L11. Upside down and and awaiting rescue. by John Cooper

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12 12 2011	BEC

L11. Upside down and and awaiting rescue.

Long Pond, Clapham Common view map

It actually floats better upside down, than the right way up,,rather strange.
Before the Maiden Voyage I put Duct Tape over all the seams in the deck, just in case, that was a good choice.
There was a strong wind blowing which was bringing the boat into the side of the pond.
As soon as it was close enough I threw a rope across the boat and pulled it in quickly before it could sink.
There was very little water inside the boat.
Back to the drawing board.

Canon PowerShot G6
1/160s f/4.0 at 28.8mm full exif

other sizes: small medium large auto

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John Cooper		17-Dec-2011 03:32
Bob, this pond is only waist deep. Now if the boat sinks, will I go in and get it, and risk death by hypothermia. Or will I walk away, and leave this beautiful expensive boat on the bottom. I have to ask myself, do I feel lucky,,,,

sunnybob		15-Dec-2011 21:29
in the words of Sir Donald Campbell.. "its lifting... I'm going" hope that pond isnt as deep as lake windermere (grin)

John Cooper		15-Dec-2011 20:40
Bob, Slow speed ?, testing ?. Surely you jest ?. This is my plan, seal the boat carefully so it will keep floating whatever position it ends up in. Fit a three bladed prop for more speed and grip. Drive it at full throttle down the pond and see what happens. Repeat above until,, A Boat sinks. B I get control and have a very fast boat. In the words of John Cobb (hero) I dont go slow, I am here to break world records.

sunnybob		15-Dec-2011 14:00
with 6 volts and a smaller prop, it will go much slower. at slow speeds you can adjust rudder control, and check for balance under way. once you are happy with the boat on slow speed then you can go back to 12 volts, and check again, and then onto the big prop and check again. Youve jumped in at the deep end, with an unknownboat /motor /prop combination. I would rather take smaller steps testing the way as I went.

John Cooper		14-Dec-2011 19:57
Bob, the propellor is only 45mm diameter, if I take it down to 35mm would it push the boat along with only 6 volts turning it. The torque that twists the boat comes from the motor, not the prop, it is quite a large motor in relation to the boat. If I put the boat on the work bench and rev the motor fast, the boat twists dramatically. Rev it slowly and there is no twist at all.

sunnybob		14-Dec-2011 19:53
its not so much the diameter, as the angle of attack on the blades. you have a racing prop. it turns a huge amount of water. starting that going quickly on a 6 volt battery will make the motors and wiring heat up with the resistance. either a fuse will blow or the wiring will fail. the main reason I suggest 6 volts is to get it to sit higher in the water, then it will get up onto the plane quicker, with less drag on the prop. Its also an easy mod to do, and will give you more info on what is the best combo of voltage and prop angle for the boat. I dont think youll ever get it to turn fast though, its just too long for its width.

sunnybob		14-Dec-2011 13:52
you said it sat very low in the water, removing one battery will help reduce weight, but if you do, you would need to reduce that prop diamter or the starting torque would raise the amps unacceptably high, and could cause a wiring failure.

John Cooper		13-Dec-2011 23:23
Bob, I dont really want to fit outriggers, that will spoil the look of the boat. I think it will run fine in smoother water, if I avoid fast acceleration. The massive torque only occurs when I open the throttle fast.

sunnybob		13-Dec-2011 18:42
wildly overpowered John. Fun but frustrating. take out a battery and run it on 6 volts. reduce the prop diameter by 25%. the lightened hull and slower torque should work well. But with that rudder and that beam (or lack thereof) you might want ot fit outriggers to get you round the twisties.

John Cooper		13-Dec-2011 18:40
That is heresy Derek, the Bootlegger is designed purely for speed, it is its birthright. Speed is everything, cruising is nothing. I have a feeling I should change the prop to three blades instead of two, that should slow it down, give it more grip. Maybe wait until the pond is flat, the waves were quite big in relation to the size of the boat.

Derek Slater		13-Dec-2011 13:30
I think BEC has done a very good job of documenting the maiden voyage John Forget any redesign work just drive it a bit slower job done :-)

Dave Beedon		13-Dec-2011 08:23
Initial trials are a resounding success in spite of the less-than-stellar ending. I'm sure the naval engineer responsible for the building of this vessel will no doubt return with a modified boat to get revenge and vindication. Three cheers for BEC's effort in capturing the action. Onward and upward, John!

exzim		12-Dec-2011 20:30
The design team of the Mary Rose strikes again, or "There seems to be something wrong with our bloody ships today"

jCross		12-Dec-2011 20:19
Very cool, John!

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