Toroidal propellers: gas burn reduction potential?

Step 1 - Get a few guys together to buy a prop.
Step 2 - Get someone to 3d scan it.
Step 3 - Print on a 3d printer.
Step 4 - lost wax cast in aluminum.
 
Eden Island said:
Dumb question. Does this technology have a place in duoprop applications like my Volvo D3? The duoprops claim ~30% increase in efficiency over single prop. Would toroidal props increase that further? Do they exist?

Stainless duoprops were about $2500 five years ago. What would toroidal run?
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Duoprops reduce slip --- Maybe end up being pretty comparable, but less drive train complexity?
 
Look at the props on this new Eaglecraft.

"We are finishing up a 39' research vessel for a valued First Nation Community customer. More to come once it hits the water!!"

329503061_1271844473715244_2398104680753465948_n.jpg
 
Boom! They have a good marketing machine set up. Too bad the CAD is weak right now and adding one or two to a 23 foot boat could push it over the luxury tax threshold. If my boat was lightly loaded in theory the cruise range would extend to 470 miles or more with a 20% increase in efficiency. No need to go slow on a trip up the inside passage, a great place to do research.
 
Seems like all it may be is marketing, that’s why the focus on on the recreational boating community rather then commercial.

Easier to sell snake oil too
 
They don't need any marketing at all if the product is really all that good. It would sell like hot cakes, as long as economics make sense.
I am always suspicious to all those companies claiming they have great product but not actually delivering it in any reasonable volume. If you can't go online and buy it - most often it doesn't exist or doesn't work, or is a complete scam.
 
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Rain City said:
Maybe they're just terrible at business
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I can tell you one thing, the rep/salesman I spoke with as nice of a guy he was didn't know enough about boats to be talking to me about props. He couldn't answer my questions because he didn't understand how it is. So like I said before. I'm out. Will not support this product because it makes no sense. As cool as a product they are and I'm sure they perform well, still makes no sense.
 
I would consider buying a set when the price comes down a bit and they manufacture 14" diameter. I spend a lot of time pulling trolling gear at 9-11 knots and my propslip at 2500 rpm doing these speeds is close to 40 % as I'm pushing hullspeed but not on plane. I burn .7 l/nm trolling which is the same consumption in my boat as cruising at 28 knots 4300rpm where my propslip comes down to 10%. Without a doubt the Toroidal props would greatly reduce slip while trolling and also while running in the low 20s as is so often the case offshore in unfavorable sea conditions. We do have some debris in the water where I fish but not as much as the BC coast , more likely to hit a turtle than a log but they are pretty solid objects too. I may not live long enough to pay them off but find the concept pretty intriguing. An average fishing day for me is 10 hours and probably 6-7 prospecting at trolling speed, easy to put in 100-150 miles a day .
 
I think once Yamaha starts offering them as an option, the truth will be known. That might take a couple of years. I’m willing to wait and see. Let’s face it, our current systems are ancient and there’s gotta be a better solution. Just think about that tiny piece of metal spinning controlling everything we do on the water. I for one am thankful people think out of the box and try.
 
like i said before in this thread, and same in the fuel consumtion measurement thread. You can calculate fuel consumtion on modern engines based on RPM. Outboard engines dont even start to make their power curve nominally until after 3500 RPM. Yes all engines are a bit different, however they nominally like to be around 4 grand at a cruising speed of 28-32 MPH. Somewhere in that range. So the numbers dont add up to what they are claiming to be. Only way to save fuel is run at lower RPM. Period the end. There might be a tiny bit less caviation with these props... maybe, however no way you can save 30 percent on fuel. Not a chance. I call ******** based on science.
 
I’ve never heard or read of anyone claiming 30% fuel savings but a guy I know has two of them on his boat and says 20% savings in the mid-range RPM is consistent—-He has twin F300’s and loves those props

The guy who built my boat just ordered two Sharrows for a boat he built for another guy that’s powered with a pair of F425’s. Just the deposit to begin work on those props was in nose-bleed territory but I’m leaning forward in my chair to see what his fuel burn turns out to be

The brain exercise for me isn’t necessarily how long it would take to amortize the cost of those props based on a 20% fuel savings. The collateral reward would be just burning less gas on a long trip and steering clear of fuel docks

But even if someone gave me a pair, I’m still not convinced they’d hold up around wood debris.

Last summer I went through Christie Pass and could have built a nice cabin with a full sized porch from the amount of wood I had to plow through...

One stick getting sucked into the flukes of a Sharrow? Maybe a wedge-shaped log that gets in there and doesn’t come out?

The one thing I do know about those props: If you ding one of them with twins, the other has to come off, too
 
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