The rise of electric Boats

[Narfi]

You lost me with lead acid..... Considering weight, discharge rate, charge rate, and usable amps, wouldn't an electric powered boat pretty much mean lifepo4?

[jbinbi]

Have posted about this company before

https://www.greenlinehybrid.com/en/yacht/greenline-40

This is a 40' motoryacht. weighs 20k lbs. Has 2kw of solar. Has 2 14kw drives.

Can run 20 mi at 5kts on battery only. (This is no recharge while running).

Take a seawind 1160 with no mast. It is 14k lbs. Put solar all over its bimini, you can easily get 4kw. I think you can run it at 40 mi then at 5kts. Most loop cruisers do about 40- 60 mi per day.

I wouldn't do this without some backup based on dino juice, but pretty darn close to this being a real solution.

[Simon.Sails]

I have researched a lot of electric-only boats and they're really only feasible with strong diesel generators as you mentioned.

But an all-electric sailing cat for me is primarily a sailing boat that's got sufficient range from the battery in most situations (20-60nm depending on speed without regen), but has to be able to regenerate the batteries easily through hydro props and solar. I think any attempt to pretend it's a diesel engine will make the boat far too heavy. Solar is relatively cheap and efficient in the tropics, batteries are still too heavy/expensive.

Obviously if the attitude is I want to go from A to B in any condition, whenever I want then diesel's the way to go.

[valhalla360]

Originally Posted by Adelie

I made the 5-6kt estimate for the EP-9.9 based on performance data for a 10,000lb Cal-34 that should make 5.0kt on 3850W and 6kt on 6720W using a normal prop for an inboard.

The Gemini is lighter and has a longer waterline but the Elco has a smaller prop optimized for dinghy planing speeds.
Yes the Gemini will be more heavily loaded but that puts it on a par with the Cal.

So like I said 5.0-5.5kt with the 9.9 and maybe 6.0 or so with the 14.

At full discharge the batteries will only supply about 200Ahr, which at 48v is 9.6kWhr. Less than that is usable.

The boat is 10.21m long and 4.29 wide.
Given the need to transit locks you want to leave 2.5-3.0’ clear each side for line handling.
So cover the middle 2.5m x 10.21m with panels. At 200W/sqr-m that’s about 5.1kW of panels. Daily output would be about 20-21kWhr.
If you skimped on side openings a little and went 3x10.21 then you could install 6.1kW with daily production of about 24-25kWhr.

If they were willing to accept the added complexity fold out or slide out panels could be used on each side then the whole boat could be covered for 8.7kW nameplate production providing 34-35kWhr/d.

4kt boat speed would require about 2kW. To me that would be plenty going down stream where current would increase my speed over the ground. At 4kt speed thru the water I could get going at 0800 on battery and a little solar by 1000 solar is providing all traction power and starting to recharge the mornings use. By 1500 or so battery is approaching full charge but solar is fading at battery starts to draw down.

As previously indicated the upstream portions are a problem that would require additional power either from a generator or from a gas outboard. Or go full power starting about 0900 on battery and some solar anchoring about 1400 so the battery can be mostly recharged for tomorrow’s sprint. Yep, multi-day slog to go 20nm(?) up current.

I assumed they would motor the whole loop, I don’t see many people willing to take down and put the mast back up more than once. If they can’t live with the 4kt or so motoring speed then they should just accept the use of fossil fuels.

Yep, they would take a loss selling the panels. But they would have used a lot less fuel too which is a money savings.
The loop is about 6000mi, so that $2-6k in fuel costs saved.
The costs would be close to even.

All this is moot, the OP has a different much larger and heavier boat that would be difficult to do this with.

I was making the estimate based on actually doing the loop in a Gemini. We had a 25hp 4stroke with a big low pitch work prop. 6kts is going to be up around 10kw. Maybe half that for 5kts with the larger 6kw electric outboard.

Even if you can make 5kt on 4kw, with only 9.6kwh (maybe 5kwh usable), you will have very limited range. An hour under battery and then you are largely limited to 10am-2pm for moving using solar directly for propulsion. If the tidal currents in Georgia suggest you should leave at 7am but you can't leave until 9am, you will be bucking a strong current all day. Very limiting.

