Sharrow Props and diesel outboards

[backinblue]

This was an interesting watch. I remain a little skeptical that the conventional prop was not an optimum match to the boat, but still it's yet another impressive test for the Sharrow prop. Not sure how that may translate to an inboard diesel, but still it's an interesting newer prop technology.

https://boattest.com/sharrow-showdo...2jE&utm_content=216346074&utm_source=hs_email

 

[Nick14]

You beat me to the punch, I was also going to post this today.

There have been several encouraging reports on the Sharrow prop:

Sharrow Propeller receives rave review from BoatTest

https://www.passagemaker.com/technical/sharrow-propeller

I believe they were initially available for outboard motors, but now are offered for conventional inboard motors as well:

https://www.sharrowmarine.com/sharrow-nx-inboard

It looks like the performance advantages are significant. I thought the Advance data were particularly impressive - how far the boat actually moves for each revolution of the propellor compared to the pitch. Clearly that's an improvement in efficiency - more of the engine's power and thus fuel used is translated into forward motion. In a time when diesel fuel prices north of $6/gal will probably be with us for a while, this is non-trivial. More speed and less fuel usage are good.

Some of the criticisms this performance advantage might be weighted against are susceptibility to damage and ease of repair. I'm no prop expert, but it does look like those complex loops would be (much?) harder to repair than a simple prop blade, and unlikely a local shop would just be able to hammer it out. It's also been questioned if the open look design might snag fishing or other lines more easily, though perhaps that could be mitigated to some extent with a line cutter on the shaft.

There are also observations on a Sharrow prop being more expensive than a conventional one, I have no idea how much more (though with fuel prices where they are, the payback time might not be that long).

What does everything think about these? Would you want one on your boat?

 

[backinblue]

I know they were initially very expensive and custom ordered only. They are now available for some standard outboard models. I would not expect support from a prop shop for damage, but a reasonable question that maybe Sharrow could answer.

 

[BandB]

First, I do believe in Sharrow Props and their potential.

However, I put no stock in this test. Tested only against one prop which may not have been the best for the application. Tested on 300 hp Cox Diesels that very few own. Tested on a Catamaran that even fewer own. I can't translate any of this to other boats and engines and applications. Independent? Only the verification of the results. However, the test was determined by Sharrow. It's like all the anchor tests on favorable bottoms to the favored anchor or testing outboards against others of different horsepower. I saw a test of IPS 1200 vs. MAN 1000's and looked quite favorable, but I had the same boat performance curve with MAN 1200's which were better.

So, I still believe in Sharrow, but I'm convinced a good prop shop could have improved what the five blade did with other props. On top of that a test on a 300 hp Cox on Voodoo provides no real information for most of us.

 

[BandB]

You beat me to the punch, I was also going to post this today.

There have been several encouraging reports on the Sharrow prop:

Sharrow Propeller receives rave review from BoatTest

https://www.passagemaker.com/technical/sharrow-propeller

I believe they were initially available for outboard motors, but now are offered for conventional inboard motors as well:

https://www.sharrowmarine.com/sharrow-nx-inboard

It looks like the performance advantages are significant. I thought the Advance data were particularly impressive - how far the boat actually moves for each revolution of the propellor compared to the pitch. Clearly that's an improvement in efficiency - more of the engine's power and thus fuel used is translated into forward motion. In a time when diesel fuel prices north of $6/gal will probably be with us for a while, this is non-trivial. More speed and less fuel usage are good.

Some of the criticisms this performance advantage might be weighted against are susceptibility to damage and ease of repair. I'm no prop expert, but it does look like those complex loops would be (much?) harder to repair than a simple prop blade, and unlikely a local shop would just be able to hammer it out. It's also been questioned if the open look design might snag fishing or other lines more easily, though perhaps that could be mitigated to some extent with a line cutter on the shaft.

There are also observations on a Sharrow prop being more expensive than a conventional one, I have no idea how much more (though with fuel prices where they are, the payback time might not be that long).

What does everything think about these? Would you want one on your boat?

