F470 CRRC Owners, help!

[leandroflaherty]

Hello everyone. I recently purchased a Zodiac F470 CRRC. I currently have a 2stroke 1990's 35hp Evinrude/Johnson on it. I am wondering if anyone here has a similar configuration from which they could recommend a propeller size?

What I have on it now is way off, the 35hp was on a heavy boat twice the bulk of this inflatable. Hoping I can get a solid recommendation to start with instead of throwing money away on props.

Thanks so much!

[Squid Boat]

Welcome mate, roll up floor or hard deck?

[paintman]

You need to do several runs at wide open throttle with your boat normally laden.
Note the boat's speed and what the engine revs are at WOT (the WOT revs figure being the more important if you haven't got a speedo or GPS)
Find the engine manufacturers recommended WOT range for your engine & see where the figure you achieved is.
Once you've got that you can select the best prop for your usage without a lot of trial & error.
Have a look at this thread & you'll get the idea:
http://www.rib.net/forum/f36/prop-op...5hp-71277.html

[leandroflaherty]

@squidbote, its a roll up. I use it as a dinghy, rolls up on deck.

[leandroflaherty]

Thanks @paintman .. There is no prop on it for me to test rpms (i have a tach), the prop it came with was waaay off and will not stay in gear from lack of thrust. So i am jumping in blind, hence advice for the first one. Was hoping someone here had same boat and motor to emulate. Right now I am guessing its a 10x15 what I need. Cheers

[paintman]

Don't know whether you've seen this, but might be worth having a play - select length 15-17 & it suggests 13 pitch, select 13-15 & it suggests 14 or 15 pitch.
https://www.miwheel.com/outboard-pro...zing-analysis/

[leandroflaherty]

Thanks for the link @paintman!

[office888]

How many persons and gear do you want to transport? How many gallons of fuel do you want to carry for what range?