RE: [bolger] Jet Ski motors, weight
Richard:
I sent your inquiry about jetski Hp and weight figures to Larry Pulyon and
he asked me to post this reply:
(Chuck)
Hey Richard,
The Kawasaki JS550 Jetski motor is actually 530cc's. You can figure in
the low 30 hp range as output for the average (worn) engine from the
eighties. Add about ten or twelve if the head has been shaved and another
few for after market pipe and larger carb. I figured the Jetfish motor to
be around 40 or so. But that can go up to a monster 100hp with full race
modifications! That why the best answer you can get is 35 - 45 hp range for
stock engines. I weighed the components and found the engine was fifty
ponds, pump, drive shaft, wires etc bring the package up to 75 lbs. The
portion of the jetski hull I used for engine mounts, driveshalft bulkhead,
and jet pump mount was 25 pounds. So, the dry weight can be safely figured
at an even 100 lbs and be very close.
A curious thing about these engines is there isn't a whole lot of
difference in weight and size between the 300cc and 750cc. So if you are
planning on powering a heavier boat you may want to consider going to the
larger engines. If you saw the Jetfish on the water at Jim's Messabout you
saw what a 550cc engine could do. There was a lot of power available, but
getting it to push a full sized boat through a pump designed for a much
lighter hull proves quiet a challenge.
Here's a link to my website that is devoted to using jetski power for
boats. Of particular interest to you will be the link entitled "Cut up Your
Jetski". There you will find a large number of photographs with step by
step instructions on cutting up a JS550 Jetski and "melding" it to a skiff
hull.http://jetjon.homestead.com/page1.html. There's a forum, and an
email link to me if you have questions. There are also photos of all the
jetski powered boats I know of (there's more, they just haven't found me
yet). I've been in three of them, xboat, Webbjet, and Jetfish. Tim has
very reasonably priced plans (Webbjet Link) that include an entirely
different engine mounting technique than I developed. I saw it, touched it,
and say it's good quality engineering. There's also an article about Lil
Squirt - my Australian friend Jason came up with nearly the exact same
layout as I did, and used it in a small picklefork hull. He said the ride
is invigorating and the turns awesome. There's also photos of other boats
in the gallery - some with emails. All of the people who posted their
emails did so to make themselves available to help others develop their own
boats. They are boat builders and boatlovers much like yourselves.
A final thought. There are thousands of jetskis out there that are
getting too old and ugly to keep up with the new monster skis but could
still serve as a whole new power source for homebuilders. It's something
like turning all the VWs into dune buggies, etc. back in the 70's. Yes they
are noisy and dirty and should probably be destroyed - but so are our
beloved outboards. I built the entire Jetfish (including trailer), cut it
apart, and am building it again all for far less than it would cost for a
single 25hp jet outboard! I you want to truly have fun with the 300 - 550cc
engines then design small two seater hulls for them that match their
performance capabilities. There are lot's of 10 and 12 foot designs that
have been forgotten but would make really interesting platforms for jetski
power. We'll, I guess that was the short answer. :-))
Larry
Jetfish Man
I sent your inquiry about jetski Hp and weight figures to Larry Pulyon and
he asked me to post this reply:
(Chuck)
Hey Richard,
The Kawasaki JS550 Jetski motor is actually 530cc's. You can figure in
the low 30 hp range as output for the average (worn) engine from the
eighties. Add about ten or twelve if the head has been shaved and another
few for after market pipe and larger carb. I figured the Jetfish motor to
be around 40 or so. But that can go up to a monster 100hp with full race
modifications! That why the best answer you can get is 35 - 45 hp range for
stock engines. I weighed the components and found the engine was fifty
ponds, pump, drive shaft, wires etc bring the package up to 75 lbs. The
portion of the jetski hull I used for engine mounts, driveshalft bulkhead,
and jet pump mount was 25 pounds. So, the dry weight can be safely figured
at an even 100 lbs and be very close.
A curious thing about these engines is there isn't a whole lot of
difference in weight and size between the 300cc and 750cc. So if you are
planning on powering a heavier boat you may want to consider going to the
larger engines. If you saw the Jetfish on the water at Jim's Messabout you
saw what a 550cc engine could do. There was a lot of power available, but
getting it to push a full sized boat through a pump designed for a much
lighter hull proves quiet a challenge.
