vertical shaft engine in outboard well for blowing holes

[hobbit]

I have a vessel which has an outboard well in the cockpit. Would it be possible to mount a vertical shaft engine in the well to use as a blower? If so, what sort of HP would be needed...and what sort of prop size/pitch would be ideal....I am thinking about a vertical shaft diesel...any ideas on shaft length...is the whole idea crazy

[capt dom]

You are not crazy. The issue is engineering it correctly then fabricating it so it can be
removable. Take a look at the brand new 55 hp power head on the link below:

http://cgi.ebay.com/ws/eBayISAPI.dll...#ht_500wt_1156

This unit is light weight but gasoline driven. Its brand new and the price is right.
I have a few light weight, Kubota 2 cylinder Diesels but you would need a right angle drive to make it work.

You need to mount a prop into a solid thrust tube that is about two inches larger diameter than the prop then make a
circular intake screen about a foot tall weld a splined shaft to fit into the bottom of the engine and through the hole
in the engine well and either make the hole thing so it is removable or so you can raise it up and down, in the well.

[FISHEYE]

A 3-20 hp vertical shaft lawnmower engine will works too.Replace the bowl carburetor with a marine diaphragm carb.Keep in mind that whatever prop you use may have to be a left hand prop.I helped design a blower like this for a friend.You may have to have a prop shop bend a prop to be a left hand.Or cast your own prop.Or design it with a gearbox that reverses the prop.Also you have to have a way to attach the prop to a shaft.Most prop shafts are splined so you can use the stainless steel shaft off a outboard engine.And extend the shaft using some kind of a coupler that wont vibrate loose.You will need waterproof sealed bearings to support the shaft in the tube.Or just use brass or stainless steel bushings.You can use aluminum or PVC for the tube.You can have slots or cut outs for the water intake.Or extend the tube way below the engine with support brackets that are welded or bolted so they dont fall apart.Its all trial and error when building something like this.Honda lawnmower engines are the best to use.They start easy and are quiet.Some even have electric start.