Electric motor types

The Doldrums usually have plenty of Sunshine. Between being stuck in the Doldrums with discharged electric system or an empty diesel tank, only the electric motor has a prayer of replenishing power.

-Will

 

How will the electric motor replenish power?

 

By using it as a hydro generator I guess. Been fiddled with on cruising yachts as long as I can remember where the shaft would run an alternator with the transmission in neutral, but it would not compete with solar or wind generation in this era.

 

I think it is superior to a wind generator and solar in several aspects. It does not take deck space. Also, wind generators create a high risk for injuries. The work at night and when it is overcast. I think that an electric motor that can also be used as a hydrogenerator is a good compromise. Ideally it would have two propellers; one for propulsion and one for charging.

 

I was referring to the system as a whole. Electric power can be induced into storage in any number of ways by a sailor, but it is very difficult to extract and refine fossil fuels without an oil rig and refinery.

One could even design a generator that fell and rose through the depths to spin a turbine.

Something like this carbide toy submarine. At a certain atmospheric pressure, gas would release to float the device back to the surface spinning the whole time.

-Will

 

@gonzo I guess it depends on how the boat is used, it seems that coastal day sailing is huge on the east coast here. Hydro units I have seen are relatively low output, but useful if underway most of the time like trans oceanic cruising..

I would think it would be relatively easy to make an outboard style hydro unit with an off the shelf impeller out of epoxy laminate to mount the alternator, then rectify output and run it through an MPPT controller to maximise yield. It seems the most output you can expect with hydro on say sub 45' cruising yachts, before the drag penalty becomes too onerous is around 120 watts.

Useful while under way, but you would still need solar and wind to avoid topping up via diesel.

 

120 watts continous is more than enough to keep the lights and basic systems working. A charger that outputs about 10A is pretty good. For day sailers, I suppose there is shore power when at the dock.

 

I switched to lithium batteries a while back and discovered that I needed an AC charger for the initial charge and only owned lead/acid chargers.

Buying locally was stretching things for a device possibly used once, $250-400 AUD depending on output (10-20a). On Aliexpress I found a 25a charger (with capacitor boost for cranking) for $100, and I believe the output is close to advertised via charging time.