On Mar 14, 6:30 pm, wrote:
"Wm Watt" wrote:
For "load" read "displacement"

Herein lies the problem. There's more to "load" than "displacement"
and some of it is unpredictable. For instance, how much wind will you
ever motor against? -shrug- Who knows?

Very true but wind is what makes sails work. (The questioner wanted an
outboard for when there was no wind.) Auxilliary power on sailboats is
almost exclusively for windless conditions and restricted waters
(approaching and leaving moorings, narrow channels, canals, lift
bridges, etc.). Wind and waves aren't a good reason for sizing the
auxilliary.

And how much current will you
ever motor against? -shrug again-

Yes, but useful power is limited by the boat's speed to length ratio,
where speed is relative to current. Trying to make headway against a
current which is about equal to "hull speed" is futile. Thankfully few
currents are quite so fast. There is only so much power you can
reasonably apply to a displacement hull. Any more and you're just
heating the atmosphere and wasting fuel.

Another part is, no matter how much horsepower you
generate with an engine, if you don't transfer it effectively to the
water with a proper prop, the hp is of no use. If I'm reading you
correctly though, your theory is for calculating only hp and leaves
other "pushing parts" to be calculated by some other theory. yes/no?

Yes, I've noted there has to be a conversion from nominal or rated
horsepower to effective horsepower.


Whatever the case, my theory is.... you can never have to much power.
You can have to much weight though, which is why I wish someone would
market a 2 cycle high thrust outboard.

Too much weight and fuel consumption, sort of an SUV of a sailboat.
Interesting to note that heavier engines increase displacement and add
somewhat to power requirement.

Wm Watt wrote:

On Mar 14, 6:30 pm, wrote:
"Wm Watt" wrote:
For "load" read "displacement"

Herein lies the problem. There's more to "load" than "displacement"
and some of it is unpredictable. For instance, how much wind will you
ever motor against? -shrug- Who knows?

Very true but wind is what makes sails work. (The questioner wanted an
outboard for when there was no wind.) Auxilliary power on sailboats is
almost exclusively for windless conditions and restricted waters
(approaching and leaving moorings, narrow channels, canals, lift
bridges, etc.). Wind and waves aren't a good reason for sizing the
auxilliary.

I think you should add conditions where tacking is impractical. I have had
to do my share of motor sailing into headwinds, and there, the sails were
used
more for stability than forward thrust.

Also, I agree entirely with Charlie Morgan about the effectivitiy of high
thrust
engines for sailboats. When shopping for a new engine for my 2 ton sailboat,

I originally bought a Honda. When I discovered it had a high gear ratio, I
returned
it and bought the High Thrust T9.9 Yamaha. It is a heavy engine, but I
installed an
assisted motor mount, which helps a lot. However, I can't lift the engine
into the
cockpit like I used to do with my Silver Century Seagull, another great
sailboat
engine with an even higher gear ratio than the Yamaha. I think Honda putting
a
larger prop on it's 'high-thrust', high gear ratio engine is a poor
compromise. It will
still churn up a lot of water, with reduced thrust. I prefer having an
engine with extra
reserve power. I have had too many occurences where my boat could not make
headway into very strong winds and/or currents. The only thing I don't like
about
my T9.9 are the tiny jets in the carburetor, which are continually blocking
up. I am
actively working on solutions for that, such as fine 10 micron inline filters
and changing
out my fuel system with newer hoses. Could also be the gasohol we get now,
despite
doctering it up with stabilizers. Yamaha has not come out with a good fix
yet, so I
hope my measures will get rid of the problem.

Sherwin D.



And how much current will you
ever motor against? -shrug again-

Yes, but useful power is limited by the boat's speed to length ratio,
where speed is relative to current. Trying to make headway against a
current which is about equal to "hull speed" is futile. Thankfully few
currents are quite so fast.

Guess you have never had to negotiate one of the many 'tidal cuts' in
Florida and the Bahamas, or ever tried to go upstream against a strong
current on the Mississippi River ( I have).

There is only so much power you can
reasonably apply to a displacement hull. Any more and you're just
heating the atmosphere and wasting fuel.

Not if your boat is going slower than it's hull speed.



Another part is, no matter how much horsepower you
generate with an engine, if you don't transfer it effectively to the
water with a proper prop, the hp is of no use. If I'm reading you
correctly though, your theory is for calculating only hp and leaves
other "pushing parts" to be calculated by some other theory. yes/no?

