Yes, Amel overpitched the prop on the Volvo on purpose. Volvo suggested that one of several reasons that you might want to restrict the top speed of the engine was "reduced noise."
I don't know what Amel did on the Yanmars. I am sure somebody here can answer that...
I wouldn't tell them "under 3000" but rather give them 3000 as the target. Lower speeds will result in lower net power output from the engine, so you don't want to drop much.
I have owned two boats with a "Classic" 3 blade MaxProp (including Harmonie) and have been very happy with them. They work, they are easy to care for, no bearings, seals, or other parts that wear out. Every haulout I take mine apart and clean and grease it. I keep a zinc on the end, and all has been good.
I have no experience with Flexofold specifically. My fleet experience with folding props is limited to Martec brand props on racing sailboats. Not applicable to a SM installation, but I didn't particularly like them, both from a maintenance and a performance under power standpoint. The maintenance issue was wear of the pivot pins. They needed regular replacement.
In the real world, I very much doubt there is anything other than a theoretical performance difference between any of the major brands of folding or feathering props. Certainly in sailing performance, and even in motoring the differences aren't really going to be significant. Many folding props struggle a bit with reverse, but I suspect that is more a case of the helmsman needing to rev the engine more than he was used to.
One nice thing about a Maxprop: Based the experiences of other SM owners who have them installed by Amel in the early production run, you know exactly which one to get and where to set the adjustable pitch without trial and error. No need to pay the premium for the model with in-water pitch adjustment.
And as a total aside.... Speaking of "premium," the new 5 blade Maxprop is a beautiful piece of machinework! Priced like fine jewelry, but I imagine it is runs really, really smoothly. Certainly not worth it for the two or three hundred hours a year I have the engine running, but it would certainly make me the star of the boatyard at haulout!
Rock Sound Harbour, Eleuthera, Bahamas
---In amelyachtowners@..., <sailw32@...> wrote :
Bill, Thank you for your detailed reply. If I understand you correctly and correct me if I am wrong, Amel purposely over pitched my fixed prop to restrain it from attaining higher rpms and Volvo is fine with that. So, can owners with Yanmars obtain max rpms? I can't imagine I would want to hear my engine running higher than 3000 rpm , I feel as though I am over stressing it at that , I know it stresses me . So whatever prop I should buy , I should have them sell me a prop size and pitch that keeps my TMD22a under 3000 rpm. I know you were involved in the charter business , do you have any experience with Flexofold or Max Prop ?