Propeller Size for a YF

[Ruben]

Just bought a 79’ 58 YF and it came with very undersized propellers. The current props are 27x28 and during the sea trial she was slow and RPMs topped out at 2500 with no turbo whistle. The boat came with 28x31 from the factory. Prop shop is suggesting 28x30 because of the age of the engines. Any thoughts or suggestions? Engines are 8v-71s with 462hp and 2” shaft.

 

[Captain Ralph]

If you do not have a bow thruster, talk with your prop shop about increasing diameter.
Give up that one inch of pitch with a dual purpose.

 

[CGHOST4]

Ruben, Give us more information on the boat, Hull number, engines, and hours. If they are 871 TI's they are 435 HP. I can look up what props I was running before my repower, but I am not sure what engines you have.

Caesars Ghost
1980 58YF #472

 

[cww]

Ruben, Give us more information on the boat, Hull number, engines, and hours. If they are 871 TI's they are 435 HP. I can look up what props I was running before my repower, but I am not sure what engines you have.

Caesars Ghost
1980 58YF #472

435hp at shaft, 462hp at crank. The 30hp difference is the estimated loss through the tranny and bearings.

 

[cww]

Just bought a 79’ 58 YF and it came with very undersized propellers. The current props are 27x28 and during the sea trial she was slow and RPMs topped out at 2500 with no turbo whistle. The boat came with 28x31 from the factory. Prop shop is suggesting 28x30 because of the age of the engines. Any thoughts or suggestions? Engines are 8v-71s with 462hp and 2” shaft.

Go with 28x30 Michigan DQX, I just did this on my boat and man did it improve performance. Engines turn same RPM as they did with the 28x31 Dyna-Quads.

 

[Ruben]

Ruben, Give us more information on the boat, Hull number, engines, and hours. If they are 871 TI's they are 435 HP. I can look up what props I was running before my repower, but I am not sure what engines you have.Caesars Ghost1980 58YF #472

HATAN4050879, 2 8v-71 462bhp 450shp ~2300 hrs

 

[Ruben]

Go with 28x30 Michigan DQX, I just did this on my boat and man did it improve performance. Engines turn same RPM as they did with the 28x31 Dyna-Quads.

How much more speed did you get with the DQX? Just wondering what improved specifically?

 

[cww]

How much more speed did you get with the DQX? Just wondering what improved specifically?

The improvements are noticeable. The biggest one is the boat used to struggle getting on plane with full fuel tanks or even the slightest dirty bottom. It was always sort of a "will it or won't it?" question whenever I took people on the boat to lunch or dinner at a restaurant on whether the trip would be at 16 knots or 9 knots. Sort of like the boat version of erectile dysfunction, because then when it wouldn't get up and go everybody on board is asking what's wrong with it. That problem just flat went away, now unless the bottom is absolutely filthy it will reliably plane every time with no struggle. That was worth the price of admission by itself.

The other improvements are the boat is at least a knot faster at any given setting over 1950. Reduction in vibration, although that's probably just because the old props needed tuning and one could have been bent. I've since had them reconditioned as spares. It's a noticeable difference, and I'm very pleased with the outcome.

 

[Ruben]

The improvements are noticeable. The biggest one is the boat used to struggle getting on plane with full fuel tanks or even the slightest dirty bottom. It was always sort of a "will it or won't it?" question whenever I took people on the boat to lunch or dinner at a restaurant on whether the trip would be at 16 knots or 9 knots. Sort of like the boat version of erectile dysfunction, because then when it wouldn't get up and go everybody on board is asking what's wrong with it. That problem just flat went away, now unless the bottom is absolutely filthy it will reliably plane every time with no struggle. That was worth the price of admission by itself.The other improvements are the boat is at least a knot faster at any given setting over 1950. Reduction in vibration, although that's probably just because the old props needed tuning and one could have been bent. I've since had them reconditioned as spares. It's a noticeable difference, and I'm very pleased with the outcome.

Great info. Thanks for the insight. I went ahead and ordered a pair today. The price was only 800 more than the dyna quads. Figured it was worth it

 

[Captain Ralph]

[FONT=&quot]I understand Michigan is making the DQXs in Vietnam now by Nakashima.

Sadly, I still have a problem with anything from over there.

[/FONT]