Transom reglueing-PVC sib.

[Nos4r2]

Some questions about Ballastboy's PVC sib transom repair.

It's got the transom almost completely off, but apart from that the boat is unpatched and no leaks so it's well worth regluing.

The rubber transom holders are totally off-from both the boat and the transom. So...

Given that the Polymarine guide says use single part hypalon glue to prime the transom before glueing with 2 part PVC glue, can we use 2 part hypalon glue to prime the transom before glueing with 2 part pvc glue as I've got more here than I can use before it goes off?

[jyasaki]

Nos;

What you're trying to do is to use an adhesive that adheres to the different substrates, then stick the differing glues together.

The 2-part hypalon glues are not a hardener and adhesive a la epoxy resins, but rather an adhesive and a "modifier" that renders the bond more resistant to chemical attack (at least that's what the stuff I use says.) I use this stuff to attach hypalon to aluminum, and it holds quite well (assuming I take the time to prep correctly); I would suggest that the 2-part is superior to the single part in just about any application (even if you forego the additive.)

I've tried the single part hypalon glue once, attaching some accessory bits to a SIB, and was less than impressed with its performance.

In short, I'd say yes, you can use the 2-part, and it would probably be preferable.

jky

[captnjack]

Agree, the 2 part has always been vastly better than 1 part for every use I have ever had or needed.

[Nos4r2]

What you guys have said is what I thought too, but I'm wondering if there's a reason that the PVC glue won't bond to the 2-part hypalon, given that the PVC glue 'welds' rather than adheres?

[jyasaki]

No. The PVC glue "welds" to PVC in much the same manner that the hypalon glue "bonds" to hypalon. In neither case does much actual dissolution/intermixing/hardening take place (though I may be worng; if a chemist/materials engineer can provide clarification, I'm open to correction.)

The glues have minimal penetration into the fabric material, and rely on their rather tenacious tensile strength to form the bond.

The glue-to-glue joint should be fairly reliable between any normal hypalon adhesive and and normal PVC adhesive. Usually both are some kind of super rubber-based contact cement, so they stick quite well to each other. Difference, I think, is primarily in the solvent used to attain fabric penetration (and a majority of that is flashed off before bonding.)

Might get iffy if you throw in a urethane adhesive; I don't have any experience trying that.

jky

[Nos4r2]

What I thought was PVC glue is effectively like polystyrene cement,? Ie it melts the parent materials together? Thats why i'm slightly confused.

[captnjack]

Originally Posted by Nos4r2

What I thought was PVC glue is effectively like polystyrene cement,? Ie it melts the parent materials together? Thats why i'm slightly confused.

They do. At least when I had a PVC boat it seems to and all my PVC plumbing seems "melted" together.

But I doubt this impacts whether your PVC glue will or won't adhere to the 1 or 2 part hypalon glue you are using as a primer. They probably suggested 1 part since its cheap and works good enough in that application.

[Nos4r2]

Originally Posted by captnjack

They do. At least when I had a PVC boat it seems to and all my PVC plumbing seems "melted" together.

But I doubt this impacts whether your PVC glue will or won't adhere to the 1 or 2 part hypalon glue you are using as a primer. They probably suggested 1 part since its cheap and works good enough in that application.

I think I see... I thought maybe the PVC glue had the same effect on the hypalon glue as it does on PVC?

[Poly]

Originally Posted by Nos4r2

What you guys have said is what I thought too, but I'm wondering if there's a reason that the PVC glue won't bond to the 2-part hypalon, given that the PVC glue 'welds' rather than adheres?

As far as I know Polymarine's adhesives have a different formulation to e.g. Bostik's and its not quite as simple as saying 1 part v's 2 part.

Originally Posted by Nos4r2

I think I see... I thought maybe the PVC glue had the same effect on the hypalon glue as it does on PVC?

If it is Polymarine's glues - then they both seem to use the same "hardener" - which is a 'standard' hardener used for polyurethane type materials to make it more rigid (4,4-MDI) . i.e. the hypalon adhesive hardener appears to be the same as the the PVC one. So I can't see any issue mixing them.

As I understand it the general issue with using hypalon adhesive on PVC is that the plasticisers (small molecules which make PVC flexible) migrate out the material and then "unstick" the glue.

I can't see any reason not to use the 2 part. But then there also seem to be no reason not just use the main part of the 2 part (i.e. leave out the 107 Hardner).

All this may be different for Bostik!

[captnjack]

Originally Posted by Nos4r2

I think I see... I thought maybe the PVC glue had the same effect on the hypalon glue as it does on PVC?

I am not sure. The real issue to me is why doesn't PVC glue stick to the transom? I am guessing it peels off and that's why you need a hypalon glue on there as a primer glue.

[Nos4r2]

This is making more sense now.
It'll probably have to be Polymarine glues as I have polymarine 2 part hypalon glue here then.

I really don't want to risk any possible incompatibility issues.

[Peter_C]

When regluing my wooden transom, I just used the Stabond PVC glue and haven't had any issues with delaminating.

[jyasaki]

Originally Posted by captnjack

They do. At least when I had a PVC boat it seems to and all my PVC plumbing seems "melted" together.

