# Outdoors > Outdoor Transport >  12ft Jetboat build

## Spanners

After many months, Ive finally started.
3.6m long, 1.35 at the chine, 0.8? sides - cant remember the width - 1.5?
Anyway - its a Wattscraft 3.1? that has been scaled up about 20% to suit what I was after.
After getting it tacked together, its ALOT bigger than I thought LOL - however it will do exactly what I want it form - 3 up hunting and exploring.
Its very tall in the sides - might need booster seat to see over the screen!
Thanks to a mate who owns a Seadoo shop (Capital City Seadoo) , I have pieced together the best mongrel possible,
Pretty happy the way the engine setup has come out - if designed and built from scratch, it would have been almost exactly the same.
Brought a 97 XP 800 from him - 787 engine, using 787 Fuel injected exhaust as it runs on the opposite side to normal and hooks under the carbs thus making more room.
Have deleted the middle drive shaft and used the rear one only and the front coupler.
Pump is a Kawasaki Ultra 250 unit - spline and impeller boot as as if it was made for it.
Shaft seal is early 90s seadoo bearing and seal type unit.
Water box needs to be shortened about 4" and its all good to go.
Motor had rebuild 4 hrs ago and have just done the carbs, so it should be reliable



On its way home




















Couple of issues - folder couldnt do a bend fully and denting the top of the gunnels trying
Had to cut it 80% back and twist to get it flat.
Next one will have a new folder as they spent '11.5' hrs on it and had to send the bottom out to someone else, and couldnt do the screen.
Do the math$ - over it - just want to build.

What Ive learnt in 4 hrs:
-Make sure you have a mate around to help man handle bends etc
-6mm 5083 doesnt like bending on 2 planes.
-3mm isnt much better
-Wear a glove on offhand as tacking gives bad burns over a few hrs
-More tacks required as there are alot of stresses involved and they ping at 12" spacings

Welding the bum up at the mo - top and seat in maybe tomorrow

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## veitnamcam

Cool:thumbup:
Is that the final size of the open area for seating etc?

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## Spanners

Ya. 3 wide on bench seat. 
Looks long at the mo as the screen isn't on and you're seeing right back to the dash edge from the bow

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## madjon_

saw the tacs  spacing an thought,"Spanners gunna love welding that"
good outcome though

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## JoshC

Nice mate, have always wanted to make one of these. High sides on a small boat is a good thing   :Wink:

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## longrange308

What was it worth?? Looking for one this size

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## ebf

Will the proving ground be the Hutt river north of the Melling overbridge ?  :Psmiley:

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## Smiddy

will the be room on either side of the engine for gear storage

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## Barefoot

> Will the proving ground be the Hutt river north of the Melling overbridge ?


Wait for a bit of rain and do a full run all the way you your thinking?

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## Spanners

> What was it worth?? Looking for one this size


Prob owe me 8-9k all said and done. 
Got stitched on a couple of jobs on it so bumped the cost up a bit

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## Spanners

> will the be room on either side of the engine for gear storage


Yip. Under seat also

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## sako75

You will appreciate the high sides when three big lads get in it and she is rolling through the turns

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## Spanners

Not much progress today as new flash Harry welder puked..
New one arriving tomorrow

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## Philipo

Good to see it's finally coming together, Should be good for shits'n'giggles. 

Looks like I'd need a cushion to sit on though lol

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## kotuku

cant wait to see you and philipo hurtling round the jetsprint circuit-at that size she'd be as nimble as a horny poledancer!great bloody project though spanners!

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## outdoorlad

What dead rise have you gone for?

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## Scouser

> cant wait to see you and philipo hurtling round the jetsprint circuit-at that size she'd be as nimble as a horny poledancer!great bloody project though spanners!


+1 will be watching this thread with interest, and green gills  :Grin:

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## kotuku

scouser youre leadin the cheer squad so off to the bathroom and shave them legs lad. :Psmiley: 
Did you realise pengy is doing all the acrobatics in the squad so be prepared for some catching! :Wink: 
 the dundees will be the judging panel -theres enough of em! :Have A Nice Day: 
 i reckon this outfit will be faster than  kim dot com runnin from uncle Hone :Omg:

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## Scouser

Bwahaharrrrr........recon mein freund kim 'blot' has never run in his life!!!!!!.......

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## Spanners

13 deg deadrise. 
Just found out the seat I have is for the smaller version and obviously doesn't fit. 
New one on way. 
Seating position might be bit higher now  :Have A Nice Day:

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## Spanners

Got a bit of room around the engine  :Have A Nice Day: 
Might even be able to put storage on top of it too LOL

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## craigc

I watched phill and mark folding it; they looked like they were having fun...

