[PUP] Get home engines

[John Marshall]

I'm sure you are right about prop inefficiency, Bob. My main can push  
the boat at about 7 knots on 70 horsepower while the wing barely gets  
over 5 knots with my 70 hp wing running flat out. Having the rudder  
over 8 to 10 degrees doesn't help. I have a three-blade Gori folding  
prop.

We had expected that the lack of thrust across the rudder would be a  
big deal when we trolled with the wing engine, running 1.5 to 2 knots,  
but there is (barely) adequate rudder capacity to handle the boat at  
that low speed in the kind of seas that are calm enough for fishing.  
Rudder authority gets decent above 3 knots and is more than adequate  
at 5 knots, as long as you give the AP enough authority (20 to 22  
degrees minimum).

Of course, the boat will only back in circles no matter how fast you go.

We played around with the wing once with the premise of getting some  
"twin engine" steerage effects out of it in case my thrusters died. It  
was awkward to use the two different control systems, one on each side  
of the instrument panel, but it kind of worked. Backing the main and  
revving the wing in forward turned the boat at lot faster than rudder  
alone, and also at zero speed. In a "thruster emergency", that's how  
I'd augment my rudder when coming into the dock. Clearly not nearly as  
good as twins from that regard, each of them off center, but better  
than nothing.

The idea of an extra rudder and better prop would improve situation a  
great deal, I'm sure. But given how incredibly reliable well- 
maintained diesel engines are, I'm content with the compromises I've  
got. I personally view the wing as something to maintain control of  
the boat while I figure out how to fix the main.

Regards
	John

John


On Sep 15, 2009, at 6:00 PM, bob Austin wrote:

> John,
> Have you ever considered a separate rudder for the wing engine?  I  
> have a friend who had several refinements:  1 a rudder, 2 counter  
> rotating from the main, 3 controlable pitch rather than folding.  He  
> was quite successful in using it for close quarters maneuvering.
>
> My observation is that most of the wings are so in-effecient because  
> they use less than maximum effeciency props.  For example, using a  
> Martec, vs a Maxiprop, the latter being more effecient.
>
> Take care,
>
> Bob Austin