Here's a link to my website that is devoted to using jetski power for
boats. Of particular interest to you will be the link entitled "Cut up Your
Jetski". There you will find a large number of photographs with step by
step instructions on cutting up a JS550 Jetski and "melding" it to a skiff
hull.http://jetjon.homestead.com/page1.html. There's a forum, and an
email link to me if you have questions. There are also photos of all the
jetski powered boats I know of (there's more, they just haven't found me
yet). I've been in three of them, xboat, Webbjet, and Jetfish. Tim has
very reasonably priced plans (Webbjet Link) that include an entirely
different engine mounting technique than I developed. I saw it, touched it,
and say it's good quality engineering. There's also an article about Lil
Squirt - my Australian friend Jason came up with nearly the exact same
layout as I did, and used it in a small picklefork hull. He said the ride
is invigorating and the turns awesome. There's also photos of other boats
in the gallery - some with emails. All of the people who posted their
emails did so to make themselves available to help others develop their own
boats. They are boat builders and boatlovers much like yourselves.
A final thought. There are thousands of jetskis out there that are
getting too old and ugly to keep up with the new monster skis but could
still serve as a whole new power source for homebuilders. It's something
like turning all the VWs into dune buggies, etc. back in the 70's. Yes they
are noisy and dirty and should probably be destroyed - but so are our
beloved outboards. I built the entire Jetfish (including trailer), cut it
apart, and am building it again all for far less than it would cost for a
single 25hp jet outboard! I you want to truly have fun with the 300 - 550cc
engines then design small two seater hulls for them that match their
performance capabilities. There are lot's of 10 and 12 foot designs that
have been forgotten but would make really interesting platforms for jetski
power. We'll, I guess that was the short answer. :-))
Larry
Jetfish Man
Oars are pretty close, particularly if you carve them from driftwood
with a knife you already have and use driftwood thole pins....
You could argue that ALL pollution comes from that power source, but
you could further argue that the pollution was going to happen with or
without the oars.
Another interesting source of propulsion:
Thomas Firth Jones, in "Boats to Go", describes an inboard made from a
Honda 4 stroke stationary engine. Air cooled. 5hp, with a reduction
gear, plenty of power for a Chebacco, probably more than enough due to
the reduction gear. No reverse, unfortunately. I'll bet he'd sell some
drawings
with a knife you already have and use driftwood thole pins....
You could argue that ALL pollution comes from that power source, but
you could further argue that the pollution was going to happen with or
without the oars.
Another interesting source of propulsion:
Thomas Firth Jones, in "Boats to Go", describes an inboard made from a
Honda 4 stroke stationary engine. Air cooled. 5hp, with a reduction
gear, plenty of power for a Chebacco, probably more than enough due to
the reduction gear. No reverse, unfortunately. I'll bet he'd sell some
drawings
--- In bolger@y..., pvanderw@o... wrote:
>
> Solar cells and wind turbines, if you are willing to overlook
> pollution during manufacture.
>
> --- In bolger@y..., "James Fuller" <james@p...> wrote:
> > I imagine that the molecules of pollution occur when the air is
> compressed.
> > probably using either natural gas or coal
> > to produce the electricity to run the compressor on land or gas or
> diesel to
> > run the compressor on the boat.
> > Its pretty hard to imagine any power source in use today that does
> not
> > pollute at some point in the energy cycle.
> >
> > James Fuller
> > ----- Original Message -----
> > From: <cliff25@w...>
> > To: <bolger@y...>
> > Sent: Monday, August 13, 2001 10:23 AM
> > Subject: Re: [bolger] Re: Jet Ski motors, weight
> >
> >
> > > <<I understand there is a method of propulsion (I don't remember
> the
> > > name) which involves a bunch of rotating vanes...>>
> > >
> > > The French have developed a compressed air engine that is in use
> today.
> > > The fleets of vans using them claim a 110 mile range, a top
speed
> of 65
> > > mph, and not a molecule of pollution. An onboard compressor can
> handle
> > > recharge needs. Sounds like the engine of the future to me.
Why
> not in
> > > boats?
> > >
> > > Cliff
Fine, but this has nothing to do with how that power is applied, and
I'd want a heck of a good maintenance program on the air tank so it
didn't explode my boat. I suppose the French used oilless air pumps
for zero pollution, and hand cranked them?
> > >
snip
> > >
> > >
I imagine that the molecules of pollution occur when the air is compressed.
probably using either natural gas or coal
to produce the electricity to run the compressor on land or gas or diesel to
run the compressor on the boat.
