RickR
11-24-2002, 08:55 AM
Just got back from Grouper fishing in Forrest's neck of the woods (FLA Panhandle) and I have some problems with "The Other Boat"
The "Other" is a Sportcraft 25' walkaround cuddy similar to the Donzi F-25 (5000lbs dry wo/engine)
Problem is we blew up the 200 Yamaha for the 3rd time so replaced it with a 1995 225 Saltwater rebuilt Yamaha.
Performance is similar to the 200Y but RPMS are down 700. I am assuming the 225 has a different gear ratio.
Our partner did some prop swapping and I've got a prop slipping problem.
We are running a 15" large diameter Yamaha Stainless which has a unique blade the is about half way between a round ear and a cleaver. It cavitates till 4200RPMs. When it hooks up RPMs drop 300 and speed increases 3MPH. After it hooks up it will hold down to 3700RPMs then start slipping again.
With the prop "hooked up" 33MPH@4500RPMs 36MPH@5000RPMs with 1/1.75 gear ratio that would be 17.5% slip, 1.86 12% slip
With prop cavitating 16MPH@3900RPMs (49% slip @ 1/1.86 :( )
Is the different gear ratio causing the slipping?
Can I remedy the problem with a round ear with a larger blade surface area and a smaller pitch?
Are large diameter 13" pitch props available for the Yamaha?
Anyone have one for sale?
Thanks!
The "Other" is a Sportcraft 25' walkaround cuddy similar to the Donzi F-25 (5000lbs dry wo/engine)
Problem is we blew up the 200 Yamaha for the 3rd time so replaced it with a 1995 225 Saltwater rebuilt Yamaha.
Performance is similar to the 200Y but RPMS are down 700. I am assuming the 225 has a different gear ratio.
Our partner did some prop swapping and I've got a prop slipping problem.
We are running a 15" large diameter Yamaha Stainless which has a unique blade the is about half way between a round ear and a cleaver. It cavitates till 4200RPMs. When it hooks up RPMs drop 300 and speed increases 3MPH. After it hooks up it will hold down to 3700RPMs then start slipping again.
With the prop "hooked up" 33MPH@4500RPMs 36MPH@5000RPMs with 1/1.75 gear ratio that would be 17.5% slip, 1.86 12% slip
With prop cavitating 16MPH@3900RPMs (49% slip @ 1/1.86 :( )
Is the different gear ratio causing the slipping?
Can I remedy the problem with a round ear with a larger blade surface area and a smaller pitch?
Are large diameter 13" pitch props available for the Yamaha?
Anyone have one for sale?
Thanks!