Oceanvolt Hybrid Motor

[StuM]

Originally Posted by foamcows

The number that really stands out to me is the distance you can motor on 100 liters of fuel... 325nm (https://oceanvolt.com/twin-saildrive-10/). What I am struggling to find is what is the expected distance one can cruise on a traditional diesel config with 100 liters of fuel?

At the end of the day, miles per liter is all that matters to me.

If I get more miles per liter with the hybrid system motoring versus a normal diesel system, the decision is made because it only gets better from there with electric anytime I am not motoring around.

Depends entirely on speed. If that is not stated, then it's just more of the same old OV marketing b*llsh*t.


Extrapolating the consumption figures for my 43ft cat, I should get over 600NM for 100 litres of fuel at 2 knots. Not that I've ever actually tried that


Other figures for the same setup: 325 NM at 3.5 knots or 100NM at 8 knots

[StuM]

Originally Posted by foamcows

The number that really stands out to me is the distance you can motor on 100 liters of fuel... 325nm (https://oceanvolt.com/twin-saildrive-10/). What I am struggling to find is what is the expected distance one can cruise on a traditional diesel config with 100 liters of fuel?

I also not from that link:
Suitable up to: 50ft/10000kg


Not many 45-50ft cats come at a 10 000kg cruising displacement


And the usual "magic EP horsepower":
Equivalent horsepower: 2 x 20-30hp ( 10kW = 13.4HP)

Besides, how many 45- 50ft cats have engines that small?

[Adelie]

Originally Posted by foamcows

Was interesting to read the first ten pages and then the last ten pages, going from everyone arguing it will never work to being shown real world numbers indicating it actually can.

Currently starting out our planning process for purchasing a new 40-50 ft cat in the next year or two and trying to figure out what makes more sense... your traditional diesel or the OV servo prop hybrid configuration.

The number that really stands out to me is the distance you can motor on 100 liters of fuel... 325nm (https://oceanvolt.com/twin-saildrive-10/). What I am struggling to find is what is the expected distance one can cruise on a traditional diesel config with 100 liters of fuel?

At the end of the day, miles per liter is all that matters to me.

If I get more miles per liter with the hybrid system motoring versus a normal diesel system, the decision is made because it only gets better from there with electric anytime I am not motoring around.

The OceanVolt system is a series hybrid. As such it will lose 15-25% in range comparted to a direct drive ICE or parallel hybrid using the same prime mover (ICE engine). A series hybrid converts the energy from the ICE to electicity (at a 7-13% penalty) sends that power over cables (which will cost in the region of (1%) to the motors which convert it back at 7-13% penalty.

With a direct drive ICE the power the motor "delivers" depends on where it is measured, at the crankshaft before the transmission or at the prop after the transmission and drive seal. The transmission will enact a 2-3% penalty in power and the shaft seal a bit more.

As a guess, using the same amount a fuel a direct drive system could go 390nm at the same speed. A parallel hybrid might be a bit better. At low maneuvering speeds at each end a parallel hybrid could use the electric drive and shut down the ICE.

The EU did a study of hybrid marine propulsion (HYMAR) which ultimately concluded parallel was generally the better system for several reasons, significantly better fuel efficiency being one of them. Another technology the Europeans have pursued for decades is controllable pitch props. The efficiency advantage is significant to them because of the high cost of fuel. In the US where the fuel has tended to be cheap, a lower cost, low maintenance fixed prop was the better economic choice.
https://www.boats.com/reviews/all-about-saildrives/

Of note in the OV system, the prime mover is a 10kW ICE. Regardless of how big the prop drivers are, past the first 20nm or so of a long run when the batteries have been expended, the boat will only move as fast as 10kW (13hp) can move the boat. Unless your are using 1-2kW solar panels which will boost the speed by 1/4kt or so.

[Yihang]

Originally Posted by Adelie

The OceanVolt system is a series hybrid. As such it will lose 15-25% in range comparted to a direct drive ICE or parallel hybrid using the same prime mover (ICE engine). A series hybrid converts the energy from the ICE to electicity (at a 7-13% penalty) sends that power over cables (which will cost in the region of (1%) to the motors which convert it back at 7-13% penalty.