Its pretty hard to imagine any power source in use today that does not
pollute at some point in the energy cycle.
James Fuller
probably using either natural gas or coal
to produce the electricity to run the compressor on land or gas or diesel to
run the compressor on the boat.
Its pretty hard to imagine any power source in use today that does not
pollute at some point in the energy cycle.
James Fuller
----- Original Message -----
From: <cliff25@...>
To: <bolger@yahoogroups.com>
Sent: Monday, August 13, 2001 10:23 AM
Subject: Re: [bolger] Re: Jet Ski motors, weight
> <<I understand there is a method of propulsion (I don't remember the
> name) which involves a bunch of rotating vanes...>>
>
> The French have developed a compressed air engine that is in use today.
> The fleets of vans using them claim a 110 mile range, a top speed of 65
> mph, and not a molecule of pollution. An onboard compressor can handle
> recharge needs. Sounds like the engine of the future to me. Why not in
> boats?
>
> Cliff
>
>http://www.angelfire.com/mi/mmmkkk/
> (Last of the Red Hot DJs)
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or flogging dead horses
> - pls take "personals" off-list, stay on topic, and punctuate
> - add your comments at the TOP and SIGN your posts, snip all you like
> - To order plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA,
01930, Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject tohttp://docs.yahoo.com/info/terms/
>
>
>
Solar cells and wind turbines, if you are willing to overlook
pollution during manufacture.
pollution during manufacture.
--- In bolger@y..., "James Fuller" <james@p...> wrote:
> I imagine that the molecules of pollution occur when the air is
compressed.
> probably using either natural gas or coal
> to produce the electricity to run the compressor on land or gas or
diesel to
> run the compressor on the boat.
> Its pretty hard to imagine any power source in use today that does
not
> pollute at some point in the energy cycle.
>
> James Fuller
> ----- Original Message -----
> From: <cliff25@w...>
> To: <bolger@y...>
> Sent: Monday, August 13, 2001 10:23 AM
> Subject: Re: [bolger] Re: Jet Ski motors, weight
>
>
> > <<I understand there is a method of propulsion (I don't remember
the
> > name) which involves a bunch of rotating vanes...>>
> >
> > The French have developed a compressed air engine that is in use
today.
> > The fleets of vans using them claim a 110 mile range, a top speed
of 65
> > mph, and not a molecule of pollution. An onboard compressor can
handle
> > recharge needs. Sounds like the engine of the future to me. Why
not in
> > boats?
> >
> > Cliff
> >
> >http://www.angelfire.com/mi/mmmkkk/
> > (Last of the Red Hot DJs)
> >
> >
> > Bolger rules!!!
> > - no cursing, flaming, trolling, spamming, or flogging dead horses
> > - pls take "personals" off-list, stay on topic, and punctuate
> > - add your comments at the TOP and SIGN your posts, snip all you
like
> > - To order plans: Mr. Philip C. Bolger, P.O. Box 1209,
Gloucester, MA,
> 01930, Fax: (978) 282-1349
> > - Unsubscribe: bolger-unsubscribe@y...
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
> >
Seehttp://jetjon.homestead.com/page1.html
Bruce
Bruce
--- In bolger@y..., richard@s... wrote:
> So, to go along with my very modern looking Bolger Chebacco
Cruiser,
> I"m toying with replacing the outboard and slop well with the
> recycled power unit from a jet ski!
>
> Anybody have any HP and weight figures for the powerhead? Anyone
know
> where to look?
The horsepower and fuel consumption are way out of line for
a sailboat. The minimum is in the 40 hp range, and I suspect
that some are up over 100 hp since the last time I looked.
If you wanted to do a river running Diablo on the other hand
this might be just the ticket. I was thinking of trying one
in western AK 7-8 years ago. The powerheads and drives were
pretty simple in the ones I looked at and I didn't think
that it would be difficult to mount one in a conventional
boat. They are not efficient.
HJ
richard@...wrote:
a sailboat. The minimum is in the 40 hp range, and I suspect
that some are up over 100 hp since the last time I looked.
If you wanted to do a river running Diablo on the other hand
this might be just the ticket. I was thinking of trying one
in western AK 7-8 years ago. The powerheads and drives were
pretty simple in the ones I looked at and I didn't think
that it would be difficult to mount one in a conventional
boat. They are not efficient.
