Shaft length questions/education...

[Azonic]

Can someone describe to me the basics in why the shaft length is important.

I know certain issues like shorter to avoid crap on fishing boats, longer for deep hulls etc...

But what are the specifics of why a short shaft may not work on certain boats and Vice Versa...

Thanks..

Just trying to soak up as much info as possible

 

[QC]

Re: Shaft length questions/education...

Hulls are designed for either a 15", 20" or 25" in shaft . . . The height of the transom, splash well etc. are all important. If you are installing one onto a bracket and then mounting that bracket onto a clean transom then this is maybe your call. If not, then it is the boat's decision, you don't get much say in the matter

Moving to OB, non-repair. We try and keep this section free of engine (motor) discussions.

 

[Azonic]

Re: Shaft length questions/education...

And how do those shaft lengths effect the boat...

I have seen alot of jack plates and such...
People lifting motors, lowering, etc...

Where should the prop be? I guess

 

[JB]

Re: Shaft length questions/education...

The anti-ventilation plate must be at water level when on plane and the prop just below the bottom of the boat for maximum thrust and minimum drag without prop ventilation.

If the shaft length does not fit, the boat will either handle like a garbage scow (shaft too long) or the prop will be in air (shaft too short) and not move water.

 

[Azonic]

Re: Shaft length questions/education...

I do not know what the anti-ventilization plate is... I can take a guess...but rather be certain...

The entire prop below the boat level?

I should have no problems with water levels, more concerened about prop location I guess...

 

[QC]

Re: Shaft length questions/education...

The anti-ventilation (AV) plate is the flat horizontal part directly above the propeller. Water level comment was about the boat underway. Another way to say it is the AV pate should be even with the boat's bottom as a good starting place. You do NOT want it to be 5 inches up or 5 inches below which would be the result if you had the wrong shaft length.

 

[Azonic]

Re: Shaft length questions/education...

Got it...

I think..

I will mount what I have and see where she hits..

Measuring versus old motor is not getting me a good picture..

THanks