How do I measure for shaft length?

[dhornsey]

As the final stage of re-powering we're replacing our shaft and prop. I need to tell the machine shop how long to make the new shaft, but I'm not positive how to make this measurement.

The boat has a full keel with a stern hung rudder. Where should the propeller sit in the aperture? Right in the middle? Closer to the boat or the rudder? Our existing prop isn't a great guide as it's the folding type with a casing bolted right to the hull.

Any advice appreciated!! Thanks.

[capttb]

Not that it's much help but the diagram attached would seem to indicate the prop has to go pretty much as far forward as possible also.Pacific Seacraft Corp. - Pacific Seacraft 31

[Wayne25]

On a powerboat inboard, if you have a 1" diameter shaft you should have about 3/4" between the prop hub and the skeg.

[sander06]

Leave enough space for a zinc and call it good.