The Blue View - Clam Shell Patch for Inflatables

We were on our way to the local Lowes to pick up parts for a house project a few days ago, when the subject of repairing things in remote parts of the world came up. What a difference it makes having a car and just about any conceivable part available only minutes away. Marcie reminded me of a few years ago, when we were exploring the hundreds of tiny anchorages in Tierra del Fuego and Patagonia. We were anchored in a snug little cove for the evening with the anchor in deep water and two lines ashore, and after we were all settled in, we put the dinghy up on the davits. It wasn't unusual to experience large katabatic winds there, usually late at night. Right on schedule, at about 3am, a “racha”, or katabatic wind (also known as a “williwaw”), came blasting down the mountain behind us, and the 135 lb. (60kg) dinghy became more of a kite than a boat. The wind lifted the dinghy up against the solar panels with such force that a corner of one of the panels tore a 3-inch hole in the starboard pontoon of the inflatable. rowing the inflatable

Most of the anchorages in this area require lines ashore, so having a dinghy is quite important. Knowing we would be hundreds of miles between chandleries and being aware of how important the dinghy was, we came prepared. I had a couple of square feet of hypalon patch material, and a fairly fresh kit of two part adhesive. The next morning I pulled out our patching materials and adhesive, only to discover that the accelerator, one part of the two part adhesive, in our unopened, six month old kit had totally evaporated.

Not to worry – it was only the 'accelerator', which would imply that given enough time, the adhesive itself should still cure. I tried a small amount on a scrap piece of material, but even after 24 hours, the adhesive still remained tacky and wouldn't hold. I tried heating the adhesive – no luck. When I was a boy, patching a bicycle inner tube involved lighting the adhesive with a match and letting it burn a few seconds. This didn't work on the hypalon adhesive, however.

Maybe we could get by with one pontoon deflated... it had three chambers after all, and two were still inflated. I put the dinghy in the water, and the bow and port side pontoons kept the dinghy afloat, even with my weight. Rowing it was rather comical, however. It quickly swamped, so I couldn't sit down and row. I stood up and paddled it, but it was slow going and only wanted to go in circles. Trying to tow 300 foot (90m) lines ashore in a half submerged dinghy that only went in circles would have made a great Mr. Bean video.

I pondered our dilemma for awhile, then remembered I had once seen a product called a 'clam shell patch', a mechanical patch that could be used for patching an inflatable. I rounded up a few scrap pieces of aluminum, plastic panels and rubber gasket material and set to work.

anatomy of a patch


patch in place

The illustrations above show my first version of the concept. It still leaked air rather copiously, so I added a rubber gasket on both sides of the tear.

patch parts

The second attempt worked quite well. The patch held well enough to keep the pontoon inflated for about 24 hours. As long as I pumped it up each day before it was needed, it would stay inflated long enough to get our lines ashore in the evening and retrieved in the mornings. The patch served us quite well until we reached Ushuaia and could get a new kit of adhesive shipped in. It now resides with our patch supplies as an emergency repair kit.