phwrd
Petty Officer 1st Class
- Joined
- Jul 30, 2007
- Messages
- 294
This is in the iboats prop store and thought that it might help some of us with our initial prop questions. (images didn't copy & paste but are on link)
link : http://boatpropellers.iboats.com/propeller-tutorials/rpm/?**********=070301677&*******=534787687
First, Determine Manufacturer's Recommended RPM (see image 1)
Find the manufacturer's recommended RPM range in the owner's manual or ask your dealer.
Then, Determine Your Wide Open Throttle (WOT) RPM
For safety and efficient performance, it is critical that your engine operates within the RPM range recommended by the manufacturer. Matching the right prop for the load is the most significant factor of RPM adjustment.
Effect of Prop Pitch on RPM (see image 2)
A pitch change can increase or decrease the RPM's and bring RPM's into the recommended range. A 2" increase in pitch (for example, from 21" to 23") typically results in a decrease of approximately 300-400 RPM.
Test for Maximum RPM (see image 3)
Using the existing propeller or a new propeller, make test runs to determine the maximum RPM and boat speed. Vary the trim angle for optimum performance.
RPM Higher Than Recommended (see image 4)
If the actual WOT RPM's are above the recommended RPM range, install the next larger pitch propeller to decrease your WOT RPM. Re-test the WOT RPM.
RPM Lower Than Recommended (see image 5)
If the actual WOT RPM range is below the recommended range, install the next smaller pitch propeller to increase your WOT RPM. Re-test the WOT RPM.
When you combine all these factors, you have the information you need to select the correct propeller for maximum performance, safety, and fuel efficiency.
link : http://boatpropellers.iboats.com/propeller-tutorials/rpm/?**********=070301677&*******=534787687
First, Determine Manufacturer's Recommended RPM (see image 1)
Find the manufacturer's recommended RPM range in the owner's manual or ask your dealer.
Then, Determine Your Wide Open Throttle (WOT) RPM
For safety and efficient performance, it is critical that your engine operates within the RPM range recommended by the manufacturer. Matching the right prop for the load is the most significant factor of RPM adjustment.
Effect of Prop Pitch on RPM (see image 2)
A pitch change can increase or decrease the RPM's and bring RPM's into the recommended range. A 2" increase in pitch (for example, from 21" to 23") typically results in a decrease of approximately 300-400 RPM.
Test for Maximum RPM (see image 3)
Using the existing propeller or a new propeller, make test runs to determine the maximum RPM and boat speed. Vary the trim angle for optimum performance.
RPM Higher Than Recommended (see image 4)
If the actual WOT RPM's are above the recommended RPM range, install the next larger pitch propeller to decrease your WOT RPM. Re-test the WOT RPM.
RPM Lower Than Recommended (see image 5)
If the actual WOT RPM range is below the recommended range, install the next smaller pitch propeller to increase your WOT RPM. Re-test the WOT RPM.
When you combine all these factors, you have the information you need to select the correct propeller for maximum performance, safety, and fuel efficiency.
