HP and Choice of Power Unit

[Kessica]

The boat I am planning on building is the 23 foot Wooden Shoe as detailed here : http://www.nexusmarine.com/wooden_shoe.html

The quoted engine size is between 160 and 220 hp for a cruise speed of 30 knots and a top speed of 45 knots.

I have read many threads here trying to understand HP and loadings etc, and as I undertstand it, the lower the HP the faster the revs will have to be to get the boat to travel at comparable speeds. Keeping the engine at full throttle will cut down on engine life.... Common sense that one.

I am in the UK and planning on using a diesel. After perusing Lancing Marine : http://www.lancingmarine.com/ It appears that there are many kits available.

Speed is not an issue, I dont necessarily want to travel at speed but just enjoy leisurely cruises using the smallest power unto as possible with the most efficiency. From what little information there is on this craft, I understand that this is a semi-displacement hull. It should be reasonably easy to get this hull up and onto the plane. If this speed were to be maintained with a little room for a sightly higher speed, could the engine capacity be reduced?? Or in other words what would be the minimum HP requirements be ?

A 6.2L Chevy is a rather huge lump and highly expensive. The plan is to try to get a second hand engine, recondition it and rebuild it and marinise it in the process. I have a good friend whi is a qualified mechanic and works on may engines, wo I can call up on for advice and help. I know I would probably end up spending as much but doing it myself will not only teach me more about the subject, I will be able to spread the cost whilst still remaining active on the project without having to take out a re-mortgage on the house simply for a engine !

Im still new the this whole area so please ignore my stupidity