HJ
richard@...wrote:
>
> So, to go along with my very modern looking Bolger Chebacco Cruiser,
> I"m toying with replacing the outboard and slop well with the
> recycled power unit from a jet ski!
>
> Anybody have any HP and weight figures for the powerhead? Anyone know
> where to look?
>
>
<<I understand there is a method of propulsion (I don't remember the
name) which involves a bunch of rotating vanes...>>
The French have developed a compressed air engine that is in use today.
The fleets of vans using them claim a 110 mile range, a top speed of 65
mph, and not a molecule of pollution. An onboard compressor can handle
recharge needs. Sounds like the engine of the future to me. Why not in
boats?
Cliff
http://www.angelfire.com/mi/mmmkkk/
(Last of the Red Hot DJs)
name) which involves a bunch of rotating vanes...>>
The French have developed a compressed air engine that is in use today.
The fleets of vans using them claim a 110 mile range, a top speed of 65
mph, and not a molecule of pollution. An onboard compressor can handle
recharge needs. Sounds like the engine of the future to me. Why not in
boats?
Cliff
http://www.angelfire.com/mi/mmmkkk/
(Last of the Red Hot DJs)
<<Transferring a drive train into a "normal" boat may void the exemption
rendering the installation in violation of federal law.>>
This is kind of silly but I can't resist. Why not then just mount the
whole jet ski into the cockpit of your homebuilt? No more tiller
problems!
;^)
Cliff
http://www.angelfire.com/mi/mmmkkk/
(Last of the Red Hot DJs)
rendering the installation in violation of federal law.>>
This is kind of silly but I can't resist. Why not then just mount the
whole jet ski into the cockpit of your homebuilt? No more tiller
problems!
;^)
Cliff
http://www.angelfire.com/mi/mmmkkk/
(Last of the Red Hot DJs)
Chris
The Voith-Schneider drive could certainly be used on a boat with a flat section under which to mount
it. The problem comes that it is seriously complex, requiring good engineering to make in the first
place and high maintenance during its operating life. These factors would seem to make it not
suitable on a boat which was designed to be economical. Putting her aground on even the softest
mudbank might turn out to be awfully expensive. (Crack, Snapple & Pop sounds followed by expressions,
perhaps not mild, of dismay as the parts in the boat just went round and round and the boat stayed
just where she fetched up)
The publication "Boats and Harbors" regularly carries ads for an inexpensive, low power, air cooled,
diesel engine. When I spoke to the advertisers a couple of years ago, they hadn't found a reverse
gear to mount on it but one can be arranged with v-belts and a jackshaft. That might do the trick, be
affordable, and solve the problem.
Jim
smith@...wrote:
The Voith-Schneider drive could certainly be used on a boat with a flat section under which to mount
it. The problem comes that it is seriously complex, requiring good engineering to make in the first
place and high maintenance during its operating life. These factors would seem to make it not
suitable on a boat which was designed to be economical. Putting her aground on even the softest
mudbank might turn out to be awfully expensive. (Crack, Snapple & Pop sounds followed by expressions,
perhaps not mild, of dismay as the parts in the boat just went round and round and the boat stayed
just where she fetched up)
The publication "Boats and Harbors" regularly carries ads for an inexpensive, low power, air cooled,
diesel engine. When I spoke to the advertisers a couple of years ago, they hadn't found a reverse
gear to mount on it but one can be arranged with v-belts and a jackshaft. That might do the trick, be
affordable, and solve the problem.
Jim
smith@...wrote:
> --- In bolger@y..., "Lincoln Ross" <lincolnr@m...> wrote:
> > I understand there is a method of propulsion (I don't remember the
> > name) which involves a bunch of rotating vanes sticking out of the
> > bottom of the boat, which are angled as they go around to produce
> > thrust in any desired direction. I think they are used on tugboats,
> > but I wonder if there are small units meant as bow thrusters on big
> > yachts? Maybe one of these could be adapted? I'm thinking maybe
> > there would be a way to get the vanes all pointed forward when not
> > in use, so it wouldn't drag much while sailing.
>
> These are cycloidal drives, the most common name associated with
> their production being Voith-Schneider. There is a good picture at
>http://homepages.svc.fcj.hvu.nl/brok/legomind/insights/roer/intro.html
> but the description of how it works is not quite perfect.
