How feasible is 100% renewable electric cruising right now?

[valhalla360]

I know most on this forum are coastal or ocean sailors but one option where it could be viable is canal cruising.

When we did the Eire canal, even in the worst weather, the canal was typically calm and at least somewhat protected from the wind and there aren't too many places where you are more than 5 miles from a place to tie up. Often speeds are limited anyway, so no great loss losing a little speed. Going thru locks, a burst of thrust is handy but rarely more than a few seconds at a time, so battery power isn't a big issue.

On the Eire, a lot of the town docks did have electricity and on a dedicated boat, you could install quite a bit of solar as long as you tie up away from shade.

[CatNewBee]

Maybe the engines have more torque, maybe they are a little more efficient than combustion engines. But the foremost question is: how to collect sufficient energy and how to store it, and also for how long it will last.

All electric is possible, especially for a sail boat. Just stop motoring and use your sails, use electric propulsion only to get in or out of the marina for lets say 5-10 miles maximum, re-charge the battery by recuperation using your sails and the engine / propeller. If you moor without shore power, you may have to stay some days longer at one place until your batteries are recharged sufficiently by solar / wind generator to be able to leave to the open sea.

If you are a sail boat cruiser, you use your diesel any way not so often I guess.

A diesel gen with some gallons of fuel could help you in some trouble, I would not just rely on the solar panels / wind generators, especially if you need a lot of power in an emergency situation.

[KTP]

I do not know why it has to be either/or. Most inboards have a long prop shaft. If you could have some sort of clutch mechanism you could add in a 5hp brushless motor belt drive to the prop shaft after the diesel transmission. In calm waters when you want to quietly putter around at 3 to 4 knots, use the electric motor plus a modest battery bank, say 10kwh. You would likely be able to go 20 miles or more like this...totally silent.

In chop or if you need to go faster, engage the 25 to 50 hp diesel and away you go.

[john61ct]

And put a nice big alt on that same diesel to quickly recharge the LFP bank.

Can also run a watermaker and your freezer/fridge directly off the engine.

Redundancy and flexibility

[GTom]

Originally Posted by KTP

...replace some of the ballast in a sailboat with the battery pack would be ideal...

Very interesting idea! Encapsulated lead-battery keel, just like old times but now the keel has an other function

[RaymondR]

It's a great feeling when one is attempting to clear an exposed anchorage or lee shore in adverse weather conditions to know that one has a good reliable, powerful diesel and a couple of hundred miles of range in the fuel tank.

[kmacdonald]

How feasible is 100% renewable electric cruising right now?
It's not. Not even close. Doesn't even deserve consideration.

[GrowleyMonster]

Originally Posted by KTP

I do not know why it has to be either/or. Most inboards have a long prop shaft. If you could have some sort of clutch mechanism you could add in a 5hp brushless motor belt drive to the prop shaft after the diesel transmission. In calm waters when you want to quietly putter around at 3 to 4 knots, use the electric motor plus a modest battery bank, say 10kwh. You would likely be able to go 20 miles or more like this...totally silent.

In chop or if you need to go faster, engage the 25 to 50 hp diesel and away you go.

This has been done and if the system is well engineered, it can work nicely. As a plus, when using the diesel you can engage the electric motor for use as a generator to put some charge back into the batteries. All this does, really, is enable the propulsion diesel to double as a generator with zero overhead. Turnkey systems like this have been installed in production boats but many owners find them overwhelmingly complicated. One company in England called I believe Hybrid Marine, uses Beta/Kubota diesels as the ICE. Not sure what electric motor is used, probably something like a ME0913 or ME1306 but the smaller 5kw motors would work nicely with a Beta 10, for boats under 35 feet or so.

For retrofit of a hybrid drive, the problem is that you not only need to plan for the weight and volume of the batteries, motor, controller, charger, and inverter, (you can lose the old 12v house bank if you install redundant DC/DC converters to get 12v from your propulsion bank) but also the weight and space taken up by diesel engine, fuel tanks, cooling, and probably 12v start battery. On some boats this is probably doable. on others, maybe not so much. Oh, and you would have deeper pockets, yeah, than simply going electric or diesel.

It would seem that you could use the electric motor in a parallel hybrid plant as a starter for the diesel, depending on the transmission. Especially if you have a compression release lever on the diesel. Most of the electric motors in common marine propulsion use can be loaded REALLY heavy for short bursts of power. For instance, 15hp from a 6hp motor for 60 seconds or less. That would eliminate the start battery. In an emergency as a backup you could tap the propulsion bank for 12v, and crank the diesel with the supplied starter motor, though this is not recommended practice for obvious reasons.

I considered piggybacking an electric motor over the shaft when I still had the old Atomic 4, but I had to pull the A4 to get a badly leaking fuel tank out, and I asked myself if I REALLY wanted to put the smokey old clankasaurus back in there, or not. Not seemed like the better option. But it was a near thing. And in the end, after adding 600lb or so of batteries, getting rid of the gas engine and associated crap seems like a good thing, on this boat.

[u4ea32]

Originally Posted by GrowleyMonster

I have never seen a "smart" charger that performs a proper equalization.

