prop acting weird

[jimmyz32]

:confused: when i'm running WOT 4" below keel on a 17'2" keywest 6300 rpm 7" of setback . when i back off just a hair the bow comes up like 6" then i gag it again and i goes back down again. Is that normal? what can i do to fix the problem ? do i need to raise or lower the motor? i have had it set as high as 2.5" below the keel turns 6700 rpms flys good but it wont carry a load. So i kept going down with the jack plate till i'm now to this point. what can i do? :(

[transomstand]

I've driven a number of boats that act like that. I believe it's more an issue with trim angle than engine height. Some could get down right ill mannered unless you bump the trim in a little when you back off.

Pete

[jimmyz32]

is it just a raker problem? is there a better load carring prop that i can surface?

[jimmyz32]

Also i was running flat trim.

[transomstand]

I'm hesitant giving advice on a hull/engine I'm not familiar with, but generally speaking, engine thrust will want to push the bow down. When you reduce thrust, your not "pushing down" as much on the nose, but a high rake prop is still generating a lot of lift. I guess I'm using a lot of words to say your boat sounds pretty normal. As long as there's no heart stopping handling problems when you back off, I think your fine.

Pete

[jimmyz32]

ok thanks buddy. :)

[props4u2]

The motor is either too high, or there's not enough cup in the prop, when you let off the prop hooks up and raises the bow, when you stab it, it slips the prop and the bow drops. Lower the motor 1/2" & see what it does.

Lee

[jimmyz32]

thanks for the info lee i will try that. what would have more cup than a raker ? mabe a 4 blade?

[pyro]

Geez, I'm no expert here, but it sure sounds to me like your prop is generating some good stern lifting properties, and when you lose thrust, your transom drops, which may make it appear that the bow is lifting up. As was stated above, sounds OK to me. Sounds like your prop carries a load very well with those characteristics.

[jimmyz32]

Thanks Pyro. When Someone Goes To The Front Of The Boat. I Can't Hold Up The Front. Also Another Question If I Get A 24 Raker Can I Jack Up My Motor More? Right Now I Can Turn My 22 Raker 6700 Rpms With It Set At 2.5 " Below The Pad. But The Bow Drops As Soon As Someone Gets In The Boat.so If I Get The 24" Raker Would I Beable To Run That High And Carry A Load Still I Only Need About 6400 Rpms To Be In My Sweet Spot.

[transomstand]

Welcome to the "Grand Propeller Experiment". Everbody here is in it, or has been in it. You can go to the poor house in a big hurry if you try to do it on your own. The big advantage you have is your location. Get out to some of the boating events in your area(seems like there's one most every weekend). You'll almost always find someone with a prop you can try. There's a big event coming on the Swannee in a few weeks, post on there that you need to try some props, I'll bet you find plenty of people with props you can try. There is one hard and fast rule, "If you break it, you bought it", so be prepared for that. It's also a great way to meet the outstanding people in our sport, and you'll learn a lot just from seeing different boats and setups.

Pete

[jimmyz32]

thanks !! good idea i'll check it out. :D