motor yacht propellers

[salishpaddler]

I'm hoping to learn here if it's worthwhile in terms of fuel economy and efficiency to consider retrofitting standard 3-blade props with automatically variable pitch props or high efficiency slow turning props similar to those on our newest submarines. Has anyone had experience with either with information to share?

48 ft CPMY, semi-displacement hull, two Cat diesels in PNW waters.

[sailpower]

Originally Posted by salishpaddler

I'm hoping to learn here if it's worthwhile in terms of fuel economy and efficiency to consider retrofitting standard 3-blade props with automatically variable pitch props or high efficiency slow turning props similar to those on our newest submarines. Has anyone had experience with either with information to share?

48 ft CPMY, semi-displacement hull, two Cat diesels in PNW waters.

Hatteras has been doing this in their MY/SF models for years; large multi-bladed props with deep gears. Some were almost 4-1 reduction.

But those are boats that get up on plane.

Not sure how much bang for the buck you would get at hull speed.

[salishpaddler]

Originally Posted by sailpower

Hatteras has been doing this in their MY/SF models for years; large multi-bladed props with deep gears. Some were almost 4-1 reduction.

But those are boats that get up on plane.

Not sure how much bang for the buck you would get at hull speed.

Primarily interested in improving fuel economy at leisurely speeds. Some folks use only one engine. I'm not interested in doing that, but I am interested in the prospect of more knots at lower engine RPM. Holy Grail, I guess.

[a64pilot]

There are many reasons to go to multiple blades, but fuel consumption is not one of them.
As a general rule, the more blades you have the more drag they produce.
I’m not aware of a self pitching power Boat prop, but you verily likely could reduce fuel consumption with a variable pitch prop and of course a pyrometer.
Enough to pay for the prop? Unlikely.