Fixing 3" Cut in Hypalon RIB

[gettinthere]

My 1987 vintage hypalon dink still holds air with no problem (spent the bulk of it's life in Florida). That's 24 years and counting. If you're junking your 10 year old, it is either PVC or something is wrong.

[zeehag]

wasnt until recently that dupont released the patents on hypalon-- there is now no longer a lifetime limitation on the fabric, as the imitators are not as good as the original product.

[fstbttms]

Originally Posted by gettinthere

My 1987 vintage hypalon dink still holds air with no problem (spent the bulk of it's life in Florida). That's 24 years and counting. If you're junking your 10 year old, it is either PVC or something is wrong.

+1

My mid-80s Avon still holds air like the day it was made. The bottom, well that's a different story.

[Mark Johnson]

My AB Hypalon RIB is also an oldie. It was vandalized a year ago in a way intended to be non repairable. I have considerable experience fixing these, but this was a challenge because the numerous cuts were close enough to require one large patch, as well as RIGHT next to the rub rail, where there was no room for a patch.

I always keep a square foot or two of my dinghies color of Hypalon fabric around. My preference is two part Bostick glue, but it has a very short shelf life, so when cruising, I carry their one part as well, which has a longer shelf life. In over 50 patches over the last 35 years, none have ever failed. (with either type)

I cut the patch with rounded corners, or totally round, then, after thorough acetone washing of both parts, I scribe it on the dinghy. Then I tape all around what I have scribed with my favorite tape, 3-M 471 blue plastic tape. (NAPA) This stuff is solvent resistant and abrasive resistant too. Next I use a dremel tool to abrade both the dinghy and patch underside to a consistent fuzzy appearance, without removing to much.

Next, I QUICKLY apply the glue as thinly as is still 100% covered, to surface A and surface B, with a small acid brush. Now wait 15 minutes until dry. Repeat the coating process. Now wait only 5 minutes! (If the glue instructions differ, ignore them)

After this 5 minutes, carefully roll the patch into position on the masked off area. (no bubbles)

Next you can remove the tape, but hold the patch down as you go, so as not to pull glue out from under the patch. This is followed by first, "firm as possible pressing", then hammering a bit, with a rubber hammer and something soft underneath.

For a really neat job, I finish up with acetone removing any excess glue from around the patch.

In this case, I had to remove the rubrail first, apply the patch, then re-apply the rubrail.

To remove any glued on part, you heat it with a glue gun, waving it back and forth, to heat the 6" in front of where you are working.. At the same time you use a putty knife to lift the part, GENTLY. Apply heat very gradually, and there is a point almost, BUT BEFORE the fabric comes apart, that any glued on part just comes right off.

After making my patch where the rubrail had been, I re-applied the rubrail, just like a patch. (All day job)

The other problem was that over 10 years, every seam on the boat, had their edges all fuzzy and frayed, where strings of the fabric core were coming out, and a bit of the Hypalon outer layer were flapping up.

To fix this, ONE SEAM AT THE TIME... I masked off both sides of the seam (same tape as above), and first I worked 5200 under the outer layer of Hypalon. Then wiped the outside clean with solvent, and applied a third row of tape right down the middle, to glue down the flap. A couple of days later, I peeled off the 3-M tape, and repeated the process of taping the seam. This time I made a 1/8" wide bead of 5200 right on the exposed edge of the seam, and immediately pulled the tape on each side.

I basically glued down and then covered the edge of every seam on the boat! It has held up for a couple of years now, and I think I'm good for 10 more years!

This process did take a couple of weeks and couple of hundred dollars worth of tape and caulk, but the dinghy was both expensive, and it had a cradle and many other labor intensive accessories made just for it. Otherwise I might have just bought a new one...

For some folks, it is worth the effort... BTW, Beware of aluminum floor RIBS, if you want longevity. (ours is fiberglass) The aluminum floor models have a weak link, it is the bond between the paint and the aluminum. The tubes are glued to the floor after the floor is painted, and before the glue job fails, the paint bond usually does. At least this has been my observation.

Hope this helps, Mark

[endoftheroad]

Mark,

Do you ever use 2 patches (one on the inside)?

[Mark Johnson]

Originally Posted by endoftheroad

Mark,

Do you ever use 2 patches (one on the inside)?

I haven't, no... The longest rip I have repaired is a 4" clean cut, in which case I would make a patch about 7.5" long and 3' wide like the round one in the photo. This spreads out the load a LOT, and I think one side is sufficient.

