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Old 03-02-2023, 11:55   #31
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Re: Toroidal Props. Wow!

proo = prop
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Old 03-02-2023, 16:43   #32
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Re: Toroidal Props. Wow!

Quote:
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Radically quieter than traditional propellers"

Leaked submarine tech. They always cover a military sub's props with a tarp when its in dry dock. Prevents photo snooping.
Given that the noise from wind generators is a serious complaint for many people, perhaps wind-gen manufacturers should be taking a good hard look at the technology.
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Old 08-05-2023, 11:01   #33
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Re: Toroidal Props. Wow!

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Exactly my point, you can't feather or fold this prop.
In addition, with the shape of this prop, it's almost like having a solid disc there.
I hope this kind of design catches the eye of some major shipbuilders who have the resources to study this better. Buying a $5k prop for a $30k fishing boat? Yea, nah. Buying a 5k prop for a $500k sailboat? Sure, if it's a noticeable improvement.

AND with electric propulsion becoming more common I wonder if these will be useful there.

A prop shape that lends itself to higher efficiencies across a broad RPM range.
A motor which is capable of high RPM, but often will be at a much lower cruising speed.
A prop shape which may be very efficient as a hydro-generator when under sail.
A system to allow for disconnect to just let the prop spin freely, minimizing drag, when generation isn't needed.
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Old 08-05-2023, 11:11   #34
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Re: Toroidal Props. Wow!

Regarding their testimonials, this is the one that makes the most direct comparison to me. A 57' motor cat with dual 300HP diesel outboards.

Cruising at 18kts, saving 46% fuel at that speed.
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Old 08-05-2023, 21:40   #35
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Re: Toroidal Props. Wow!

Toroidal props aren’t going to do anything for cruising sailboats, they have unpowered drag similar to a fixed prop. Cruising sailboats would better spend money on folding or feathering props

My understanding is that at “high speeds” & rpm’s they provide more savings. So fast cruisers and power boats and maybe even dinghies will benefit significantly.

For vessels operating at displacement speeds (large ships and trawlers type cruisers) savings will be moderate. Currently ship design is in flux as most operators have dropped speeds by 10-25% resulting in significant fuel savings. This is a big enough change that some ships are having their bulbous bows removed and their engines replaced. Yes, in some instances T he fuel savings is worth it to drop $10-50M on an engine replacement. Also there is significant experimentation going on with alternative fuels. I can see ship designers waiting a number of years before playing with toroidals.

For cruising powerboats, especially hybrids, a controllable pitch prop would result in better fuel savings, pitch can be adjusted to get best fuel efficiency from an engine.

Toroidals are fixed pitch and optimized for a specific speed. Unless you always cruise at a specific speed it’s not going to be the most efficient overall.

I would love to get a hold of one for my dinghy, but not if it’s going to cost $500.
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Old 29-05-2023, 07:07   #36
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Re: Toroidal Props. Wow!

Can't wait until the research is there to produce for a displacement hull. Worried about drag? Install an electric motor and use it as a generator and get rid of you wind Genny and hydro Genny. Time will tell. Love the tech progress.
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Old 06-07-2023, 06:48   #37
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Re: Toroidal Props. Wow!

I've noticed lately there are sites with 3D printer files for lower HP outboards. Might be worth a try. I have a trolling motor I'm going to try it on hopefully soon 👍
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Old 06-07-2023, 06:54   #38
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Re: Toroidal Props. Wow!

Apparently the big advantage of toroidals is lower noise.

There might be a little efficiency gain but massive efficiency gains are media fluff by sites looking for clicks & views.

If you 3D print you will need to manually sand and fair the surface in order to avoid seeing a loss of efficiency.
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Old 06-07-2023, 07:16   #39
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Re: Toroidal Props. Wow!

Their lack of blade tips allows them to operate quieter, useful for drones and leaf blowers, but not much of a factor for boating.
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Old 06-07-2023, 12:22   #40
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Re: Toroidal Props. Wow!

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Originally Posted by Phyrcooler View Post
I’ve been watching this developer for a while. Multiple documented tests showing improved efficiency. However, all that I’ve seen so far have been high speed SD hulls. I’m curious if they’re seeing similar gains in the 7 - 12 kt displacement range.

As a pilot, I’m also interested to see where this may go. Improvements like this in speed, efficiency, and sound reduction will be a significant boon.

Lastly, the one interesting thing I noted was when they were bragging about the sound reduction with triple 300 outboards - was that it was all “propeller noise”. It may be… but I’m dubious. They are reporting comparisons were made at the same SPEED, not the same RPM. I’m guessing that the motors with standard props were turning hundreds of RPM’s faster to achieve the same speed… and a lot of the sound reduction with the Sharrow prop was motor and exhaust noise reduction at lower RPM’s. So, yes… noise reduction BECAUSE of the props. But not so much PROP NOISE….? But that’s just my guess watching the video. YMMV. Others more wise than I may have different opinions.
Yes but that only points to an even better result -same speed at lower RPM.

And in reference to guesses about cost, the article says "Sharrow is already selling its toroidal props, CNC machined to fit a wide range of common outboard motors from most major manufacturers. The drawback here is price; they cost US$4,999 a pop regardless of which model, where a regular propeller might go for closer to US$500. "

On another breakthrough news item, Toyota claims "it has made a technological breakthrough that will allow it to halve the weight, size and cost of batteries" with their solid state batteries. I would like to see where this claim leads...
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Old 06-07-2023, 18:44   #41
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Re: Toroidal Props. Wow!

While I remember back in the '70's people not wanting to buy a replacement color TV because they were going to wait for 3D color TV, I think I'll wait for a folding toroidal prop before I replace my folding VariProp.
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Old 07-07-2023, 05:22   #42
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Re: Toroidal Props. Wow!

I saw a pair of these on an outboard boat in our marina. I didn't even know that's what they were called. Pretty impressive looking!

Given the price, I think this says more about the direction my marina is going than about the technology. More of us old cruisers are dying off every year, and all kinds of flashy new (and very expensive) day boats are showing up.
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