Jetpack?

houser · 20 January 2008, 13:10

Anyone has any insight into this technology, or care to comment on this anyway?:
Looks interesting in theory:
http://www.zodiacmilpro.com/library/index.html
(Sea Rib Open 700 - New 7 M, 200 HP diesel waterjet)

http://www.swordmarine.com/WhyJetPac.asp

best
jtm

Nos4r2 · 20 January 2008, 14:17

Looks suspiciously like the Isuzu 2.8 diesel in there.

codprawn · 20 January 2008, 15:54

This was discussed a long time ago. The general feeling was that it looks vulnerable to damage with constant wave jumping. it also looks like it could be swamped quite easily!!!

Poly · 20 January 2008, 16:22

Quote:

Originally Posted by codprawn

The general feeling was ...

I am not sure that it is possible to draw a "general feeling" from what was a pretty brief discussion. They have been mentioned here a few time and there were as many "thats an interesting idea" statements as there were "that will never work".

Nos4r2 · 20 January 2008, 17:46

Actually, I'd be more interested in how strong the 2.8 Isuzu engine is when it's putting out 200hp. It's only 109hp in a car.

houser · 20 January 2008, 17:58

sorry,

Searched for "jetpac" but found nothing....some other searches (jet pac) yielded that it has already been discussed.
Interesting unit though....
I wonder what speeds you could get comparatively...and if it's any closer to a sterndrive or an outboard in performance compared to other jetdrives of the past.
Is it better at all performance-wise I wonder?
The beauty in theory is obviously in shallow water (priority for me) combined with room on a 6-8 m RIB.

best
jtm

prairie tuber · 20 January 2008, 22:32

Quote:

Originally Posted by Nos4r2

Actually, I'd be more interested in how strong the 2.8 Isuzu engine is when it's putting out 200hp. It's only 109hp in a car.

The 109 hp capacity in the automotive application probably has more to do with cooling mechanism limitations, than to do with the strength of the engine's internal components such as connecting rods. In a marine application you have:

a) an unlimited supply of cold engine coolant, and more importantly;

b) an unlimited supply of cold liquid coolant for the of intercooler, which would allow you to boost the hell out of it with out having the EGTs go through the roof.

I think the concept is quite interesting, but could see where it may make short work of a transom if it's used for wave jumping.

Nos4r2 · 20 January 2008, 22:39

Quote:

Originally Posted by prairie tuber

The 109 hp capacity in the automotive application probably has more to do with cooling mechanism limitations, than to do with the strength of the engine's internal components such as connecting rods. In a marine application you have:

a) an unlimited supply of cold engine coolant, and more importantly;

b) an unlimited supply of cold liquid coolant for the of intercooler, which would allow you to boost the hell out of it with out having the EGTs go through the roof.

I think the concept is quite interesting, but could see where it may make short work of a transom if it's used for wave jumping.

You have a point. The 109hp version in my car doesn't even have an intercooler.

prairie tuber · 20 January 2008, 22:41

To be honest, I have no idea if the jetpac uses one either, but they'd be silly not to.

Nos4r2 · 20 January 2008, 22:56

If it's got one it's between the turbo and the intake manifold. The turbo has an air filter bolted to it.

<edit> I should RTFM... Cambelt isn't exposed.

prairie tuber · 20 January 2008, 23:33

I just checked the site & yes, the 200 hp diesel is intercooled. The enine cooling system is close loop with a watercooled radiator.

A quick google search for 'sword marine jetpac' produced this article;

http://www.bymnews.com/news/newsDetails.php?id=20275

codprawn · 20 January 2008, 23:53

I see they also do a 300hp petrol version. Think I would prefer an outboard.........

seahorse · 21 January 2008, 04:33

Quote:

Originally Posted by houser

sorry,

Searched for "jetpac" but found nothing....

I wonder what speeds you could get comparatively...

I drove those units a few years ago when they were under development by the inventor Bill Lawson, before he sold to Sword. They worked well, did not wander at slow speeds like previous water jets, and they performed better than the equivalent powered stern drive. You can't believe how quiet they are.

http://www.swordmarine.com/default.asp

http://www.boatingnews.com/News/deta...&nChannel=News

http://www.patentstorm.us/patents/7220154-claims.html

Poly · 21 January 2008, 09:07

Quote:

Originally Posted by codprawn

I see they also do a 300hp petrol version. Think I would prefer an outboard.........

but you are not in the market for a jet drive - the USP is not that its a big engine - its that you can have features/benefits normally only available on an inboard without loosing the space or cutting holes in the hull etc.

it does address many of the disadvantages of an inboard instalation.

codprawn · 21 January 2008, 11:19

Don't you mean losing???

houser · 21 January 2008, 11:37

Interesting, thanx for that.

Don't suppose you've driven one in winter/ice conditions and can comment
whether it could be configured for use in winter w ice .e. reinforced impellers or the like? Just curious...

best
jtm

Quote:

Originally Posted by seahorse

I drove those units a few years ago when they were under development by the inventor Bill Lawson, before he sold to Sword.

seahorse · 21 January 2008, 13:02

Quote:

Originally Posted by houser

Interesting, thanx for that.

Don't suppose you've driven one in winter/ice conditions and can comment
whether it could be configured for use in winter w ice .e. reinforced impellers or the like? Just curious...

best
jtm

I tested the engines in Florida where the only ice is was in our drinks! Better contact the factory for that kind of info.

Poly · 21 January 2008, 16:58

Quote:

Originally Posted by seahorse

I tested the engines in Florida where the only ice is was in our drinks! Better contact the factory for that kind of info.

Since you are one of the few people to have actually seen one of these in the flesh do you think there is any justification in the concerns people expressed about the forces acting on the transom? i.e. is it suited to wave jumping?

jwalker · 21 January 2008, 17:11

Unless you're clean out of the water, I'm not sure the loads will be so high since the unit has it's own buoyancy.

Although lots of pics on here and in magazines have folk showing off with their boats out of the water, if you drive properly you may find you rarely get into that situation.

I don't understand the oo-ing and ahh-ing that folk do when they see a boat out of the water, and therefore out of control, with it's bow 3mtrs into the air. Kinda like doing handbrake turns in yer car.

Perhaps I'm too old to know.

Poly · 21 January 2008, 19:13

Quote:

Originally Posted by jwalker

Unless you're clean out of the water, I'm not sure the loads will be so high since the unit has it's own buoyancy.

Although lots of pics on here and in magazines have folk showing off with their boats out of the water, if you drive properly you may find you rarely get into that situation.

I don't understand the oo-ing and ahh-ing that folk do when they see a boat out of the water, and therefore out of control, with it's bow 3mtrs into the air. Kinda like doing handbrake turns in yer car.

Perhaps I'm too old to know.

JW - has no one told you the higher you can get your boat out the water the bigger everyone will believe your manhood is

. Perhaps its the kind of midlife crisis that boyracers have... ...they love putting stereos and big amps on their boats too!

Each to their own I suppose - although I guess your point is if you are going to jump waves buy a big petrol outboard. If you want a diesel jet - you are probably not wanting to jump waves anyway.