The other issue is that the sanding prep for a "perfect 20 year bond", would be VERY difficult to do on the inside. Reaching in there with some 80 grit and sanding by hand, would undersand some areas, miss others entirely, and remove material you don't want to beyond the patch area.

The prep done on the outside, by contrast, is within the borders of the abrasive resistant plastic tape, so I can use the Dremel's "oval cone, pointy abrasive tip", right up to and even a bit over the plastic tape. This preps ONLY where the patch will go, and removes NONE of the precious Hypalon coating that will be beyond the patch. (I use the point of the tool near the edge, then more of the side of the wheel as I get away from the edge). I'm not talking about a light scuff here... The patch surfaces are really fuzzed up, WITHOUT going through the outside coating into the fabric. Then I wipe the fuzz off with Isopropyl alcohol, and let dry.

That long patch in the photo, under the rubrail, took me about an hour to prep. IF you solvent wash the surfaces beforehand to get off any "UV protectents" or slime, and do a thorough prep, the patch will be plenty strong! Probably stronger than beforehand.

Now... If you get a 3' jaged rip, doing a patch on the inside as well, even with a half assed prep inside, might make more sense?

BTW... The glue is obviously bad if it is set up, but if it is half way there, it will be like stretchy snot. (no good). If it is like wet snot, it will still work, but not as well, because it is hard to spread quickly. I spread the glue on that long oval patch in about 30 seconds per surface! THAT'S how fast it has to go, or you get little balls of glue, that show, and make a bit less of a neat patch. Really fresh glue is thin like maple syrup, and spreadable, just like regular contact cement. A LOT of the glue supply "goes off" on the shelf, before it is sold!

Good luck, Mark

[Mark Johnson]

Typo alert! In my first paragraph above I said: a patch 7.5" long and 3' wide... WRONG!
I meant 7.5" long and 3" wide... M

[endoftheroad]

Are all Avon RIB's made of Hypalon?

A friend of mine has one that is about 10yrs old and let me cut some pieces out for patches. He says that you can use the Hypalon from an old dinghy and not buy patches as I am having a hard time finding patches locally. The fabric on this Avon in in good condition.

Is this true?

I will be using a 2 part glue and will be paying close attention.

Thanks

[Mark Johnson]

Yes, Avons are Hypalon, and cutting up an old dinghy should be fine... if it is in good shape.

For new fabric... The patch kits are ridiculously high priced. I bought it off of a
4' wide roll in Trinidad, (about 4' square, was maybe... $90 US) and in the States, authorized repair facilities for Hypalon dinks are the place to buy a square foot or two. You may get a long rip some day...

My anchor rode locker's witches hat, was made from the largest piece of Hypalon that I have bought. (Trinidad)

May all of your patches hold air... Mark

[psneeld]

My Avon patch kit recommends stitching the tear fist with a herringbone stitch then gluing on the patch.

I've never done that and most of my patches last 10+ years...but then again I've never had more than a 1 inch tear on the bottom...fortunately never one in the tubes.

[Mark Johnson]

I have never seen that done, but if a tear was so jagged, or would not stay together due to the shape, size, or location of the cut, it might help hold it closed for the patching process.

Compared to the patch, it would add no strength at all, and would make the repair just a bit lumpy under the patch, but it would be a solution to the above problems. I never felt the need...

BTW, When applying the glue, always be careful NOT to get glue down inside the tube. You could glue the inside halves of the deflated tube together!

The key is to have just the right amount of goo on the brush, as you approach the open cut, and don't brush across the opening, go length wise.

Mark

[endoftheroad]

The witches hat was quite the sweet project.

Fwiw,
I heard that Dupont's patent ran out so perhaps the Hypalon patches in todays repair kits may be of lesser quality or even worse made in China.
So in some cases one may have more faith in a 10yr old Hypalon inflatable to be used for spare material.

[Mark Johnson]

I would sure feel better with the real thing!
M.

[endoftheroad]

Mark,
One thing never mentioned.
In what climate conditions do you perform your surgery?

I may patch my two 3" cuts tomorrow but there are 2 times in the 24 hour period forcasted for 85 humidity and even 80 for the high temp. But much of the period is about 70 percent humidity.

I will be working in a shop with an OK air conditioner that should keep the humidity and temp down.

Should I proceed with my plans?