I was agreeing with you on 5kw in solar is possible. That was already pulling back a little around the sides. Adding some kind of fold out contraptions to get more is just getting silly. Plus this huge array (even the smaller 5kw option) will kill your speed in any kind of headwind.

On the 200 miles of the Mississippi, 4kts and let the current boost it is certainly viable and we practiced that the first time to extend range as we didn't have a good feel for our range the first time around. At times we were making over 11-12kts SOG. Most of the other areas, the currents are typically much more modest. As you approach the upriver side of dams, current is negligible and there are many areas where you face adverse currents including tidal currents.

Actually pretty common for sailboats to do the mast up/down twice. Though if we do it again, we will probably leave the mast at home for the entire trip.

We spent a little over $2k in fuel but with your keeping of a secondary gas outboard for extra power, I would be surprised if you don't spend $1k on fuel. I would expect a seaworthy 5kw array with support platform along with repairing the fiberglass where you mounted it to easily be over $10k and if professionally done could be $20k or more. I wouldn't expect more than a grand or two on resale of used panels of unknown history. Far simpler to keep the solar modest, go for a bigger battery bank and plan on charging at marinas if doing a lot of motoring. Then the upgrades are useful for the long term.

Actually, the OP's boat idea is very much relevant. Just a matter of scaling it up. If he were to find a twin inboard with one engine failed, retrofitting one electric and keeping the operational diesel could be a nice option if he gets it for a steal, without doing silly outrageous modifications.

PS: One thought on the 4kt assumed speed. The loop is typically done in a year (winter in the north, hurricane season down south drive this). It was around 7500nm when we did it. Ignoring currents. Assuming 4k, that's 5.25hr motoring per day...every day (no down days for touring, bad weather, etc...). When you factor in docking, anchoring, locks, lift bridges, probably closer to 6hr per day average.

At 6kt, that's about 3.5hr per day (call it 4.25hr with ancillary stuff). That makes it much more viable to mix in some longer runs to free up non-travel days.

So while theoretically possible to do it at 4kts, artificially low speeds start adding impracticality to the equation.

A 45kwh lithium battery bank (40kwh usable) powering a 15kw electric outboard (operating at 10kw for a 6kt cruise speed), gives you about a 25nm range under battery (probably 50% of our travel days). Recharge on marina shore power over night. Then have a small 5kw generator. If you need more range, that can keep you at 6kts for 8hr or around 50miles by combining generator and battery output. Plus if anchored out, you can recharge overnight off the generator. That will cover probably 98% of travel days on the loop. There are only 2-3 longer days, for that accepting 5kts which as you indicate would increase the range. Keep the solar to a more modest system for house loads. When you are done with the loop and go back to day sailing, you still have a perfectly viable boat.

[Adelie]

Originally Posted by Narfi

You lost me with lead acid..... Considering weight, discharge rate, charge rate, and usable amps, wouldn't an electric powered boat pretty much mean lifepo4?

For a Cal-34 the batteries I indicated previously and a 10kW motor would weigh almost exactly the same as an Atomic-4 and the fuel tank they replace.

Charging rate is only important if you are plugging in or have a big surplus of panel capacity. But then if you have that big surplus you are going to use it for higher speeds or longer daily motoring distances.

For a catamaran it might or might not be an issue. Depends on the specific boat and the owners attitudes.

FLAs have a big cost advantage over all other batteries except DIY LFP.

Everything is a tradeoff. Don’t like the limitations of a particular electric setup, pick a different one with different limitations or stick with ICE propulsion.

[valhalla360]

Originally Posted by Narfi

You lost me with lead acid..... Considering weight, discharge rate, charge rate, and usable amps, wouldn't an electric powered boat pretty much mean lifepo4?

If you just want something for daysails to get you in and out of a marina, lead acid is viable.

In the KWH battery bank sizes needed to make longer distance motoring viable, yes, lithium is the only real option. And really considering the usable storage, the cost difference is small.

