Re: 6r74c prop choice differences

[David Stanton]

Since you are just using it as a trolling motor alongside your 75 HP, you probably don’t care about wide open throttle performance, as it’s not going to plane the boat off anyway. Given the size of the boat, I’d use the 3-blade – it will grab more water and function better in a wind at trolling speeds. I have used a 6 and a 7-1/2 HP motor on a fairly heavy, wide, deep 16′ Aluminum boat for fishing that we get free to use when we rent a 58 foot houseboat on Lake of the Woods in Canada, with no other motor on it. I believe this boat is rated at 40 HP max, and is driven at the tiller. When back-trolling for walleyes against a wind, 2-blade props do not work well. When you have to rev the motor up some while backtrolling against wind and waves to maintain the 1 or 2 MPH trolling speed, the 2-blade props gets to a point where they lose their grip and the motor cavitates, where 3-blade props work much better. If all of your trolling is going forward, the 2-blade will likely work OK, but I’d still go with the 3-blade for a better grip of the water. At low to medium RPM trolling speeds, propeller pitch doesn’t mean a lot.

For the last several years on the same trip, I now use a late 1980s 15 Johnson (of course with a 3-blade). It back-trolls as well as the smaller motors, but gets me up between fishing sports faster on the remote portage lakes I run them on.
Dave