Rehabbing An Inflatable

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Inflatable boats come in all sorts of configurations and sizes. Some are light, easily transportable, and when deflated can be stowed in a space a fraction of their in-use volume. Others have rigid floors that trade that portability for better performance on the water. All are pretty stable platforms, are highly maneuverable, and usually cost far less than a hard-hulled vessel able to perform the same tasks.

On the other hand inflatables are often a nightmare to row, are best used in calm waters, and the sun can do a number on all of them. Remember, these boats are really air-filled, rubber- or PVC-coated fabric balloons. And like all such fabrics, by being extremely flexible and exposed to ultraviolet radiation, their life expectancy is limited.
Because of their buoyancy and their low displacement, such inflatables have a huge cargo-carrying capacity. In addition, because their air is held at very low pressure (mostly 2.5–3psi versus a motor vehicle tire’s 30–50psi) they are inherently safe—they lose air slowly when punctured. Also, except for the smallest, most inflatables have between two to four flotation chambers.
Take my battered, 31-year-old Achilles dink. Like all its brethren, it has suffered chemical degradation thanks to sunlight. Then came the mechanical impact of submerged rocks, or from rubbing against crustacean shells on pilings. Further, while being dragged to a launch site, sand abrasion inevitably was the result (and if used as a sled for cargo, the damage was even greater). The final blow, more often than not while in storage, were the hungry rodents and their stubborn failure to accept that expensive plastic fabrics were toxic food for their young or old. These meals often left sizable holes into what had until then been a seaworthy vessel. Regretfully, I have yet to find nearby a single hairless-tailed corpse of that clan—one that would attest to the validity of my alimentary argument.
Air-supported vessels are hardly a modern idea. Even in antiquity, air-filled animal bladders were used as water-wings to assist a human swimmer, or for supporting bulky cargoes in fording streams or rivers. It was not until the mid-1850s, when rubber-impregnated fabric was introduced, that substantial improvements finally took place.
The next step was the introduction in our own times of a flexible sandwich consisting of a nylon or polyester outer coating over a durable fabric mesh, and placed on the mesh’s other side, an impermeable inner bladder made of PVC. The priciest dinghies have these inner and outer coatings made of Hypalon—a synthetic rubber that retards UV damage and its attendant short life expectancy and buoyancy loss. However, some PVC coatings and formulations seem to work just as well. The problem is that repair procedures and materials for each type can be unique, so you must first identify the coating used on your boat. If in doubt, a short call to your manufacturer should take care of that.

Should air leakage be the problem, it would be a good idea to first check whether your inflation valves are at fault. After all, it’s possible the air-leak problem could be caused by a defective valve, which would be easy and inexpensive to remove and replace. To test it, simply unscrew each valve body, place it backwards in your mouth, and with its cap pushed aside, blow hard in the opposite direction used when inflating (while making sure your lips and teeth are in contact only with the valve’s rigid structure, and nothing else). Should you succeed in pushing air this wrong way, that valve must be replaced and if you are lucky, that will be the end of the leak problem. If so, get two, plus an inflatable air-pressure tester, if you do not already have one. (Automobile tire gauges are meant for high-pressure loads only, as they do not even begin to register below 20 pounds. They are totally useless here). With two valves, you will have a spare one to use, lend, or trade as the occasion might arise. With a good valve in place you are now ready to determine the size and complexity of the inflatable segment of your rehab project.
If there are cuts and holes to span, now is the time to assemble the materials for that patching task. Here you will find several suppliers, most of whom provide a kit. This usually includes a set of instructions, a sheet of abrasive paper to give “teeth” to the damaged surface so the mending patch will adhere firmly to it, a bonding agent, and a 6-by-12-inch sheet of rubber. Some will also include a ½-inch to 1-inch roller to press out all air between patch and hull (if not, you can get a cheap one at any hardware store), plus sometimes a tube of cleaning fluid. You will also need a pair of scissors to cut the patch, plus plastic gloves and a mask. Remember, the chemicals you will be dealing with are toxic and volatile compounds, so good ventilation is essential—and so is inhalation protection—hence the need for both gloves and mask.

My preference has always been to work with a single materials source whenever possible, for their interaction is then a known factor. In my case I chose Inland Marine for the patching kit. It is designed to work with either Hypalon or PVC, even though their directions recommend a different cleaning fluid for each. However, both are available at most hardware stores. Once you have decided which process fits your boat, cross out the other, so you don’t mix them up. Then make a checkout list, for the process will take several days—and make sure your list is correct.
Bear in mind that for all the chemical steps needed to rejuvenate your boat, the most crucial, and the one most likely to be rushed, is the prepping process—the foundation to all the bonding work you will be performing. So, unless you enjoy building sand castles and waiting for the incoming tide to wreck them, check and double check that each step your directions call for has been done. Don’t cut corners or skip steps. If you are like me (impatient to get the job under way and done), you are apt to misread or willfully avoid or overlook some instruction. That will pretty much guarantee you will later be backtracking, and what earlier had been a simple matter is apt to be a major mess.

