prop pitch

[chrishelen]

Hello everyone,
I have just replaced my 6 hp inboard with a 10hp both diesels, the question i have is will the old prop be ok,or do i need a new one.The prop at the moment has 3x6 inch blades,and the pitch is15 inches or there abouts. chris.

 

[sailorman]

http://www.castlemarine.co.uk/pitch.htm

 

[chrishelen]

thanks for that it would seem my prop fits the bill size wise, but i think the petter required a left handed prop, so need a new one anyway it seems
regards chris.

 

[sailorman]

keep the prop & change the petter /forums/images/graemlins/wink.gif

 

[chrishelen]

The petters sold, good little engine never let me down once,not enough horse`s for a 26ft boat though, got a volvo penta 10horse should be a bit better if i can get the right prop.

 

[oldharry]

As a fellow Eventider, welcome! Have you checked out http://www.eventides.org.uk/ - a huge amount of useful info about Eventides and other MG designs.

Re the prop, if you are anywhere near the Hamble, and know what size prop your engine needs, try the Ffoulkes Chandlery Barge just above the bridge at Burseldon - they have a containerful of props of all sizes and shapes. They will also take your old one part exchange.

Not that it matters now but the 12x15 prop on your Petter would have been very inefficient as the pitch would have been much too coarse. Optimum pitch is around 2/3rds the diameter for a displacement hull, so a 12" prop is most efficient with a pitch of around 8" - 10" at <1800rpm shaft speed, with a water speed of around 4 - 6 kts.

A 12x15 prop is more appropriate to a planing hull with higher shaft speeds.

 

[chrishelen]

Hi old harry thanks for the tip on the prop, no wonder my boat was a bit slow on the donk,never mind buy a new prop whats money cant take it with me, as for the eventiders very good site a bit underused i feel,regards chris.