Hybrid Saildrive?

[TiggerToo]

Has anyone here have direct experience, or even second-hand experience, of hybrid sail drives?

I remember Nigel Calder tried something out on his boat a couple of decades ago, but things have probably moved on since then.

 

[dunedin]

Not sure what you means by “hybrid saildrive” (as “saildrives” have generally been simply a routing of the drive from the engine)?

But clearly a lot of thought, prototyping and now some production versions of electric and hybrid propulsion are starting to come onto the market. Also was a good report of an ePropulsion electric drive fitted to a Sadler in a recent Yachting Monthly (albeit done by the owner of a business selling electric drives). And suspect if you went to Southampton some of the exhibitors would be delighted to talk to you about electronic propulsion on a nice new yacht - but need a deep wallet.

I am not an expert, but an interested watcher, and my summary would be:
- electric propulsion is definitely the direction of travel for boats - but currently most proven and effective for inland waterways craft, tenders etc
- production electric drive options starting to be offered for RIBS, offshore multihulls, exotic day sailing boats and now some premium sailing yachts - eg Arcona and Salona, but at a very substantial price premium and short range
- the physics of energy density of diesel vs battery still mean that it is very challenging to get an electric power range for a yacht beyond 20-30 miles or so, and hugely more challenging at 7 knots into a breeze/tide than at 4 knots in flat calm as most are quoted at.

Like cars, hybrid drive options can give much longer range but with extra complexity, whether
(a) parallel hybrid with both diesel and electric motors; or
(b) serial hybrid with diesel (or fuel cell) generator powering an electric only drive.
This latter seems an attractive option for long distance cruisers, who may have both Diesel engine and generator today.

Electric regeneration by a “saildrive“ is a focus for development - because it will be important, but currently not particularly effective unless on a sailboat than can cruise regularly at 8+ knots (see reports on Jimmy Cornell’s Elcano catamaran). The shape of propellor needed for drive is different from that for regeneration so will likely need sophisticated variable propellor geometry. Look out for a lot of progress over the next 10 years.

The key thing is to do the maths calculations on any social media or marketing claims. The physics is currently quite challenging. If you haven’t checked the maths personally then don’t believe the hype - yet.

So a lot of activity and a lot of progress currently. I would love a twin electric drive Ancona - but the cost premium if specked with decent battery range would buy a decent second boat, I suspect. So unless got a canal barge (where weight of cheap batteries not an issue), only need to motor 5-10 miles in gentle weather and/ or a very large budget, probably better to wait and watch for a bit.

PS. If want any relevant replies, need to start with a bit more of your maths inputs - type, size and weight of boat; typical usage patterns; motoring range needs; depth of pocket etc

 

[Tranona]

On the hybrid front, nothing much has happened since the Calder programme (which was not saildrive, but much bigger shaft drive) simply because the physics have not changed. Hybrid for yachts is a dead end for all the reasons Calder concluded and nobody is doing any development.

However as dunedin explains lots of developments on electric drive pods from both ends of the spectrum - that is small day sailors at one end and big (45'+) performance cruisers at the other end. The former work quite well as range requirement is limited and easy to arrange mains charging. The latter because the boats are big enough to have substantial battery capacity and fast enough sailing to make use of regeneration from the props. Even then you are only looking at 60 miles of usable range so best suited to applications like charter boats in the Med hopping from marina to marina or weekending from a marina base.

In between for the 30-40 boats electric is a long way off because of the poor energy density of batteries. Not a problem for day sailing (just expensive to install) but no good if you want the sort speed/range we expect now for cruising. Most yachts of that size have range of between 50-80 hours at 6 knots, whereas electric might give 8 hours at 5 knots. Current cruising boats are unable to sail fast enough (6 knots minimum) consistently for any regeneration to extend motoring range.

 

[vas]

worth checking sailing uma on utube though, real case of el. drive on a 30something foot sailboat with liveaboards pushing the limits a bit (spent the winter in Norway ffs!)

 

[dunedin]

worth checking sailing uma on utube though, real case of el. drive on a 30something foot sailboat with liveaboards pushing the limits a bit (spent the winter in Norway ffs!)

They are on at least version 2 B by now - perhaps changed again, but this was the last version I am aware of Sailing Uma - Oceanvolt

The 2B installation is an OceanVolt SD15 (ie 15kW motor), a good bit of kit.
Not found much about battery capacity, but one quote I heard was could motor at 6.5knots (in flat water, no wind) “but only for an hour”. Which would suggest a very short range - see post #2 above.

This one shows some more recent developments, and very tasty - the twin drive (to get enough power) Salona Salona 46 - Oceanvolt and the Ancona looks similar tech.
But again battery size and range very low, specified for a US electric propulsion enthusiast, and if you have to ask the price …….

