greatlakestate
05-17-2009, 07:51 PM
First, thank you all for the past 3 months with the help on my boat, it is finally in the water and running!!!
My set-up is a 31" Prather deep vee 3.5 outboard lower unit, 700 motor, water cooled Jetti 600 w/12 cells, Octura x440. I would guestimate about 25 - 30 mph with a 6 minute run time. All parts are running cool, with a nice stream of water from my hull outlet. Not crazy fast, but once I fooled with the throttle and weight a bit, a small portion of the hull and the outboard were the only thing in the water. Fine for what I'm looking for. Trim seems to be extremely level and smooth, but I am having a problem with cavitation.
I cranked the K&B outboard height adjustment all the way up to start. The prop shaft is just about level with the point of the vee on the transom. I am getting cavitation about midway coming out of the hole, then it will plane. I have to back it off once it gets up and then it eventually hits a sweet spot at about 80% throttle. Once it gets going and well out of the water, I can open it up. This process takes a lot of throttle control and doesn't happen everytime. I I am wondering if dropping the outboard a bit will help...I see a lot of FEs with a prop very close to the surface, so I figured this is where I should start. Maybe I need a different approach since this is an outboard and has a plate just over the prop, etc...
Where should I start my tuning process...any ideas from the experts? Thanks!
My set-up is a 31" Prather deep vee 3.5 outboard lower unit, 700 motor, water cooled Jetti 600 w/12 cells, Octura x440. I would guestimate about 25 - 30 mph with a 6 minute run time. All parts are running cool, with a nice stream of water from my hull outlet. Not crazy fast, but once I fooled with the throttle and weight a bit, a small portion of the hull and the outboard were the only thing in the water. Fine for what I'm looking for. Trim seems to be extremely level and smooth, but I am having a problem with cavitation.
I cranked the K&B outboard height adjustment all the way up to start. The prop shaft is just about level with the point of the vee on the transom. I am getting cavitation about midway coming out of the hole, then it will plane. I have to back it off once it gets up and then it eventually hits a sweet spot at about 80% throttle. Once it gets going and well out of the water, I can open it up. This process takes a lot of throttle control and doesn't happen everytime. I I am wondering if dropping the outboard a bit will help...I see a lot of FEs with a prop very close to the surface, so I figured this is where I should start. Maybe I need a different approach since this is an outboard and has a plate just over the prop, etc...
Where should I start my tuning process...any ideas from the experts? Thanks!