Somebody splain gear ratios

[pstephens46]

In reference to lower units. Say a gear is 2:1 versus 1.75:1. I was thinking 2:1 was 1 turn of crank for 2 turns of prop shaft. Is that correct or ass backwards?

[DennisG01]

In reference to lower units. Say a gear is 2:1 versus 1.75:1. I was thinking 2:1 was 1 turn of crank for 2 turns of prop shaft. Is that correct or ass backwards?

It's the ratio of enginerop. Same basic idea as found in truck rear ends.

Edit: I don't know where that smile thing came from... was supposed to be engine "colon" prop

[boscoe99]

Bass ackwards.

Two turns of the crank shaft equals one turn of the propeller shaft. Or 1.75 turns of the crank shaft equals one turn of the propeller shaft.

Holds true for cars/ trucks unless they are in over drive. In which case the crank shaft turns slower.

No outboard motor uses an overdrive configuration.

[pstephens46]

Bass ackwards.

Two turns of the crank shaft equals one turn of the propeller shaft. Or 1.75 turns of the crank shaft equals one turn of the propeller shaft.

Holds true for cars/ trucks unless they are in over drive. In which case the crank shaft turns slower.

No outboard motor uses an overdrive configuration.

Interesting. Always figgered those prop shafts spun faster than motor.

[99yam40]

Interesting. Always figgered those prop shafts spun faster than motor.

got to get the torque up to get the prop the power to turn down in the water

[boscoe99]

And there are other reasons why it is advantageous for a propeller to slower rather than faster.