I have been lurking on this forum for a few weeks trying to get a better understanding of how to select the right prop to optimize performance.
So far I still have only a weak grasp of the variables.
My particular circumstances are a 1996 scout 153 sportfish with a yamaha f50. I bought the boat with a 10x15 aluminum prop that has a few nicks in it.
I have only taken it out in Monterey bay and there is usually surface chop and wind so my top speed is hard to pin down reliably.
Checking it with a gps I can get up to 25 knots pretty quick at 5400 rpm and with a smoother stretch of water and a bit of time the speed may hit 28 knots. Yamaha lists the rpm range for this motor as being 5000 to 6000 rpm. I feel confident in my ability to monitor the tach and keep it under 6000 rpm should underpropping it be best suited to my needs.
The problem is when I load the boat down with three adults and a few crab pots, the boat can barely get on plane and my throttle response at low speed leaves a lot to be desired.
My typical cruising speed is around 15 knots and I can't imagine ever needing to go over 20 knots in the kind of conditions I experience on the bay. I do plan on loading the boat down with a fair amount of weight on a regular basis. Furthermore next summer I can picture my 6 year old (as well as an occasional adult) being ready to try wakeboarding or innertubing behind the boat so I would really like to prop it for optimal hole shot and lower speed performance.
I have looked at the yamaha website and they have a performance bulletin for a f50 on a 16' smokercraft. It has a 10 5/8 x 12 prop and hits 5800 rpm at 32 mph.
This has me thinking of going for a prop with a pitch of 10 or 10 1/2. When I looked at the props on iboats site they show a few 10 pitch props in a 12" diameter.
I am hoping some of you can help me understand the pros and cons of going with a larger vs smaller diameter prop in my particular application and also make any pitch recommendations that might seem appropriate.
I am inclined to stay with an aluminum prop for right now as I have to pass over a lot of barely submerged rocks heading out into the harbors main channel and even if I don't hit a rock with the prop I imagine my brother or wife might.
I am also a bit overwhelmed by all the variety in manufacturers. Is it just a matter of buying from whoever has the dia and pitch at the best price or should I stay away from or seek out certain brand names?
thanks for any and all ideas
Karl
So far I still have only a weak grasp of the variables.
My particular circumstances are a 1996 scout 153 sportfish with a yamaha f50. I bought the boat with a 10x15 aluminum prop that has a few nicks in it.
I have only taken it out in Monterey bay and there is usually surface chop and wind so my top speed is hard to pin down reliably.
Checking it with a gps I can get up to 25 knots pretty quick at 5400 rpm and with a smoother stretch of water and a bit of time the speed may hit 28 knots. Yamaha lists the rpm range for this motor as being 5000 to 6000 rpm. I feel confident in my ability to monitor the tach and keep it under 6000 rpm should underpropping it be best suited to my needs.
The problem is when I load the boat down with three adults and a few crab pots, the boat can barely get on plane and my throttle response at low speed leaves a lot to be desired.
My typical cruising speed is around 15 knots and I can't imagine ever needing to go over 20 knots in the kind of conditions I experience on the bay. I do plan on loading the boat down with a fair amount of weight on a regular basis. Furthermore next summer I can picture my 6 year old (as well as an occasional adult) being ready to try wakeboarding or innertubing behind the boat so I would really like to prop it for optimal hole shot and lower speed performance.
I have looked at the yamaha website and they have a performance bulletin for a f50 on a 16' smokercraft. It has a 10 5/8 x 12 prop and hits 5800 rpm at 32 mph.
This has me thinking of going for a prop with a pitch of 10 or 10 1/2. When I looked at the props on iboats site they show a few 10 pitch props in a 12" diameter.
I am hoping some of you can help me understand the pros and cons of going with a larger vs smaller diameter prop in my particular application and also make any pitch recommendations that might seem appropriate.
I am inclined to stay with an aluminum prop for right now as I have to pass over a lot of barely submerged rocks heading out into the harbors main channel and even if I don't hit a rock with the prop I imagine my brother or wife might.
I am also a bit overwhelmed by all the variety in manufacturers. Is it just a matter of buying from whoever has the dia and pitch at the best price or should I stay away from or seek out certain brand names?
thanks for any and all ideas
Karl
