HANDLING A SINGLE SHAFT 43 FT BOAT

[nabeelah]

How difficult will it be to handle a 43ft boat(13.3m x 4.3m) with a single 750-800hp vessel,shaft driven,bow & stern thrusters,14 deg aft deadrise? Any ideas on rudder size?? Is this a keel must have situation?? If yes how big?? Willa prop tunnel help in effeciency??

[Fortunate One]

Faizal,

Sounds like you need a naval architect to oversee your project.

I would say with a bow and stern thruster you could maneuver that boat easily.

I owned a small single screw diesel and that was a handful at times. Especially with a large prop.

Once you get into keel depth and rudder size, well that's where professional assistance comes in.

Area above the waterline is another consideration. More area, the more it's going to be influenced by the wind. The larger the keel, the harder it is to handle in a side current.

If I were going single screw and thrusters, I'd go with hydraulic thrusters over electric. Electric thrusters can pop fuses if they're worked hard.

Why not just go with a pod system?

It seems to me that they're easier to install from scratch when compared to struts, shaft logs and props.

[CB&T]

Hey, My new boat is a single engine 12 degree deadrise with out a keel and she is very east to handle, The trick is to have a large oversized rudder. She turns on the dime, and backs fairly straight with some momentum. But it is all in the rudder. Good luck. My wheel is a 28 X 33. I do not have a thruster..

[iguana1]

Drove a boat that sounds very similar for years. 43 downeast with a single screw and no thrusters. Not hard at all, just back and fill......

[nabeelah]

Thanks alot CB&T and Iguana-your comments are well taken and I am very grateful for your shared experiences.
Hi Mike,pods may become a pain in my butt as you know that we live in a remote place on earth and servicability,back up etc are very limited.Shafts are all over the place here.but I do get your point that pods may be the wave of the future!!
If I do go single...the choices will be between Scania 800hp vs John Deere 750hp vs Cummins 715hp.The JD is priced the same as the Cummins and approx 20K lesser than the Scania.The torque of the JD is impressive!!

[Greg S]

Thanks alot CB&T and Iguana-your comments are well taken and I am very grateful for your shared experiences.
Hi Mike,pods in Fiji may become a pain in my butt as you know that we live in a remote place on earth and servicability,back up etc are very limited.Shafts are all over the place here.but I do get your point that pods may be the wave of the future!!
If I do go single...the coices will be between Scania 800hp vs John Deere 750hp vs Cummins 715hp.The JD is priced the same as the Cummins and approx 20K lesser than the Scania.The torque of the JD is impressive!!

There is one thing about the Cummins engines no one has mention.....The QSM-11 runs a dry exhaust manifold and turbo, in my shop we have over 10 turbo's less than 2 yrs old.
No they do not hold up like a wet turbo....We build new M-11's with wet exhaust and turbo's FYI..Look over Deere they may be dry too, I don't know about these engines, seems like they make changes once a year. Deere is trying to catch up with the rest of the marine market for High Hp..
The other engine company's including Volvo have 850~900 Hp prototype engines running for test. I doubt that deere is that agressive, I use to go to there engineering meetings every year, and they would visit my shop in Atlanta. My 2 cents worth...Thanks and have a good weekend Greg DPM.

[algdog]

I run a 42 ft downeast style, 5 ft keel, large rudder
600hp, 30 x 32 5 blade, 2 to 1 trans
the boat backs very easily, steers in reverse with the rudder
and almost turns in its own length