Switched to Electric

[Fah Kiew Tu]

I'm not an electrical engineer but I don't think that math is right - maybe an EE can weigh in. I suspect that the limiting factor is some combination of battery charger capacity and battery chemistry (how fast the battery will accept a charge). And I think for a lot of owners a small ICE running on propane would be preferable to a diesel or gasoline propulsion engine.

Oh yes, uh huh, for sure.

I so want to lug 8kg cylinders of LPG out to my boat. For fun I'll leave it to someone else to work out how long it'd take to use the contents and how many you'd need to carry as deck cargo.

Or go alongside a fuel dock with bulk supplies (which likely doesn't actually exist anywhere) to load up the BIG INTERNAL TANKS with LPG.  Because they're *such* a convenient shape to fit into a boat hull.

Not to mention the sniffers and blower system that would be totally necessary... and let's not forget the hydro testing every so often.

Great idea, wonder why it hasn't been done already...

FKT

 

[Ukuri]

You don't need to be an electrical engineer to figure this out, you just need a little arithmetic.

Discharging, a 15kWh battery will run a 5kW load for 3 hours (15/5 = 3). If you run the electric motor at the same time as the genset, you'll get up to 6 hours of run time (15/(5-2.5) = 6).

Recharging, a 2.5kW generator will take 6 hours to recharge a fully discharged bank (15/2.5 = 6).  

If you run on battery only for less than 3 hours and then recharge, you'll have to run the genset for twice as long as you ran on batteries because the genset puts out half the power of that the motor draws. 

So let's break this down...

Scenario 1: Short trip, run on batteries only, then recharge...Silent running for up to 3 hours then recharge via genset for up to 6 hours. 

Scenario 2: Long trip, run on batteries plus genset for up to 6 hours then recharge for another 6 hours for 12 hours total genset time.

Scenario 3: Too long trip: anything over 6 hours of motoring.

The range under any of these scenarios is just the motor run time multiplied by the speed of the boat under the weather and tide conditions encountered.

EDIT: I suggest you look at the propane consumption per hour figures for propane-capable generators...

BUT the above figures are for a power boat.

Don't you blokes sail anywhere?

Common scenario, wind's a bit too shy so drop the heady, fire up the motor, pull in the main, get a bit of apparent happening and a bit more drive from the main, back the motor back to about 20% and hand over to the tiller pilot.

In 15ish years of sailing my 22' trailer sailer I can only remember two occasions when I had to run the 5hp outboard for more than 2 hours straight.

 

[IStream]

Good for you. I sail whenever I can too, including motor sailing. However, on many of my trips I have long distances to cover and little or no wind, not to mention a foul tide, which is basically guaranteed for any trip over 6 hours. Motoring a sailboat is a regretful reality for many of us.

 

[DDW]

So let's break this down...

Scenario 1: Short trip, run on batteries only, then recharge...Silent running for up to 3 hours then recharge via genset for up to 6 hours. 

Scenario 2: Long trip, run on batteries plus genset for up to 6 hours then recharge for another 6 hours for 12 hours total genset time.

Scenario 3: Too long trip: anything over 6 hours of motoring.

So, your electric boat is suffering the drone of an ICE for 2x the time you would have had to listen to it without the electric...

But, most of the dichotomy in this thread has everything to do with where the boat is sailed. I've kept a sailboat on SF Bay for about 40 years now. I've probably used 30 gallons of fuel in that time. I arrived with my current boat 2 years ago with 40 gallons in the tank and it will probably last another 10 years or more if I don't go anywhere else. If you are using the boat in season (say, April - Oct) you will very, very rarely use the motor for anything but maneuvering in and out of the slip (and there are no moorings, so no worries about charging). If I had the choice, and intended to not go further than the GG, electric is the winner hands down, every time. 

