Bart wrote:
....

I like your logic Jeff. My opinion also. The danger of going too
small
is not a happy one, while going too big is not a terrible penalty.

One thing I forgot to mention is that the number presumes a reasonable
prop - one that's about 55% efficient. If you use a 2 blade folder,
you might think you're underpowered. Mine work OK, but given my light
weight (10K lbs) and slippery hulls (11:1 length to beam) I really
expected to be able to power over 10 knots, but 8.5 is the practical
limit.

Also, while I think you have enough juice for your needs, I don't
think you will be overpowered. If you were using it as a motorsailer,
and expecting to exceed hull speed even when fighting a headwind,
you'd want 100 hp or more. And you'd probably be swinging a 4 blade
prop, although you can make a good case for a big variable pitch prop
on a motorsailer.

Bart wrote:
I like your logic Jeff. My opinion also. The danger of going too
small
is not a happy one, while going too big is not a terrible penalty.

Well, it costs more money, plus loss of space in the boat &
added weight. It's a case of "more is better" (up to a degree).


Jeff wrote:
One thing I forgot to mention is that the number presumes a reasonable
prop - one that's about 55% efficient. If you use a 2 blade folder, you
might think you're underpowered.

Yes but with a too-small or ineffective prop, more
horsepower isn't going to do much good, it's only going to
make bubbles & waste fuel.


.... Mine work OK, but given my light
weight (10K lbs) and slippery hulls (11:1 length to beam) I really
expected to be able to power over 10 knots, but 8.5 is the practical limit.


Wouldn't have expected that... is that full RPMs? Do you
think it's the props?


Also, while I think you have enough juice for your needs, I don't think
you will be overpowered. If you were using it as a motorsailer, and
expecting to exceed hull speed even when fighting a headwind, you'd want
100 hp or more. And you'd probably be swinging a 4 blade prop, although
you can make a good case for a big variable pitch prop on a motorsailer.

Yes, that would be the way to go. As for horsepower, we have
become lazy & spoiled... most boats could do quite well with
far less than the owner think acceptable... and I mean
sailboats, not the obscenely overpowered motor boats (for
example, my own motorboat is overpowered by about 30%, which
I would not call obscene but it's got one of the smallest
engines I've ever heard of in a boat of it's type & size).

Fresh Breezes- Doug King

DSK wrote:
Yes, that would be the way to go. As for horsepower, we have
become lazy & spoiled... most boats could do quite well with
far less than the owner think acceptable... and I mean
sailboats, not the obscenely overpowered motor boats (for
example, my own motorboat is overpowered by about 30%, which
I would not call obscene but it's got one of the smallest
engines I've ever heard of in a boat of it's type & size).

I don't know Doug. I think I'd call that obscene.

.... my own motorboat is overpowered by about 30%, which
I would not call obscene but it's got one of the smallest
engines I've ever heard of in a boat of it's type & size).



Bart wrote:
I don't know Doug. I think I'd call that obscene.


Well what about the same hull & same disp with twin 400s? Or
those 16' sliver shaped bass boats with twin 225 outboards?

I know of two sisterships of ours, one has the same engine &
the owner grips that he wants twins & more power, the other
has a 165 Perkins and the owner thinks the boat has "about"
the right amount of power. I think it would do just fine
with 90hp.

A fellow I used to work with tried to earnestly convince me
that his 17' runabout absolutely needed more than 150 HP in
order to "plane properly." Oh well.

DSK

I think you should take it out and put in a steam engine.

DSK wrote:
.... my own motorboat is overpowered by about 30%, which
I would not call obscene but it's got one of the smallest
engines I've ever heard of in a boat of it's type & size).



Bart wrote:
I don't know Doug. I think I'd call that obscene.


Well what about the same hull & same disp with twin 400s? Or
those 16' sliver shaped bass boats with twin 225 outboards?

I know of two sisterships of ours, one has the same engine &
the owner grips that he wants twins & more power, the other
has a 165 Perkins and the owner thinks the boat has "about"
the right amount of power. I think it would do just fine
with 90hp.

Bart wrote:
I think you should take it out and put in a steam engine.

DSK wrote:
.... my own motorboat is overpowered by about 30%, which
I would not call obscene but it's got one of the smallest
engines I've ever heard of in a boat of it's type & size).

Bart wrote:
I don't know Doug. I think I'd call that obscene.

Well what about the same hull & same disp with twin 400s? Or
those 16' sliver shaped bass boats with twin 225 outboards?