Remember, too, that temperature plays a major role here, so don’t begin when there is snow on the ground and you are wearing mittens to ward off the cold. Start with the big holes, making sure your patch will extend generously over all sides of each. If the hole or tear is bigger than say, 2.5 inches, and if it’s a ragged one, it’s most likely the work of Mr. or Mrs. Rat or their cousins. Remember them when you are ready to store your dink again. After you have trimmed the hole’s edges into one continuous circular or oblong shape, a good idea would be to consider patching both sides of it and reading the instructions once again. If the patch must also bridge a seam, be extra careful. That could be a problem spot, so be generous with your bonding material there. First mark and overlap the patch up to a good 1 inch all around the hole to ensure a good bond and cut your patch (or patches) accordingly.
That done, proceed with the bonding process as the instructions direct. In my case this included a curing time of up to two days at ambient 75–85°F. If that is not available, a heating pad or lightbulb can help do that job well. Check out the proper heat-source distance with a thermometer. Your kit may also have other specs, so follow them carefully. Incidentally, if you have problems securing a parting rub-strake or the half-flapping rubber bases for D-rings, use the above procedure to secure those as well.
So now you have carefully followed all directions and have successfully mended all holes and cuts. But wait, you won’t know that for sure until after the curing process has been completed. And then, to be doubly sure, wait an extra day. That done, it’s time to inflate your boat. If you have your air gauge, pump each chamber up to a taut, but not stressed condition. Take a reading and remember it, or better yet, write it down. Now brush soapy water over each of the patched areas you worked on and around the valves as well. Check all chambers. If any are still deflating, pinholes will need to be internally repaired after you are thoroughly satisfied your patched surfaces are not leaking. An internal sealant will take care of them.
I used Inland Marine’s sealant. It comes in a quart container and claims it’s enough to treat an entire 12-foot boat. So if you have a three-chambered dink, one-third of the material should be allocated to each. Before you apply it though, make sure there is someone around to help you tumble the boat for the next three or four hours. That action needs be redone every half hour to properly distribute the sealant over all the internal surfaces. Once you and your crew are set, remove the valve and insert the proper amount in accordance with the manufacturer’s directions. That done, the valve must be speedily reinstalled. The sealant sets quickly once it is in contact with air. Now re-inflate the boat to just below taut. To be doubly sure, if you have earlier noticed an adjacent chamber going slack, place sealant there as well, following the same drill. Either way now you are ready to roll the dinghy sideways, and end over end, too. Don’t forget to keep enough beer or other essential fluids at hand to keep that tumbling crew happy and fit throughout the whole process.
You might also see abraded areas that while not yet leaking, can make the boat look shabby. A topcoat will provide a protective and cosmetic film. I used MDR’s grey product. A quart of it is enough to lay one coat on most boats. It is also available in white, red, yellow, blue, and black and requires the use of a dinghy cleaner. I used MDR’s own Amazon, and followed their directions to the letter.

Holes on the boat’s flooring or sole can be easily detected and treated the same way as the hull. Sizable ones, if any, should get a patch on both sides. And if you go into salt water or areas heavy with marine life, you might want to add a “designed for inflatables” copper-based bottom paint to the outer side. For an 8–11-foot dinghy, one quart should take care of it.
The rigid plywood flooring in my dink had two problems. First, its panels were delaminating. Secondly, I had lost one of the slotted side rails that keep the panels aligned and in place. Not being overly fond of refinishing plywood, and after some hesitation, I took the coward’s way out and got a set of floor panels from Achilles. It came complete with the rails, but not before I had created a substitute out of a 1/2-inch electrician’s PVC pipe whose end view I had altered from a closed “O” into a 3/8-inch-wide, full-length open “C.” If you have the same problem, make one yourself. It does the job well and it’s a hell of a lot cheaper.
If the above problems and cures prove to be more than what you bargained for, consider this. Today’s sport and tender inflatables from nearly all reputable makers are mostly affordable and come in several distinct flavors, all based on their sole type: Air-Supported, Roll-Up, and RIB (Rigid Inflatable Boat). Whichever road you choose—the brand-new way or rehabbing the old—at day’s end you should have a dink you can trust. Take good care of her, she’ll reciprocate with good, long-term, dependable service.