Ken shared:  am considering swapping to the feathering (Hundestat)

props, although I probably won't do it for cost, and space reasons. I'm

still interested in being able to run in single engine configuration (on my

twin engine boat), during super-long passages, but the most likely scenario

is that I'll go with some sort of shaft locking system.

Scott wonders:  Ken, you have more money than God, why go through the
complexity of installing a shaft locking system when your only taking about
10 or 20% efficiency difference locking a wheel?  I'd think having both
those beautiful motors humming along in your engine room would be music to
your ears?  Considering the range on your boat I don't understand why you'd
want to shut an engine down?  How much fuel can you buy for the cost of
locking the shafts?  Call me stupid, but I just don't "get" it.

Scott Bulger, Alanui, N40II, Seattle WA

Scott said in response to my posting: "...Considering the range on your boat
I don't understand why you'd
want to shut an engine down?  How much fuel can you buy for the cost of
locking the shafts?  Call me stupid, but I just don't "get" it...."

Scott: The reason for trying to pick up the extra efficiency is being able
to run at the speed I'd like, with having an adequate fuel reserve.

Let's say I were doing the San Diego direct to the Marquesas run (I think
it's around 2,300nm). I carry only 3,000 gallons of fuel. On a passage like
this, I'd like to arrive with at least 500 gallons left over.

So .. I've got 2,500 gallons, to run 2,300 miles. In other words, I need to
consume no more than about 1.1 miles a gallon.

On my boat, at 7 knots, running twin engines, running at 1.1 miles per
gallon is possible (I think .. I've only done a little testing). The problem
is that I don't like the idea of running at 7 knots. We crossed the Atlantic
at 8.3 knots, and it felt like a good speed. The problem is how to "stretch"
my fuel. One technique is to run single engine, and the other is to carry
more fuel. Adding an extra 500 to 1,000 gallons of fuel is fairly easy. I
can also lock one shaft, and get the same effect.

Given that major passages like this are so rare, it might not be worth the
hassle to install extra "stuff" on my shafts, when the problem can so easily
be solved with fuel bladders. I always believe a boat should be optimized
for what you do a lot, not what you might do once or twice in the life of
the boat.

Actually, if I were 100% certain I could make the run at 7 knots, I would
just run at 7 knots, whether I liked it or not. On a passage such as the
Marquesas run, I would start at 7 knots or less, and only speed up when I
were 100% certain that I knew what my fuel range is. I'd relax a couple
days, do my fuel calcs, and perhaps speed up a little. A couple days later
I'd run the calcs again. Even if I load an extra 1,000 gallons of fuel, this
is still the approach I'll take.

All of this said.. we decided to cheat and take a third approach to solving
the problem, which is to pick a route that doesn't involve a long passage.
We will be crossing the Pacific via a route that makes our longest distance
between fuel stops only 1,000 miles. I can run this at 10.6 knots if I want!
(but, will probably slow down just to save money).

Now to switch to the other topic being discussed (which is the real topic of
this discussion)...

My prior boat (a Nordhavn 62) had a single engine, and a wing engine.

As Scott pointed out, a net that fouls the main prop, could foul the
feathering prop. But, the odds are low. Feathering props are feathered
during normal running. This means the blades are folded up, and the
feathering prop is not spinning. A net should not wrap itself around the
prop. On our Atlantic crossing, another Nordhavn did wrap a net around its'
prop, and ran for days to shore on the wing engine alone. [They did try to
cut off the net, but weren't able to]

Scott also mentions the issue of needing a separate supply of fuel for the
day tank. I agree. Without an ability to have the fuel for the wing engine
completely isolated from the main fuel supply, any fuel related failure,
which most diesel engine failures are, is likely to also clobber your wing
engine. On my N62 I was able to isolate the fuel for my wing engine, and
once when I was 200 miles offshore, I lost my main engine (fuel problem),
and ran to shore on the wing - no problem.

The bottom line: in both of these cases, without a wing engine, it would
have been a tough situation.

When I was "between trawlers," shopping for our present boat, it was amazing
how many boat manufacturers hadn't really thought through "get-home"
capability. I kept hearing about (from the salesmen) fishing boats running
the Bering Sea with a single engine, and no get-home capability. To me, this
is utter nonsense. Most commercial fishing boats have an engineer onboard,
serious dive equipment, and a good set of professional tools. Most
trawler-owners do not have an engineer aboard ship [Note: I'm a software
engineer, but that doesn't count]. Most are smart people, but I doubt a very
high percentage are adequately prepared to solve a serious diesel engine
problem or net-wrapped prop.

Some boat manufacturers do have complicated get-home setups, that assume you
can run a chain to your genset, so that it can power your prop. This
accomplishes nothing for a net-wrapped prop, and given that the main engine
never seems to fail when the sun is shining, and the seas are calm --
running that chain to the genset, in real-world conditions of a boat that is
being slammed, is not as easy as it sounds.

-Ken Williams
www.kensblog.com
Nordhavn 68, Sans Souci