On Nov 15, 2:59*pm, "Morgans" wrote:
"a" wrote

Even more aviation: you could not maintain altitude: couldn't get up
on to planning speed.
But 5 knots? My 25 foot swing keel O'Day (think of the keel as a
vertical wing) could do that in a reasonable breeze and it
was NOT a fast boat.

s
Not surprising, to me.

Every boat has a "hull speed" than can be calculated, relating mainly to
length, that applies in a strictly displacement mode. * *The longer, the
faster, generally. *The O'Day 25 (used to have one) had a hull speed of
about 6 1/4 knots. *To go faster you would have to apply enough HP (LOTS
more HP) to get up on plane, and I suspect the one engine in the power boat
did not have enough power to get it over the hump. *Also consider that a
considerable amount of one engine's HP would be consumed by rudder drag,
since the rudder would have to be nearly 45 degrees to keep the boat going
straight.. *Also, the 5 knots mentioned is probably not terribly accurate,
since the accuracy of a power boat's "speedometer" is not very good at low
speeds.

It hurts my head to think about what parts of the two engines were
common, and which were different.

Not that bad, I think. *Camshaft, crankshaft, oil pump, water pump, harmonic
ballancer, distributor, alternator.

_ Jim in NC

The notion of that O'Day hull on the plane scares me! There was no
plane as such on mine, it would have to be balanced on its centerline
somehow! Digging deep into memory I seem to remember speed increases
as power to the 1/4 power after a displacement hull is around hull
speed, trying to climb its bow wave. I think that also represents the
'kick' in power it takes a planing hull to get on its step. Hmm,
aviation link. Maybe sea planes?

There was talk a couple of decades ago about some airplanes getting on
their step, the idea might have been to getting past the desired
cruise speed then slowing down would lead to a more efficient AoA,
rather than doing what most of us do coming out of a climb -- just
accelerate to cruise, trim things up, then sit back and manage the
airplane.

I'm not sure, re common parts of an engine, that the alternator needs
to be different. I think they'd work either way, the rectifiers
wouldn't care about the phase of the AC at their input. You probably
meant to type fuel pump.