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RC Benchy

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ddmckee54:
Benchy's first "sea trials", floating in the kitchen sink, did not go well. 

The good news, he didn't leak...  And with my intended 12V battery, I still needed ballast to get down to the waterline.

The bad news, there's WAY too much weight ABOVE the waterline.  Once he starts to roll, he just wants to turn turtle.  (Probably didn't help anything that SOMEBODY added not just one but two turrets, a chain gun, a Captain, and a radome.  All high above the waterline.  My 12V sealed lead acid battery's gotta go, just too much weight above the waterline.  When I took that out, I was able to ballast Benchy back down to the waterline and get some stability, no more trying to turn turtle anyway.  I've got a 4S Lipo ordered, a 3S with its' 11.1V was just cutting the 11V minimum for the sound system a bit too close.

Don

awemawson:
I seem to remember vaguely that there is the 'centre of gravity' and the 'centre of bouncy' to consider one having to be higher than the other.

The story is told, and I really hope that it is true, that a British Naval shipyard strongly suspected that their designs were being stolen by a foreign power to build their own ships. Several designs were 'doctored' by altering plate thicknesses so that an inherently unstable vessel would result, and sure enough on launch day said foreign power had a ship turn turtle.

. . .I do hope that it's true, but even if not it's a good tale !

vtsteam:

--- Quote from: vtsteam on April 27, 2022, 02:27:09 PM ---I guess a fair amount of weight low in the hull will be helpful, as there's a lot of top hamper and weight above the waterline. Can't see the underbody, but form stability doesn't look like a strong point. She'll like lots of batteries, maybe even, dare I say it, NiCads for weight.....

--- End quote ---

And the safety factor of NiCads (NimHs, actually to be more precise) vs explosive hobby quality LiPos in a water setting is a further advantage.

Of course you don't need either for flotation, stability and waterline tests, just add convenient weights to the hull to see how she will float, and handle pushing around, then decide which batteries you need by weight, or if the design is feasible for what you want to do.

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