The limit switches I installed in my Raymarine ST1000 Tillerpilot last
winter worked perfectly.

http://home.maine.rr.com/rlma/ST1000mods.htm

The unit functioned all season without my having to give it a second
thought.

"Strider" was decommissioned on the Equinox, six weeks earlier than normal
due to my upcoming month long trip to observe completion, sea trials, and
delivery of the "R/V Rachel Carson".

http://www.umces.edu/vessel/progress.html

I thus join the many landbound members of this group till spring. I will
have a couple more weeks of boating though, listening to 2400 HP of MTU
diesels driving tons of water through the twin Hamilton waterjets at speeds
over 20 knots. It's always a thrill watching a boat I designed come to life
and this one will probably be my magnum opus.

--
Roger Long

"Roger Long" wrote in
:

I will
have a couple more weeks of boating though, listening to 2400 HP of
MTU diesels driving tons of water through the twin Hamilton waterjets
at speeds over 20 knots. It's always a thrill watching a boat I
designed come to life and this one will probably be my magnum opus.


Thank goodness the taxpayers are paying at the fuel dock...(c;

That's one of those boats where when you shove the throttles up it sounds
like someone flushing a toilet in the daytank....(c;

Knowing how inefficient the jets are, how many GPH is she guzzling at 20
knots?

"Larry" wrote


Knowing how inefficient the jets are, how many GPH is she guzzling at 20
knots?


These boats actually spend a small proportion of their time at cruising
speed and only about 10% flat out. Most of the time is spent maneuvering
around slowly. The jets are even more inefficient at those low speeds but
total power requirements are so low that it isn't a big issue.

The real efficiency for a boat running around doing research in a shallow
bay is being able plow through an oyster bar if there is a navigational
error and still being operational as opposed to needing to be towed
immediately to a shipyard where they would spend the better part of a year's
fuel bill. The additional shallow areas they can operate in safely also
greatly increase her scientific value. There are hundreds of square miles
open to here that would be closed to a prop version.

Of course, two years ago, when we were all sitting around running the
numbers for jets vs props, we were saying, "Wow, even if fuel goes as high
as three bucks a gallon, these numbers still favor jets."

--
Roger Long

On Tue, 23 Sep 2008 13:27:29 +0000, Larry wrote:

"Roger Long" wrote in
:

I will
have a couple more weeks of boating though, listening to 2400 HP of
MTU diesels driving tons of water through the twin Hamilton waterjets
at speeds over 20 knots. It's always a thrill watching a boat I
designed come to life and this one will probably be my magnum opus.


Thank goodness the taxpayers are paying at the fuel dock...(c;

That's one of those boats where when you shove the throttles up it sounds
like someone flushing a toilet in the daytank....(c;

Knowing how inefficient the jets are, how many GPH is she guzzling at 20
knots?

It's easy enough to do a ball park estimate. Assume something like
2/3rds power at cruising speed, and 1 gph for every 20 hp. That works
out to about 80 or 90 gph, about the same as a big sportfish or
motoryacht comparably powered. That seems like a lot at first glance
but I doubt they will be doing much long range cruising with it.

I also forgot to mention that the jets are one size larger than would
normally be installed. Like props, their efficiency goes up with diameter.
The boat will be moving more water at a slower speed so the effeciency won't
be as bad as on a yacht where they would probably install a jet one size
smaller than would be optimum for boat and engine size.

--
Roger Long

"Roger Long" wrote in
:

The real efficiency for a boat running around doing research in a
shallow bay is being able plow through an oyster bar if there is a
navigational error and still being operational as opposed to needing
to be towed immediately to a shipyard where they would spend the
better part of a year's


Is there anywhere I can see a cutaway of what the pump looks like, inside.
My experience is with jetskis and small, single impeller jet boats. If
these pumps suck in anything bigger than a dime, it wedges itself in
between the impeller's aft end and the stator's forward end, destroying the
pump, most times catastrophically, i.e. they explode.

Those pumps must have some way to keep the rocks passing through the moving
parts and not getting wedged in between the moving parts and the static
parts that keep the flow from being rotational, instead of straight back
power.

We're very careful not to get Mercury Sport Jets and jetski pumps anywhere
near anything solid it can suck up. The bar gaps in the intake grates is
way too far apart for efficiency to filter out the rocks that will destroy
them.

Wayne.B wrote in
:

It's easy enough to do a ball park estimate. Assume something like
2/3rds power at cruising speed, and 1 gph for every 20 hp. That works
out to about 80 or 90 gph, about the same as a big sportfish or
motoryacht comparably powered. That seems like a lot at first glance
but I doubt they will be doing much long range cruising with it.



My only experience with larger motoryachts is the Hatteras 56 FBMY owned
by a friend. Her twin 730hp 8V92-TA twin turbocharged diesels could
make the fuel flow meter read 56 GPH if you ran her wide open, giving
Dan heart palpitations if he saw it...(c;

He drove it around like a trawler with a 50hp Perkins in it. Offshore,
I took the opportunity to clean the carbon deposits out of the exhausts,
leaving a really impressive black cloud miles long...covering up the
trail from the outlet of the mascerator pump.

