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.