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[Colin Bishop]

Practical experience using the recommended Graupner Speed 600s:

https://www.rcuniverse.com/forum/rc-scale-boating-103/2658247-model-slipways-trent-lifeboat-full-biuld-up-review.html

https://srcmbc.org.uk/2016/01/03/rnlb-maurice-and-joyce-hardy/

https://www.youtube.com/watch?v=TlfVKMcz2_8

Plus this one:

https://www.rcwatercraft.co.uk/trent-lifeboat/

If it works then copy it!

Colin

[SimonCornes]

Glad to see things are improving.
You say you'd like higher RPM - that could be achieved by going to 4S, your ESC and the 540/1's are rated for it. I know I suggested lower voltages earlier but that was with the power hungry Johnson motors. The 540's on 4S will still draw less current than the Johnson's on 2S.

That’s interesting- I might just try a 4S pack !!

[Abandon Ship]

That’s interesting- I might just try a 4S pack !!

I've got a couple of boats that run 4S but I use 2 x 2S packs in series so I can lay them each side of the keel to keep the weight as low as possible. Just a suggestion as I don't know what batteries you have to hand.

[SimonCornes]

Thank you for that suggestion. As things stand the boat had a 6v 1300 gel cell on the centreline quite far forward. I’m thinking of moving that back to just in front of the LiPo propulsion battery to reduce the tendency of the bow to dig in but of course it has to sit on the correct waterline but that might result in a better ‘bow up’ sit at full throttle. It’s a 5000 3S that I have so I was thinking of maybe buying a smaller capacity one although I have a 5000 2S but that’s no help. Maybe a lighter 3S or two light-ish 2S’s in series? As it stands I don’t have a use for the existing 2S though - I part exed the boat it was used for when I acquired the lifeboat. Probably better with a lower capacity 3S? I’m also a bit concerned about a 4S because the motors are rated up to 15v and I’m sure a fully charged 4S would exceed that??

[Abandon Ship]

Fully charged 4s (nominal 14.8v) will be 16.8v but that shouldn't be a problem. They will also loose some of that quite quickly as the voltage curve of li-po's drops quite quickly at the top and bottom ends of the scale. There will also be a slight drop through the electronics of the ESC.
The only thing to watch is the motor temperature - if the prop size/pitch creates a heavy load and you run flat out they will tend to get warm. The motors are about 65% efficient, so about 1/3 of the power they use will be heating them up.
If you do try 4S, check temperatures regularly until you're happy that nothing's overheating.

[SimonCornes]

Thank you. Plenty more fun to be had here!!

[HMS Invisible]

You get motor over-temperature protection from a polyswitch soldered to a brush terminal then bent round & epoxied to the motor case.
You've got a considerable weight and space saving with a ten amp fully electronic dual esc including bec.