BAR (Blade Area Ratio) Sailor Style vs Fast Yacht Style Propellers

[rotorman]

I would like to know what is the difference between the different style of propellers.
What I understand so far is that propellers can be
1) Cruiser Style .65 BAR
2) Sailor Style 0.55 BAR
3) Fast Yacht Style 0.4 BAR
I am most interested the difference between a Sailor Style (what I have) and a Fast Yacht Style (SkipJack - recommended by a supplier).
Regards
Geza

[marshmat]

Hi rotorman,

I'm not sure where you get the terms "cruiser", "sailor" and "fast yacht" from in this context.

Assuming you're talking about disc area ratio (DAR), i.e. expanded area of all blades divided by total area of propeller disc:

A longer, narrower blade is, generally speaking, more efficient and sees less interference from adjacent blades. That's a factor that pushes the designer to choose a low DAR, i.e. fewer, narrower blades.

At the same time, you need sufficient blade area to prevent cavitation (vacuum bubbles forming on the trailing face). Long, narrow blades (low DAR) means reduced blade area, increasing the risk of cavitation. If you have a diameter constraint, as is usually the case, you are often forced to select a higher DAR, i.e. more blades and making them wider, so that the prop can transmit full power without cavitating.

[rotorman]

Hi Matt,

thanks for the reply and the info. The terms "BAR, cruiser, sailor, fast yacht" were used by the propeller supplier.

Regards
Geza