>
> These have been available for scale model boats for some time,
> and there is a fantastic animated graphic at
>http://members.surfeu.at/fprossegger/english/vsp-function.html
> This picture is worth thousands of words of description, especially
> because you can't even see this action if you see a real boat in
> operation! The theory is similar to that required to understand how
> helicopter rotors generate directional thrust.
>
> The key advantages are perfect directional control, the ability to
> run the drive motors at a constant RPM (for peak power) and the
> large blade area at constant speed can give significantly lower
> noise levels than a standard prop with it's higher tip speeds.
> Cycloidal drives sometimes see work in minehunters for this reason.
>
> Given the low power requirements of most Bolger size boats, it might
> even be possible to build your own drive. The theory is quite
> straight-forward (even if the drive isn't!) and many of the boats
> with a flatter bottom might easily be adapted to one of these.
>
> Remember that the drive is both your prop and rudder. At the rear, it
> can function as a source of vectored thrust. If placed forward under
> the bow (as on harbour tugs), you would want a vertical "fixed
> rudder" to anchor to back, give directional stability underway, and
> to act as a pivot when you use "side thrust" on the forward mounted
> unit.
>
> Finally, as to reducing drag, consider that the blades have a
> constant cross section, and could be withdrawn vertically into the
> hull, allowing for alternate propulsion or beaching. Drawings of
> harbour tugs with this drive show a substantial steel cage, capable
> of supporting the weight of the vessel, around the drive unit.
>
> --------------------------------------------------
> Chris Smith <smith@...>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or flogging dead horses
> - pls take "personals" off-list, stay on topic, and punctuate
> - add your comments at the TOP and SIGN your posts, snip all you like
> - To order plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject tohttp://docs.yahoo.com/info/terms/
--- In bolger@y..., "Lincoln Ross" <lincolnr@m...> wrote:
their production being Voith-Schneider. There is a good picture at
http://homepages.svc.fcj.hvu.nl/brok/legomind/insights/roer/intro.html
but the description of how it works is not quite perfect.
These have been available for scale model boats for some time,
and there is a fantastic animated graphic at
http://members.surfeu.at/fprossegger/english/vsp-function.html
This picture is worth thousands of words of description, especially
because you can't even see this action if you see a real boat in
operation! The theory is similar to that required to understand how
helicopter rotors generate directional thrust.
The key advantages are perfect directional control, the ability to
run the drive motors at a constant RPM (for peak power) and the
large blade area at constant speed can give significantly lower
noise levels than a standard prop with it's higher tip speeds.
Cycloidal drives sometimes see work in minehunters for this reason.
Given the low power requirements of most Bolger size boats, it might
even be possible to build your own drive. The theory is quite
straight-forward (even if the drive isn't!) and many of the boats
with a flatter bottom might easily be adapted to one of these.
Remember that the drive is both your prop and rudder. At the rear, it
can function as a source of vectored thrust. If placed forward under
the bow (as on harbour tugs), you would want a vertical "fixed
rudder" to anchor to back, give directional stability underway, and
to act as a pivot when you use "side thrust" on the forward mounted
unit.
Finally, as to reducing drag, consider that the blades have a
constant cross section, and could be withdrawn vertically into the
hull, allowing for alternate propulsion or beaching. Drawings of
harbour tugs with this drive show a substantial steel cage, capable
of supporting the weight of the vessel, around the drive unit.
--------------------------------------------------
Chris Smith <smith@...>
> I understand there is a method of propulsion (I don't remember theThese are cycloidal drives, the most common name associated with
> name) which involves a bunch of rotating vanes sticking out of the
> bottom of the boat, which are angled as they go around to produce
> thrust in any desired direction. I think they are used on tugboats,
> but I wonder if there are small units meant as bow thrusters on big
> yachts? Maybe one of these could be adapted? I'm thinking maybe
> there would be a way to get the vanes all pointed forward when not
> in use, so it wouldn't drag much while sailing.
their production being Voith-Schneider. There is a good picture at
http://homepages.svc.fcj.hvu.nl/brok/legomind/insights/roer/intro.html
but the description of how it works is not quite perfect.
These have been available for scale model boats for some time,
and there is a fantastic animated graphic at
http://members.surfeu.at/fprossegger/english/vsp-function.html
This picture is worth thousands of words of description, especially
because you can't even see this action if you see a real boat in
operation! The theory is similar to that required to understand how
helicopter rotors generate directional thrust.
