SailNet Community banner

1 - 20 of 21 Posts

·
Registered
Joined
·
504 Posts
Discussion Starter #1
ATTENTION

Unless you work in a boat yard and know exactly what you're doing, 3M 5200 should never, ever be used on your boat. Never.

It is appropriate for: Keel/hull joints and hull/deck joints.

3M 4200 should almost never be used.

Bedding and sealing require sealants, NOT ADHESIVES.


Mods, I'm sure you'll see the wisdom of this post and make it a sticky.


CARRY ON
 

·
not Sully or Dandelion
Joined
·
195 Posts
OK Pal since you are so damn smart tell us why.

And BTW. Stop f*%$ing shouting.

ATTENTION

Unless you work in a boat yard and know exactly what you're doing, 3M 5200 should never, ever be used on your boat. Never.

It is appropriate for: Keel/hull joints and hull/deck joints.

3M 4200 should almost never be used.

Bedding and sealing require sealants, NOT ADHESIVES.


Mods, I'm sure you'll see the wisdom of this post and make it a sticky.


CARRY ON
 

·
Registered
Joined
·
1,174 Posts
I think just simply saying is has uses limited to permanent bonds only is preferable as there are a myriad of uses for something intended to be permanent beyond a deck or keel joint.
 

·
Registered
Joined
·
5,607 Posts
did I read 4200 is no good for bedding thru-hulls?

3M 4200 should almost never be used.
Bedding and sealing require sealants, NOT ADHESIVES
 

·
Registered
Joined
·
504 Posts
Discussion Starter #9
OK Pal since you are so damn smart tell us why.

And BTW. Stop f*%$ing shouting.
Well, buddy, it’s because 5200 and 4200 are prolific and in almost all cases, used for purposes they’re not designed for. I see countless posts where people are asking which of the two is appropriate for a wide range of uses; the problem is that neither are appropriate. They are truly adhesives. In fact, they are very, very good adhesives. Used in the wrong way, though, they don’t do the job right and, once used, often result in damage to the parts the unwitting owner wanted to seal and damage to the boat. For example, ports and hatches - NOT a place where you want adhesive. You want a pliable sealant, such as butyl caulk (if it’s a plastic) or 3M 101.

I hope that’s helpful, champ. And I wouldn’t shout if I didn’t have to, but I’ve made post after docile post on this topic. So, I’ll yell a little. Wait ‘til I get started on recoring and 2-part polyurethanes. You’ll hear me then, too. Amigo.

did I read 4200 is no good for bedding thru-hulls?
4200 does have uses; though they’re limited. Certainly thru-hulls are a good use. I’ve used 4200 for a number of things.

Both 4200 and 5200 are great products. They are just massively over-used. That’s my point.

Words of wisdom...!!!!
Thanks MaineSail! I have about six thoughts a day on average. Some are good, some aren’t. This afternoon I had (1) 5200 is good for two things on boats and (2) I like bread. I thought the latter wasn’t worth posting about. Until now.

You can say that again.
 

·
Registered
Joined
·
110 Posts
Recommendations?

I think it would be more helpful if instead of posting "don't use this!" someone with expertise and serious attention to detail (hint hint Maine Sail..) would post a list of recommended sealants to be used in a variety of situations. That way when some newby boat owner googles "deck hardware bedding" they'll get an authoratative list.

Not only that, but I'm once I get my manual windlass rebuilt I'm going to have to bed it to the deck with something....

Just my $.02
 

·
Registered
Joined
·
1,942 Posts
i used 4200 to rebed/attach/repair my v berth hatch. the frame is cracked in to pieces, and was leaking. so for now i did what i needed to, it seems the only maker of the trapezoidal hatch for a hunter 27 stopped making them.

my plan is to make a new frame out of stainless steel in the next month or so
 

·
Telstar 28
Joined
·
1,000 Posts
I'm not sure that 5200 is even appropriate for hull-keel or deck-hull joins. 4200 does have some good uses on a boat though.
 

·
Registered
Joined
·
504 Posts
Discussion Starter #13
I think it would be more helpful if instead of posting "don't use this!" someone with expertise and serious attention to detail (hint hint Maine Sail..) would post a list of recommended sealants to be used in a variety of situations. That way when some newby boat owner googles "deck hardware bedding" they'll get an authoratative list.

Not only that, but I'm once I get my manual windlass rebuilt I'm going to have to bed it to the deck with something....

Just my $.02
The list below was scanned by another forum owner from the Jamestown Distributors print catalog. It's very helpful. I'm sure MaineSail could elaborate more and probably have some amazing photos to go along with it.

I would secure the windlass with fasteners and a good backing plate. To bed it, try 3M 101. :)



 

·
Registered
Joined
·
504 Posts
Discussion Starter #14
4200 definitely does have uses. Limited uses, but it's good stuff.

I used 4200 to mount a board holding my battery charger/maintainer and to mount a piece of teak to which I could attach the swing mount for my GPS. No fasteners in either case - just the adhesive.

I've had halyards catch the swing mount a number of times. The 4200 is strong enough to hold the GPS and the mounts no problem. It's not going anywhere.

