itself now. And the wood mounting pad is only where the pump is locatd now.

So I either need a really elaborate bracket or to glue the plastic strainer part of the rule pump to the hull itself.

Is 5200 up to this task?

[PAR]

Yes, 3M 5200 is strong enough to mount your pump, but I wouldn't use this, as it's so adhesive, you'll never get it off (cleaning for example) without breaking it. Use 3M 101 or other lower "tack" sealant/adhesive.

[mydauphin]

5200 won't adhere that well to oily, dirty o aluminum. It will release over time in these. For bilge pump, screw it to like wood or starboard material then glue that to hull with 5200 or epoxy.

[~~~J~~~]

I thought about that -- I'd have to degrease the bilge (it's fiberglass) and use a stick to sand lightly to give it something to stick to. There has been a lot of oily water in there over the last 20 years.

I thought I would glue the base of the pump (which is small, cheap, and replaceable and comes off with two plastic lock tabs from the whole pump.)

What I don't like about the idea of screwing the pump to wood is that would mean whatever the thickness of the wood is the thickness of additional water that will still be sitting in the bilge at all times. Maybe that's nothing - it's impossible to suck out every drop of water so maybe it's foolish to worry about an additional 1/2", but ... Also it will be really difficult to screw the pump to the wood in place as I'd have to reach in under the engine to do it and have very little work space (about 9" height 30" back but with an obstruction in the way.)

[mydauphin]

The answer.... have two pumps...Really
I forgot to mention, I used an aluminum plate for mine, little thiner
But seriously have a big pump higher and a small one down lower to get residual.

[PAR]

Any time you use a sealant or adhesive, it's assumed you'll clean the contact areas first. If this is the case, 3M 5200 will stick quite well, probably too well. Use polysufide (3M 101).

If you feel industrious, you can remove the strainer from the bottom of the pump, which is the part that forms the lower housing. Inside you'll find a small hole, which on small pumps is about 3/4". The plastic is PVC, which works well with standard plumbing stock.

Glue a piece of 3/4" pipe to the bottom of the inlet to the pump impeller with PVC cement. Cover the end of the pump with a course screen and you now have a flush fitting inlet. I've done this fairly frequently to make a pump suck the last drops out of a V bottom boat. I usually place the pump intake about 1/8" off the bottom of the boat.

The much smaller screen will clog faster then a regular strainer, but it can be managed if you keep the boat covered, when not in use.
Of course you'll need to make a bracket to hold up the pump now, but this isn't a particularly difficult engineering problem.

[TollyWally]

Starting fluid makes an excellent bilge cleaner for removing greasy residue. Captal idea about the pipe Par.

[mydauphin]

I use dish washing soap like Cascade original, it doesn't foam easily, but is very strong and cleans well.

[~~~J~~~]

Thanks for all the input. Am planning to soap and soak the bilge a bit, then light sand, then wash out and dry. I was planning to use rubbing alcohol to clean the surface as the final go, but read on the tube of 5200 (that I got before Par's advice) that alcohol impedes the 5200 from setting. I don't understand that as I thought the point of rubbing alchol is that it evoparates totally and leaves no residue behind...

Do I have to worry about oil that has "soaked into" the gelcoat surface over the last 20 years, or if the surface looks good and clean am I good to go?

If I have another hydraulic hose bust in the future, do I have to worry about hydraulic fluid or oil disolving the 3M 5200 or 3M 101 once it's set?

[TollyWally]

I can't speak from experience about the tenacity of 101. I'd like to know more about it. I never use 5200, I use 4200. It sticks mighty damn well but isn't quite the set in stone adhesive that 5200 is. I know they make a chemical that will cut 5200 but I don't know what it is. I'm guessing that hydraulic oil would be ok or else you'd here folks talking about how you can remove 5200 with hydraulic oil. This is just speculation on my part. Interested to hear the concensus. Try the starter fluid, you'll be amazed.

[mydauphin]

A few times I had to remove 5200 from hull fittings, the fiberglass broke and I attacked 5200 with Blowtorch. It still did not go easily.

[PAR]

3M 101 isn't nearly as tenacious a grip as 5200. 4200 is slightly less then 5200, but more importantly is more flexible. 3M 5200 is fairly hard where cured, but 101 and 4200 are more pliable.

I remove 5200 with a hot knife. It's chemical resistance is quite good, so I wouldn't worry about a little spilled milk (or oil).

[BeauVrolyk]

Try a piece of metal, bent in a "Z" shape. The upper horizontal part of the metal screws to the top of your piece of wood you already have. The bottom horizontal part of the "Z" shape goes under your pump and you mount the pump to that. Then, you'll be down to less than 1/16" of metal between bottom of pump and hull.

That said, I would just glue the sucker on with 3M 101 or 4200. 5200 will work fine but you will never get it off if you have to, and from your description it's a place that's hard to reach and will, therefore, be really hard to work on cutting the 5200.

5200 doesn't care at all about oil, gas, hydro, there are VERY few things that can dissolve 5200 - I've never seen one. You need to use a wire hot knife to cut it.

[Frosty]

5200 is a permanent adhesive, in other words don't use it if you think it might sometime need to come off.

As far as bilge pump mounting is concerned I have long since given up with gluing wood to the floor, you have already lost 1 inch or so by doing this.

I mount the pump on a stick and attach it up where I can get to it. It can then be positioned to the depth you want especially in sumps.

I use the same principle for the float switches too.

Some of my pumps are just held by the pipe itself as I like to mop out to a perfect dry hull. They can be easily raised.

I also like Johnson pumps that can be snapped apart and cleaned.

[dockdave]

If you play with boats and fix other peoples stuff, you learn quickly that you should be licensed to use 5200. Overkill almost all always.

[BurnabyRocket61]

Does anyone know if the 5200 is less flexible than sikaflex 292? Or is there anything else that might be even more firm with as good a bond? I'm planning to bond the edge of the raised epoxy/ply deck to the primed alumimun hull. and since I plan on painting over this joint with Perfection, the less movement there is, the less the chance of the paint cracking?

[mydauphin]

How about just use epoxy fairing compound?

[BurnabyRocket61]

Good idea, I had thought about that, but I wasn't sure of its bonding strength, and with the difference in air temp to water temp in some of the lakes up here I'm sure there will be some fairly rapid expansion and/or contraction when it's put in and hauled out, and the last thing I need is for that joint to separate. A crack in the paint is one thing but water egress to the holds below is another. As you can see i've already used 292 on the ends of the livewell/ beer cooler, but I'm not to worried about the paint there since its below deck.

[PAR]

3M 5200 is more rigid the 292 and has a stronger bond.

You want to "marry" your modifications to your hull, but retain enough flexibility to account for the dissimilar material expansion rates. I'd recommend West System GFlex epoxy for this job, with properly prepped Aluminum. It will be flexible enough and still very rigid.

[Frosty]

292 will break down with oily bilge water.

[BurnabyRocket61]

Well I used a product from Industrial Formulators called Gel Magic. It's a 2 to 1 gel epoxy that within a few minutes of being mixed turns to the consistency of vaseline. It' designed to bond two dissimilar substrates that have a gap, it's easy to work with, fillets nicely, cures to touch in about two hours, and the best thing is that it does not sag, so no more guessing how much silica you need to mix to get the right consistency. So thanks, and I'll let you know if and when it fails, and the paint cracks, at which point I figure I'll run a bead of UV poly along the crack and call it a day.