The key advantages are perfect directional control, the ability to
run the drive motors at a constant RPM (for peak power) and the
large blade area at constant speed can give significantly lower
noise levels than a standard prop with it's higher tip speeds.
Cycloidal drives sometimes see work in minehunters for this reason.
Given the low power requirements of most Bolger size boats, it might
even be possible to build your own drive. The theory is quite
straight-forward (even if the drive isn't!) and many of the boats
with a flatter bottom might easily be adapted to one of these.
Remember that the drive is both your prop and rudder. At the rear, it
can function as a source of vectored thrust. If placed forward under
the bow (as on harbour tugs), you would want a vertical "fixed
rudder" to anchor to back, give directional stability underway, and
to act as a pivot when you use "side thrust" on the forward mounted
unit.
Finally, as to reducing drag, consider that the blades have a
constant cross section, and could be withdrawn vertically into the
hull, allowing for alternate propulsion or beaching. Drawings of
harbour tugs with this drive show a substantial steel cage, capable
of supporting the weight of the vessel, around the drive unit.
--------------------------------------------------
Chris Smith <smith@...>
Very good point. In fact, I may want to look into high thrust
outboards and probs instead. Say, optimized for max power 1.5 hull
speed?
Any thoughts?
outboards and probs instead. Say, optimized for max power 1.5 hull
speed?
Any thoughts?
--- In bolger@y..., "Lincoln Ross" <lincolnr@m...> wrote:
> I suppose this has nice advantages in terms of low drag while
sailing,
> and nothing to catch and break when running aground. However, this
is
> going to be quite inefficient. Jet ski designs are meant for
moderate
> thrust at high speed, (say up to 40 knots?), and you want high
thrust
> at low speed (say up to 5 or 6 knots). You may find that when you
are
> trying to get away from a lee shore in a blow, you won't have
enought
> thrust, and I suspect you will have very high fuel consumption in
> normal use. Horsepower will not be a good way to select a drive,
since
> efficiency will vary a lot depending on design details. Certainly
you
> will need much more horsepower than for an outboard. If you want
> efficiency, you will probably need the drive
> unit from a large jet boat coupled with the motor from a small one.
> It's much better in terms of efficiency to move a lot of water
through
> a small velocity change instead of a little water through a big
> velocity change. That's why geared down propellors and 4 strokes
work
> so well on our type of boat, and that's one reason why the old time
> boats with big props and slow engines worked on lower horsepower
than
> we would expect today with our high revving 2 strokes.
>
> I understand there is a method of propulsion (I don't remember the
> name) which involves a bunch of rotating vanes sticking out of the
> bottom of the boat, which are angled as they go around to produce
> thrust in any desired direction. I think they are used on tugboats,
> but I wonder if there are small units meant as bow thrusters on big
> yachts? Maybe one of these could be adapted? I'm thinking maybe
there
> would be a way to get the vanes all pointed forward when not in
use,
> so it wouldn't drag much while sailing. Quite a research project,
but
> if you had one I bet it would be more suited to low speed use.
> --- In bolger@y..., cadbury@s... wrote:
> > --- In bolger@y..., richard@s... wrote:
> > > So, to go along with my very modern looking Bolger Chebacco
> > Cruiser,
> > > I"m toying with replacing the outboard and slop well with the
> > > recycled power unit from a jet ski!
> > >
> > > Anybody have any HP and weight figures for the powerhead?
Anyone
> > know
> > > where to look?
> >
> snip
> > Max
I suppose this has nice advantages in terms of low drag while sailing,
and nothing to catch and break when running aground. However, this is
going to be quite inefficient. Jet ski designs are meant for moderate
thrust at high speed, (say up to 40 knots?), and you want high thrust
at low speed (say up to 5 or 6 knots). You may find that when you are
trying to get away from a lee shore in a blow, you won't have enought
thrust, and I suspect you will have very high fuel consumption in
normal use. Horsepower will not be a good way to select a drive, since
efficiency will vary a lot depending on design details. Certainly you
will need much more horsepower than for an outboard. If you want
efficiency, you will probably need the drive
unit from a large jet boat coupled with the motor from a small one.
It's much better in terms of efficiency to move a lot of water through
a small velocity change instead of a little water through a big
velocity change. That's why geared down propellors and 4 strokes work
so well on our type of boat, and that's one reason why the old time
boats with big props and slow engines worked on lower horsepower than
we would expect today with our high revving 2 strokes.
