Ugh. Cleaning the dinghy bottom. It was one of the last chores we had to do before re-launching the boat.
Even though we have dinghy davits and pull the dinghy out of the water every night to prevent barnacles growing, there’s still a certain amount of growth on the bottom (on our previous boat, without davits, we hoisted it every night using our whisker pole — see more about how to do that here). If not cleaned periodically, the dinghy motor (or rower!) has to work harder and harder to move the dinghy at all, speed suffers and fuel consumption increases.
So you have to take the dinghy ashore, take the motor off, flip the dinghy over and clean. Really fun. Actually, the first time we did it on our first cruising boat (after not having hoisted it and with a nice crop of barnacles), we didn’t know any better and cleaned it on the deck of the boat. Talk about a big mess!
Two things we learned from that: pull the dinghy out of the water at night both for security and to significantly slow the barnacle growth, and don’t clean the dinghy on the foredeck.
Still, we’d never really hit up on a good way to clean the dinghy bottom. Admittedly, it was easier while the boat was in the yard, hence why we wanted to do it before re-lauching.
A couple of years ago, we hit upon the technique of using a green scrubby over a putty knife and that helped some (read more about that here).
Then, a few months ago, Dave’s brother sent him an article from the Pensacola, Florida newspaper that said WD-40 could help clean boat bottoms. So we tried it. To be honest, we didn’t find it to be a breakthrough. A reader had suggested Krud Kutter, but that didn’t do much for us either.
But it got us thinking about what might make it easier. I went looking for other things to try and found both a can of powdered Barkeeper’s Friend (a cleanser with oxalic acid) and an unopened bottle of Liquid Bar Keeper’s Friend that the previous owner had left on the boat.
I did a quick online check to make sure that oxalic acid wouldn’t hurt hypalon or the fiberglass bottom. Everything that I could find said that it was okay with hypalon, fiberglass and even PVC dinghies.
WOW! The powder Bar Keeper’s Friend (usually abbreviated to BKF) was good, but the liquid was amazing in how fast it cleaned the gunk off.
I wet the hull, squirted some of the Liquid BKF on it, went over it with a green scrubby folded over a putty knife and it was pretty well clean. I rinsed it off and re-did any stubborn spots, rinsing thoroughly after it was all done. The photo at the top of this article shows the before and after: the side further from the camera is done. Even the little “barnacle footprints” came off completely — and so much more easily!
With Dave and I working together, it only took a little over a half hour to have the whole dinghy bottom and tubes where they were in the water looking almost new — a task that previously took considerably longer. Then we put on two coats of Star-Brite Polish with PTEF, which helps considerably to keep stuff from growing.
I haven’t found Liquid Bar Keeper’s Friend in any local stores but stocked up from Amazon. I discovered that they now call it “Soft Cleanser” but it’s the same formula; a 13-ounce bottle was just enough for our dinghy. Even better — it’s about the cheapest thing we’ve tried other than elbow grease! The Star-Brite is available almost anywhere that sells boat polish, including Amazon.