Yes, I've noted there has to be a conversion from nominal or rated
horsepower to effective horsepower.


Whatever the case, my theory is.... you can never have to much power.
You can have to much weight though, which is why I wish someone would
market a 2 cycle high thrust outboard.

Too much weight and fuel consumption, sort of an SUV of a sailboat.
Interesting to note that heavier engines increase displacement and add
somewhat to power requirement.

On Sat, 17 Mar 07, sherwindu wrote:
I can't lift the engine into the
cockpit like I used to do with my Silver Century Seagull

Tell me about it. Or it's nice to set it in cabin to lock it up. Plus
the tendency to list, and/or squat the stern, and lift the bow,
instead of adding stability low and amidships where weight needs to be
(I've almost convinced myself to go inboard next time.... but not
quite).

I think Honda putting a
larger prop on it's 'high-thrust', high gear ratio engine is a poor
compromise.

For you and me maybe. But for them, it's a profit maximizing decision
that prolly works pretty well on their bottom line. But at least
they're honest about what it'll do. They're claiming only a 15%
increase in thrust. Sounds about right to me.

The only thing I don't like about
my T9.9 are the tiny jets in the carburetor, which are continually blocking
up.

Honda has the same problem. I spent 30 minutes yesterday cranking and
cussin' at mine. Never did get it started. So it's off to the shop
with it (again). I no longer have the patience. Hopefully I'll get it
back in a few weeks (as opposed to months like last time). Meanwhile
I'll putter along with my ol' ancient standby Evinrude. It ALways
starts, no prob.

I am
actively working on solutions for that

If you come up with one, please post it here.

Rick

Actually, repairing a blocked carb on the Yamaha is tiresome, but not that
difficult.
After dissassembly, just run a very fine wire through the jets to open them up.

A more pro-active way would be to buy only premium gasoline. Make sure your
fuel system is clean, hoses, tanks, etc. Use a stabelizer like Sea Foam or
Stabil in
the gas tank. Put a fine filter (about 10 micron) in line with your fuel
delivery system.
I am going to try all the above next season. Now that I hear that Honda's have
the
same problem, I regret even less my decision to go with Yamaha. Honda is
obviously catering to the power boat community.

Sherwin D.

lid wrote:

On Sat, 17 Mar 07, sherwindu wrote:
I can't lift the engine into the
cockpit like I used to do with my Silver Century Seagull

Tell me about it. Or it's nice to set it in cabin to lock it up. Plus
the tendency to list, and/or squat the stern, and lift the bow,
instead of adding stability low and amidships where weight needs to be
(I've almost convinced myself to go inboard next time.... but not
quite).

I think Honda putting a
larger prop on it's 'high-thrust', high gear ratio engine is a poor
compromise.

For you and me maybe. But for them, it's a profit maximizing decision
that prolly works pretty well on their bottom line. But at least
they're honest about what it'll do. They're claiming only a 15%
increase in thrust. Sounds about right to me.

The only thing I don't like about
my T9.9 are the tiny jets in the carburetor, which are continually blocking
up.

Honda has the same problem. I spent 30 minutes yesterday cranking and
cussin' at mine. Never did get it started. So it's off to the shop
with it (again). I no longer have the patience. Hopefully I'll get it
back in a few weeks (as opposed to months like last time). Meanwhile
I'll putter along with my ol' ancient standby Evinrude. It ALways
starts, no prob.

I am
actively working on solutions for that

If you come up with one, please post it here.

Rick

On Wed, 21 Mar 07, sherwindu wrote:
Actually, repairing a blocked carb on the Yamaha is tiresome, but not that
difficult.
After dissassembly,

........ (the tiresome part.... as well as reassembly)

just run a very fine wire through the jets to open them up.

That's the "not that difficult" part.

A more pro-active way would be to buy only premium gasoline. Make sure your
fuel system is clean, hoses, tanks, etc. Use a stabelizer like Sea Foam or
Stabil in the gas tank. Put a fine filter (about 10 micron) in line with your fuel
delivery system.

