viberation ?

[Tim Powell]

My 52c has new shafts balanced props new cutless bearings all new between tranie and end of prop.There seens to be a viberation (which may be in my mind) it is not exactley a viberation. When I put my hand on the back of the chair and hold one finger in the air it does not move.But there is a wood pecker like viberation i have had several guys ride with me. I have got several openions one thing they all ask me 3 or 4 bladed props (they are three ). The props are big eared things Jack knows the brand I got the same answer from two diffrent people they say it is the watter hitting the bottom of the boat frankely i belive that to be bull. But when i feel the vibration it is not a viberation as i know
a viberation like a bent shaft. It is like a machine gun hitting the botton and it is only from about 13
to 20 knots.
Is this common feature of three bladed props? Will changing props cure the issue?

[GCSI]

Tim: I have a 52c and experienced the same thing. Did a short haul to remove my 4 bladed props for service / balance, put on a spare 3 bladed set to use in interim. The 3 bladed props had a very noticeable vibration compared to the 4 blades. Couldn't wait to get my 4s back on the boat!

[Tim Powell]

Tim: I have a 52c and experienced the same thing. Did a short haul to remove my 4 bladed props for service / balance, put on a spare 3 bladed set to use in interim. The 3 bladed props had a very noticeable vibration compared to the 4 blades. Couldn't wait to get my 4s back on the boat!

couple of questions please 1. what engines do you have 2. what size are your props 3. what is the top end rpm 4. what is the top end speed 5, what size are the props Tim

[saltshaker]

Tim you have 3 blade Radice wheels on your boat. Bret bought Southern Pride, the 3406 boat out of Tampa so his numbers will be different from yours.

[GCSI]

Tim: For what it's worth:

3406E @ 800hp
2350 max RPM
32kts max, light load
1:92:1 Gears
2.5" shafts
32x33 props, 4 blade

Gotta love the Cats!

Brett

[GCSI]

Tim: It's my understanding that Sam's propeller division (propeller place.com) will rent propellers. Might be a good idea to rent a few that you "think" would work and dedicate a day to playing musical propellers finding the right match. After getting close then have a prop shop make final tweaks on a purchased pair. Brett

[Spellbound]

Tim --- FYI

QSM11 @ 715hp
2530 max RPM
29.3kts light load full tower
2.03:1 ZF Gears
2.5" shaft
31X34 #4 cup, 4 blade

Take a look at your rod tips (in chair) when running. Slight vibration, and I mean slight from chair/deck is normal, minimal, moderate to excessive will be noticed in tips.

Good Luck Tim.

[Tim Powell]

thanks CGSI i know you are enjoying the boat you are lucky you got it i went looking and just could not get to it just before you got it . I flew to florida and got off the plane had a emergency phone call and returned on the next flight. Just ment for you to have it.

Toby thank you too they are impressive mumbers and the fuel burn is super i know
Did you have to change props when you changed engines. You still got the old ones.
I do not think I have a viberation. The boat is smooth it is like a wood pecker. I put one enginei out of gear and the same thing and then the other the same thing. Your way of rods in the chair was a way that another person said do. The tips are shaking but they are quick shape not like a out of balance tire Short quick viberations. Like a playing card in a bycle spoke crazy one said it was watter hitting the bottom just can not swallow that. WE have ran the boat and got the numbers with the three bladed props and have given the numbers to Big rock prop shop to run the numbers on their computer program should have answers this friday.