Hybrid Saildrive?

[dunedin]

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.

Quite. Hope you don’t mind my format editing of your post, but ”do some maths” is the key for any realistic debate on electric propulsion. Opinions with no numbers, on this topic, are rarely a good basis.
The big issues with regeneration at sea are
- cruising speed - hence why today fast carbon cats are the best platforms; and
- weather patterns - rarely get fair wind and calms in 3 hour batches - often 3 weeks wind followed by 2-3 weeks calm

 

[lustyd]

Seems to be working well enough for those doing it though, so maths isn't everything.

 

[adwuk]

Sailing Uma's latest video, posted yesterday, is an interesting watch. Shows the kit installation (at least some of it), and in use with some useful numbers on regen.

 

[Loopy]

I exchanged some emails with Oceanvolt a few months back as our Volvo engine is quite old at this point. It's some really interesting technology. Unfortunately, range is the issue. I'm prepared to sacrifice some range to make the switch from diesel to electric, but even with a giant battery bank, you'd be lucky to get 20-30 miles out of it. The diesel with a full tank can motor for 150-200.

 

[Tranona]

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.

This approach has been tried - at least partly over 10 years ago when a number of Lagoon Cats were equipped with twin electric motors, big battery bank and a sizeable (10KVA from memory) generator for the Caribbean charter market. The argument was that the boats had high electrical demands (air conditioning, big fridges, electric cooking) and the propulsion was a smaller portion of total consumption. The generator was located in the front of the cockpit in a sound proof box. While it sort of worked there was no regeneration and sophisticated control systems were needed to allocate and balance power between the sources (batteries and generator) nad the consumers. Proved all a bit too much for boats required to be reliable day in and day out with minimal maintenance and clients tended to motor more than expected meaning the generator ran almost constantly while underway.

This type of hybrid only makes sense when the propulsion demand is very small compared with domestic as on cruise ships which are almost all diesel electric with electric steerable drive pods. It could well be that a MOBO with high domestic loads and low speed and range requirements could make use of this approach. However current MOBO buyers seem mostly to be in love with ever larger and more powerful propulsion diesel and rely on old style generators for domestic requirements.

 

[Zing]

I looked at it installed in the ITA cat. There they had a 22Kw genset feeding two 15Kw Ocean Volt motors and some extra lithium. I don't really see any point. Weight wise compared to conventional motors, little difference, but heavier when the large battery bank is considered. Fuel efficiency will be a little worse than direct propulsion because of conversion losses. Advantages: Maybe a better balance of boat weight distribution. The ability to run silently for a short distance, but then again a decent engine installation is near to silent anyway from outside of the boat. Hardly a compelling case.

 

[dunedin]

Sailing Uma's latest video, posted yesterday, is an interesting watch. Shows the kit installation (at least some of it), and in use with some useful numbers on regen.

Not watched in detail, but that looks to be a repeat of an older video done some months back, when they fitted their second electric installation using OceanVolt 15kW drive.
Nice drives, but with Uma's setup a very short range in real world - see earlier posts #5 and #13 above (eg they said an hour at 6.5 knots)

 

[Daverw]

The main difference this time is the servo controlled prop which allows optimising of the regen,

 

[jwfrary]

This approach has been tried - at least partly over 10 years ago when a number of Lagoon Cats were equipped with twin electric motors, big battery bank and a sizeable (10KVA from memory) generator for the Caribbean charter market. The argument was that the boats had high electrical demands (air conditioning, big fridges, electric cooking) and the propulsion was a smaller portion of total consumption. The generator was located in the front of the cockpit in a sound proof box. While it sort of worked there was no regeneration and sophisticated control systems were needed to allocate and balance power between the sources (batteries and generator) nad the consumers. Proved all a bit too much for boats required to be reliable day in and day out with minimal maintenance and clients tended to motor more than expected meaning the generator ran almost constantly while underway.


This type of hybrid only makes sense when the propulsion demand is very small compared with domestic as on cruise ships which are almost all diesel electric with electric steerable drive pods. It could well be that a MOBO with high domestic loads and low speed and range requirements could make use of this approach. However current MOBO buyers seem mostly to be in love with ever larger and more powerful propulsion diesel and rely on old style generators for domestic requirements.

Interestingly a few princesses have been fitted with pretty large lithium banks with inverters supplying the AC load and a DC generator to charge the batteries very quickly. From what I hear works very well even runs thr air con overnight.

Generators sound proofed of course or a high rpm sets quite intrusive.

