The rise of electric Boats

[zstine]

What’s up with OceanVolt Pricing and Claims!? Big marketing BS connected to big dollars!

Looking at the twin 10kw linked previously:
-Claim 10kW is equal to 20-30hp or 40hp to 60hp total for the twin. These are both power ratings and 10kW is actually 13.4hp or just 27hp total. I understand the argument that the electric motor makes torque at low rpm and you can down size, but not half the size!
-Claim 10nm range with a 10.5kWh battery. So the boat has a total of 20kW in engine power, therefor at WOT you get just 30 minutes of run time and at a ‘cruise’ of 50% throttle, 1 hour. So they assume you can go 10knts with 10kW in the ‘up to’ 10,000kg boat. Pretty slippery boat! I’m guessing the boat needs to be more like 5000kg to get near those numbers.

System Price is $85,000 USD!!! What?

- 10.4kWh bank (4x LG Chem 2.6kWh) is $2,940 (EVWest)
- AC-9, 27hp motor with controller & regen $2,650 qty 2 is $5,300 (EV West)
- Victron charger Skylla-TG 50A/48V $1,603, emarineinc
- 10kW Generac generator, $1,050
- $2000 for a shaft, coupling and prop
- balance of sys, switches, wire, etc. $3,000 est.
Total price is $15,893… less than 20% of OceanVolt price

Now I would add 15kW of solar and 3 or 4 times the battery bank, but I wanted to show an equal comparison.

[Adelie]

Originally Posted by valhalla360

Maybe with a strong tailwind you are doing 2.5kt. Had a 5hp auxiliary that could be deployed on our 34ft cat and maxed out in calm conditions was 3.0kt in testing.

Even so, 0.5kw for 24hr is 12kwh. 1.5kw of solar panels will only be expected to produce around 6kwh/day if everything is operating ideally and there are no house loads.

Headwinds...I'm talking about 5kts headwind can bring the boat to a halt with as little power as you are suggestin.

Assuming outboards are equivalent to the inboard is a mistake.

Outboards are generally geared and propped for planing speeds. That's why some manufacturers produce what are generally known as HighThrust models. The gear ratio between engine and prop is changed and the prop is different too, pitch and maybe a bit more diameter. The net result is more thrust and speed from the engine for a given throttle setting or better fuel economy for a given speed. I bought one for my boat after motoring on my last cruise was rather dismal. Have not checked how much things have improved yet.

Once again, if there's wind, the sails will start to draw. 5kt I I put up the drifter and make 2.5-3kt.

[newhaul]

Originally Posted by Adelie

Assuming outboards are equivalent to the inboard is a mistake.

Outboards are generally geared and propped for planing speeds. That's why some manufacturers produce what are generally known as HighThrust models. The gear ratio between engine and prop is changed and the prop is different too, pitch and maybe a bit more diameter. The net result is more thrust and speed from the engine for a given throttle setting or better fuel economy for a given speed. I bought one for my boat after motoring on my last cruise was rather dismal. Have not checked how much things have improved yet.

Once again, if there's wind, the sails will start to draw. 5kt I I put up the drifter and make 2.5-3kt.

But will you make headway into that 5 knots on the nose. No sailboat points that high

[NPCampbell]

Originally Posted by valhalla360

You avoided the question. It was how much to do 5kt or 8kt.

Of course, that 1.2kw number is based on dead calm conditions. Any kind of head wind and they won't be making 3kts.

Most displacement hulls can be propelled at less than 1/3 of their hull speed for very little power regardless of the power source. This is because power required to propel a hull goes up with the cube of speed. There are inverse cubed scaling factors based on weight, shape of the hull, LWL etc but those are constant.

For example, for a particular boat, 1.5kw may power it to 2kts, but going 4kts doesn't require 3kw, it requires 6kw. 6kts requires 24kw, 8kts requires 48kw, and so on until you get close to hull speed.

The problem with an underpowered boat becomes evident when you are fighting a 1.5kt current and a weak headwind with 15 miles to go to get to the marina. You need the ability to sustain hull speed for several hours or you might as well anchor.

That amount of energy won't come from batteries for the same reason that the range on electric planes is weak. You can try increasing the amount of batteries you carry but at some point the weight of the batteries fights your speed and range.

We need a jump in energy density technology. Tesla's new battery was a nice jump (16%?) but we need another 200-300% for it to be able to handle the "Oh darn" situations on a boat.

[Simon.Sails]

Originally Posted by valhalla360

Fact is probably 99% of new boats aren't and never will do an open ocean crossing so hydrogenation is very much a niche product.

Even on a big cat, enough solar to do anything meaningful in terms or propulsion isn't reasonable...plus it kills the sailing performance to squeeze 2-3kw of solar panels.

