could my prop be too big?

[scon]

is there any possible way my prop is too big? its a 21 p on a alpha one motor is a 305 inboard...it plains out well but seems like it should have more (in lack of words) pep? top speed is sround 40-43....rpm is 3800-4000...is this good? or can i get more out of it?

 

[Bondo]

Re: could my prop be too big?

could my prop be too big?

Ayuh,... Sounds like ya need a 19" or even maybe a 17"...

 

[rutcutter]

Re: could my prop be too big?

That max rpm sounds low to me but you need to know what the max rpm for your motor is. If your rpm is low then you need to go down in pitch.

 

[Tail_Gunner]

Re: could my prop be too big?

is there any possible way my prop is too big? its a 21 p on a alpha one motor is a 305 inboard...it plains out well but seems like it should have more (in lack of words) pep? top speed is sround 40-43....rpm is 3800-4000...is this good? or can i get more out of it?

21@3900
20@4100
19@4300
18@4500
17@4700 .............
16@4900..............

Lots of assuming there but thats a general rule...It would be to your advantage to post your gear ratio its on the lower part of the out drive..The boat is not setup properly now..It could be your tach thats off or timing etc..There are a lot of varialbes..With gearing... gps speed and rpm numbers it easy to help out..