I just put an order in for a Sharrow propeller for my 895. It will be interesting to see if they can come up with a custom prop that yields similar performance as reported in boattest.com on a World Cat 320 with twin Yamaha 300’s. Has anyone had any experience with these new propellers?
Please post an update after you have them. If they provide a 30% reduction in fuel use at cruise speed I'd buy them in a second. If it's more like a 10% improvement then it's a much tougher sell for me.
I chatted with Jeff from Sharrow today. My boat and single engine combo is going to be a new propeller design for them. Their engineers have come up with a design that will yield improvements across the rpm range and rates high on their improvement scale. It's based on a similar propeller design they've already proven with 15" pitch but mine will be a 14" progressive pitch so not really new as far as the engineering is concerned but technically it's a new design. They want to do it. Given the prop test data supplied by me they don't need to do testing with my current prop. Next it goes to design for developing the design in the CAD system. Then either a new stainless billet will be made or they may be able to use an existing one - not sure yet. Then the 5 axis machining. They had hoped to had it ready in June but if a new billet is needed and depending upon machining schedules it may be later. The same "deal" applies in that if I don't like it I get my $500 deposit back.
Heres another prop update from Jeff at Sharrow. The design and 3D CAD model is done. The billet cast blanking is in work. Machining time is in the queue. They may be able to accelerate delivery from their last estimate but will wait until the billet is ready to provide a delivery date.
I just watched the BoatTest.com video on the Sharrow with twin 300s. I like the continuous loop to eliminate drag (I think it's really an accounting for the loss of pressure differential due to span wise flow and works in a way like winglets on a wing). I would have suspected the additional material closing the loop would not produce any thrust while adding drag. I know a few experimental aircraft have utilized a loop/pseudo bi plane wing for similar reasons, but the performance wasn't profound. I guess what I'm getting at is I'm very interested to see your results as the 30% fuel savings would be valuable in this market. I'd also like to see what a pair might cost for my 2x200s.
We've completed the detailed on-water tests with the PowerTech 4 blade and the Sharrow 4 blade props and have safely returned to the slip. That is however without a 0-20 comparison as I forgot to place that parameter on the test sheet. My test engineer and I have confidence that the data is valid and was gathered under like conditions for boat weight, tides and winds (or lack of). The sharrow prop test results mirror (with slight variations) the PowerTech 4 blade prop test data. The differences are in the "noise level" and variations one might get on multiple tests with the same propeller under actual sea conditions. It's surprising and a real disappointment. Of note though is the Sharrow is quieter by about 4 decibels at mid and high engine RPMs. Sharrow is baffled by this and says they’ve never failed to show a significant improvement over standard propellers. They emphasized that the slip rates were higher than they should be seeing with the Sharrow prop and this should be solvable. They graciously offered my deposit back but would like to investigate further to determine what they did “wrong” and get it right. This is their first application with a heavy boat and a big single engine. So what the heck I’m still in. They are sending an engineer out from Florida to do a bit more testing next Wednesday. Stay tuned.
That is a spectacular looking propellor. It’s a pity it does not really meet all the expectations, but good on you for hanging in there. I am sure you will learn more in the end from staying the course. And good on the manufacturer for the offered support.
I am sure that we are all waiting with fingers crossed for the results of the next steps. It certainly shows that there is art as well as science in propellor design and selection. It will be great to talk with their test engineer.
Karl Sanstrom from Sharrow arrived last Wednesday as planned. And surprise, he brought another Sharrow propeller with him. Its one they had in their inventory - a 3 blade with a 13.9" pitch and a larger diameter than the 4 blade previously tested on my 895. My adult son joined us for testing. We again baseline tested my Power Tech 4 blade as it was a different day with warmer temperature. Tide and wind were similar and negligible. We then installed and tested the Sharrow 3 blade. I'm still waiting for Karl to get the completed test data to me but I can say this. I was pleased with the results. The Sharrow was noticeably quieter, seemed to hold plane at slightly slower speeds, accelerated from 0-20 much quicker than the Power Tech, and had a higher WOT speed. I expect it will show some slightly better fuel use numbers but need to see the completed data to confirm that. After the testing we played around a bit - the propeller response overall felt good. And heres a big surprise. But first some background... I installed a Raymarine autopilot a couple years ago. It functions great at low speeds but it "wanders" at planing speeds and doesn't hold a straight line. Raymarine and I diagnosed the problem to be just too much torque pull in one direction with the big single F300. The fix was to install a mechanical rudder sensor. I haven't yet got around to doing that. I planned to use the autopilot mostly at low speeds so not a big deal. Now back to the Sharrow test... We were cruising along at slow speed on autopilot. I opened up the throttle a bit to get on plane and forgot to disengage the autopilot. And then realized the autopilot was working great and holding a straight course even at planing speed. More testing is in order but it appears the torque pull is less with the Sharrow and this may have solved my autopilot issue. I expect to receive the test data shortly and also hear from Karl on analysis from their engineering team as to if this propeller is the right one or if they can do better. Stay tuned :')
My propeller arrived yesterday. That’s the same one we last tested with the 3 blades, 13.9” pitch, 15.5” diameter. Based on our testing Sharrow engineering says this proven design is the best they can do. Any changes would likely result in a loss of performance in one area or another. The test engineer that was here still hasn’t sent me all the completed and charted test data. He’s on vacation:,)
I installed the propeller on my boat this morning. I just took her out with the new prop. Less weight then the earlier formal testing as only 1/3 fuel and only 1 person. BUT... this time I just played around and didn't worry about capturing test data and instead concentrated on how she felt and performed. The boat is transformed. I can feel the faster acceleration. Less noise. I can hold a 16mph plane at 3800 rpm. Easily hit 5400 rpm at WOT. Less fuel burn across the range except idle and slightly above and WOT. Here's icing on the cake. I can't tell any difference in the pull it takes to turn the wheel when on plane and turning port or starboard. Torque pull is basically nonexistent. And autopilot works great. This propeller does do what I hoped in combining the slow speed performance of my 4 blade PowerTech and the high speed performance of the 3 blade Yamaha and then improved on it across the rpm range. The ROI based on fuel savings is from 5-8 years for me of course it will vary based on hours per year and fuel prices. I’m quite happy to say the least. Oh and I had 2 paddle boards strapped on top.