I know of two sisterships of ours, one has the same engine &
the owner grips that he wants twins & more power, the other
has a 165 Perkins and the owner thinks the boat has "about"
the right amount of power. I think it would do just fine
with 90hp.

There's not enough room in his engine room...and he would have to put a
paddle wheel on back and then he wouldn't fit in his slip....

Bart wrote:
I think you should take it out and put in a steam engine.


That would suit me just fine. I am comfortable with
technology on the level of shoveling coal.

DSK

According to GPS I clocked ECHO powering at
8 knots+ @ 2500 rpm! It showed 9.4 knots!
At one point--which I do not believe [GPS's
can show erratic speeds at times]. However at
that rpm it never dropped below 8.0 knots and was
typically around 8.3 - 8.4 knots or more. At the time
I was in the channel going against a very slight flood
which I estimated at 0.0 knots to be conservative.
Yanmar specs say this is a burn rate of 2 gal/hr
for this rpm.

Later at against a stronger adverse current in the Sound,
the GPS showed a steady 6.3 to 6.4 knots. I'm guessing
my speed to be ~ 7 knots @ 2000 rpm. I'll have to do some
calculations to better estimate the current drift. Yanmar
specs stated a burn rate of only .96 gal/hr at that rpm. If
true then my expectations have been greatly exceeded. I
thought I would have to throttle back for fuel economy. Well
I can do that and still go fairly fast.

Hull speed was about 3300 rpm although I would have to test
more to be more accurate. It was throwing a pretty big double
wake at this rpm. The extra rpm does not seem to give me
much more speed for the extra throttle. Max rpm for the engine
is 3800 rpm and max long term cruise is 3500 or 3600 rpm.
I won't need to go that high unless perhaps I'm towing. I'm guessing
my speed was around 8.5 knots at 3300 rpm.

The engine was louder, and fuel consumption much higher I'm sure
for only a small gain in speed. On the plus side, I felt like I had
plenty of power in reserve. I will be able to motor along at lower rpm

and conserve fuel while making good speed.


Everyone aboard was impressed with the engine. I had doubts
about the motor making this much power at such a low rpm.
The large diameter, super efficient Flexofold prop seems to be
the key. The smart choice is to pick the best prop for motoring
in forward and reverse. Unlike feathering props the Flexofold has
a very efficient shape for motoring--both forward and reverse. The
folding feature gives it low drag under sail--of course anything is
an improvement over a fixed three-blade prop. I'm happy with the
choice. I could not have picked a better prop.

http://www.flexofold.com

This has been a great day. On par with the day I finished
painting ECHO a few years ago. Next up are new fuel tanks
and a larger rudder.

Yanmar recommends running in the engine at high rpms during the
break in period. So I was motoring faster than I would have normally
heading out of the marina.

On the humorous side, my transmission controls have been
reversed from the original shifter directions--up for forward/down
for reverse.

Leaving at nearly dead low, I managed to run agound on a sand
bar not listed on the chart. Which would have been no big deal,
except my transmission controls were reversed. After shifting to
neutral, I attempting to motor off. However, I shifted it back into
forward by mistake, and made the situation worse. In time I'm
sure I'll get used to the reversed controls. The combination
of running a little faster than normal and mixing up forward and
reverse combined to get me stuck pretty well.

Believe it or not I actually winched myself off using my
organ grinder! Frankly, I am flabbergasted that it worked!
I ground in the winch on high gear as far as it would go and
then switched to low gear and pulled myself off. The
anchor was set so well I had a harder time recovering it
than I did pulling myself off! In the past I'd thought about
removing the organ grinder, but it has come in so handy,
so many times. I can lead a line to it from any place on
the boat. No matter how high a load a sail or line puts on
it, a child could winch it in.

Lessons Learned: Never to work to someone elses
schedule. My crew was in a hurry to go home. I tried to
accomodate him. It was a mistake. I should have stayed
at the dock and found someone else.

Looking back on several situations in the past eight years where
I later regreted being in a hurry; in each case I was trying to
accomodate crew's schedules or trying to stick to my own plan,
and this got me into trouble. Sometimes plans need to be
changed!

Now that I have a reliable and efficient power plant, and a
comfortable boat, I can do it all myself. Additionally, I am going
to make a point to tell people that I am never on "a schedule".
Schedules cause problems. Breaking a schedule makes many
problems disappear.