Outboard Motor for Typhoon Senior

[G. S Murphy]

I am replacing the Nissan 5hp, short shaft, 2 stroke outboard engine on my 1985 Typhoon Senior, Dorus Mor, with a new outboard. Does anyone know:
1. Is short or long shaft preferred?
2. What is the ideal horsepower.
3. Which pitch screw is preferred: 7, 7.9, or 8 in.? The 7.9 comes standard.

Considerations: The vertical distance from mounting bracket to bottom of the hull in 13 in. But, wave action in a slow sailboat means one wants the screw buried a little deeper than in powerboats so it doesn't cavitate in seas. The formulae I've seen seem to apply to powerboars where you want the anticavitation plate 1-2 in. below the hull. A short shaft would put it about 4 in. below the hull. Is this enough? The long shaft would be about 9 in. below the hull. Another consideration is the larger head size of the new 4 stroke engines. Will the lazarette close completely? 2-strokers are illegal in California if made in 2001 or later. Would think the 7 in. pitch would be preferred with a 5.7 knot hull speed, but has anyone tried it? Would appreciate any experience out there.



gsmurphy@ix.netcom.com