With a direct drive ICE the power the motor "delivers" depends on where it is measured, at the crankshaft before the transmission or at the prop after the transmission and drive seal. The transmission will enact a 2-3% penalty in power and the shaft seal a bit more.

As a guess, using the same amount a fuel a direct drive system could go 390nm at the same speed. A parallel hybrid might be a bit better. At low maneuvering speeds at each end a parallel hybrid could use the electric drive and shut down the ICE.

The EU did a study of hybrid marine propulsion (HYMAR) which ultimately concluded parallel was generally the better system for several reasons, significantly better fuel efficiency being one of them. Another technology the Europeans have pursued for decades is controllable pitch props. The efficiency advantage is significant to them because of the high cost of fuel. In the US where the fuel has tended to be cheap, a lower cost, low maintenance fixed prop was the better economic choice.
https://www.boats.com/reviews/all-about-saildrives/

Of note in the OV system, the prime mover is a 10kW ICE. Regardless of how big the prop drivers are, past the first 20nm or so of a long run when the batteries have been expended, the boat will only move as fast as 10kW (13hp) can move the boat. Unless your are using 1-2kW solar panels which will boost the speed by 1/4kt or so.

Parallel offers better efficiency for long range motoring at high consumption rates but I can see why the OV system offers more flexibility:

-Only one ICE on a catamaran , you could get a 16w DC genset and run one of the OV motors at full power. Which seems to be sufficient on an outremer 45.

-Could use the smaller DC genset to charge batteries instead of firing up the 50 HP engine. Whisperpower has some sweet DC gensets.

Are there any parallel systems on the market for smaller crafts? The idea of using the ICE engine to drive the electric motor as a genset sounds pretty good, if it's a mono or a tri.

[Adelie]

Originally Posted by foamcows

Thanks for the feedback. Couple of questions, do single hull figures pair up well with multihull? Also, is this a standard datapoint captured for boats? Meaning is this similar to how cars are rated for mpg?

My impression is that most cruising cats have somewhat lighter displacements compared to same length monohulls but have somewhat higher wetted surface area (a bigger problem at low speeds). The reason they tend to be faster sailing is the very high SA/D ratios (very big effect), longer waterline length (small effect) and very high length to beam ratios (small to moderate effect at higher speeds).

The Cal 34 I want is 33'3", 9500lb, lwl-26'0" with an SA/D - 18.0
Gemini 105MC: 33'6", 8,000lb, lwl-31'9", SA/D-27.7

The "standard" engine for the Gemini was a 27hp diesel. Different models had outboards.

The Cal came with an Atomic-4 which could have been 30hp or 18hp,
The heavier Mark-III model came with a 25hp diesel.

Motoring my guess is that a Gemini will have a slightly higher top speed than the Cal due to the longer waterline and maybe slightly better fuel economy at high cruise (6.5kt) but the Cal will have a better mpg at economy cruise (4.5-5kt) due to the lower wetted surface area.

The manufacturer's spend a lot of time getting engine size right for boats. Too large an engine and they are wasting money. Too small and they get customer complaints. In between there is some play.

[Adelie]

Originally Posted by Yihang

Parallel offers better efficiency for long range motoring at high consumption rates but I can see why the OV system offers more flexibility:

-Only one ICE on a catamaran , you could get a 16w DC genset and run one of the OV motors at full power. Which seems to be sufficient on an outremer 45.

-Could use the smaller DC genset to charge batteries instead of firing up the 50 HP engine. Whisperpower has some sweet DC gensets.

Are there any parallel systems on the market for smaller crafts? The idea of using the ICE engine to drive the electric motor as a genset sounds pretty good, if it's a mono or a tri.

Using exactly the same engine, in a parallel system you will get better fuel efficiency at the same speed or a higher speed for the same rate of fuel draw.

Betamarine has hybrids with 20hp and up for the ICE and a 10kW electric drive which generates 6kW when drive is engaged, or 6kW at rest if an extra clutch is installed.
https://betamarine.co.uk/he-hybrid-propulsion/

I don't believe any of these can be used in a sail drive installation.