Well, Jack, I suspect you're not using the PVC pipe cement on your boat, so that's kind of a moot point.

The telling point would be if you can disassemble a glued PVC fabric repair job with a bit of heat. I've never owned a PVC boat, so I haven't tried; maybe someone else could chime in (Peter_C took his boats floor off, so he should know.) If it comes apart without damage, the material can't have been welded through gluing.

But I doubt this impacts whether your PVC glue will or won't adhere to the 1 or 2 part hypalon glue you are using as a primer. They probably suggested 1 part since its cheap and works good enough in that application.

As I stated before, I've tried the 1-part, and it didn't hold worth spit (not my first choice of wording.) Maybe not the best test, as conditions may not have been ideal, etc.; but I've had little trouble with the 2-part, and those were likely in similar conditions. Since we're talking about a reasonably critical section of structural integrity (transom falling off = bad), I'd think you want the strongest repair you can come up with, wouldn't you?

jky

[captnjack]

Originally Posted by jyasaki

Well, Jack, I suspect you're not using the PVC pipe cement on your boat, so that's kind of a moot point.

The telling point would be if you can disassemble a glued PVC fabric repair job with a bit of heat. I've never owned a PVC boat, so I haven't tried; maybe someone else could chime in (Peter_C took his boats floor off, so he should know.) If it comes apart without damage, the material can't have been welded through gluing.




As I stated before, I've tried the 1-part, and it didn't hold worth spit (not my first choice of wording.) Maybe not the best test, as conditions may not have been ideal, etc.; but I've had little trouble with the 2-part, and those were likely in similar conditions. Since we're talking about a reasonably critical section of structural integrity (transom falling off = bad), I'd think you want the strongest repair you can come up with, wouldn't you?

jky

On my old PVC boat I pulled the (old) 1 part sealed patches off with heat and pliers. The 2 part patches I never tried to remove because they were stuck a helluva lot better and never delaminated for the rest of the time I owned the boat (4 years). I own a hypalon boat now and have never needed to patch it. I did use a 1 part glue to attach little 3"x3" registration sticker plaques, they are gradually coming loose after 4 years. But they are non-structural and I actually used the weak glue there on purpose because I wasn't sure I liked them that well and wanted a future option to remove/replace them.

I have no idea why anyone would recommend 1 part glue for anything RIB related PVC or hypalon, but for some reason the OP is saying someone is recommending 1 part hypalon glue on the transom. I have no idea why and I am not actually recommending 1 part glue - in my experience it dries out, loses its elasticity and bond over time and just overall sucks.

Just postulating on why it might have been suggested by a manufacturer.

[Peter_C]

Originally Posted by jyasaki

The telling point would be if you can disassemble a glued PVC fabric repair job with a bit of heat. I've never owned a PVC boat, so I haven't tried; maybe someone else could chime in (Peter_C took his boats floor off, so he should know.) If it comes apart without damage, the material can't have been welded through gluing.

The PVC parts of a Zodiac that are not thermo bonded can be pulled part with heat if they don't fall off after 10 years. No damage and no bonding as the glue used is a mechanical bond mostly. Acetone cleans the glue off with a lot of physical labor. I found scuffy pad removes the glue, but doesn't remove hardly any of the PVC boat material. Before reinstalling the floor/transom/etc. a tool for roughing up the PVC material, and an MEK wipe will build a strong bond. The transom wood needs to be sanded, and roughed up also. Cleanliness is very important to a good bond. If there was something that needed repair or such on the transom I would personally use epoxy.

[Locozodiac]

Nos,

Why would you like to use Hypalon glue on a PVC sib. That I know Hypalon glue is for Hypalon fabrics and PVC glues are for PVC fabrics. If 2 part much better, will hold and last longer, one part is only for instant small emergency repairs that won't last that long.

Happy Boating

[Nos4r2]

Originally Posted by Locozodiac

Nos,

Why would you like to use Hypalon glue on a PVC sib. That I know Hypalon glue is for Hypalon fabrics and PVC glues are for PVC fabrics. If 2 part much better, will hold and last longer, one part is only for instant small emergency repairs that won't last that long.

Happy Boating

Have a read of this link and it'll become clear. It's the same job that needs doing on my mate's sib.

Zodiac Dinghy Transom Repair « Polymarine Paints, Adhesives, Parts & Accessories

[Peter_C]

Nos4r2, do you think that the person in the link you posted is doing a professional job?

From my perspective there are more than a few things I would question. Why wasn't MEK mentioned as a pre-glue application to soften the PVC material as per the manufacturers instructions? Never sand material off, which means no power tools. Leaving glue on the material is not very good prep work. The joints do not need to be clamped for 48 hours as the glue sets in around 20 minutes. That is why you only mix enough glue for the job you are doing, as it dries quickly once the Toluene is added. So the only place I have seen mentioning of using Hypalon glue, is from the manufacturer of the glue...Hmmm... Where is the Zodiac repair guy with all the truthful answers?

[Nos4r2]

The link isn't saying sand fabric off with a powertool, it's saying remove old glue from a joint between dissimilar materials.

[ballastboy]

thank you one and all...me and nos are going to do a bit of homework before fixing the zed...i have put some pictures up so you can see where the transom has come away