Seeking Prop advise for a 48C

[Plan B2]

A friend has a 1989 48C that was powered and propped for speed. He doesn't run the the canyons and wants to use the boat more for weekend cruising on the inland waterways.
There in lies the problem: Too much low end torgue for his style boating. We are looking for prop recommendations to improve the close quarter manuverability.

He is running 8V92TAs rated at 735 hp each
The props are three blade 34X36
When at idle, the boat jumps several ft when even placed in gear (forward or reverse) Making close manuvering very tricky.

Does anyone here have experience with his set up or better still; Had that set up and made a change to improve handling?

 

[saltshaker]

Before doing anything I would make sure the idle is set properly and that the throttles are returning to idle. Not sure what you would change prop wise. The boat needs to be propped correctly period. You could go with a slightly smaller diameter prop but not sure it will make much of a difference. Big engines with big props are going to dig in when engaged. One of my neighbors thought I backed down to hard when docking. When I told him I was at full idle he was surprised.

 

[Plan B2]

Recent survey for engines show all parameters are correct regarding Idle, and WOT. The boat had a weird set up four blades that were not correct an were working the engines too hard at cruising speeds. The boat originally came with the three blades 34 X 36 as confirmed from the build sheet. And those were on the boat and put back on to complete the survey and verify WOT and speeds per the original design specs.
Just hoping someone else with a similar set up has found the best dia and pitch for a cruising style use.

 

[capttonyf]

A friend has a 1989 48C that was powered and propped for speed. He doesn't run the the canyons and wants to use the boat more for weekend cruising on the inland waterways.
There in lies the problem: Too much low end torgue for his style boating. We are looking for prop recommendations to improve the close quarter manuverability.

He is running 8V92TAs rated at 735 hp each
The props are three blade 34X36
When at idle, the boat jumps several ft when even placed in gear (forward or reverse) Making close manuvering very tricky.

Does anyone here have experience with his set up or better still; Had that set up and made a change to improve handling?

If everything Jack Mentioned Checks out to be normal all I can say is, "Gears, In and Out, In and Out" Most all High HP Convertibles/Sportfish and Most High Speed newer Boats including MY's Jump and Squat if you just throw them in gear. Even out in the channel I would bump in and out alternating Motors a few times to start forward motion before just putting both in gear. And if it's a No Wake Zone Most New Sportfish will never have Both motors in gear at the same time. The Idle Speed through the water is to fast. If this is the case have your friend practice putting the boat quickly in and out gear so as to get just a few prop rotations per bump to slow down his docking speeds. To Spin Old Motor Yachts, Yes you put them both in gear, apply a little throttle and then wait for something to happen but these newer boats very seldom will you ever just put two motors in gear to spin them and back them into a slip. It's an alternating in and out affair unless your a macho man trying to show off.

 

[Cricket]

Practice practice practice, since all of the parameters are in spec and with 24 years of getting dialed in I wouldn't touch a thing.

 

[dsharp]

That's why they came up with trolling valves in gears. You can't have everything. To get top speed you have to add horsepower and lose weight and it makes close quarter handling exciting. I suspect that's why some of the big sport fishers add thrusters.

 

[Regal2800]

I have the same engines in my 52c and while it does squat and move fast at idle i dont think it is an issue at all. simply engaging in and out of gear is all that's needed in close quarters.