This video is a follow up to my original Sharrow propeller review. After a month with the prop I have been able to dial it in to squeeze out slightly better fuel economy.
I mean, running 4k at 22 knots is massive for fuel economy, idk why everyone judges these at WOT and then determines they're no better. Everyone just glazes over that mid high speed efficiency bump without even mention, it's weird. They're horribly expensive tho. On small boats like this it's not worth it, but if you have something that takes up serious dock space then it's a worthy consideration, assuming they get it right the first time or will correct it later if they didn't. It is a very limited band of enhancement, but it is quite noticable.
Chris, thanks again for choosing to let us in on your learning experience and taking the time to document the results. And congrats on sticking with it until certain results were achieved. I'd put your sweet spot at 4500-4550: Almost the same efficiency and a couple more mph. Would love to hear from you again after you've used it in some 'big water'. Take care.
I just put my new sharrow on. I'm saving 15% in fuel cost and it should pay for itself in 8 -9 years if I don't hit anything or sell the boat or lose it in the hurricane
Seriously, if you look at the data at 4250, the increase is massive. Also, the comparison should be made at the same rpm. I've seen lots of sharrow prop reviews. Above a certain point the advantage starts to shrink until it is a wash. 5k is a lot no doubt. Nice job for an Aggie!😊
Great feedback. It makes sense that with such a radical new prop design there would be a learning curve for how to maximize performance. I know you said this would be your last video on the Sharrow, but it would be interesting over time to get updates, such as if there is a difference in how the boat handles in rough seas, etc.
Thank you for taking your time to let the world know about your experiences with this new prop, it is the first non sponsored video I have seen of a Sharrow prop. I am not a fanboy of Sharrow props because of their price. Even if their claims of 35% were true (I don’t believe they use real world numbers) It would take 20 years for me to recoup the cost in gas saved (I have twin outboards). That being said, your efficiency comparisons are way off. It is incorrect to compare MPGs at different speeds, which is what you are doing (in this case) when comparing MPGs at the same RPM. Since the MPGs are derived from speed and fuel burn, the only correct comparisons are “MPGs to fuel burn” or “MPGs to speed”. So comparing your 29.1 MPH Sharrow to your 29.2 MPH old prop comes out to 3.8% MPG increase with the Sharrow. I did a linear extrapolation (between27.6MPH& 24.3MPH) of your old prop for 26.9MPH and got 2.81GPH fuel burn, so the Sharrow prop has a 24% MPG increase at 26.9MPH. Since this is the best MPG (on plane) of the Sharrow, it is probably the best that it will be. This is way better than what you got, but it is also uses extrapolated fuel burn, not “real” fuel burn. This extrapolation is just a “best answer I can do with the data I have”, so to really compare the efficiencies of these props you need to get the data for the old prop at the same speeds of the Sharrow data you already have. Of course same day, same conditions would be best, but actual fuel burn at same speeds is best way to compare. As far as trim tabs are concerned, I would not be worried about them being the same position for each prop. I would run them where I already know I like them for the old props, and get my data for each 5mph change (or 2 or whatever you want) starting at 15. Then I would find out where I like the tabs with the Sharrow props and get the data for those. So same speed at same comfort level sounds like apples to apples for me. My opinion is that below 15 mph doesn’t matter to me because I don’t spend much time there, but when in really snotty conditions I do wind up going 15 to 20 to be more comfortable, but wind up burning way more gas. But when I am going 15 to 20 and trying not to fall completely of the plane, having the grunt to maintain that speed matters more than economy. I keep up with how much gas I burn and how many miles I go in a season (aren’t modern electronic great) and I have averaged about 1.5MPG every year for the last 6 years. I think at the end of the season with the new prop you will be able to give us a more comprehensive review of your fuel burn and everything else. I look forward to watching it.
You mentioned that you were retracting your trim tabs from your old normal running attitude, so did you try doing the same thing with your old prop first, because in general pulling up the trim tabs does improve fuel economy, less drag, with any prop. Did you try to dial in the old prop for fuel efficiency, before you tried to dial in the sharrow? Is this apples to apples like before, or is this now apple tabs to orange tabs? (Which IMO could easily account for the fuel efficiency difference)... Also, I'd love to see details on the wetted surface area of both props... Above ~9 mph The major factors impeding forward motion are air resistance and water resistance against the hull, and lower unit (drag). Rpm ahould not be the points of comparison, ground speed and water speed (load), relative to fuel consumption are. So did the prop provide an increase or was it just the change in the running attitude with less drag from the trim tabs?
As a point of comparison, winglets on commercial planes only reduce fuel consumption by about 5% and they also reduce noise signature by about 5%... For commercial vehicles operating over long distances, continuously,, that adds up over time, but so too does flying the plane more slowly... Rpms should have nothing to do with the conversation about these props. Speed, load, and fuel consumption, as well as decibels, are the only things that should matter.
Excellent comment - it is somewhat of an apple to oranges comparison. The problem is the standard propeller required trim tabs to keep it on plane whereas the Sharrow does not. Additionally, my original propeller would start to porpoise when trimmed higher while the Sharrow does not. So yes, you bring up a very good point, but due to the drastically different handling characteristics I cannot get an exact comparison. The Sharrow just grips the water so much better.
With what they are charging for the props they should send out an engineer with each full set to zero in the boat so you can take advantage of its design.
Sharrow hates honest reviews, always has! They are quick to CYA because they spend a ton of money on paid reviews. Why, because anyone with a lick of common sense would laugh in their face, $5k for maybe 10-15% better performance over a narrow rpm range. It’s a joke, a fad, nothing more. They want one thing, to position the company for sale, that’s all. It’s PR lipstick on a pig, that’s it. Good on you for listening to them and running it again only to confirm your previous data, total waste of money.
