On Sat, 28 Jun 2008 04:27:51 -0700 (PDT), Mark
wrote:

I'm seeing many older jet boats, say the 2000 sea-doo challenger 1800
or 2002 sea-doo islandia for sale locally. What are the fuel economy
on these older ones? Anyone know where you can find the information
out? Someone told me they get 5 hours on a tank, but I see the have
41gal tanks, so they are burning 8 gal/hour?

We have an example of the first jet boats sold in the US, a
turbocraft, SN 10. 1958 I seem to recall. Came with lifting eyes fore
and aft. You attached tow lines to the one and the anchor to the
other. Four clamshell vents at the gunnels. It came with a Graymarine
flathead six, 109 hp. My kid brother swapped in a Buick six that got
us 3700 RPM up from the 3200 we had been getting. Eighteen gallon
tank. Skiing it would go 3 hours or so. Neither engine was big enough
to drive the pump at rated engine speed and you can't change anything
out, like you can a prop or gearbox. So, many jet boats have a
mismatched drive train that may not be especially good for mileage. On
a small lake the actual top speed doesn't really matter much.

Casady

(Richard Casady) wrote in
:

you can't change anything
out, like you can a prop or gearbox.

Simply not true. There are the same kinds of impeller pitches as there are
props.

http://solas.com/products/pwc/impeller/impeller.htm

Older jetboats also have different impeller pitches available but are
getting hard to find. Try a prop shop in your area...

(Richard Casady) wrote in
:

you can't change anything
out, like you can a prop or gearbox.

Oh, about the SeaDooDoo Islandia powered by 2-stroke jetski engines....

Never talk about "mileage" around jetski-powered boaters. They just get
angry.

A properly tuned SeaDooDoo 2-stroker can eat 14 gallons per hour PER
ENGINE.

Don't forget to carry your VISA. You're gonna need it!

Though not as "cool", Mercury Sport Jet 2-strokers aren't so high
performance, trying to squeeze every rev out of a too-small jetski engine
whining away at high RPM to produce power. 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.

Jet boats are VERY inefficient power plants for anyone interested in fuel
management.

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

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.

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.

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."

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?

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.

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