Anonymous wrote:

And how about an Amazing new electric boat motor based on fish fins!

Having looked at that page there are a few things that come to mind. The first (already mentioned in the comments) is how long does that membrane last? how much does it cost in money, complexity and time to change it or even inspect it?

The next thought is that one of the problems with IC engines that most electric motors don't have is reciprocating parts that aside from being noisy, tend to wear much quicker as well as being less efficient.

The last thought is about stream speed. The outlet of this motor is very small. Anyone following the history of jet engines might have noticed, a large diameter slower moving stream is much more efficient than a small diameter high speed stream. Outboards with "high thrust" propellers on them are larger diameter, low pitch to move more water at a lower speed. This leads to some question of their claim: "The FinX is 20 to 30% more efficient than propellers." (note they said "than propellers" so how the prop is driven is not relevant) Their output jet is maybe two inches in diameter or less compared to 10inches or more from a prop. There is not even  shroud around the outlet to help change speed to volume using the venturi effect.

Of course the size of the unit and drag thereof compared to the resulting stream is another question.

So at first glance, this is a concept that (like hydrojets) is best used for high speed craft... if it can get the craft up to high speed in the first place. Call me skeptical but certainly I am wait and see on that one. (I note they have not yet actually used this unit to push a boat... or it has been such a flop they don't want to publish the video) Their web page is somewhat deceptive too, there was one link to "data sheet" that magically turned into a "preorder now" button when you click it (so you have to remove the item from your shopping cart)... and of course the picture of a boat planing at high speed is not using their motor as they have no motor rated for such use at all.

Anonymous wrote:

Jim,
now I have re-read your initial posting of this thread, and I am about to turn more positive to you conversion project.

Your plans have changed from long-distance to local or coastal cruising. The matter of battery range is therefore not so important, and with that Honda generator in cold st.by, hidden in the cockpit locker, the battery bank needs not be that big (2-5 kWh?).
I checked the Honda  EU2200i generator. It can even be made to run synchronously with a second Honda, if you later find you could use more power.
The lovely thing with this Honda is that, besides being good, it is light enough (21kg) to bring ashore for service, repair or replacing it. Much cheaper than if you get trouble with a diesel.

With this setup, there is less need to complicate things by turning your ship it into a complete solar plant. After all, you have a car. If you let your Honda generator burn up to 10% of what the car burns in a year, you could well end up with 100-200NM range based on the Honda power alone. I suggest you keep it simple for the first summer. That will soon show you your needs.

However, the greenest way of propulsion is sailing. Therefore I stress the need for keeping the rig sorted out so hoisting sail doesn’t possess a big obstacle. I also keep saying that cambered junk-sails are the greenest of all, since they let you move upwind both effortlessly and fast enough.

I apologise if my earlier postings have sounded discouraging, and I wish you good luck!

Arne

PS: Just for the record; what is the ‘burst’ power of the electric engine?

PPS: That lovely young couple on Youtube surely was resourceful and not shy of doing some hard work! Being on the wrong side of 60, I prefer to cut corners and rather lower my ambitions. I am not quite the Houdini that I used to be...

Hi Arne, Thanks for your comments and support. I appreciate it. Apology accepted.

The eyes of the JRA and my boat club are upon me, so I'd better produce and keep folks informed. It's a bit complicated, comparing apples and oranges. For the time being, I need to point to experts to answer some of the questions that arise. I'll be better informed as time passes.

Yes, I'd best keep things simple in the first season. 

The electric motor, applied to sailboats is in the early stages of development. At this point, one hears, "Oh that's nice but the range is too short." It's like the saying, "Junk rigs are fine except they don't go well to weather." How long will it be before that assumption is put to rest by your cambered sail? I think your cambered sail concept is the most important development of the junk rig in generations, made possible, of course by modern, stable fabrics. You made a huge investment of time, thought and labour into its development. You can be proud. But I know you don't want to rest on your laurels. I know, we wish we were on the other side of 60 with the owners of Uma. 

I was a Houdini in my youth. I'm fortunate to have a large engine space on Hobbit. (A Benford 30' Sailing Dory) As engine spaces go, it's amazing. However, I've had to teach myself the choreography of careful twists and turns to get in and out without stress.

How will the range question be answered? To have better batteries is our first thought. Meanwhile, the owners of SV Uma have answered that question for themselves. When they navigated the Intracoastal Waterway, sailing, and motoring, they managed their range deficit by study, planning, timing, and patience. (Of course, they don't have to adhere to a tight schedule.) There is a word for that: seamanship. Good seamanship. Who would know? That's all our ancestors had. They are "voyaging on a small (energy) income," to borrow a phrase. :-)

Of course, there will still be many places you can't go because power is a necessity to overcome extreme situations. There are still lots of great places to go to!

BTW, there is an adapter available to convert a Honda EU2200i from gasoline to propane or natural gas. So you have a choice of one of three fuels at any one time.

"All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as self-evident." -- Arthur Schopenhauer

For anyone interested in looking into electric drive, there's a useful site at:

https://plugboats.com/

Of particular interest to me, with a boat that doesn't suit outboard motors very well, be they petrol or electric, there's a comprehensive guide to pod motors.

And how about an Amazing new electric boat motor based on fish fins!

Check out the video series (I linked to the first video, I think there are three in total) and/or read here: https://www.sailinguma.com/electro-beke

This is an excellent link. I strongly suggest reading this page before posting declarative statements based on hasty assumptions.  It will answer many of your questions, better than I. 

Concerning the philosophy behind the author's choice to go to electric, I like their "mission statement":

We have found that having a solid plan and the patience to wait for the right weather and tide is the key. - After all, we own a sailboat. They are inherently slow. We are not in a rush. We love the idea of being self-sufficient. But, for those who sail with schedules, are short on time, lack the patience to sit out a wind hole, feel the need to power their boat to hull speed, enjoy maintaining a diesel engine or are just set in their ways, then an electric motor probably isn’t the right choice. 

Did you maybe mean Uma and Sailing Uma?

https://www.youtube.com/watch?v=_L1xmG5Kndw