[Narfi]

Ok... In my fantasy land it 'might' be possible.
49x26 cat, roof built large to start with at 30x20, temporary frames put up for an additional 6x20 behind and 12x20 in front for the loop scinario.
= 48x20 solar x ~14w per ft2 (16 for glass panels and 14 for walk on down the center but call it all 14 for the math) = 13.44kw x 4 per day = 53.76kwh per day

+60 batteries = 113.76kwh usable for the day
/8hrs = 14.22kw or 19hp

It should be doable for that size boat, barely.
Of course that is everything working perfectly on a cloudless day and not fighting any current. (this is a fantasy land)


-----------------------------------------------------------------------

IF that is doable, then what are the weight penalties? Is it possible without sacrificing your entire payload?

Yanmar 4JH5E = 443lbs dry x2 = 886lbs
Torqueedo Deep Blue 25 Sail Drive (acknowledging a loss in power) = 692lbs including 12.8kw battery usable x2 = 1384lbs

Motors with integrated batteries total 500lbs more than the specified Yanmar engines. However we have 25.6kw of battery already.

Would probably already want 10kw of battery so combined with the 25.6 we need another 35kw of lithium, lets call it 40 for a buffer, torqueedo has a 40kw battery so lets go with that.

Torqueedo BMWi3 40kw battery = 615lbs

Fuel, we still need fuel for the generator, but not nearly as much as before. Lets go with 40gal instead of 160 gal.
120x8 = 960lbs saved

So +batteries - fuel saves us 345lbs

So far we have motors +500 and energy storage - 345 = 155lb weight penalty

Solar...... Suppose we would have gone aggressive with solar even with the yanmars and compared to a 3kw array.
We need another 11kw of solar =~ 1750lbs

That puts us at 1905lbs added so far
Additional roof and racking? 500lbs?
Additional electronics and controllers and wiring? 250lbs?

Total = 2650lbs more than if we just went diesel

Generator..... probably need a larger one, but left it as a wash...... honestly if I go diesel I would get huge alternators and no generator so thats dishonest..... but for this exercise thats what I did.

For a boat this size, The solar, battery, and motors are 'just' possible if pushed to their limits and the weight is doable but not attractive.

Cost.... If going electric for normal sail/crusing life before/after, the main cost would be the extra solar and roof/racking extensions.
If selling the solar for 1/2 price after, and doing all the labor myself as a hobby, the fuel savings might be a wash???

[Adelie]

4kt speed is not an artificially low speed, it’s a practical limitation of the system.
At that speed practicality or impracticality is a function of users expectations.

If users are unwilling to live with the limitations then they should us an ICE.

[newhaul]

Originally Posted by Narfi

Ok... In my fantasy land it 'might' be possible.
49x26 cat, roof built large to start with at 30x20, temporary frames put up for an additional 6x20 behind and 12x20 in front for the loop scinario.
= 48x20 solar x ~14w per ft2 (16 for glass panels and 14 for walk on down the center but call it all 14 for the math) = 13.44kw x 4 per day = 53.76kwh per day

+60 batteries = 113.76kwh usable for the day
/8hrs = 14.22kw or 19hp

It should be doable for that size boat, barely.
Of course that is everything working perfectly on a cloudless day and not fighting any current. (this is a fantasy land)


-----------------------------------------------------------------------

IF that is doable, then what are the weight penalties? Is it possible without sacrificing your entire payload?

Yanmar 4JH5E = 443lbs dry x2 = 886lbs
Torqueedo Deep Blue 25 Sail Drive (acknowledging a loss in power) = 692lbs including 12.8kw battery usable x2 = 1384lbs

Motors with integrated batteries total 500lbs more than the specified Yanmar engines. However we have 25.6kw of battery already.

Would probably already want 10kw of battery so combined with the 25.6 we need another 35kw of lithium, lets call it 40 for a buffer, torqueedo has a 40kw battery so lets go with that.

Torqueedo BMWi3 40kw battery = 615lbs

Fuel, we still need fuel for the generator, but not nearly as much as before. Lets go with 40gal instead of 160 gal.
120x8 = 960lbs saved

So +batteries - fuel saves us 345lbs

So far we have motors +500 and energy storage - 345 = 155lb weight penalty

Solar...... Suppose we would have gone aggressive with solar even with the yanmars and compared to a 3kw array.
We need another 11kw of solar =~ 1750lbs

That puts us at 1905lbs added so far
Additional roof and racking? 500lbs?
Additional electronics and controllers and wiring? 250lbs?

