Hybrid Electric Cats?

[rockyluciano21]

I've been reading up on these trying to understand if this is a good option...

I love the idea of being totally off the grid and having unlimited range... seems to be where the industry is heading

Does anyone know if this is a viable technology?

Who is working in this space and what are the pros and cons of an electric solar-powered Cat?

[Pete17C]

"Hybrid Electric" suggests a small gas/diesel engine (generator) to charge the batteries which then drive electric motors for propulsion.

which is certainly possible

[myocean]

see this thread:
https://www.cruisersforum.com/forums...or-172720.html

It probably does not make sense to start one more.

[barnakiel]

A hybrid is when the genset charges the bats or drives the el-motors directly / semi-directly.


Good idea and works OK in cars.


How well it works in your boat depends on how you use the boat.


For some of use it is the best option, for others the worst. Imagine how you are going to use your boat and you have your answer.


b.

[mcarthur]

We're planning on hybridizing our 50' powercat. Planning electrical side of everything at the moment since covid means we can't get our hands dirty. But the extra time means better solar and some new higher efficiency products to market that will really help.

[valhalla360]

First, you have to define the type of hybrid and what your goals are.
- Parallel Hybrid: Either the electric or ICE motors can directly drive the propeller.
- Serial Hybrid: ICE is used to generate electricity, with the electric motor driving the propeller.

Either option can and typically does include a battery bank to absorb the peaks and valleys in supply vs demand.

In cars both of these options can create large improvements in efficiency. In city driving, you may go from heavy acceleration away from a stop light, cruise at 40mph with modest power demand then no power demand as you come to a stop light followed by sitting stationary waiting for the green light (all repeated every minute or two). A hybrid can set the engine to run at the average power demand. During light demand, the extra power goes into the battery and during heavy demand, the battery covers the extra demand.

In displacement cruising boats, typical motoring is a mile to get out to open water and then once up to cruising speed, you don't touch the throttle for literally hours. There really isn't the peaks and valleys in power demand to take advantage of. At the same time, there are losses due conversion of ICE mechanical energy to Electrical energy and then back to mechanical energy at the prop. The net effect is for motoring, it's less efficient compared to just connecting the diesel directly to the prop.

That said, assuming it's a new boat or you need to re-power anyway, there is the potential for a different kind of hybrid. While motoring, it's common for cruisers to use only one of the motors as cats track nicely even under one motor and under moderate conditions, that's plenty of power.

So a potential solution: Let's say the standard is a pair of 30hp diesels plus a generator in the boat you are looking at.
- In one hull install a standard diesel of 45hp directly driving a prop.
- In the other hull install a 10kw generator and 10kw electric propulsion motor (~15hp for a total of 60hp)
- Moderate size battery bank...maybe enough for 5-10miles range under battery power at moderate speed.

Most large catamarans have 2 propulsion diesels and a generator for house loads. this would replace one of the 30hp diesels with a 10kw electric motor plus a larger battery bank. In a new installation, it should be cost neutral to install.

This has the advantages of standard propulsion without the downsides of a hybrid.
- Docking/maneuvering: you almost never use significant throttle, so you still have twin engine operations. At worst, you need to learn to adjust for slightly different performance between sides.
- Motoring short distances: You can operate under battery power (stored from cheaper shore power or collected over a few days from a solar system).
- Motoring long distances: You run on the big diesel.
- In emergency conditions, you turn on both diesels and you have as much range as you have diesel fuel same as a standard twin diesel.
- You have the redundancy of twin engines...really even more as the battery bank can give you some range if both diesels fail.
- With the larger battery bank, you have the option to run the air/con at anchor for a day or so off battery rather than cranking up the generator but if you are out for multiple days, you have a generator that can power all your house electrical needs as long as fuel holds out.