Yamaha 225

Hi!

I tried a Fountain 47 with 3x900 one time. It had 3 No 6 drives and was quipped with 4-blade Merc cleavers. The boat ran great, but I was really supprised about the bad cruise speed. (and I guess huge consumption too) We ran about 70 mph at 4000 rpm. and 120 at little over 6000. That made me believe the props were not efficient at 70 and under that speed also. These props were the original from year 2001.

So what has happened to prop design since then? I assume a 5 or 6 blade (for example) Hering would "bite" a lot better at cruise speeds? And what about top speed? I thought the boat would run faster with 2700 horse power...?

Any suggestions about what would work well is much apprechiated!! I want to buy that boat one day. And what would 3 new props cost? I am not satisfied with anything else than what gives the boat the best top end speed, accelleration and cruise speed. (Props are IMPORTANT!!!!!!!!!!!)


Thanks,
Erik

bbladesprops

Without knowing the prop pitch we can not determine the efficiantcy at various speeds. Also we need gear ratio.

Yes, most boats are less efficiant in the middle numbers than at the top because more boat is in the water. 5 and 6 blade props will help mid range numbers and even top numbers if the slip percent in high on the top. If the 4 blade props are hooked up well in the top rpm areas, they will likely have the better speed numbers. Angles the blades are attached is known as rake. New design Mercury #6 propellers come in 3 different rake angles and in 5 and 6 blade configurations. This is true for the other #6 propeller manufacturers also.