I've also cruised a lot of the length of both coasts of North America. There are very few places like SF Bay - I can't think of any until you get into the trades to the south. In the Chesapeake you are going to want more motor and more range - there is often little wind but at least you can anchor and wait just about anywhere. In the PNW, if you are going to go anywhere beyond a daysail from the marina, again you are going to want more than an electric can give you - distances are long, wind very unreliable, recharging facilities absent, currents very strong, the water is deep, and passes are on a clock which you must obey. George Vancouver explored it in a rowboat but it wasn't convenient or comfortable. 

So whether electric is a good idea or bad idea is highly contextual, there is only a match or mismatch to the venue. If you are cruising long distance, you are necessarily changing venues, and the argument for electric at this point is weak, unless you are immune to inconvenience. Some people are, like the people who don't have any motor (but it is a small group). 

 

[TJSoCal]

So, your electric boat is suffering the drone of an ICE for 2x the time you would have had to listen to it without the electric...

Sure, maybe 5% of the time when you need to motor for a longer distance. Compared to 95% of shorter distance, in & out of the slip motoring time with no IC at all. Including, as Ukuri says, giving just a little bit of a boost when wind is dead and silently motorsailing at couple knots rather than facing the choice of slatting or listening to the IC motor. 

Electric clearly isn't for every boat everywhere, but it's not for nobody anywhere.

 

[IStream]

Sure, maybe 5% of the time when you I need to motor for a longer distance. Compared to 95% of shorter distance, in & out of the slip motoring time with no IC at all. Including, as Ukuri says, giving just a little bit of a boost when wind is dead and silently motorsailing at couple knots rather than facing the choice of slatting or listening to the IC motor. 

Electric clearly isn't for every boat everywhere, but it's not for nobody anywhere.

FIFY.

 

[Zonker]

SF is a high wind venue during the summer sailing season.

Brisbane is nearly in the trade wind belt. And a 22' trailer sailer doesn't need much wind.

Lots of other places in the world ARE low wind venues. PNW/Long Island Sound/Chesapeake Bay. Med is on/off. Southern Mexico/Costa Rica/Panama (west coast) can be mostly wind free. 

I haven't run my motor above ~1.4 KW yet because I also replaced the cutlass bearing during the repower. I'll crank it up in the weeks to come after I get a few more hours of run time. 

Um I've never heard of cutless bearings need bedding in or anything. IMO they're ready to go as soon as installed. Were you told otherwise?? I've read a lot of supplier's literature on bearings over the years.

 

[DDW]

Sure, maybe 5% of the time when you need to motor for a longer distance.

That depends on how you define "need". No one needs to motor any of the time anywhere. The world was after all mostly explored by boat before the invention of the ICE. It was a little slow, a little dangerous, and there were places they didn't (and couldn't) find. With enough patience, nearly anything is possible.

But as examples, we went the length of the Great Lakes. Motored all the way across Ontario, no wind. Motored most of the way across Erie, no wind. Motored up the Detroit and St. Claire rivers, no wind, 3 knot current against. Motored half way across Huron, no wind. With a couple of months to do that trip maybe you'd be able to do with an electric auxiliary (or maybe not). It isn't just a matter of waiting till the wind fills in tomorrow. Could be weeks. And in the mean time the black flies would have consumed you. 

I sail anytime I can (by that I mean either I have no destination for the evening, or I'm moving at at least 2-3 knots). My boat sails well in light wind, and the sails can be (and usually are) up anytime we are motoring (no chafe or slat problems). But in 15,000 miles on this boat my engine usage is astonishingly high. Not in SF Bay, not in the trades, but nearly everywhere else. 5% is a fantasy everywhere else, or a sign of the patience of Job. Take a trip up the Inland Passage from Seattle to Juneau and tell me how that 5% worked out. 

Oh, and I didn't say "not for nobody anywhere" - if you are cruising any distance out of the trade belt it is for very few people. Daysailing out of a marina, it would work in a lot of places. 

 

[Kolibri]

Um I've never heard of cutless bearings need bedding in or anything. IMO they're ready to go as soon as installed. Were you told otherwise?? I've read a lot of supplier's literature on bearings over the years.

