Anyone have an electric "pancake" drive installed on their diesel?

[CaptainPete222]

Nanni has an electric drive that goes between the engine and the sail drive (or shaft) that enables the use of electric power for relatively short stints and eliminates the need for a generator, as the electric drive generates more than my present 10kWh generator. The drives are sometimes referred to as "pancake" drives. I'm hoping to get some feedback about pancake drives from anyone with direct knowledge and/or from those on this forum who haven't used this type of drive on their boat, but understand the pros and cons of these systems more generally.

As I mentioned in another recent thread, I've been looking for a way to supplement my sail propulsion when heading to a windward destination and the present plan is to take my electric 6kWh outboard off my dinghy and put it on a bracket on one of my chubby cat's transoms, a very inexpensive solution that enables me to (hopefully) take advantage of the solar power I'm generating (20-22 kWh per average sunny day) and my battery bank (38kWh), while also avoiding the negatives of running one of my diesels (noise, small amounts of exhaust making its way in the cockpit, needing to go to a marina to fuel up on dubious quality fuel). FYI, I'm also getting better sails, which should go a long way to improving my boat's ability make its way to windward.

These pancake drive systems are fairly expensive (roughly $45,000 for two 15kWh drives, installed) and I seriously doubt that my boat's value will increase nearly that amount, so those issues are definitely on the con side of the balance sheet. That said, my generator has a huge number of hours (former charter boat) and is more of a headache than it's worth. Replacing it would be costly, so, unless I'm prepared to do without, that cost would offset the cost of the pancake drives. And, I'm not willing to do without a generator despite my solar production and battery bank capacity for reasons not worth getting into here.

Subtracting the cost of a new 10kWh generator and the install from the price of installing the pancake drives makes them a bit more reasonable from the standpoint of cost. I'm thinking that the difference in cost will be offset somewhat by the increase in the value of the boat having those pancake drives, which, as I mentioned, give me two generators and thus the added benefit of redundancy. Although I have no plan to sell my boat in the foreseeable future, I always think about "what if I have to sell my boat tomorrow?" I'm also guessing that the interest in so-called "all electric" boats (they aren't) will continue to increase in the next few years, at least that's what the number of people who search for "electric boats" on YouTube would suggest.

So, if anyone has some feedback from experience with these drives (reliability? is it even possible to find someone to fix these and, if so, what's entailed? etc) or, for the many people on this forum with general knowledge about electric drive systems, I would greatly appreciate your input. Thanks in advance.

[skipperpete]

I’ve only had hands on experience with one of the flywheel generators, the Yanmar KMG65E and only because of a leaking rear crankshaft oil sea which required the removal of the generator. I’m not a big fan of em because all bilges get a bit flooded at some time and the generator is bound to to get raw water in it eventually. The yanmar one is a Dc generator and the output is changed to AC via two connected electronic boxes which I assume are inverters. It all seemed to work well.
I also saw one of these things fitted to a Steyr engine but never had any involvement with it.

[jamhass]

Beta offers a similar system. Check their website.

[seandepagnier]

The smaller an electric motor is, the cheaper it is. A smaller motor can output the same power as a larger motor by spinning faster. You can save money and weight by using a smaller motor with a gear box or similar. electric motor cost about $20 per pound.

A 1 pound motor can easily output 2kw or more if spinning fast enough. The idea of this costing thousands for a motor is ridiculous. A 12kw motor could be under $200

It is 2021, the idea to keep your diesel power is the wrong one. If you are going to make this modification, the right thing is to remove the engine completely. I never used an engine and never needed one. Only waited 20 minutes one time for wind sailing from indonesia to usa.

[mcarthur]

They are essentially a parallel hybrid. You don't need pancake motors, (almost!) any electric motor can be used if you use a belt drive to the prop shaft. You may/may not need a clutch as well depending on whether your diesel gearbox can freewheel and the power you are putting on/in. A number of manufacturers are offering them, but there isn't much takeup that I've noticed.
We are deciding whether to DIY on our existing shafts (it has almost nothing to do with the diesel - brand/new/old/big/small). Or we can just use a pod/outboard which may be easier in the long run that mucking about on the shaft even though we get a lower shaft with larger prop.

[mlydon]

I would think the boat had air conditioning - if you scrap the genset and can’t power ac, resale would be harder......

[CaptainPete222]

Originally Posted by seandepagnier

The smaller an electric motor is, the cheaper it is. A smaller motor can output the same power as a larger motor by spinning faster. You can save money and weight by using a smaller motor with a gear box or similar. electric motor cost about $20 per pound.

A 1 pound motor can easily output 2kw or more if spinning fast enough. The idea of this costing thousands for a motor is ridiculous. A 12kw motor could be under $200

It is 2021, the idea to keep your diesel power is the wrong one. If you are going to make this modification, the right thing is to remove the engine completely. I never used an engine and never needed one. Only waited 20 minutes one time for wind sailing from indonesia to usa.

