Im going to start trying to figure out the correct prop size for my boat. Right now it has some way undersized 18x13 props under it because the previous owner fished a ton and wanted to troll way down. I have 7.4 liter engines with 1.5:1 transmissions. I’m familiar with propping a boat and what to look for I’m just kind of looking for a starting point or if someone even knew what was in there from the factory that would be awesome.
Thanks in advance
-Grant Litynski
The Michigan Wheel calculator gives a starting point of 17x16 for a 3 blade prop based on a 30 kt top speed, 1.5:1 gear ratio and a 340hp with a target of 4300 RPM at WOT. Dropping the RPM target to 4200 returns a size of 18x16. Ideally you want to be in the 4200 - 4400 RPM range at WOT.
I'd confirm if you have enough hull clearance with the 18" props or if you should go down to 17". If the 18s fit well, I'd take them to a shop and see if they can re-pitch them. From what the calculator returns, an 18x15 or 18x16 should be appropriate, and there's a reasonable chance they'll be able to add about 2 inches of pitch to the existing props.
Awesome thank you
Here is a photo of what prop should be on your commander 336. There is a 336 on the hard for the last 5 years sitting under wrap. It’s a 3 blade DJ/EP MI/FED with heavy cup. I’m sure this was not original as it doesn’t have the Chris Craft logo from the factory stamped in the hub. You’re mid cabin 336 is heavier than my 332 so they put larger diameter on those vs the 332 which i have 16 x 17 originals.
Grant - do you have 1.25" shafts? if so i have a set of 17 x 18's that need a home. they are in great shape and i have been storing them for years