Yes. I would consider them. However, on Center Console on order, am saying "no."

The last I knew, repairs had to be done by sending them to Sharrow. That would mean you'd need spares.

I like that they're quieter. I like reduced vibration.

I've seen other comparisons that compared against multiple props and they only slightly beat the best choice of other props.

Now, comparing against Mercury Stainless Steel, the Sharrow aluminum is double the price and the stainless steel is four times the price. I'm not spending that for a possible 1 mph and the inability to repair locally. We have three Mercury Racing engines ordered and they've been tested extensively with a variety of props.

Do I believe they may be slightly better? Yes. Do I believe worth an additional $40-50,000 on a CC? No. Do I want to only be able to send them to the manufacturer for repairs? No.

Do I believe 40% fuel savings? Not even close. Read this article and look carefully at the numbers and only marginal difference vs. best prop choice.

https://www.tradeonlytoday.com/columns-blogs/prop-2-0

What happens if you get Sharrow and they aren't the ideal pitch, you don't hit max RPM? What about returns and exchanges? A lot different than dealing with local supplier.

Too early for me and these outlandish boattest tests do nothing to reassure me. Staged and not against necessarily the ideal alternative.

I believe they still have work to do to mainstream their props. I would suggest rather than competing or working against manufacturers, they try to make agreements with engine builders and sell as OEM options. Convince Mercury and you'll have me.

If I believed numbers like 40%, they'd have me interested. I'm betting on real numbers against the best alternatives being more in the range of 5-10% maximum. I've seen this before. IPS makes similar claims but they depend on running one speed, not the full range. Their true numbers in actual use are much less.

 

[Nick14]

More test results with the Sharrow propellor have been posted by BoatTest:

https://boattest.com/article/sharro...G_w&utm_content=223080369&utm_source=hs_email

Though this test was on an outboard powered center console, the results seem consistent with other evaluations showing about a 15%-30% improvement in fuel economy, and speed at a given rpm, in the mid-range.

I hope to try a Sharrow prop on my new Helmsman 38 Sedan build (if the pricing works out).

 

[rslifkin]

If it's got better propulsive efficiency, I really want to see them make a smaller, possibly aluminum version that would be suitable for dinghy outboards. Every bit of extra efficiency counts there, as it means either you can use a smaller, lighter engine, or you can carry less fuel. And on something as small as a dinghy, less weight helps performance and makes the dinghy easier to carry for the mothership.

 

[Nick14]

If it's got better propulsive efficiency, I really want to see them make a smaller, possibly aluminum version that would be suitable for dinghy outboards. Every bit of extra efficiency counts there, as it means either you can use a smaller, lighter engine, or you can carry less fuel. And on something as small as a dinghy, less weight helps performance and makes the dinghy easier to carry for the mothership.

I don’t (yet) know the exact price of a Sharrow prop, except for numerous comments of ‘expensive.’ Reading the various articles that have come out on them and the complex manufacturing process, involving making a unique mold for each prop, casting stainless steel, and then CNC machining to very tight tolerances, it certainly sounds more expensive than making a conventional prop.

Especially at current volumes, I suspect it wouldn’t be cost-effective to make a small prop for a dinghy. The prop would probably cost as much (if not more) than the motor, and maybe more than the entire motor + dinghy setup. That’s likely why they’re going after the high end market first, where the cost can be justified.

The descriptions of the props also talk about how thin the blades are compared with conventional props. Aluminum might not have the necessary strength at those thinnesses.

Like with most new manufactured goods, hopefully the cost will come down with time and experience. The latest article talks about Sharrow’s collaboration with Yamaha, with the props to be manufactured in a Yamaha plant with greater capacity. Hopefully that will bring down the price.

 

[Nick14]

Another test of Sharrow's props, still outboards but this time with a 'heavy' cruiser:

https://boattest.com/article/sharro...dGw&utm_content=224394217&utm_source=hs_email

The results so far look impressive to me. But, Sharrow is 18-24 months out from designing a prop for inboard diesels (unless you want to pay them a five figure design fee up-front and then buy props in quantity).