She always ran better and started easier after I cleared her throat. Of
course, the number of no wake zones makes her planing areas rather
limited. She could make a beautiful wake going off towards the elated
surfers near the beach....

Opening an engine room door at WOT, it's a great idea to be wearing
hearing protection. Big two strokers can be LOUD!

As soon as I got her systems working, they decided they were too old to
haul it all down the marina docks any more, sold her and moved into a
nice house in a gated community in Mt Pleasant. Dan's wife said we
looked lost on weekends without the engine rooms to play in. She wanted
to get us an 8V92TA on a big engine stand for the multicar garage we
could take apart and put back together on Saturdays....(c;

I don't think the new snooty neighbors would have the same appreciation
for its wonderful sound revving up that we do, so the project was
scrapped before it started.

http://www.youtube.com/watch?v=aTRHYvVysQI
Dan's ran just like these....

Roger Long wrote:
The limit switches I installed in my Raymarine ST1000 Tillerpilot last
winter worked perfectly.

http://home.maine.rr.com/rlma/ST1000mods.htm

The unit functioned all season without my having to give it a second
thought.

Good for you! I have a ST4000 wheelpilot, it's old and the gears in the
drive motor stripped last year.

Those nice folks at Raymarine won't sell you replacement gears, but they
will sell a complete motor assembly, for a mere $500.

I went to a local surplus store and bought a brand new power window
motor for 12 bucks. An afternoon's work in the shop and I had it fitted
to the ring assembly that turns the wheel..

Has worked a treat all summer.\


Cheers
Marty

On Tue, 23 Sep 2008 09:50:10 -0400, "Roger Long"
wrote:

"Larry" wrote


Knowing how inefficient the jets are, how many GPH is she guzzling at 20
knots?


These boats actually spend a small proportion of their time at cruising
speed and only about 10% flat out. Most of the time is spent maneuvering
around slowly. The jets are even more inefficient at those low speeds but
total power requirements are so low that it isn't a big issue.

The real efficiency for a boat running around doing research in a shallow
bay is being able plow through an oyster bar if there is a navigational
error and still being operational as opposed to needing to be towed
immediately to a shipyard where they would spend the better part of a year's
fuel bill. The additional shallow areas they can operate in safely also
greatly increase her scientific value. There are hundreds of square miles
open to here that would be closed to a prop version.

Of course, two years ago, when we were all sitting around running the
numbers for jets vs props, we were saying, "Wow, even if fuel goes as high
as three bucks a gallon, these numbers still favor jets."

Been driving the same Turbocraft jet drive runabout for fifty years.
Came with a 109 hp Graymarine flathead six that you could kick start
with a crank. Handy, since the only thing that ever went wrong was the
reverse rotation starter, that took weeks to replace.[ flywheel was at
the front of the engine.] Replaced it with a Buick V-6 that my brother
marinized with kit parts. Great boat. Came with lifting eyes. The
front one is ideal for the anchor. There are chocks for the rode. The
rear one is ideal to attach the ski tow line. Came with clamshell
vents on the gunnels. Remote operated spotlight. The engine is
central, under a doghouse that detaches with two one finger latches.
It has a hinged lid, to open for ventilation before starting engine.
You can sit in it, it's padded. You you lift out the rear bench seat,
just forward of the fuel tank and fill the oil cups on the pump while
the nonexistant fumes escape. Came with both bilge fan and bilge pump.
Both trouble free all these years. Hull number 10 of the first jet
boats sold in the US. One oddity is the foot operated
throttle that is not a red hot idea.

Casady

On Tue, 23 Sep 2008 09:50:10 -0400, "Roger Long"
wrote:

The real efficiency for a boat running around doing research in a
shallow bay is being able plow through an oyster bar if there is a
navigational error and still being operational as opposed to needing to
be towed immediately to a shipyard where they would spend the better
part of a year's fuel bill. The additional shallow areas they can
operate in safely also greatly increase her scientific value.

Breaking this out for emphasis:

There are hundreds of square miles open to her that would be closed to
a prop version.

It seems you don't know the Chesapeake Bay well.

The Bay stretches 200 nm, covers 64,000 square miles, and has 12,000
miles of shoreline. Its average depth is 21'. More than 24% of it is
less than 6 feet deep. No, that is not a typo.

The jets extend your baby's working area by tens of thousands of square
miles of the most environmentally "interesting" areas.

And you don't "plow" through an oyster bar, you *hit* one and stop
very, very quickly. Your hazard is the junk suspended in the foot or
two of soft mud on the usual bottom. Though we draw 4', we often anchor
in 4.5' at high tide, sometimes see stretches of 3' as we gunkhole
(cautiously) through skinny water to get to a good anchorage, sometimes
see the knotmeter reading higher than the depth sounder -- and feel no
need to tack.

Yup, it's different than you're used to.

The Bay is unique, the world's largest estuary. We've explored it for
25 years and still haven't gotten to some of the places on our list.

Enjoy discovering the Bay on your sea trials.

--
Jere Lull
Xan-à-Deux -- Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/