Epic adventurer - Solar boat trolling motor

I got one step closer to setting out on my zillion mile epic adventure on the mighty Murray river, on my little solar powered boat.

That step included testing just how much juice I was going to need to run the trolling motor, and seeing if the solar panel I have will provide enough.

My boat is a displacement hulled catamaran. That means it doesn't do the skimming across the top of the water thing that most other racing cats do, so it's very outdated for racing, but it floats well, and the hulls are very low drag.  At their widest, they measure only 20cm or so. They are 4.2m in length, so they slide through the water without a lot of effort. Probably even slicker than a kayak.

The result of all this is that I can tick along at walking pace with an electric trolling motor on it's slowest setting.

I like walking pace.

In fact, aside from jet aircraft pace, and insane motor bike pace, walking pace is my favourite pace.

So I think, the result of all that is that I should be able to power my little boat with my single solar panel. That question has been nagging at me for ages. My solar panel says it delivers a maximum of 230w at 37v and also mentions 7.5 amps or so.  I think that means that at 12 volts after an MMPT solar charge controller, it will offer the battery a maximum of 19 amps. Probably much less.


I just put my trolling motor in a bucket of water (large bucket) and ran it through my multimeter. As far as I can tell, it draws around 12 amps on the lowest speed setting. I'll be taking a 120 amp hour deep cycle lead acid battery. From memory, before I had the solar panel, that battery gave around 5 hours cruising when I ran it down to 11v. But my memory is terrible for stuff like that.

Also as far as I can tell, I think that means I should be able to cruise for a reasonable amount of time each day. There's also the option of running a bit faster during the middle of the day, when my solar panel is generating the most power. It would be nice to leave the battery with a healthy amount of charge at the end of each day so that I could use some for light, charge my phone and UHF radio, and to power a laptop so I can get some blog posts out.

I'll probably want to set up camp each afternoon when there is still plenty of light, and get up early each morning to pack up camp and get under way when the river is at it's best. If I leave a full battery at the end of each day, I should be able to set off at first light, and then make up the charge by the end of the afternoon.

Or something.

But I have no idea how this will all pan out in the real world.

What I need is a 36v to 12v MMPT solar charge controller that actually works, and wasn't sold to me fraudulently by that trader on E-Bay.

Now I don't trust the world any more.

But I'll probably get over it.

But on the up side I now know how much current my little trolling motor draws, and I've also found a brand new way to inject a lot of oxygen into my fish tank very quickly, and perhaps mince fish.

Which is nice.

This is the trolling motor on it's highest speed setting.

Excited water.

120 Things in 20 years thinks it's found the worlds fastest way to empty a large bucket of water all over itself and it's shed, without actually picking it up and tipping it over itself.


  1. Hi, This is a good post, indeed a great job. You must have done good research for the work, i appreciate your efforts. Looking for more updates from your side. Thanks freshwater trolling

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  4. Hi all!
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