That's a strange argument for me. First people claim electric isn't feasible because it doesn't have their 1'500nm range, and then hydrogeneration isn't feasible because nobody's sailing at sufficient speed or does ocean crossings...are we talking local cruising only? because then electric should be pretty ideal no?

Solar panels are heavy, but not nearly as heavy as diesel.
Again, it's all about expectations rather than requirements.

[Simon.Sails]

Originally Posted by zstine

What’s up with OceanVolt Pricing and Claims!? Big marketing BS connected to big dollars!

Looking at the twin 10kw linked previously:
-Claim 10kW is equal to 20-30hp or 40hp to 60hp total for the twin. These are both power ratings and 10kW is actually 13.4hp or just 27hp total. I understand the argument that the electric motor makes torque at low rpm and you can down size, but not half the size!
-Claim 10nm range with a 10.5kWh battery. So the boat has a total of 20kW in engine power, therefor at WOT you get just 30 minutes of run time and at a ‘cruise’ of 50% throttle, 1 hour. So they assume you can go 10knts with 10kW in the ‘up to’ 10,000kg boat. Pretty slippery boat! I’m guessing the boat needs to be more like 5000kg to get near those numbers.

System Price is $85,000 USD!!! What?

- 10.4kWh bank (4x LG Chem 2.6kWh) is $2,940 (EVWest)
- AC-9, 27hp motor with controller & regen $2,650 qty 2 is $5,300 (EV West)
- Victron charger Skylla-TG 50A/48V $1,603, emarineinc
- 10kW Generac generator, $1,050
- $2000 for a shaft, coupling and prop
- balance of sys, switches, wire, etc. $3,000 est.
Total price is $15,893… less than 20% of OceanVolt price

Now I would add 15kW of solar and 3 or 4 times the battery bank, but I wanted to show an equal comparison.

Where did you get these figures from? I'm currently in contact with them regarding my future cat and you're nowhere near what I'm currently quoted for a twin SD10/SP10 system cost-wise.

[newhaul]

Originally Posted by Simon.Sails

Where did you get these figures from? I'm currently in contact with them regarding my future cat and you're nowhere near what I'm currently quoted for a twin SD10/SP10 system cost-wise.

So what are the numbers that they are giving you?
And what is the makeup of the system?

[Simon.Sails]

Originally Posted by newhaul

So what are the numbers that they are giving you?
And what is the makeup of the system?

I'm waiting to receive a final quote - I've received a price list though, it's roughly half the price from above. But the real figure for me will be the difference between the standard Yanmar diesels and the Oceanvolt system excluding the batteries (as I want large house bank batteries either way).

I've also requested reference range/consumption figures from a similar cat they did. Will report back when I get it.

[valhalla360]

Originally Posted by newhaul

Kite sailing ?
No mast required

Please, live stream the video has you kite sail up wind around blind corners of a 150ft wide river as a 3x5 tow upbound is sliding sideways around that corner.

It should be exciting.

[newhaul]

Originally Posted by valhalla360

Please, live stream the video has you kite sail up wind around blind corners of a 150ft wide river as a 3x5 tow upbound is sliding sideways around that corner.

It should be exciting.

It is just a bit of fun and a potential option. You already know the only reason I leave saltwater environment is to drydock for hull maintance

[valhalla360]

Originally Posted by Narfi

Very rough generalization shouldn't you get roughly 1/4 of your cats footprint as roof space for potential solar? (not counting purpose built full length solar arrays that look butt ugly imo)

34x16(i dont know your beam) = 544 / 4 = 136ft2
Randomly googled some marine solar panels and found 18w/ft2
136x18 = 2448

(same numbers ran on a 40x18ft boat = 3240)
(same numbers ran on a 60x26ft boat = 7020)

back to yours, of that 2448 potential per perfect sunlight hour, what do you get in a day? I would think that would be getting pretty close to your 7.5kwh?

Purpose built with a larger roof say 1/3rd instead of 1/4th would change the numbers enough to potentially tip the scale without ending up 'too' ugly?

34x16 = 3264kw
40x18 = 4320kw
60x26 = 9360kw

You misunderstood...7.5kw of solar was an array of panels nominally rated at 7.5kw. Generally, a good rule of thumb is solar panels will generate 4 times their nominal rating in kwh...so 7.5kw of solar would generate about 30kwh per day or about 90kwh in 3 days to replace the 80kwh plus run house loads and account for efficiency losses storing that power.

A 7.5kw array is massively too large for a 34x14ft cat even if you cover every square inch of topsides.

Yes, if you move up to a 60x26ft cat, you get close to being able to fit 7.5kw of panels but that assumes no rigging and the entire boat covered in panels...plus a boat 4 times the size is going to take more power to move at the same speed.

