New Toroidal props

[Alan de Enfield]

Regarding hydrodynamics, Sharrow Marine has developed a range of propellers that significantly advance rotor technology, which halted after the 1830s. Designed as twisted loops instead of traditional blades, the devices have ‘solved the most basic problem of rotary propulsion. Specifically, tip cavitation and vortices have been eliminated or significantly reduced, transforming your entire boating experience,’ explains the company.

 

By decreasing and even eliminating tip cavitation and vortices, the Sharrow models also dramatically reduce noise and energy loss when a boat cruises through open waters. Additional benefits include 50% more reverse thrust, 30% more range, less vibration, and doubled speed at mid-range RPMs. Putting its products to the test, Sharrow demonstrates in the below video the dramatic difference in noise production between a standard propeller and its toroidal design. 

 

toroidal propellers turn your drones + boats into noiseless machines (designboom.com)

[StephenA]

I bet getting things like rope, plastic and tyres off them is a lot of fun.

[Alan de Enfield]

5 minutes ago, StephenA said:

I bet getting things like rope, plastic and tyres off them is a lot of fun.

 

I'd of thought it would slide off easier than on 'blades'. There is no narrow root for the rubbish to get around.

 

 

 

Edited January 28 by Alan de Enfield

[Tony Brooks]

A quick scan of both sites did not seem to provide any scientific test results (I may be wrong about that) only claims. Remember Axiom props?

[StephenA]

4 minutes ago, Alan de Enfield said:

 

I'd of thought it would slide off easier than on 'blades'. There is no narrow root for the rubbish to get around.

 

 

 

But if something gets into those blade gaps......

 

their own blurb says "in open water" - I have no knowledge of the frequency of prop fouling on open water but I imagine its pretty much zero compared to canals.

 

[magnetman]

Looks like quite a lot of extra load on the driveline. I hope they have done calculations for stern tube wear, gearbox thrust and engine mounts.

 

Presumably if it produces 30 percent more range it must be extracting more power from the engine. 

 

Figures needed. 

[Alan de Enfield]

14 minutes ago, StephenA said:

But if something gets into those blade gaps......

 

their own blurb says "in open water" - I have no knowledge of the frequency of prop fouling on open water but I imagine its pretty much zero compared to canals.

 

 

It does indeed and I suppose the open water does have less risk of prop fouling than the canals, but in my case I have had more 'unmarked' lobster pot ropes around my prop when coastal cruising than I have had on the canals (doesn't read as intended but I'll leave it - not many lobster pots on the canals I know - I mean any type of prop fouling) 

 

That is why we carry diving gear on the lumpy water boats.

 

Sailors are being urged to throw their support behind a Cruising Association (CA) petition, which calls for Minister of State (DEFRA) to improve the way static fishing gear is marked for the safety of all small craft at sea.

CA president, Judith Grimwade says poorly marked lobster pots and fishing gear are the most difficult and unpredictable hazard facing coastal cruising people.

Fishermen, too, report the loss of expensive gear as a result of entanglements. These encounters could even be life-threatening. In one year alone the RNLI dealt with 295 incidents of fouled propellers.

Most CA members say they would try to sort the problem out themselves so this could be a fraction of the actual number. One lifeboat station said 25% of their call-outs were purely from boats caught up in fishing gear.

A CA spokesman said: ‘We think it is time for everybody with an interest to work together to find a solution, particularly one that is cheap and practical for our fishermen. With this aim, the CA hopes to secure a government consultation about the effectiveness of the current guidance and the merits of enforceable regulations for the whole of the UK.

‘The MCA tells us that the same issue was raised at recent meeting of the UK Safety of Navigation committee. RATS member, John Lansdell and Ian Wilson will attend the next meeting of UKSON in May.’

Edited January 28 by Alan de Enfield

[magnetman]

The Sharrow MX™ is suitable for 150- 450 HP outboard motors and sterndrives

 

Total cost $4,999. 

 

okay !

 

crowthers anyone ?

 

https://www.sharrowmarine.com/store/mx

Edited January 28 by magnetman

[Alan de Enfield]

6 minutes ago, magnetman said:

The Sharrow MX™ is suitable for 150- 450 HP outboard motors and sterndrives

 

Total cost $4,999. 

 

okay !

 

crowthers anyone ?

 

https://www.sharrowmarine.com/store/mx

 

 

OOooooooooo thats quite a lot.

[jonesthenuke]

55 minutes ago, Alan de Enfield said:

Regarding hydrodynamics, Sharrow Marine has developed a range of propellers that significantly advance rotor technology, which halted after the 1830s.

 Hmm, so all those modern super quiet, super efficient submarine propellors are built to an 1830s design?🤣 Better tell the navy.

[IanD]

51 minutes ago, magnetman said:

Looks like quite a lot of extra load on the driveline. I hope they have done calculations for stern tube wear, gearbox thrust and engine mounts.

 

Presumably if it produces 30 percent more range it must be extracting more power from the engine. 

 

Figures needed. 

If you go and read the articles there are actual test results; IIRC at the same engine power, they deliver something like 20% more thrust. This shouldn't be a problem for any driveline.

 

Alternatively for the same speed they lower fuel consumption by the same amount, with no more thrust on the driveline at the same speed.

