Mercruiser 37 engine

Thanks for the help.I was wond

Thanks for the help.I was wondering does anyone know how fast would i be going if I'm running at 4000rpm's on my engine my prop is 15/17. if I would change it to different pitch would i increase power.

"I use this one from time to t

"I use this one from time to time..
http://www.rbbi.com/folders/prop/propcalc.htm

to many variables for a hard number but you should be close.

http://www.go-fast.com/Prop_Slip_Calculator.htm"

"If you do go up in pitch you

"If you do go up in pitch you will increase slightly in speed but it will be harder for the engine to get you there depending on wind, wave and loading of the boat. 2 people vs 4, full tanks vs half-full, etc. Some people carry 2 props to go from cruising to water skiing, tubing etc.. If you are like that you may want to consider a Piranha Propeller, I've used them and have a newphew with a 2008 Glastron 220hp GT-205 that went from the stock prop of 21p 3 blade to a 22p 4 blade piranha, cuz it's mostly just him and 1 or 2 others and they each weigh 120lbs soaking wet. WHen he want's to do tubing he puts on 4 18P blades with the same hub.

http://www.piranha.com/

I ran a 22p 4blade vs a 23p 3 blade SS prop, broke 1 blade and .25 of another and had no problem finishing the day excpet a very very mild vibration, that I could feel and i'm very sensative about my boat. If I was more concerned about being unbalanced I could have removed 2 bad blades and put the 2 good blades opposite and had a nice SPEED Prop, just not much bite.

hope this helps"

I though diameter of prop has

I though diameter of prop has something to do with all this also. None of the calculators takes diameter into consideration. If I have a 14" do I just stick with that? Over on the Volvo Penta board they're more concerned with size rather than pitch.

"I've did some searching,

"I've did some searching,

"Diameter keeps a boat on plane better but has more drag so less top end."

"In general you should use the largest diameter prop that your boat is capable of swinging, and that is determined by tip clearance. If tip
clearance from blade to hull is too small, the shaft loading becomes asymetric and will result in excessive wear and vibration. The normal
clearance recommendation is for no less than 20 to 30% of prop diameter. On the other hand, using a prop with too small a diameter will result in greater slip under heavy load."

"As prop diameter increases, the torque required to turn it at a specific speed will increase."

Read more: Boat Propeller Basics: Essential Prop Design Considerations for Boaters - http://motor-boats.suite101.com/article.cfm/boat_propeller_basics#ixzz0CJLG5NRp

PS.. Good News for Torque-Shift Propellers !!!"