I had a set of three hatches bedded in 4200 that I needed to remove from one boat and reinstall on another. Bad, bad choice for 4200. It bent one of the hatch frames and was UNBELIEVABLY hard to completely remove from the frames.
 

·
Señor Member
Joined
·
1,457 Posts
NOLA -- scream all you want, you're doing a very good thing!

All too frequently the typical boat owner is faced with a very limited selection of products at the chandlery -- and thinks that that's all there is to it. In my experience, 5200 is almost always the most heavily stocked item on the shelves with a little bit of 4200 thrown in. BoatLife products are usually not that well stocked, and SikaFlex is a pretty rare find.

And as we've seen often, newer owners will ask a question akin to "I've got this #10 flat head machine screw to fasten, so do I use the 16oz framing hammer or the 5oz brad hammer?" It's not that they're stupid, it's just that they don't know any better.

5200 is the SuperGlue of the marine world. About the only thing I would use SuperGlue on is an open laceration (yes, it works very well for this.)
 

·
Registered
Tartan 37
Joined
·
5,309 Posts
I'm not sure that 5200 is even appropriate for deck-hull joins.
I too am somewhat confused? Why then do many builders use 5200 for their hull/deck joints...and often seem to promote their use of it in their advertising?



On a related not...Sooo...what do I use for my new traveler install?
 

·
Registered
Joined
·
504 Posts
Discussion Starter #17
NOLA -- scream all you want, you're doing a very good thing!

All too frequently the typical boat owner is faced with a very limited selection of products at the chandlery -- and thinks that that's all there is to it. In my experience, 5200 is almost always the most heavily stocked item on the shelves with a little bit of 4200 thrown in. BoatLife products are usually not that well stocked, and SikaFlex is a pretty rare find.
Thanks PorFin. I agree about the inventory at marine stores. It drives me nuts.

T37Chef - this is the key to my point here. Things like travelers and windlasses are held in place by mechanical fasteners. In your case, use the appropriate size and type of bolt and a good sized washer (you really don't need a backing plate on a traveler because of how it loads). The sealant protects from water intrusion. It does not provide additional holding power. So, use 3M 101 or a similar polysulphide.
 

·
Registered
Joined
·
2 Posts
Hello all!

To NOLA sailing,
You mentioned 2-part polyurethanes in one of your replies, I would like to hear your thoughts about them. This is my first post, I hope it is appropriate to ask.

Cheers.
 

·
Super Moderator
Joined
·
6,773 Posts
Some...

Over the last 35 years of my boating life I've learned nothing is permanent, not even a keel joint and it will eventually need to be re-bedded in the future. For me, with mechanical fittings, such as stanchions, I find that even 4200 is significantly adhesive than necessary for mechanical fittings..

I like 3M 101 because it's easy to remove in the future and it does not have the "DEATH grip" of 5200 or the "half death" grip of 4200 that is not needed in 98% of mechanical connections.

In my experience the polyurethane sealants continue to harden until they become almost brittle and polysulfides tend to stay rubbery for the duration depending on UV exposure..

My Take & opinion, from years of experience, is that in 5, 10 or 20 years the 3M 101 polysulfide will still be very close to it's rated 416% elongation at break and the polyurethanes like 5200 or 4200 will potentially be less than that of 101 given nature of polyurethanes and how they tend to harden/cure over time....

Here's a summary of the products in the 3M line:


Elongation at break and tensile/grip strength:

3M 5200 = 1350% Tensile Strength = 700psi
3M 4200 = 900% Tensile Strength = 300psi
3M UV4000 = 800% Tensile Strength = 300psi
3M Silicone = 350% Tensile Strength = 220psi
3M 101 = 416% Tensile Strength = 139psi



Some additional things to consider:


The tensile strength of polyester laminated & resinated fiberglass (what your boat is made of) is between 400 and 500 psi!

Why one would want to adhere something to their hull at 500-700 psi, that will literally tear the gel coat clean off the substrate, if not removed patiently and carefully, is out of my realm of comprehension!

If you must use a 3M polyurethane use 4200 not 5200 but I find 3M 101 to be a great product that has never leaked on me.

I also use Sikaflex products but they don't make a polysulfide. In the Sika line I really like Sikaflex 291 and 201US.

Elongation at break and tensile/grip strength:

Sika 201US = 550% Tensile Strength = 175psi
Sika 291LOT= 700% Tensile Strength = 220psi

Personally I don't find the BoatLife polysulfide as long lasting or flexible as the 3M 101 and it tends to turn yellow fairly quickly.

4200 is a fine product but it's still a bear to remove compared to 3M 101 and certainly overkill for bedding mechanically fastened through bolted hardware. I've tried UV4000 but don't like the clean up and it also turns yellow so it's really not all that "UV"? UV 4000 is neither a polyurethan nor a polysulfide it is a polyether.

You should avoid the use polysulfides or polyurethanes on some plastics thus Dow 795 structural glazing silicone is my choice for acrylics or lexan...

One thing I never hear mentioned is that Polyurethanes do not like UV yet I see folks use it constantly in UV exposed settings. If your polyurethane bead is exposed it will and can eventually crack & fail.

