shaft angle question?

[scattered_grass]

Anyone with a single-screw boat, or has had experience running one, I have a question for you: what do you think about a 32' w/ a shaft angle of about 19 degrees? It seems to be very steep, plans are for a 480hp Cummins..this angle will allow no more than a 25" wheel. I am talking about the Drum Runner, I'm sure alot of you have heard me gripe about it haha..I have heard from some that you must have an angle this steep on a boat this size...I have heard that she will plow with this angle..Just looking for some feedback from someone who knows. here are some pics of the shaft/ Thanks!

[gottaflylee]

Send Captain Jay Kavanagh a PM, he runs a single Screw BC boat out of Hat...

[Captain Jay Kavanagh]

Yes that is awful steep.

On my 51' BC single screw it is closer to 9deg.

On my 30' BC single screw it was steeper and I really don't know what it was, but it will be around 10 or so, I will get it as flat as I can and still get wheel clearance.

25" wheel, I think that is a little big for that hp, I would think it would be closer to a 22".

My 30' BC with 370 hp swung a 21" diam wheel I think.

You get speed out of pitch, not dia.

[Capt.Troy Crane]

Yes that is awful steep.

On my 51' BC single screw it is closer to 9deg.

On my 30' BC single screw it was steeper and I really don't know what it was, but it will be around 10 or so, I will get it as flat as I can and still get wheel clearance.

25" wheel, I think that is a little big for that hp, I would think it would be closer to a 22".

My 30' BC with 370 hp swung a 21" diam wheel I think.

You get speed out of pitch, not dia.

I agree Jay,

I run two B' series myself and swing two 21 x 23 3 blades with a light cup and make my turns fully loaded.

My old 30 footer with a single b series I swung a 24 square 4 blade and made my turns.

The shaft angle should not have any effect on the boat plowing, your weight distibution will do that.

The only problem you might encounter is the angle of your engine and the clearence under the engine box lid.

A down angle gear will be about 7 % I think and you need to make sure you don't exceed the angle limit imposed by the engine manufacture.

I know of a guy who did and he lost a lot of oil when running in a swell of any kind.

Good Luck,
Troy

[scattered_grass]

I appreciate it Capt. Jay and Capt. Troy

[jrzcape]

Skirt,shaft angle does affect the running angle of the boat.
The diameter of the wheels gives lift and gets you up on plane more pitch = more speed, transmission ratio also affects the diameter 1.5to1=smaller diameter than 2.0to1, If when running a boat and you put the tabs down and increase speed you need more lift (larger diameter wheels) if you have a clearance problem you could change the ratio of the transmission to turn faster. I hope this helps, if you need more details give me a call i can help.

[fishfighter]

With that angle,that should lift the stern big time. Also as stated above,one hell of an angle for the engine.

[Mackey]

I ran a 480 cummins in my 34 Judge (single screw) and swung a 24x23x4 with a med cup, no problem getting WOT rpms. I assume you will have a transmission with a 6 degree down angle to help out with the angle of the engine.

[Captain Jay Kavanagh]

I ran a 480 cummins in my 34 Judge (single screw) and swung a 24x23x4 with a med cup, no problem getting WOT rpms. I assume you will have a transmission with a 6 degree down angle to help out with the angle of the engine.

What gear ratio?

[Tuna Truck]

That is awfully steep. Seems like she'd be a good candidate for a tunnel. I know it's a few steps backward to cut a big hole in the bottom of a new boat but a tunnel would allow you to improve the angle dramatically and would increase speed and efficiency. Good luck.