Fuel economy of older jet boats
 

On Jul 3, 4:03*pm, JimH wrote:
On Jul 3, 3:58*pm, JimH wrote:



On Jul 3, 2:31*pm, "Reginald P. Smithers III" "Reggie is Here

wrote:
HK wrote:
Reginald P. Smithers III wrote:
HK wrote:
Reginald P. Smithers III wrote:
HK wrote:
Richard Casady wrote:
On Wed, 02 Jul 2008 23:46:08 +0000, Larry wrote:

In a Sea Rayder 16' jetboat, the 175hp, 6-cylinder Sport Jet will
guzzle around 14-20 gallons a day, especially if you drive it
like you stole it or pull skiiers for hours.

That statement is useless without a time factor better than 'per
day',
Eight hour day would be maybe 2 gallons per hour. I don't think that
is what you meant.

Casady

Really, and 14-20 gallons wouldn't be that much for any boater with
an engine around that size who ran at a high cruise or was pulling
tubes or skiers.

You don't pull skiers, wakeboarders or tubes at high cruise.

Try reading the sentence again, braindead.

"...ran at high cruise *or* was pulling tubes or skiers."

My experience is that pulling a skier/tube at 3000 rpm, or a
wakeboarder at 2200 rpm would burn about the same or maybe slightly
more than running at 3400 without towing anyone.

What have you noticed when you are pulling skiers/wakerboarders and
tubers?

What I noticed is you cannot properly decode a simple sentence.

So are you saying there is *no appreciable difference between cruising
at 3400 rpm and pulling water toys at 2200-3200?

Could be IMO. * Depends on the boat and how it is powered.

It also depends on many other factors such as number of passengers
aboard when doing 3400 rmp and pulling water toys at 2200 rpm.

All things being equal, I doubt pulling folks in water toys and in the
boat at 3200 rmp is the same fuel burn rate as simply cruising with
those folks (no water toys) at 3400 rpm.

edit

Fuel economy of older jet boats
 

I've read that the jet boat's impeller system is about 30% less efficient
than a similarly powered outboard. Does that mean that a jet boat will get
beat by an outboard, or just use more gas?

I've got a Whaler Rage 14, and skipping along at 25-30mph it seems efficient
when lightly loaded.
It will go through 5 gallons of gas after several hours of mixed running,
but I haven't done any extended runs that would allow me to measure the mpg.

Fuel economy of older jet boats
 

On Fri, 4 Jul 2008 08:15:19 -0400, "Floyd"
wrote:

I've read that the jet boat's impeller system is about 30% less efficient
than a similarly powered outboard. Does that mean that a jet boat will get
beat by an outboard, or just use more gas?

The jet will have a lower top speed. It will burn more fuel at any and
all lower speeds.

Casady

Fuel economy of older jet boats
 

"Richard Casady" wrote in message
...
On Fri, 4 Jul 2008 08:15:19 -0400, "Floyd"
wrote:

I've read that the jet boat's impeller system is about 30% less efficient
than a similarly powered outboard. Does that mean that a jet boat will
get
beat by an outboard, or just use more gas?

The jet will have a lower top speed. It will burn more fuel at any and
all lower speeds.

Casady

It will burn more fuel. May or may not be faster. There are different type
pumps. There are axial flow, low pressure pumps that are slower speed, but
handle white water better at reloading up after losing intake water, and
there are the high pressure pumps that are faster. Kodiak and Hamilton are
examples of the first, Berkeley and American Turbine are examples of the
second. Jet ski pumps are probably the most inefficient of all the pump
designs. Small engine and high RPM's trying to move lots of water through a
small impeller pump. The newer Hamilton 212's etc are about 95% efficiency
of props.

Fuel economy of older jet boats
 

On Fri, 4 Jul 2008 15:19:27 -0700, "Calif Bill"
wrote:


"Richard Casady" wrote in message
.. .
On Fri, 4 Jul 2008 08:15:19 -0400, "Floyd"
wrote:

I've read that the jet boat's impeller system is about 30% less efficient
than a similarly powered outboard. Does that mean that a jet boat will
get
beat by an outboard, or just use more gas?

The jet will have a lower top speed. It will burn more fuel at any and
all lower speeds.

Casady

It will burn more fuel. May or may not be faster. There are different type
pumps. There are axial flow, low pressure pumps that are slower speed, but
handle white water better at reloading up after losing intake water, and
there are the high pressure pumps that are faster. Kodiak and Hamilton are
examples of the first, Berkeley and American Turbine are examples of the
second. Jet ski pumps are probably the most inefficient of all the pump
designs. Small engine and high RPM's trying to move lots of water through a
small impeller pump. The newer Hamilton 212's etc are about 95% efficiency
of props.

Our Turbocraft is axial flow, and in fifty years has never sucked air
into the intake. Weeds once. Once the ski tow rope. Had to turn the
engine and pump backwards, with a pipe wrench on the driveshaft, to
get it out. The pump is a licenced copy of a [New Zealand] Hamilton.

Casady

Fuel economy of older jet boats
 

"Richard Casady" wrote in message
...
On Fri, 4 Jul 2008 15:19:27 -0700, "Calif Bill"
wrote:


"Richard Casady" wrote in message
. ..
On Fri, 4 Jul 2008 08:15:19 -0400, "Floyd"
wrote:

I've read that the jet boat's impeller system is about 30% less
efficient
than a similarly powered outboard. Does that mean that a jet boat will
get
beat by an outboard, or just use more gas?