Polyurethanes, according to a friend who is a chemist, generally continue to harden, though at a very, very slow rate, throughout it's life span. This curing or hardening of the product can reduce the elongation before break numbers over time and is a possible hypothesis as to why we see so many failures and leaks other than the Don Casey method of bedding hardware.

Polysulfides on the other hand are not as affected by UV as polyurethanes are and while their initial rated elongation before break numbers are lower than that of 5200 or even 4200 they should not diminish over time as polyurethanes tend to. Polysulfides, even years later, are generally as flexible as the day they finished curing where polyurethanes are not.

Let's take a seacock for a example. Using 5200 for them is kind of like welding on your lug nuts. Think about it. Lug nuts go down the road at 70-80 mph for thousands of miles on end, take massive pot hole hits, deal with poor alignments, bent rims & tires out of balance. Between rim removals they rarely if ever get tightened, torqued or looked at and still nobody glues them to the studs or puts a glue between rim and hub? They don't even use blue Loctite!

A proper seacock is fastened with large main threads and proper torque, and then through bolted to the hull with multiple smaller bolts. A seacock does not spin, move or hit massive pot holes. Despite the shear lack of abuse they see, when compared to lug nuts & wheels, people still insist on "welding" them to the hull with 5200! All you really need is an underwater rated & capable sealant. Even 4200 is slightly over kill. Mechanically fastened hardware is MECHANICALLY FASTENED!! All the sealant has to do is be flexible and adhere to each surface enough to not part during any flexing.

My 30 year old boat is bedded, and was bedded from the factory, entirely with gray butyl tape. Buytl tape has about a 10 PSI adhesion but is MUCH, MUCH, MUCH more flexible than any polysulfide or polyurethane. Over 80% of the fittings on my deck, including the deck to hull joint & chain plates, are still bedded with the original butyl from 30 years ago. It's still flexible and still NOT leaking. 10 PSI !!!!!!!!!

You do not need to glue mechanically fastened hardware to the deck but the sealant does need to be flexible and seal out moisture. Butyl tape does this as do the lower adhesion polysulfides like Sika 201US, 291, LifeCaulk & 3M 101.

You're looking at an elongation of well over 3000%. This butyl bedded cleat was removed at the 29 year mark, still BONE DRY and very, very flexible!

The Core Was Still Bone Dry:



Here's one last photo. It shows a cutaway view of a section of deck core that has been potted with epoxy and then countersunk to create an o-ring effect.

In a mechanically fastened joint, genny track, stanchion, traveler, deck cleat etc. you will NEVER, EVER see movement like this and if you do you have way more trouble than a failed sealant!! Remember this is a Butyl tape bond strength of about 10 PSI, not 1000 PSI, not even 100 PSI, just 10, which is nowhere near the 502 PSI of 5200 bonding to gelcoat, or 362 PSI of 5200 bonding to stainless steel.


Please don't get me going on silicone as I hate to even use it for the very few things that it is actually a proper choice for..;);)
 

·
Registered
Joined
·
418 Posts
Not only that, but I'm once I get my manual windlass rebuilt I'm going to have to bed it to the deck with something....
Well, I still wouldn't recommend 5200 even if you think it will never have to come off...ever. It will.

I once restored a little Cape dory and at the time I thought the word RESTORE meant BOTH sides of the teak cockpit combings. I know better now.

When the boat was built, Egor the cockpit combing installer bedded the starboard combing with 5200 knowing some idiot would try to take it off. Well come to find out, Egor was not only a smarta$$ he was also clarivoyant. He knew it was going to cost said idiot over $1400.00 to pull off that combing! The guy was GOOD.

You say "$1400,:eek: How can that be? That doesn't even count the cost of filler to repair the gelcoat on the cabin side and cockpit liner the teak combing attached to and the four days it took to finish the work.

The whole thing started to unravel after the second trip to Home Depot for another scraper to replace the others I'd ruined trying to break the almost 25 year DEATH grip that Egor had applied. No, scrapers have gone up, but not THAT much.

After the third scraper was demolished, I broke out the big gun - a scraper I'd built out of heavy stainless steel with a tapered aluminum handle so one could beat the bjeez out of it with out damaging the handle...still have it too. I was really careful not to inflict further damage so it took most of the day. Was tired of the whole ordeal so when I got to the last bit (connector from the teak combing to the cabin side), in the true spirit of and the singing of 16 Tons what do you get, I let go with the final swing what even John Henry would have been proud. That last bit of splintering gelcoat let go so easily that the 2 lb. mini sledge I was using, rolled over the scraper and was propelled from my hand forward to the bow with much abandon. My "uh oh" hadn't left my lips before the hammer handle took a bad hop off a stanchion base and took at wild loop-t-loop around the bow pulpit like some drunken monkey on a jungle vine and shot out into space. All was well until the bump, bump, crash.

So that my friends is why I hate 5200. Although while my car was having the dents removed from the hood and the windshield replace, I had a whole week to bond with the boat. So unless you have and extra $1400, stay away from 5200!:D
 
1 - 20 of 21 Posts
Top