Inflatable Repair

Q:

The joint between the bottom and the hull on my inflatable sport boat has separated for about two feet in the bow area. There are no fabric tears.

Is this a repair that can be done relatively easily or does it have to be professionally repaired? Any insight will be appreciated...thanks.

A:

Your question: "Is this a repair that can be done relatively easily or does it have to be professionally repaired?" No, it is not RELATIVELY easy, and no, it does not have to be PROFESSIONALLY repaired.

I just happen to be in the same "boat" as you, as it were. The rub rails on my RIB had given up, after 8 or 9 years and required re-gluing. I got some good advice down in the Keys, from a guy who does this for a living down there. (And at "Key's Prices", it's a handsome living, indeed! )

Right off the bat, forget anything you'd normally get from West Marine. Those are at best, for weekend-patches-in-a-pinch, type repairs. I know. I've made those kind of repairs and gotten exactly those kinds of results.

1) Clean the surfaces. Soap and water to start.

2) Prepare the surfaces.

3) Sand the affected pieces. I was shocked to see that 40-60 grit is the MINIMUM required. Finer grits are considered a waste of time. I was afraid the fabric wouldn't handle it. I suppose you could wear a hole in the fabric through in-attention, but I doubt it.

4) Clean mating surfaces with Rubber Boat Cleaner. This is toluol, NOT toluene. According to this guy, acetone and toluene-based solvents do not get the surface clean enough. Needless to say, better have some GREAT ventilation handy, and no open flames, etc., etc.

5) Use Inflatable Boat adhesive. This is basically just an industrial grade version of contact cement. It has a fairly short working life, so have everything set up and ready, before hand. I got mine from the repair shop in the Keys. You may have to hunt on the Internet, or hit up inflatable boat repair shops in your area. According to my source, this is about 1 or 2 steps up in quality, from the inflatable boat repair kit, that WM sells.

6) Apply adhesive with a brush to each surface to be mated. This is a misnomer. Apply with a really short, stiff brush. Take your average 1-inch cheapy-bristle-brush and chop it to a bristle length of ¼" (one quarter-inch). According to my Guru, everybody screws up by using too much adhesive, thinking more is better. If you can see a brush pattern of adhesive (like you would if you were using paint) it is WAYYYYYY too much. A Perfect Application would be about a molecule thick. You are essentially trying to work the adhesive into the sanded sections to provide maximum adhesive surface area. Keep the brush at right angles to the fabric and really work it. If you don't start to get thumb and hand cramps, you may be doing it wrong.

Since the working life of this stuff is on the order of 15 minutes, this means you may have to repair your seam in sections, depending on how much you can apply.

7) Here's where the instructions are going to get a little fuzzy.
7A) IF your mating surfaces are identical (i.e. same fabric) wait five minutes and re-apply a second (THIN!) coat to each surface. Wait 10 minutes and mate surfaces and hold both in place for 10 minutes.

7B) If you are mating to dissimilar surfaces (like I did, with my rubber fenders onto Hypalon fabric), then you need yet ANOTHER adhesive, designed for the material in question. In my case that is called Vyna-Bond and is simply a fast-acting, high-strength contact adhesive. It should be available from the same place you get the inflatable boat adhesive. The surfaces are prepared in this sequence:
A) Sand vinyl/rubber side and clean as above.
B) Apply one coat only, of Vyna-Bond.
C) Wait 2-4 hours.
D) Apply 1st coat of inflatable boat adhesive and wait five minutes.
E) Apply 2nd coat of inflatable boat adhesive and wait five minutes.
F) Attach pieces and clamp in place for 10 minutes.

Clamping pressure needn't be excessive; duct tape or wide (> 3") masking tape should be sufficient.

Best temps are at 70º and as low a humidity as you can get. If higher humidity, let joint bake in the sun for about two hours. Moisture is considered the second leading source of joint failures, in rubber boat repairs, according to my expert.

On my own boat, a three foot repair to re-attach a rubber fender on each side to the main tubes, took approximately three hours, mostly in setup and prep. Just like frosting a cake, the most important work is done BEFORE you start frosting. I did each fender side in two stages, since about 18" was the most surface I could work with, at a time.

It's not overly high-tech, but does require thoroughness, and strict attention to cleanliness and timing. Having read your articles on lightning and your stories on the Great Lakes, I've no doubt but that your mind and temperament, are up to this repair.

Hope this helps, Charles Brennan

A:

Mr. Stewart,

I can sell you the adhesive for the repairs.  The cost is $36.00 for 750 ML (APPROX. 1 QT.).  It needs to be glued in a controlled environment (temperature and humidity controlled). 

I will tell you that the ungluing problems you are experiencing will continue until the complete floor has come unglued.

I would recommend to completely reglue the entire bottom not just what is ungluing at the present time.  Our normal charge for this repair is $390.00.

Hope this helps, please let me know if I can help further in anyway.
 

Best Regards,
Carol Hamala
Service Administrator
Triad Marine & Industrial Supply
1155 FM 518
Kemah, Texas  77565


Much thanks to both Charles and Carol for their guidance... when a course is taken,  any relevant information will be posted.