Honda has a screw on the side of the carburetor that, with a half
turn, allows the bowl to drain (thru a tube, out, next to the pee
hole... pretty handy :-). My shop sevice manager says that's the most
important thing I can do to prevent gum up. "Running" the carb dry
won't empty it completely. He mentioned everything else on your list
as well.
I asked if I could have it back in a few days. He shook his head and
said "Maybe a few weeks". Frankly, my money's on "Months", we'll see.
Those guys *really* could use some competition around here. If I have
some spare time next weekend, I may pick it up and fix it myself (but
not at the expense of my warranty... need to check on that).

Now that I hear that Honda's have the
same problem, I regret even less my decision to go with Yamaha.

Next time, you might consider Mercury as well. They're building their
own powerheads this year (they no longer use Yamaha). And they have
two "sailboat" friendly 9.9's (large dia props, low gear ratio, 25"
shafts) which seem to be a few pounds lighter than Yamaha or Honda or
anybody else I can see. I'm not sure what the difference is between
those two models (Bigfoot & Prokicker) except Prokick offers power
trim. So Bigfoot is lighter (96lbs).

Rick

lid wrote:

On Wed, 21 Mar 07, sherwindu wrote:
Actually, repairing a blocked carb on the Yamaha is tiresome, but not that
difficult.
After dissassembly,

....... (the tiresome part.... as well as reassembly)

just run a very fine wire through the jets to open them up.

That's the "not that difficult" part.

A more pro-active way would be to buy only premium gasoline. Make sure your
fuel system is clean, hoses, tanks, etc. Use a stabelizer like Sea Foam or
Stabil in the gas tank. Put a fine filter (about 10 micron) in line with your fuel
delivery system.

Honda has a screw on the side of the carburetor that, with a half
turn, allows the bowl to drain (thru a tube, out, next to the pee
hole... pretty handy :-).

Yamaha has the same screw. If you are going to be away from the boat for more than
few weeks, you should drain the carbs. I don't think that will eliminate the
problem, but
will minimize it.

My shop sevice manager says that's the most
important thing I can do to prevent gum up. "Running" the carb dry
won't empty it completely. He mentioned everything else on your list
as well.
I asked if I could have it back in a few days. He shook his head and
said "Maybe a few weeks". Frankly, my money's on "Months", we'll see.
Those guys *really* could use some competition around here. If I have
some spare time next weekend, I may pick it up and fix it myself (but
not at the expense of my warranty... need to check on that).

Now that I hear that Honda's have the
same problem, I regret even less my decision to go with Yamaha.

Next time, you might consider Mercury as well.

I hope there will not be a next time for me as I am getting close to the age
of 'shipping oars'. Of course, if I find no solution to this carb problem, maybe
the next step is a class action suit against Yamaha. I paid big bucks for this
engine and got an unreliable pain in the neck.

They're building their
own powerheads this year (they no longer use Yamaha). And they have
two "sailboat" friendly 9.9's (large dia props, low gear ratio, 25"
shafts) which seem to be a few pounds lighter than Yamaha or Honda or
anybody else I can see.

Well, a 'few' pounds won't make a big difference. It remains to be seen just how
high (not low) a gear ratio they come up with. My Seagull had a whopping 4 to 1
ratio.
No manufacturer has yet come close to that. It seems like all these four strokes
have very
tiny jets for fuel economy or possibly pollution control. That makes them sitting
ducks for
blockage. When the outboard gurus come up with a solution for that one, I'm
interested.

I'm not sure what the difference is between
those two models (Bigfoot & Prokicker) except Prokick offers power
trim. So Bigfoot is lighter (96lbs).

My Yamaha is about 100 pounds, so 96 pounds is no big deal.

Sherwin



Rick

sherwindu wrote:
It remains to be seen just how
high (not low) a gear ratio they come up with.

You say to-may-to, I say to-mah-to. I'd say 4:1 is lower than 2.92:1.

My Seagull had a whopping 4 to 1ratio.

Yup, they don't make 'em like they used to. But wasn't it a much lower
horsepower engine? It would need all that leverage to push the same
load.

No manufacturer has yet come close to that.

Not that I know of either. At least not at 9.9hp or above. Your T9.9
is 2.92:1. That's as low as I've seen currently. Mercury is 2:42:1 and
Honda is 2.33:1.

My Yamaha is about 100 pounds, so 96 pounds is no big deal.

Yamaha spec sheet shows 108. For me, 12lbs might be big enough to tip
the balance, all else being equal.

Rick