prop pitch

[ss pirate]

i have a 1979 starcraft 22' starcraft super sport with a 1977 200hp johnson. (weight w/o people 2,500 lbs.) also a 1977 evinrude 9.9 long shaft i use on occasion to troll with but its main purpose would be to get me in if the big motor fails. the 9.9 came from a 5,000 lb sail boat with a 10x5 3 blade alum. prop. it revs to high and provides very little speed. any suggestons on what pitch would be best ? if a choice is between top speed or best for trolling, i want speed.

 

[steelespike]

Re: prop pitch

without any concrete numbers from the 5" prop its difficult to know what rpm a given prop will deliver.
The sailboat may have actually been easier to push than the Starcraft up to a point.
A 5" prop at 6000 rpm and 20% slip should produce about 9 mph.Slip is likely higher in your application.
Unlikely that the Starcraft would reach that speed.
A 7" prop at 6000 20% slip could reach 13.Isn't likely to get much faster than the speeds with the 5"
It would be interesting to see the actual rpm and speed by gps with the 5"
A tinytach can get you the rpm.The 7" should run closer to the rated rpm and the 5" is likely too small.
But I think it will struggle to reach 10- mph.

 

[ss pirate]

Re: prop pitch

thanks, i will get boat out of storage in the next week or two. i will let you know how it woks out.