I think it's just a case of the shipwright being cautious with the combination of new motor and new cutlass bearing. He also told me to check the torque on the motor mount fasteners after ~10 hrs of run time. Fortunately I have access to an aerospace company tool crib . Seems like prudent advice and I'm in no rush so it's advice I will take. 

 

[Zonker]

You don't have your own torque wrench? How do you get up in the morning?

 

[Ishmael]

You don't have your own torque wrench? How do you get up in the morning?

Gravity is pretty dependable.

Oh, up. I guess out of bed doesn't count.

 

[Kolibri]

You don't have your own torque wrench? How do you get up in the morning?

I actually have 2 torque wrenches. Both are sized for carbon fiber road and mountain bikes....not sailboat motor mounts.

 

[Fah Kiew Tu]

That depends on how you define "need". No one needs to motor any of the time anywhere. The world was after all mostly explored by boat before the invention of the ICE. It was a little slow, a little dangerous, and there were places they didn't (and couldn't) find. With enough patience, nearly anything is possible.

Lots of those boats - or the bare remains - are still there, too.

Because they didn't have a motor when they needed one.

Roger Taylor's 'Voyages of a Simple Sailor' has a fascinating account of getting embayed in a windjammer and nothing they could do could get them out of it. They lost the vessel, fortunately without loss of life.

I've no problems with people installing electric drives as long as they're realistic about their range and have sorted out how they're going to recharge. It's all engineering and fitting the tech available to your particular use-case.

The others who want to tell me how I should be using MY boat so as to fit THEIR definitions can fuck right off. I sail with my beloved GF. I'm not putting her at any avoidable risk.

FKT

 

[olaf hart]

One thing we haven’t mentioned is the USA is well covered by Coastguard and Boat Assist, these things don’t exist elsewhere…

 

[Leeroy Jenkins]

coastal feature

There's two places (that I know of) on this chart to get King crab. 

 

[TJSoCal]

You don't have your own torque wrench? How do you get up in the morning?

Just use the German torque spec - gutentighte

 

[Zonker]

Not planning to head up that way, but I'll trade you a place in the Gulf Islands that is ridiculous with Red Rock Crab.

 

[Zonker]

I actually have 2 torque wrenches. Both are sized for carbon fiber road and mountain bikes....not sailboat motor mounts.

Math. Get a 6' cheater bar and use the 1/4" one

But frankly motor mounts are not exactly torque critical fasteners.

 

[Upp3]

This is when you regret the 150% genoa and feel like murdering IOR boats designers!

This is when you get canal boat?

 

[hump101]

This sounds like a fun science experiment with many things to go wrong.

In my experience with mechanical systems that are custom one-offs there is a LOT of teething troubles you don't think of. Add electrical charging and it gets more interesting (sharing loads so you don't overload the generator). Have you built this sort of thing before? A fully azimuthing drive system is NOT trivial.

Unless you use mechanical controls that limit swing from 0->360 and back again (and don't go past 0), you must use electronic controls. Which has their own set of issues. Example. Drive is at 0 degrees. You turn control to 90 degrees. Drive unit starts turning to 90 but it takes a few seconds to get there. It is nearly at 90. Suddenly you decide to rotate it 270 degrees because you need thrust in the other direction. Which path does it take? Shortest? Or does it continue to rotate in the direction you started...?

(Having had a 40' cat with 1 x 27 HP diesel (in one hull) and 1 x 9.9 / 6 HP against the other hull, I was fully able to put the boat wherever I wanted with 2 engines. Never needed 360 azimuthing capability. Nor do all the other 40' condo cats which have a lot more windage than a F40. When I bought the boat it had 2 x 9.9 mounted under the bridgedeck. They were not very susceptible to aeration except in really nasty short seas)

You do seem like the ideal use case for electric.............
 

Many thanks for your input. I have experience and access to adequate design and fabrication facilities to develop the system, so that is not an issue. We have strong currents so I would need a minimum of 5kW of continuous generation to safely operate here, and then the weights start to climb significantly. Hence the appeal of using one motor as a generator with the regen feature. During normal motoring, a single engine with steerable thrust is adequate, provided the prop stays in the water.