Total = 2650lbs more than if we just went diesel

Generator..... probably need a larger one, but left it as a wash...... honestly if I go diesel I would get huge alternators and no generator so thats dishonest..... but for this exercise thats what I did.

For a boat this size, The solar, battery, and motors are 'just' possible if pushed to their limits and the weight is doable but not attractive.

Cost.... If going electric for normal sail/crusing life before/after, the main cost would be the extra solar and roof/racking extensions.
If selling the solar for 1/2 price after, and doing all the labor myself as a hobby, the fuel savings might be a wash???

Dont forget the cost of the mounting hardware and the cost of the repair materials when you reatore to a decient sailing condition .

Then there is the resale cost of all those modifications .
An aside the recovery price is much closer to 1/3 not half

[valhalla360]

Originally Posted by Narfi

Ok... In my fantasy land it 'might' be possible.
49x26 cat.........

That's looking a lot more viable. Might be a little low on power but not crazy low. If you build in a 5-10kw generator to supplement, should be doable.

Cost/effort is the only questionable part but we did the loop to visit the places along it not just pass by, so we stayed in marinas often (inland they tend to be cheaper and anchorages are often more challenging) and could have charged the battery bank from shore power much of the time making a huge and complicated solar array redundant.

Of course, that brings up the ethics question...most marinas are not planning on you pulling 40-50kwh when they build their pricing structure, so you might plan on throwing them $5-10 to cover the cost of charging.

[valhalla360]

Originally Posted by Adelie

4kt speed is not an artificially low speed, it’s a practical limitation of the system.
At that speed practicality or impracticality is a function of users expectations.

If users are unwilling to live with the limitations then they should us an ICE.

Practical in terms of doing the loop.

Theoretically possible...yes.
Practical...no

We had friends who started in a 24ft monohull and they struggled with long days and falling behind the seasons because they couldn't keep up a decent pace.

[newhaul]

Originally Posted by valhalla360

Practical in terms of doing the loop.

Theoretically possible...yes.
Practical...no

Nothing about owning a sailboat for pleasure is practical.

[valhalla360]

Originally Posted by newhaul

Nothing about owning a sailboat for pleasure is practical.

If you want to do the loop, a boat that can maintain 6kts is far more practical than a boat that can only maintain 4kt...Really low power sailboats in general are at the lower end of practical for doing the loop. 8-10kts provides even more practicality.

Practicality for the loop is kind of like hull speed. Put in a wildly oversized motor and burn massive amounts of fuel and you can exceed hull speed but at some point, it's just not practical. Likewise, if you are willing to make wild assumptions, you could do it in a 3kt boat but other than to prove it can be done, no one is going to do it.

[Narfi]

Originally Posted by valhalla360

Cost/effort is the only questionable part

Well..... the smart money would be to store the boat for a year and buy a mid range loop boat and sell it when done and move back 'home' onto the catamaran.

Cheaper, less hastle setting up, less hassle masting and demasting, less depreciation, etc.... adventure of a new home/boat and all the quirks that come with it...... can go up the Rideau, trent/severn, etc....

Disadvantage is we don't get to live in our own home and space and cant keep an eye on it for a year......

I was thinking along the lines of a 20kw generator, you think 10 would be enough? I feel there needs to be a safety 'reserve' somewhere, and when you don't have overpowered diesels, and you cant practically carry enough batteries, an oversized generator is the only way to achieve a safety 'reserve' ?

Alternatively I suppose plan on running the smaller generator anytime the battery bank hits 50% and keep that as your reserve, that means you wont maximize your solar use, but it would let you keep a lighter/cheaper generator.

[danstanford]

Originally Posted by zstine

Yes, so you support me saying "OceanVolt claims are marketing BS"... I hope they walk back their claims before you actually buy something, since 10kw is clearly not 20-30hp.. I'd have a hard time doing business with a company like that.

My boat was shipped with a 15 HP diesel or a 6KW Oceanvolt system. I have the Oceanvolt system as I can tell you there is plenty of power, at least as much as any diesel I have had.