I guess I'm not as patient as you when it comes to getting from one place to another. ;-) My goal is to improve the ability to make reasonable headway to windward destinations, preferably by sailing there exclusively, though I'm perfectly fine with converting solar power into added propulsion from an electric engine. With the exception of a handful of the most high performance catamarans, my boat is the same as the vast majority of cruising cats you see out there--terrible when it comes to sailing upwind. Granted, I'm pretty finicky, partly because I sail a 2005 Corsair F31 for half the year here in Maine that, just today, had me trucking along at 10-11 knots close hauled and that spoils me when it comes to sailing in pretty much any other boat. But I'd be just fine with 6-7 knots from my cat in 14-16 knots of wind with a true over ground track of 45 degrees. My boat (presently) just can't do that. Not even close. Hopefully a better set of sails and a bit of push from an electric drive will remedy the problem.

Like you, I was puzzled why the cost for the pancake drives I was quoted was so high. I've found another manufacturer that has the same type of drive for 1/10 the price that I'm seriously considering. At that price, I could keep a spare.

Scrapping my Yanmars isn't an option I'm considering. They are great engines and come in very handy at times. If I can install relatively inexpensive electric drives that also act as generators and scrap my old 10kWh Fisher Panda, I'd be very happy. Electric drives would also reduce the already pretty low number of hours I run my diesel to next to nothing, which will pay off at that (hopefully distant) point in the future when I need to sell my boat. Low engine hours are always a big selling point and increases the value of any boat. No engines--or purely electric engines and generator(s), on the other hand, is, at least presently, a killer when it comes to boat resale value.

One of my other goals is to see what is possible that would be a reasonably acceptable way to use wind and solar power 99.5% of the time to move the boat around. If the bar is set at 100%, I and the vast majority of other boaters won't listen and, if the goal is to reduce carbon emissions, then those interested in achieving that goal will likely fail see any meaningful change.

Reducing carbon emissions isn't one of my objectives. As it presently stands, the limited use of my diesel engines is roughly the same as the amount of greenhouse gas that I produce following a dinner with beans.

[CaptainPete222]

Originally Posted by mlydon

I would think the boat had air conditioning - if you scrap the genset and can’t power ac, resale would be harder......

Yes, the boat has AC which I can presently run at night from the energy stored in my batteries that will be replenished if it's sunny the next day. A generator comes in handy on the very rare occasions when I want AC, it's cloudy, and my batteries are already low. The pancake drives that would attach to my diesels also act as generators that would produce more power than my present generator produces. That's a big plus for me. I'd love to scrap my generator.

[CaptainPete222]

Originally Posted by mcarthur

They are essentially a parallel hybrid. You don't need pancake motors, (almost!) any electric motor can be used if you use a belt drive to the prop shaft. You may/may not need a clutch as well depending on whether your diesel gearbox can freewheel and the power you are putting on/in. A number of manufacturers are offering them, but there isn't much takeup that I've noticed.
We are deciding whether to DIY on our existing shafts (it has almost nothing to do with the diesel - brand/new/old/big/small). Or we can just use a pod/outboard which may be easier in the long run that mucking about on the shaft even though we get a lower shaft with larger prop.

If this pancake drive option doesn't happen, I'm definitely putting engine mounts on my transoms and moving the 6kWh electric outboard from my dinghy to one of the transom mounts when we're moving the boat and the dinghy is in the davits. Just need a longer cable. But, that's just for a slight bit of added propulsion to help the boat when sailing to windward; it's not for maneuvering around in a marina or even setting my anchor.

The mechanic/electrician who recommended the pancake drive said he wouldn't consider using a belt drive system. He explained his reasoning but I'm not clear enough about what that was to repeat it here.

I did find a pancake drive that is 1/10 the price of the one I was quoted and the company made it seem like it's a DIY type installation.

[skipperpete]

Originally Posted by seandepagnier

The smaller an electric motor is, the cheaper it is. A smaller motor can output the same power as a larger motor by spinning faster. You can save money and weight by using a smaller motor with a gear box or similar. electric motor cost about $20 per pound.



A 1 pound motor can easily output 2kw or more if spinning fast enough. The idea of this costing thousands for a motor is ridiculous. A 12kw motor could be under $200



It is 2021, the idea to keep your diesel power is the wrong one. If you are going to make this modification, the right thing is to remove the engine completely. I never used an engine and never needed one. Only waited 20 minutes one time for wind sailing from indonesia to usa.

Well said! ......but you have a very lightweight very easily driven sailing machine, for many of us on the forum engines are not optional, they’re a necessity. The distinction is a bit like camping out...... I do it with 4wd and a lot of stuff but I meet others along the way who just have a backpack and very sophisticated lightweight hiking equipment.... a much freer way to go but it requires a lot of commitment.

[CaptainPete222]

Originally Posted by jamhass

Beta offers a similar system. Check their website.

Thanks. I checked out their website and only saw belt drive systems. The pancake drive I have in mind fits in between the engine and the sail drive. Lmk if I missed something and I'll take another look.