Thanks for the kind wishes, folks, they worked, in as much as I won a prize and now have a shiny new Makita tool kit. I wasn't the fastest, but won the prize for innovation. Even so I was pretty quick, as the boat I ran around neck and neck with had a GPS and was doing 7 kts, well over the maximum hull speed for my Duck Punt. I reckon we probably averaged around 6 to 6 1/2 kts around the course, with my opponent being very slightly faster on the straights but with me having much better acceleration and sharper turning circle around the marks.
The Makita lithium battery pack I was using was too hot to touch after the race, and was nearly flat. It looks like I drained most of a 54 Wh pack in a little under 3 minutes................... Interestingly the Makita pack doesn't seem to have a BMS that cuts the power when it gets abused like this, and the drill didn't really even get warm, even though it must have been running at way over it's rated power (my guess is that it was peaking at over 1 kW, based on the heat in the battery pack and short endurance). One of the spectators reckoned that the front 1/4 of the bottom of my boat was out of the water as I went around, even though I was lying as far forward as I could get, well forward of amidships. With two drills it would probably plane, I think (something for next year., perhaps........).
Here are some photos of the other contestants, taken by me, so none of my boat, I'm afraid.
The paddle boat, Ayrspeed, was fully amphibious and drove down the slip straight into the water. He competed last year, with "only" four cordless drills driving the paddles, this year he'd added two more drills driving auxiliary propellers.
Long tail drives were popular, with several boats sporting model aircraft propellers on the end of long shafts.

- Fliptail and Noa Noa - small.JPG (230.43 KiB) Viewed 1072 times
The air boat drive was pretty effective, I suspect that if we'd been pitched against each other in the heats we'd have been pretty evenly matched, as when we ran a short distance alongside each other after the race (albeit when I had a nearly flat battery) we seemed to be pretty close in speed.
The most entertaining entry by far was the gentleman who built "Something Fishy", a flapping fin propelled shark, with the pilot lying inside the submerged hull. Getting in was like something from a James Bond film, as the bow section opened up and the gentleman swam in feet first, whilst his patient wife stood knee deep in water holding it for him. It wasn't fast, but did make it around the course, with the pilot steering via a mirror mounted on the "conning tower). Only in England would you see this level of eccentricity, I suspect.

- Something Fishy - small 2.JPG (218.82 KiB) Viewed 1072 times

- Something Fishy - small 3.JPG (245.43 KiB) Viewed 1072 times
The winner was "Velociraptor", driven by a V4 array of four cordless drills driving a single shaft and model aircraft propeller via a lot of bevel gears. It was, like "Quackers", running at well over hull speed and clearly climbing her own bow wave. I suspect that with a flatter section aft she might have got up on the plane, or at least closer to it.
I believe there will be a video of the event posted some time over the next week or so. I'm also trying to get some copies of photos of "Quackers" in action, as I am keen to see what she looks like going at speed.
Jeremy
Please ask questions on the forum, rather than by PM, as it helps others and you'll get a better range of answers.