Promariner ProNautic shore power battery chargers do equalization. Balmar alternator controllers do equalization. Neither do it automatically, both require specific button press patterns to enable equalization. But both do it according to battery manufacturer specs.

[GrowleyMonster]

Originally Posted by u4ea32

Promariner ProNautic shore power battery chargers do equalization. Balmar alternator controllers do equalization. Neither do it automatically, both require specific button press patterns to enable equalization. But both do it according to battery manufacturer specs.

Sounds good. You wouldn't want it to be initiated automatically since equalization really needs to be monitored. This is how I would prefer to see it implimented.

[u4ea32]

I think its clear that 100% renewable electric cruising IS feasible, without a question.

https://www.vendeeglobe.org/en/news/...ixteenth-place

Conrad Coleman raced around the world in the latest Vendee Globe using only renewable power, no fuel or generator.

But its also clear that an electric motor does not provide anywhere near the ability to power for hundreds of miles.

So just like with sailing -- where you must sacrifice some concepts, like schedules, or that its about the destination instead of the voyage -- with a pure renewable powered boat you sacrifice some capabilities.

But none of those sacrifices will prevent you from exploring the world safely, quickly, and inexpensively. You will probably have more time to have fun, because you will stop wasting your life on fuel and engine service and repairs.

People who ARE using electric propulsion for long range cruising simply adjust their approach so they do more sailing, less motoring. For very many, this is not a problem.

I think its not reasonable to assume that you can live like you do in your 3000 square foot air conditioned home with hot tub and 80 inch TVs, washing machines, dishwashers, complete woodshops, etc. etc. on solar power. Duh. You will live differently.

But isn't that the entire point of all of this?

(I considered removing the diesel from my boat, but it works, its in great shape, so it stays until it breaks or diesel is no longer available).

[john61ct]

Of course for thousands of years humans sailed and rowed around the world. And lots died at sea, was considered just part of the territory. Some still do, and take on more risk.

The point of the thread is replacing the functionality of a decent fossil fueled propulsion engine with all-electric.

That would most importantly mean the ability to get out of a sticky emergency scenario, wind and currents driving you toward the rocks and so on. Being able to continue with a passage when becalmed in open ocean is less critical, but certainly important to many.

Seems pretty obvious in most circumstances trying to get that level of propulsion functionality from battery-only power is impractical at best, certainly geometrically more expensive than most would entertain for a repowering project.

Diesel-hybrid electrics, or returning to "doing without" aren't really IMO germane to the OP, and each deserve their own thread.

[Stumble]

u4ea,

Using anything that the Vendee Glode does as a basis for comparison is just a mistake. You know how many rpm's the drive shaft did in its entire trip around the world? Zero, they never used it, and none of the other boats ever turned their engines on either because thats the whole point. The engines are just there as an emergency after the mast has come down and there is a safety issue.

Don't get me wrong its a great proving ground, but it isn't really applicable.

[StuM]

Originally Posted by Stumble

u4ea,

Using anything that the Vendee Glode does as a basis for comparison is just a mistake. You know how many rpm's the drive shaft did in its entire trip around the world? Zero, they never used it, and none of the other boats ever turned their engines on either because thats the whole point. The engines are just there as an emergency after the mast has come down and there is a safety issue.

Don't get me wrong its a great proving ground, but it isn't really applicable.

It did quite a few revs - he used it for re-gen. But that was only feasible to keep because of his low power requirements and because he averaged well over 10 knots. Not practical for your average cruiser.

[GrowleyMonster]

Everything is an exercise in compromise. 30kts in an express cruiser, or 2gph in a small trawler at 7kts? for that matter, 80mph on the highway, or 37mpg at 60? Lambo styling, or whatever you can get for $600? Sailing with no motor, or a $200 used two stroke outboard, a $12k diesel and a big tank of fuel, a $2500 electric system that poops out after 30nm at 2kt on a shady day, oars, solar heated Stirling engine, or just stay at the dock and look pretty? I say any propulsion system is "feasible", depending on your expectations, requirements, and talents. Without anyone daring to try something new, all boating would still be hand paddling a floating log across the creek. The only "safe" boating is staying home and reading magazines about boats and cruising. That is also the cheapest. Not the most enjoyable, not the most challenging, and not the way to see the world or even a small corner of it from the water. Not everybody wants the same thing, and not every thing is ideal for everybody, or even anybody.

Closed mindedness isn't necessarily a bad thing, because it keeps a few people out of trouble who would otherwise stray off the path most trodden without sufficient knowledge or preparation. But being open to new ideas can increase a sailor's enjoyment of his chosen lifestyle as long as he exercises a mariner's prudence and thoughtfulness before comitting to a course of action.

No matter how you slice it and dice it though, cruising is still probably safer than driving, swimming, crossing the street, hiking or hunting, or many other commonplace activities. Sometimes even the most poorly prepared, equipped, and educated seem bulletproof on the water. Anybody remember Black Oak? The sea isn't a malevolent force bent on the destruction of humans, any more than it is a comforting and nurturing presence. It simply doesn't care.