 

[vas]

out of their whole setup, I really love the tiny joystick like morse control (cannot really call it morse but anyway...)
don't think their battery is anything exceptional, would guess a switch to lifepo4 would be greatly beneficial with their solar on their arch.

 

[lustyd]

Their battery is LiFePo4, drop in replacements which they bought a while ago. Quite a few I think, and they effectively take up the whole area under the cockpit. Really nice installation but a quite pricey way to get the capacity.

 

[reeac]

Speaking as someone who's owned a Lexus hybrid for over 3 years, I don't see the point for a boat. The main gain is regenerative braking in the case of a car with smaller gains due to CVT gearing permitting very high gearing when appropriate with consequently reduced engine breathing losses and greater refinement.. Admittedly the extra weight is more easily borne in a boat than a car but overall the hybrid arrangement isn't advantageous except perhaps in special cases where zero emissions are demanded for short periods.

 

[TiggerToo]

A boat hybrid will be a different kettle of fish.

An electric sail drive, a LiFePO battery bank and a (diesel) generator to supplement the auxillary, when long-range motoring is needed (50 miles?)

 

[dunedin]

Speaking as someone who's owned a Lexus hybrid for over 3 years, I don't see the point for a boat. The main gain is regenerative braking in the case of a car with smaller gains due to CVT gearing permitting very high gearing when appropriate with consequently reduced engine breathing losses and greater refinement.. Admittedly the extra weight is more easily borne in a boat than a car but overall the hybrid arrangement isn't advantageous except perhaps in special cases where zero emissions are demanded for short periods.

Yes, but like with cars the older Lexus "mild-hybrid" technology in cars has been superseded by Plug-In-Hybrid-Vehicles (PHEV) and full Battery Electric Vehicles (BEV). To use a car analogy, the most practical options for boats are
(a) Tesla style full Battery Electric Vessel - entirely powered by plug in shore power - range currently a huge issue so typically canal & river boats; marina based day sailers, short use RIBs etc
(b) BMW i3 Range Extender type Serial Hybrids - using medium sized battery with plug in recharge capability, but also able to fire up an internal combustion engine as a generator to power the electric drive to give hugely longer range (using the vastly higher energy to weight of petrol or diesel)

 

[TiggerToo]

(b) BMW i3 Range Extender type Serial Hybrids - using medium sized battery with plug in recharge capability, but also able to fire up an internal combustion engine as a generator to power the electric drive to give hugely longer range (using the vastly higher energy to weight of petrol or diesel)

I was hoping to achieve this (b), plus some regenerative capacity using hydro-gen option.
The added benefit would be the "redundancies" of the system - several alternative power generating options.
But I can't afford it (or justify the expense) over the next couple of years or so.

 

[adwuk]

An electric sail drive, a LiFePO battery bank and a (diesel) generator to supplement the auxillary, when long-range motoring is needed (50 miles?)

I'm not sure that it even needs to be a saildrive. I see it as a variation of the hydraulic drive that we have in our boat. A switch to an electric motor, in simplistic terms, means that you are using electrons and not hydraulic oil. The big advantage of electric is that when manoeuvring in the marina, I imagine that we wouldn't need to start the engine. What is the efficiency of a generator hooked up to a diesel? I believe that we get a 10% loss with hydraulics.

 

[dunedin]

Their battery is LiFePo4, drop in replacements which they bought a while ago. Quite a few I think, and they effectively take up the whole area under the cockpit. Really nice installation but a quite pricey way to get the capacity.

If your comment relates to Sailing Uma, I have struggled to find anything definitive about their battery capacity. The best I could find was a reference to 12 x 100Ah batteries - which equates to about 14kWh - hence as stated in post #3 above, in the Uma video they admitted that with the 15kW drive, they could only go for about an hour at 6.5 knots - ie a arange of around 7 miles at typical yacht cruising speed (in flat calm with no waves or adverse tide). Range I suspect would be 2-3 times that if pootle at 3 knots or so - but again in a flat calm, no waves or tide.
How many would be wiling to have a range which would not get them back from Poole to the Solent on a Sunday evening, let alone a return from Cherbourg in a calm. And certainly it would be necessary to be prepared to actually use the flappy things to go upwind in any breeze (or wait a week or so for a different wind direction)

 

[dunedin]

I was hoping to achieve this (b), plus some regenerative capacity using hydro-gen option.
The added benefit would be the "redundancies" of the system - several alternative power generating options.
But I can't afford it (or justify the expense) over the next couple of years or so.

