Get rid of the 3 blade for less drag

[Otto Dieffenbach]

Powered by an old Yanmar SB8 7H.P. (original).Present Prop: 3/4--12x7 RH 3 blade Sailor prop-lugs and some smoke at full throttle. Boat displacement 8200#, hull speed new and clean 6.85 kts.Would really like a bit more sailing speed ---- don't we all.What good and bad experiences are there? What prop and cost is there any special shaft prep?

 

[Trevor - SailboatOwners.com]

props and drag

Hi Otto -There are many opinions on which prop is best, but convention says that to get less drag (hence, more sailing speed), you'll need to go with either a 2 blade fixed (cheaper, less motoring thrust) or one of several folding or feathering props. Autoprop, Max Prop, Martec (to name a few) are all popular, and these attempt to maintain more blade surface area for motoring and less drag when sailing. However, most of these gizmos come at considerable cost and some additional maintenance. Like anything sailing related, props are a trade-off, so consider the many variables in your decision!Best,Trevor

 

[Kevin]

props

Hello Otto,You are experiencing what any sailor will experience when using a two verses a three blade prop. Three blade has better performance with greater drag. Two blade has limited performance with slightly better drag amounts. You do have choices when it comes to low drag props. They offer both reduced drag with comparable efficiency while motoring. Most low drag units now come in either a two or three blade configuration. In most cases some minor shaft alteration is needed and that usually involves removing a small amount of threads. Hope this is what you asked. Kevin