I don't think it makes much sense on a small yacht. The serial hybrid approach is used on canal boats a bit. Seems to work.

Uma sail at every opportunity which is a choice on their part, I guess that's not something everyone can do. Pobably until diesel is banned or unavailable the paradigm shift won't happen.

 

[lustyd]

I exchanged some emails with Oceanvolt a few months back as our Volvo engine is quite old at this point. It's some really interesting technology. Unfortunately, range is the issue. I'm prepared to sacrifice some range to make the switch from diesel to electric, but even with a giant battery bank, you'd be lucky to get 20-30 miles out of it. The diesel with a full tank can motor for 150-200.

This is quite at odds with actual reviews of yachts with them fitted.

 

[dunedin]

This is quite at odds with actual reviews of yachts with them fitted.

Please give references to reviews of electric yachts with ranges over 30 miles (diesel hybrids excluded), as I would love to see them.

Genuinely, as I have studied reviews of electric propulsion yachts in all magazines I can find, including translations of some overseas ones. Of the 30 or so I have studied (all of individual vessels, not true series production, pending Arcona 415 review), most have been vague about range and those that were forthcoming were all in the under 90 minutes at full power category, 30 miles absolute best pottering.

So look forward to seeing the links to study and learn more.

PS. Have seem hundreds if not thousands of reviews of cruising yachts with diesel tankage giving 150-200 mile range. Out 38 foot boat has 200 litres, and have 40 litres cans can fill if expect to do a 3 day Sea crossing in light weather (which is the sort of forecast the crew prefer for wave reasons)

 

[andsarkit]

Jeremy Rodgers did a hybrid Contessa 32 Calypso a few years ago. I don't remember the details but was quite impressed with the silent progress when leaving the pontoon. It was not meant as a commercial project but just to see what could be achieved with new technology. Some more details here: Calypso

 

[Tranona]

Please give references to reviews of electric yachts with ranges over 30 miles (diesel hybrids excluded), as I would love to see them.

Genuinely, as I have studied reviews of electric propulsion yachts in all magazines I can find, including translations of some overseas ones. Of the 30 or so I have studied (all of individual vessels, not true series production, pending Arcona 415 review), most have been vague about range and those that were forthcoming were all in the under 90 minutes at full power category, 30 miles absolute best pottering.

So look forward to seeing the links to study and learn more.

PS. Have seem hundreds if not thousands of reviews of cruising yachts with diesel tankage giving 150-200 mile range. Out 38 foot boat has 200 litres, and have 40 litres cans can fill if expect to do a 3 day Sea crossing in light weather (which is the sort of forecast the crew prefer for wave reasons)

Perhaps the Salona 46 does achieve greater range, although the video of it which gives the most info is vague. However it does suggest that a usable range of up to 60 miles could be possible. Will be interesting to see hard figures for the Arcona.

All this though is a long way away from the everyday cruisers around the UK. My benchmark would be 80 miles at 5 knots which would require a massive improvement in energy density from the batteries. At the other end of the spectrum the electric Shrimper 21 looks promising. Small price premium of £1250 over the diesel and a practical range of 6 hours/30 miles. Should work for a day sailor or overnighter. Getting on for £60k though with a decent spec.

 

[Buck Turgidson]

Jeremy Rodgers did a hybrid Contessa 32 Calypso a few years ago. I don't remember the details but was quite impressed with the silent progress when leaving the pontoon. It was not meant as a commercial project but just to see what could be achieved with new technology. Some more details here: Calypso

There was a 26 converted to electric too. It was on the market a year after the refit so whoever paid for it didn't hang on to it. £50 grand for a Co26 made me chuckle.

 

[Praxinoscope]

Unless. I have missed it, no-one seems to be a bit concerned about large battery installations on a boat, (yes I know submarines use batteries for silent running) but one only has to look through the various threads on the forum over the years to see major problems with batteries and water on just small installations, (just two 12v for instance) .
Much as I support the move away from fossil fuels, and if I could afford one I would replace my small Mariner tender o/b with a Torqueedo but not at their prices, but not sure I am ready for installing a massive battery bank in a boat just yet.

 

[Buck Turgidson]

Unless. I have missed it, no-one seems to be a bit concerned about large battery installations on a boat, (yes I know submarines use batteries for silent running) but one only has to look through the various threads on the forum over the years to see major problems with batteries and water on just small installations, (just two 12v for instance) .
Much as I support the move away from fossil fuels, and if I could afford one I would replace my small Mariner tender o/b with a Torqueedo but not at their prices, but not sure I am ready for installing a massive battery bank in a boat just yet.