The jet will have a lower top speed. It will burn more fuel at any and
all lower speeds.

Casady

It will burn more fuel. May or may not be faster. There are different
type
pumps. There are axial flow, low pressure pumps that are slower speed,
but
handle white water better at reloading up after losing intake water, and
there are the high pressure pumps that are faster. Kodiak and Hamilton
are
examples of the first, Berkeley and American Turbine are examples of the
second. Jet ski pumps are probably the most inefficient of all the pump
designs. Small engine and high RPM's trying to move lots of water through
a
small impeller pump. The newer Hamilton 212's etc are about 95%
efficiency
of props.

Our Turbocraft is axial flow, and in fifty years has never sucked air
into the intake. Weeds once. Once the ski tow rope. Had to turn the
engine and pump backwards, with a pipe wrench on the driveshaft, to
get it out. The pump is a licenced copy of a [New Zealand] Hamilton.

Casady

Mine is a Kodiak 3 stage that is a licensed copy of an older hamilton. I
have sucked weeds several times and sticks a couple times. Does not take
much of a stick stuck in the impeller to cause cavitation. Makes me think
a lot of prop boats with small dings in the prop are effecting performance
huge amounts.

Fuel economy of older jet boats
 

"Calif Bill" wrote in
m:

Mine is a Kodiak 3 stage that is a licensed copy of an older hamilton.
I have sucked weeds several times and sticks a couple times. Does
not take much of a stick stuck in the impeller to cause cavitation.
Makes me think a lot of prop boats with small dings in the prop are
effecting performance huge amounts.




Jetboat Economy.....ha ha ha....you guys are too funny!

Isn't that an oxymoron??

Fuel economy of older jet boats
 

"Larry" wrote in message
...
"Calif Bill" wrote in
m:

Mine is a Kodiak 3 stage that is a licensed copy of an older hamilton.
I have sucked weeds several times and sticks a couple times. Does
not take much of a stick stuck in the impeller to cause cavitation.
Makes me think a lot of prop boats with small dings in the prop are
effecting performance huge amounts.




Jetboat Economy.....ha ha ha....you guys are too funny!

Isn't that an oxymoron??


I did not buy an aluminum jetboat for the economy. I bought it to run
shallow and tree filled rivers. Better economy than a jetski. My 351W
engine got me about 2 mpg, 3400# 21' boat. The newer 5.7L mpi gets better,
but have not really checked on the mpg yet.

Fuel economy of older jet boats
 

On Jul 3, 4:03*pm, JimH wrote:
On Jul 3, 3:58*pm, JimH wrote:





On Jul 3, 2:31*pm, "Reginald P. Smithers III" "Reggie is Here

wrote:
HK wrote:
Reginald P. Smithers III wrote:
HK wrote:
Reginald P. Smithers III wrote:
HK wrote:
Richard Casady wrote:
On Wed, 02 Jul 2008 23:46:08 +0000, Larry wrote:

In a Sea Rayder 16' jetboat, the 175hp, 6-cylinder Sport Jet will
guzzle around 14-20 gallons a day, especially if you drive it
like you stole it or pull skiiers for hours.

That statement is useless without a time factor better than 'per
day',
Eight hour day would be maybe 2 gallons per hour. I don't think that
is what you meant.

Casady

Really, and 14-20 gallons wouldn't be that much for any boater with
an engine around that size who ran at a high cruise or was pulling
tubes or skiers.

You don't pull skiers, wakeboarders or tubes at high cruise.

Try reading the sentence again, braindead.

"...ran at high cruise *or* was pulling tubes or skiers."

My experience is that pulling a skier/tube at 3000 rpm, or a
wakeboarder at 2200 rpm would burn about the same or maybe slightly
more than running at 3400 without towing anyone.

What have you noticed when you are pulling skiers/wakerboarders and
tubers?

What I noticed is you cannot properly decode a simple sentence.

So are you saying there is *no appreciable difference between cruising
at 3400 rpm and pulling water toys at 2200-3200?

Could be IMO. * Depends on the boat and how it is powered.

It also depends on many other factors such as number of passengers
aboard when doing 3400 rmp and pulling water toys at 2200 rpm.

All things being equal, I doubt pulling folks in water toys and in the
boat at 3200 rmp is the same fuel burn rate as cruising with with
those folks at 3400 rpm.- Hide quoted text -

- Show quoted text -

I find that pulling people tends to burn more fuel than cruising at
any speed. It's the getting up on plane quickly a lot that eats up
the gas. Also because it's often my teenager and her friends and they
tend to explore the limits. Which means they end up not on the end of
the rope anymore a lot.

Fuel economy of older jet boats
 

"Calif Bill" wrote in
m:

I did not buy an aluminum jetboat for the economy. I bought it to run
shallow and tree filled rivers. Better economy than a jetski. My
351W engine got me about 2 mpg, 3400# 21' boat. The newer 5.7L mpi
gets better, but have not really checked on the mpg yet.



What's really unfortunate is the unscrupulous American dealers for the
Mercury Sport Jet-powered boats and PWC dealers who purposely DON'T tell
new owners their jets will be destroyed if they suck up a rock the diameter
of a quarter and get it wedge between the whirling impeller and the stator
1/8" behind it in the flow. Many PWC and jetboats are destroyed here
because owners don't know the difference between Australian-style flats
boats powered by filtered jets with no stator and what's being sold as
jetboats in the USA....never made to handle a rock.