[valhalla360]

Originally Posted by zstine

-Claim 10kW is equal to 20-30hp or 40hp to 60hp total for the twin. These are both power ratings and 10kW is actually 13.4hp or just 27hp total. I understand the argument that the electric motor makes torque at low rpm and you can down size, but not half the size!

This is wrong.

Where this idea that you can downsize the power comes from is the automotive world.

A small car might have a 200hp (peak output) engine but cruising at freeway speeds, it only needs 40-50hp (see the old VW bugs that only had 50hp motors and could do 60-70mph). The reason they put higher HP rated engines in is for acceleration. It took those VWs forever to get up to freeway speeds and they were total slugs off the line. By putting in more powerful engines, cars develop more HP at low speed/RPM greatly enhancing acceleration.

Electric motors generating greater low end torque created a higher percentage of the rated HP at low RPM (HP = torque * rpm) allowing for the use of lower peak HP electric motors to get similar acceleration characteristics. The steady cruise speed power demands were not controlling the motor HP rating.

For steady state operation...such as a displacement cruising boat running at a constant speed...power is power. Doesn't matter what the source is. Instead of acceleration driving engine sizing, it's maintaining cruising speed against adverse conditions, so electric or ICE both are up in their ideal power output range and the low end torque is not relevant (also, because the prop can slip while accelerating, a ICE can quickly spin up to an RPM where HP output is greater).

Maybe if you are looking at a small planing dingy, there could be some truth as the low end torque helps pop it onto plane.

[valhalla360]

Originally Posted by Adelie

Assuming outboards are equivalent to the inboard is a mistake.

Outboards are generally geared and propped for planing speeds. That's why some manufacturers produce what are generally known as HighThrust models. The gear ratio between engine and prop is changed and the prop is different too, pitch and maybe a bit more diameter. The net result is more thrust and speed from the engine for a given throttle setting or better fuel economy for a given speed. I bought one for my boat after motoring on my last cruise was rather dismal. Have not checked how much things have improved yet.

Once again, if there's wind, the sails will start to draw. 5kt I I put up the drifter and make 2.5-3kt.

Not ideal but balanced by having several times the power and still only making 3kts.

Your drifter will take you upwind in 5kts at 2.5-3.0kts...that's pretty good.

[valhalla360]

Originally Posted by NPCampbell

Most displacement hulls can be propelled at less than 1/3 of their hull speed for very little power regardless of the power source. This is because power required to propel a hull goes up with the cube of speed. There are inverse cubed scaling factors based on weight, shape of the hull, LWL etc but those are constant.

For example, for a particular boat, 1.5kw may power it to 2kts, but going 4kts doesn't require 3kw, it requires 6kw. 6kts requires 24kw, 8kts requires 48kw, and so on until you get close to hull speed.

The problem with an underpowered boat becomes evident when you are fighting a 1.5kt current and a weak headwind with 15 miles to go to get to the marina. You need the ability to sustain hull speed for several hours or you might as well anchor.

That amount of energy won't come from batteries for the same reason that the range on electric planes is weak. You can try increasing the amount of batteries you carry but at some point the weight of the batteries fights your speed and range.

We need a jump in energy density technology. Tesla's new battery was a nice jump (16%?) but we need another 200-300% for it to be able to handle the "Oh darn" situations on a boat.

True, in typical cruising speeds (say 50-100% of hull speed) it takes less power to go slower but 1/3 of hull speed for a 30-35ft boat is going to be something like 2kts and at that point, hull speed is largely not relevant. Skin friction becomes the main drag instead of hull speed limitations. Also, as you indicate, headwinds, current, waves can easily negate any headway.

Of course, most would consider a 2kt cruise speed to be unacceptable. It's not like a 6kt cruise speed is some magical rocket fast speed. It's already a slow and efficient operation.

[valhalla360]

Originally Posted by Simon.Sails

That's a strange argument for me. First people claim electric isn't feasible because it doesn't have their 1'500nm range, and then hydrogeneration isn't feasible because nobody's sailing at sufficient speed or does ocean crossings...are we talking local cruising only? because then electric should be pretty ideal no?

Solar panels are heavy, but not nearly as heavy as diesel.
Again, it's all about expectations rather than requirements.

I never claimed to need a 1,500 mile range, so not relevant to my comment. Reality is almost no one does 1,500miles on a single fill up. It's the solar/electric proponents putting up this straw man that they can motor continuously forever.

Situations where you need to motor continuously at a high percentage of hull speed are typically coastal situation. Open ocean, you can typically just wait it out.

PS: weight is not a huge impact on displacement hulls (within reason). But big solar arrays are a huge impact on aerodynamics.