I think the serial hybrid option (electric drive plus diesel or fuel cell generator) is probably already a viable practical and economic option on some types of
(a) NEW BUILD and
(b) FAST OFFSHORE CRAFT (especially catamaran)
So a boat like Jimmy Cornell's (now sold) exotic 45 foot fast catamaran, which can sail easily at 8+ knots and has masses of deck space for solar, would have been viable if a backup generator had been fitted (as I suspect the builders recommended). The savings from otherwise fitting twin diesel engines, a diesel generator and twin hydro generators would help cover the cost of the twin hybrid drives, moderate battery and serial generator. Then with moderate diesel tanks would be an attractive proposition.

 

[lustyd]

If your comment relates to Sailing Uma, I have struggled to find anything definitive about their battery capacity. The best I could find was a reference to 12 x 100Ah batteries - which equates to about 14kWh - hence as stated in post #3 above, in the Uma video they admitted that with the 15kW drive, they could only go for about an hour at 6.5 knots - ie a arange of around 7 miles at typical yacht cruising speed (in flat calm with no waves or adverse tide). Range I suspect would be 2-3 times that if pootle at 3 knots or so - but again in a flat calm, no waves or tide.
How many would be wiling to have a range which would not get them back from Poole to the Solent on a Sunday evening, let alone a return from Cherbourg in a calm. And certainly it would be necessary to be prepared to actually use the flappy things to go upwind in any breeze (or wait a week or so for a different wind direction)

They've talked about range before. 6.5kt isn't a good speed to cruise at, and they get far more range at slightly lower speeds. 12 batteries sounds about right from memory, but I seem to recall usage was more like 3-4KW while motoring once up to speed. Either way they have sufficient range for their use and the Sanoma they tested had exceptionally good range for electric only as it had a more modern hull shape.

 

[dunedin]

Anybody going to look at the new Arcona 415 at Southampton ? Arconas are lovely fast sailing boats anyway, but this is launched as the "first" cruising yacht with electric drive as standard - New Arcona 415 - Zero Emissions - A New Standard.

Not seen anything on prices yet, or if there is a comparison with any diesel engine option.

Digging into the specs I think it lists a battery size of 19kWh - but no indication I could spot of likely range under motor (which is a bit remiss).
With a 15kW drive that is about an hour and a bit at full chat, again much more if pootle at 3-4 knots. So I would guess a range of 10-30NM, again in zero wind, flat water and no tide.

So interesting as a get in and out of a marina context, but don't try to go round Portland Bill ???

Of course it is early early days, and presumably they would offer bigger batteries at extra cost - but presumably not cheap or would have started with bigger battery as standard

 

[lustyd]

Pretty sure Salona were in the 80NM range

 

[dunedin]

the Sanoma they tested had exceptionally good range for electric only as it had a more modern hull shape.

The Salona 46 twin electric drive boat was certainly in many ways a very appealing boat. But I believe it was spec-ed specifically for a US based electric boat dealer, and not seen any mention of costs for the twin drives and batteries (if you have to ask the price .....).
Digging into the information I could find it reportedly had a 30 kWh battery pack (net energy equivalent to circa 10.3 litres of diesel), sited where a conventional diesel engine and saildrive would otherwise be fitted.
With twin 15kW drives that is again circa 1 hour at full chat - at least 8 knots with that boat. Further if prepared to motor at 4 knots, so probably back to the 10-30NM effective range (again flat water, no wind, no tide).
This will change, and I would love to have a twin electric drive Arcona or Salona - but going to be a very large cost premium (and or a serial hybrid with generator) before could work the way most people use their cruising yachts.
For example, this summer we had quite a few spells of high pressure for a couple of weeks, with very light winds. Ideal for visiting places (St Kilda, Shetland, Isles of Scilly) that can be bumpy to et to in less settled weather. but many of us, even with fast sailing boats, clocked up a lot of diesel engine hours to enjoy these spells of fine weather by visiting out of the way destinations.
This will change, and in 10 years time we will be nearer to where cars are today - except that the government has been throwing £5,000 (reducing now) per car at buyers to subsidise the extra costs. Can't immediately see similar grants being given to new yacht purchases?

 

[lustyd]

Yes it suits a certain style of sailing, and motoring around on short trips is not that. It has the distinct advantage over your 10.3l of diesel that electric is available mid ocean!

 

[Buck Turgidson]

Yes it suits a certain style of sailing, and motoring around on short trips is not that. It has the distinct advantage over your 10.3l of diesel that electric is available mid ocean!

Lol.
Do some maths and tell us how long it will take to replace that 10.3l at sea!
For cruising boats we are still 2 or 3 jumps away from electric propulsion. Same with commercial aircraft unless you believe the lies.