FutureStarr

A Boat Gear Ratio Calculator

A Boat Gear Ratio Calculator

Boat Gear Ratio Calculator

via GIPHY

If you want to convert your old gear for use on your next voyage, this tool will help you do the calculations. Just type in your total gear weight, start and destination, and the length of time you'll be on the water and you'll get an estimate of how much gear you need to bring.

Boat

This calculator requires the use of Javascript enabled and capable browsers. This calculator is designed to give any missing value from the 5 variables needed for marine propeller calculations. They are engine RPM, prop gear ratio (normally for 1.5 to 3.0), prop pitch (the distance that a propeller would move forward in one revolution), prop slip (the efficiency of the prop, lower at high speed, but perhaps very inefficient at low speed) and the boat speed in mph. Enter any 4 variables and the 5th variable will be calculated. Our defaults are set up so that boat speed is the missing variable; however, you may clear any of our defaults and insert your own values.

When most people talk about a marine gearbox ratio, they mean the reduction ratio of the motor that expresses the number of times the motor turns--the number of revolutions--to turn the propeller once. Marine gearbox ratios vary between manufacturers, between the engine models of each manufacturer and between High Thrust and regular gear ratios. All you need to know to start the calculation is the pitch of your boat's propeller. Then all you need to do is go boating with a few extra supplies. (Source: www.power-transmissions.com)

Pitch

How do you go about calculating prop size for a new engine installation and almost certainly changing 2 blade fixed for 3 bladed feathering? As I understand it the aim is to achieve maximum theoretical hull speed at fast cruising rpm, but not max rpm, so what percentage of maximum revs that would be, or does one look at the torque curve for the engine. With a feathering prop, I thought pitch is not a variable, although the Featherstream does allow some manual adjustment, possibly to fine tune the installation. I also know the gap between the arc of the prop and the hull should not be less than 10% of the diameter. Beta Marine seem to supply a gearbox with either 1.5:1, 2.0:1 or 2.6:1 ratios so this must also be part of the calculation. Any other variables?How do you go about calculating prop size for a new engine installation and almost certainly changing 2 blade fixed for 3 bladed feathering? As I understand it the aim is to achieve maximum theoretical hull speed at fast cruising rpm, but not max rpm, so what percentage of maximum revs that would be, or does one look at the torque curve for the engine. With a feathering prop, I thought pitch is not a variable, although the Featherstream does allow some manual adjustment, possibly to fine tune the installation. I also know the gap between the arc of the prop and the hull should not be less than 10% of the diameter. Beta Marine seem to supply a gearbox with either 1.5:1, 2.0:1 or 2.6:1 ratios so this must also be part of the calculation. Any other variables? (Source: forums.ybw.com)

 

 

Related Articles