[beerbeerbeerbeerbeer]

Looks a beautiful piece of engineering. I wonder how more difficult they are to cast.
 

And ain’t all lobster pots all marked with flags?

 

 

[IanD]

21 minutes ago, jonesthenuke said:

 Hmm, so all those modern super quiet, super efficient submarine propellors are built to an 1830s design?🤣 Better tell the navy.

They're all tweaked designs based on conventional turbine propellers, and still waste energy in tip vortices which the Sharrow doesn't. 

 

Having dug into the details it does look like a genuine advance in prop design, unlike the Axiom. But would certainly be a lot more prone to fouling on canals, the loops will catch stuff that is thrown off with a normal prop.

 

And they're expensive because they're more difficult to make, and proprietary... 😞

[cuthound]

1 hour ago, Alan de Enfield said:

 

I'd of thought it would slide off easier than on 'blades'. There is no narrow root for the rubbish to get around.

 

 

 

 

Toroidal means shaped like a torus or doughnut.

 

That is one funny shape for a doughnut.

[Alan de Enfield]

21 minutes ago, Goliath said:

And ain’t all lobster pots all marked with flags?

 

No thats the problem.

 

They MAY have individual floats (tennis balls, milk cartons etc - the requirement is for a minimum of 3" diameter floats) and SHOULD (but rarely do) have a dan-buoy (flag) at each end of the string.

The risers can be so short that at high water the floats are under water.

The string can be several 100 yards long and it is easy to pass between the 'ends' and pick up the string inbetween the end floats.

[1st ade]

12 minutes ago, Alan de Enfield said:

They MAY have individual floats (tennis balls, milk cartons etc

And (AMHIK) your first thought on seeing a milk carton to Port and a tennis ball to Starboard is rarely "oh, that must be a line of pots - I'll slow down!"

[beerbeerbeerbeerbeer]

All this speed 

no wonder you’re all of a tangle. 
 

 

[matty40s]

2 hours ago, StephenA said:

 

their own blurb says "in open water" - I have no knowledge of the frequency of prop fouling on open water but I imagine its pretty much zero compared to canals.

 

Ok in deep water, not good in Sharrow water.

 

Absolutely rubbish 2 minute video, stationary props being lowered in and out of water and then 2 fast boats( no visible propellor turning or lack of vortices etc)

[IanD]

1 minute ago, matty40s said:

Ok in deep water, not good in Sharrow water.

 

Absolutely rubbish 2 minute video, stationary props being lowered in and out of water and then 2 fast boats( no visible propellor turning or lack of vortices etc)

So go and look up the other articles and actual tests -- not by Sharrow -- directly comparing the Sharrow and normal props. Google is your friend... 😉

[matty40s]

8 minutes ago, IanD said:

So go and look up the other articles and actual tests -- not by Sharrow -- directly comparing the Sharrow and normal props. Google is your friend... 😉

No, doesnt interest me, an advert is supposed to advertise the things capabilities. If the advert doesnt work then why should anyone bother.

It certainly wouldnt add anything to a narrowboat.

I wont be investing, I'm out.

[magnetman]

I'm working on a stern-mounted paddle wheel system which gains traction from the canal bed rather than the water. Depth adjustable..

 

All this propeller and using water nonsense is just that. Nonsense. What you want is to find something where you can get traction. Go for the solids or at least the transition between solid and liquid. Much more efficient. 

 

Canals were never built for prop driven boats. The traction came from the land beside the boat. 

 

 

 

An added feature is one can discourage others from sticking too close behind by increasing revolutions and

[ditchcrawler]

3 hours ago, Alan de Enfield said:

 

I'd of thought it would slide off easier than on 'blades'. There is no narrow root for the rubbish to get around.

 

 

 

Lock similar to what the EA have on some of their weed cutters

[IanD]

Just now, ditchcrawler said:

Lock similar to what the EA have on some of their weed cutters

 

Maybe less likely to catch stuff around the root than a normal prop, but if it gets caught through the loops then the usual remedy of going ahead/astern a few times to throw the rubbish off is unlikely to work...

28 minutes ago, magnetman said:

I'm working on a stern-mounted paddle wheel system which gains traction from the canal bed rather than the water. Depth adjustable..

 

All this propeller and using water nonsense is just that. Nonsense. What you want is to find something where you can get traction. Go for the solids or at least the transition between solid and liquid. Much more efficient. 

 

Canals were never built for prop driven boats. The traction came from the land beside the boat. 

 

 

 

An added feature is one can discourage others from sticking too close behind by increasing revolutions and

 

Buit for traction on land you need a decent towpath instead of a mudbath... 😞

 

A jet engine mounted on the roof would avoid all these problems, and would *certainly* discourage too-close followers... 🙂

[BEngo]

14 hours ago, IanD said:

A jet engine mounted on the roof would avoid all these problems, and would *certainly* discourage too-close followers... 🙂

Keep your ears warm in the winter,  as well, and if you got something with an afterburner you could make toast at the tiller.

 

N

[howardang]

20 hours ago, StephenA said:

But if something gets into those blade gaps......

 

their own blurb says "in open water" - I have no knowledge of the frequency of prop fouling on open water but I imagine its pretty much zero compared to canals.

 

Crab and lobster pot buoy ropes and long line fishing gear can wreak havok  and they are all common around UK waters.

 

Howard