I understand there is a method of propulsion (I don't remember the
name) which involves a bunch of rotating vanes sticking out of the
bottom of the boat, which are angled as they go around to produce
thrust in any desired direction. I think they are used on tugboats,
but I wonder if there are small units meant as bow thrusters on big
yachts? Maybe one of these could be adapted? I'm thinking maybe there
would be a way to get the vanes all pointed forward when not in use,
so it wouldn't drag much while sailing. Quite a research project, but
if you had one I bet it would be more suited to low speed use.
and nothing to catch and break when running aground. However, this is
going to be quite inefficient. Jet ski designs are meant for moderate
thrust at high speed, (say up to 40 knots?), and you want high thrust
at low speed (say up to 5 or 6 knots). You may find that when you are
trying to get away from a lee shore in a blow, you won't have enought
thrust, and I suspect you will have very high fuel consumption in
normal use. Horsepower will not be a good way to select a drive, since
efficiency will vary a lot depending on design details. Certainly you
will need much more horsepower than for an outboard. If you want
efficiency, you will probably need the drive
unit from a large jet boat coupled with the motor from a small one.
It's much better in terms of efficiency to move a lot of water through
a small velocity change instead of a little water through a big
velocity change. That's why geared down propellors and 4 strokes work
so well on our type of boat, and that's one reason why the old time
boats with big props and slow engines worked on lower horsepower than
we would expect today with our high revving 2 strokes.
I understand there is a method of propulsion (I don't remember the
name) which involves a bunch of rotating vanes sticking out of the
bottom of the boat, which are angled as they go around to produce
thrust in any desired direction. I think they are used on tugboats,
but I wonder if there are small units meant as bow thrusters on big
yachts? Maybe one of these could be adapted? I'm thinking maybe there
would be a way to get the vanes all pointed forward when not in use,
so it wouldn't drag much while sailing. Quite a research project, but
if you had one I bet it would be more suited to low speed use.
--- In bolger@y..., cadbury@s... wrote:
> --- In bolger@y..., richard@s... wrote:
> > So, to go along with my very modern looking Bolger Chebacco
> Cruiser,
> > I"m toying with replacing the outboard and slop well with the
> > recycled power unit from a jet ski!
> >
> > Anybody have any HP and weight figures for the powerhead? Anyone
> know
> > where to look?
>
snip
> Max
--- In bolger@y..., richard@s... wrote:
Can't help with the wieght figures, but was thinking about something
else the other day.
Most "jet skis", "personal watercraft", or whatever you want to call
them are manufactured under an exemption from the normal government
mandated safety rules that would normally apply to an inboard-powered
boat. Most of these craft carry a label stating that.
Transferring a drive train into a "normal" boat may void the exemption
rendering the installation in violation of federal law. Whether or
not this is something to be concerned about from a legal or a safety
perspective is a question that I can not answer. Whether the drive
or the installation can be modified to meet the regulations is
another I can not answer.
In the discussions on this board concerning these powertrains, I can
not recall this aspect ever being discussed, so I thought I would
mention it.
Max
> So, to go along with my very modern looking Bolger ChebaccoCruiser,
> I"m toying with replacing the outboard and slop well with theknow
> recycled power unit from a jet ski!
>
> Anybody have any HP and weight figures for the powerhead? Anyone
> where to look?Hey Richard, how's it going?
Can't help with the wieght figures, but was thinking about something
else the other day.
Most "jet skis", "personal watercraft", or whatever you want to call
them are manufactured under an exemption from the normal government
mandated safety rules that would normally apply to an inboard-powered
boat. Most of these craft carry a label stating that.
Transferring a drive train into a "normal" boat may void the exemption
rendering the installation in violation of federal law. Whether or
not this is something to be concerned about from a legal or a safety
perspective is a question that I can not answer. Whether the drive
or the installation can be modified to meet the regulations is
another I can not answer.
In the discussions on this board concerning these powertrains, I can
not recall this aspect ever being discussed, so I thought I would
mention it.
Max
So, to go along with my very modern looking Bolger Chebacco Cruiser,
I"m toying with replacing the outboard and slop well with the
recycled power unit from a jet ski!
Anybody have any HP and weight figures for the powerhead? Anyone know
where to look?
I"m toying with replacing the outboard and slop well with the
recycled power unit from a jet ski!
Anybody have any HP and weight figures for the powerhead? Anyone know
where to look?