Thats great. It sounds like you now have the result you were looking for. While you have a bit less weight on board, the different trim and other things you tried to get it to “feel” right seemed to demonstrate that test technique is all important. Data is only as good as the quality of the test process.
It will be interesting to get the data from the test engineer with the other prop for comparison, but in the mean time, you have a good result, and I am sure that everyone has learned a great deal.
Your scholarly input on the related post for propeller pitch reminded me I hadn’t input any pictures of the new sharrow propeller that now is on my boat. What’s interesting is that in the one picture you can see that on the trailing end of the propeller loop the pitch (angle) of rhe blade is quite different. Karl the engineer explained that is really is an increasing pitch in the blade from start of loop to end of loop.
Last Edit: Aug 13, 2022 12:45:21 GMT by MalcolmP: images
Those ribbons look great. I started reading up on the Sharrows and the performance looks promising. I don't think I'll be able to get past the $4999 price tag though. With the wide range of props, I'm surprised they Sharrow web site lists one price for all. At 20% it'd take me 10 years to pay off 2 of these.
Also, I notice you had to remove the small fin above the props which I assume are used for fine tuning direction, mainly on single engine set ups. Was that difficult to remove and have you had any issues pulling to one side?
I assume twin engine set ups all have the props rotating in different directions to counteract the effect.
Welcome to the forum. The Sharrow propeller is great. The F300 lower unit fin (anode) provides some protection from electrolysis when the lower unit is in the water and supposedly helps for torque pull. But even with the fin it took more steering effort to turn the boat in one direction than the other. Although she tracked nice and straight at least without autopilot. The fin was set at a couple degrees but I don't recall the exact setting. With the shape of the Sharrow blades they would have hit the fin. It is easy to remove and reinstall but I didn't need to. I just sawed off the fin (with it installed) using a hack saw. Sounds crude but it looks fine. The remaining base will still serve as an anode. Whats great as I previously commented in this thread is that with the Sharrow torque pull is no longer present. And yes you are correct, with twins and counterrotating propellers torque pull should not be an issue no matter the propeller.
Yes if its a 10 year payback or even longer with twins it may be hard to justify Sharrow propellers. I haven’t seen any Sharrow tests on an 895 or a similar size and weight boat with twins. I’d think there would be a performance improvement but not to the extent what’s being shown by Sharrow in their many of their boattest.com articles. I suspect those bigger heavier boats in the tests with twins are underpropped (for blade surface area) to start with. My 895 with the F300 was under propped with all of the 3 blade conventional propellers. There just wasn't enough blade surface area. That was much improved with a 4 blade big diameter. In other words, I suspect that if those tested boats I mentioned above had appropriate conventional 4 blade propellers to start with then the Sharrow tests would not have been as dramatic an improvement of say 30% or more in the mid planing speeds. I think the 895 with twins likely already has sufficient blade area to do the job with the twin 3 blades. I'd expect a performance improvement with the Sharrows, perhaps a 10-15% improvement at the low and mid planing speeds. That would be great but then you're at the 10+ year payback. And that additional $10k is on top of already spending $20k (or whatever it is) for twins over a single. For me with a single an additional $4.9K (that was the price when I ordered) was justifiable in order to get the better performance out of the single. I later sold 2 of my Yamaha saltwater series II props for $900 so that helped my ROI :')
I have a pair of Sharrow props arriving on the 6th so at some point I will be able to provide some test data. Any fuel improvement would be welcome but the main reason I decided to go for them is lower rpm/noise at cruise and the improved reverse thrust. The latter being due to having the full Helm Master EX being fitted later this month. I read one of the limitations to joystick docking is the poor reverse thrust with nearly all props compared to forward thrust. I am hoping the 2 products will be a perfect match.