need help figuring out correct prop

[Sea Rider]

This is not a wondering adjustment thing, in reality need to visually check what's going at back transom which is the fastest way of knowing if OB sits at the sweet transom height.

For instance can go for a wot spin on flat calm water cond with deck weight evenly distributed, trimmed for combo to ride parallel to water surface once at plane. Make close tight turns at speed, if prop aerates, lower OB a tad. If there's water splashes coming up//over transom raise it accordingly till splashes are cancelled out.

Happy Boating

 

[Faztbullet]

1) you don't want to bury a 4 blade... 2) how are you measuring speed?... 3) Prop chart shows 20% slip ...4) post a pic of mounting height

 

[Terryfish]

I'm measuring speed with GPS, I'll take a pic in the morning...

 

[Sea Rider]

More important is to know at which safe wot rpm range is OB turning at given load than max speed by GPS. You have to make 2 opposite wot runs on same water course to know excat GPS speed, unless one wot run is made on a close rowing calm water course.

For recreational boating, you can only achieve slight more top end speed while OB runs at middle wot range compared to rurring at full wot revs. Nothing expectacular that will take away your sleep or fly the boat away from earth..

Happy Boating

 

[Faztbullet]

More important is to know at which safe wot rpm range is OB turning at given load than max speed by GPS. You have to make 2 opposite wot runs on same water course to know excat GPS speed, unless one wot run is made on a close rowing calm water course.

Soooooo a GPS speedometer is inaccurate/worthless unless your on a water course......bovine scatology!!! If you have engine at WOT and trim to a set RPM say 5800 speed will be nearly identical every time if water conditions are the same.

 

[Sea Rider]

Sorry that's on your own words, not mine, never mentioned anything about speedometer being useless if that's the unit installed on lower hull side that reads speed. At a close rowing field there are no water currents to deal with and if with 0 wind just need one wot run..

If water cond remains same at a close flat no wind rowing course max wot rpm theoretically should remain same every day. But in real world boatingt your OB does not rev at same wot rpm evey single day, there are environmental issues, atmospheric pressure, time of the year conditions that varies, so does your wot rpm. Less not digress in topics that's probably of 0 interest to OP..

Happy Boating

 

[Terryfish]

Ok here is the best pic I could get of the motor height to boat

 

[Faztbullet]

The height is pretty close from the picture, the only thing I don't see is the plastic blow out ring around prop. Part number 126669. It takes up the space around front of prop and reduces ventilation...it sometimes called a weed ring.

 

[211libwtfo]

Not to turn “business” away but on offshore only forums there’s a guy there ken, he IS the prop god.

Sorry but apparently ken is not on offshore he’s on bandofboaters. Plus he owns a prop shop. And has a test prop program

 

[Terryfish]

Oh cool, thanks