Lots of the problems can be put down to poor installation. There are a great many electric vehicles on the roads these days without significant problem. A professional installation with appropriate standards is key. But in the boating world anyone with a YouTube channel becomes an expert overnight.

 

[dunedin]

Unless. I have missed it, no-one seems to be a bit concerned about large battery installations on a boat, (yes I know submarines use batteries for silent running) but one only has to look through the various threads on the forum over the years to see major problems with batteries and water on just small installations, (just two 12v for instance) .
Much as I support the move away from fossil fuels, and if I could afford one I would replace my small Mariner tender o/b with a Torqueedo but not at their prices, but not sure I am ready for installing a massive battery bank in a boat just yet.

It’s certainly on my list of things to ask an expert about before going down that route - what would happen if a decent sized (eg Tesla capacity, not the ones on current short range boats - say 75+ kWh) bank of batteries were suddenly to be covered by salt water due to a collision with an underwater object, failed sea cock etc.
Been a very small number of very spectacular battery fires on crashed BEVs, which reputedly took some very long time to be extinguished. And at sea you can’t just jump out.

AFAIK Tesla’s etc have sophisticated battery management electronics built into each group of the thousands of tiny battery cells, which help manage issues and bypass failing cells. Which is good. But as these fail safe systems are themselves electronic, I wonder how well they work when suddenly immersed in salt water?
Perhaps someone will volunteer to flood their test boat to find out?

 

[dunedin]

The main difference this time is the servo controlled prop which allows optimising of the regen,

Thanks for that. You are right it is a new Sailing Uma video – and indeed they are now on their FOURTH iteration of electric drive systems. Indeed they joked that as they installed their THIRD Oceanvolt saildrive, that they had probably now installed more such electric saildrives than any boatyard in the world.

The Sailing Uma guys are really great communicators, and a worthwhile video to watch. But be warned it talks only about electric regeneration. You won’t learn anything new on the electric drive capability or, importantly, range – which I assume remains the very low “circa 1 hour” at 15kW/20Hp.

I did say in Post #2 ….

“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.”

…. and so this has proved for Sailing Uma. Hence this change to replace a standard Gori folding prop with a new Oceanvolt electronically variable propellor.

Electric propulsion is certainly a fast moving field – and quite scary to hear them refer to their (under 2 year old) Oceanvolt SD15kW engine and saildrive as “relatively old” kit. I guess it helps to be “in collaboration with” Oceanvolt to get expensive new kit every year or so! (But this simply reflects the emerging state of the technology, and Sailing Uma are a really great platform to test and publicise the excellent Oceanvolt kit, so good on them both. Just might be different if it was your own cash involved!)

Scarily to replace the “propellor” they had to fit an entire new system – full saildrive and even a new SD15 (15kW / 20hp) motor, as the existing (very recent) motor didn’t match the new saildrive. However, it was nice to see the new engine being lifted in by hand by one person - that makes the physical replacement easier (if not on the wallet). No prices were mentioned for how much this lot would cost for an average punter.

Regarding regeneration ability, as would be expected this is much better with the more sophisticated propellor – they reckoned about twice that compared to the previous setup with a standard prop (again confirming my understanding -don’t expect decent regeneration with a standard propellor). They talked about 300W at 6.5 knots and 450-500W at 7 knots. And with a usual sailing power demand of 150-200W, they start to “go positive” above 5 knots, which is a much more realistic and useful speed for a typical cruising yacht.

(As you might expect, this is slightly better than a typical Watt & Sea transom generator mounted in the turbulence of the transom – albeit immersed versions of these are also available and perhaps much cheaper if regeneration is your only aim.)

As noted above, nothing on any battery updates to increase range, or drive effectiveness – though I spotted at one point they were motoring at 3.6 knots SOG, so presumably they pootle slowly to save battery power. And if going blue water I might worry about complexity when both drive control and propellor feathering are entirely electronic – not got the mechanical “get me home” simplicity of a diesel and a conventional prop.

So a good video by excellent communicators. And again shows rate of progress in technology – but also why most such examples are currently still “collaborations” with suppliers, and rarely conventional customer purchases (at least for sailing yachts) – with significant risk of rapid technology obsolescence.

I am an electric drive enthusiast, and expect these will be the norm in 10-15 years. But for cruising yachts it is still about the numbers currently – cost, capacity, range.