It should open up some pretty cool hunting opportunities!

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## yerimaginaryM8

Are you gonna put 6 or 10ml plastic on the bottom? and are you confident that donk will have enuff poke to push that hull 3 up plus gear given you have used fairly thick alloy for the bottom/delta and gone a bit longer than a lot of jet dinghies?

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## Spanners

No probs  :Have A Nice Day: 
The seadoo challenger is bigger and heavier and runs same engine and goes good. 
This is a practice boat really as I have a 215 hp supercharged engine but it's still in the USA

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## Spanners

Snuck down and did some work on it yesterday. 
Might be all that gets done for a while with baby in SCBU

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## Spoon

You could fit a 350 Chev in the back of that couldn't you?  :Thumbsup:

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## sako75

Hope all is well in SCBU

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## Normie

Slick!

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## veitnamcam

Any updates?

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## Spanners

Not really lol. Motor in and aligned. Seats built. Havnt touched it all year. 
I thought you would have gathered by now I start heaps of things and never finish them.. Lol
Will hit it and finish when I get back from work which is when the big boys engines land and the next one starts

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## sako75

And your little one that was in SCBU?

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## Spanners

Only for 3-4 days as precaution. 
Can't watch her sleep all the time!!  :Have A Nice Day:

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## veitnamcam

Pull finger,and on the crayons too.

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## yerimaginaryM8

what happened to this? any progress?

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## Spanners

Havnt even looked at it this year  :Have A Nice Day: 
Did the handrail before I flew out again. 
Should get to fire it up this time home.

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## Bill999

are fly in fly out jobs like putting your life on hold for 2 weeks every month?

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## Spanners

Worse lol. 4-6wks
12 months worth of shit to do in 6
I left tues 3am. waiting for a chopper .. Still

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## Spanners

And chopper canceled so waiting for another day...
I can't afford to hang round and drink $12 beers for a week!!!

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## veitnamcam

> And chopper canceled so waiting for another day...
> I can't afford to hang round and drink $12 beers for a week!!!


Shit that's cheap, was $10 US when I was in arge and the dollar was only around 50c  :Oh Noes: 

Forget the dingy we need projectiles. lots and lots of projectiles.

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## Spanners

Im in Western Oz this time not east bum fuck

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## longrange308

It running yet?
Building two this size and looking for power plants, interested in seeing how the
2 banger goes in a boat this size

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## Spanners

Na. Havnt touched it this trip back yet
I have 3x 215 hp 4 stroke packages coming but bit overkill for this size I think

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## longrange308

Now your talking, selling any of the 215s?

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## Spanners

Prob 1 or 2. Have 4  :Have A Nice Day:

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## kotuku

does it make ya nuts tighten spanners,actually if you painted it a dark brown and called it lab i reckon it would be a bloody excellent gundog.if it gets off its gunga like most jets from the time the shot is fired ya should be right under the falling duck to land it in the engine bay ,and small enough for irrigation ponds matey!

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## Spanners

There are a number of small ponds with its name on apparently lol

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## Wirehunt

> are fly in fly out jobs like putting your life on hold for 2 weeks every month?


Worse. Much worse.  When you get home, slap the cook on the arse, kick the dog. Walk past the gun cabinet it's time to climb on yet another plane and back to work.

Are you up at the island @Spanners ?

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## Spanners

Fuck that. I don't live in a prison camp. 
Offshore construction vessels is my lark

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## K95

Seeing as I have no idea about engines, if I buy a EJ20 to go in a boat and supply a Scott 752 unit do they need to be "tuned" before I could use it?

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## Spanners

Would depend on what blades are in the pump. I'm not a EJ fan. Number of reasons. Heaps of better options IMO

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## K95

I've got no idea, have a few people to ask but thought I would get a rough idea here first. I have the unit but hull and engine are still up in the air.

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## Spanners

My take, and that's only what it is... 
The crank centreline is reasonably high, the headers coming out the bottom sucks and a pain to water cool and the oil filter location 
In saying that heaps of cabbage cutter engines have been used in boats. 
There are a couple of newer Toyota and Nissan engines that would be higher up my list

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## Tommy

Many people use bike engines?

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## Spanners

Nope

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## longrange308

Can do it but lot of work , better to use ski or car engine

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## Wirehunt

Pipe laying?

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## Spanners

> Pipe laying?


Was pipe laying last year. Hated it with a vengeance 
ROV hookup and diving at the moment

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## mikee

> Was pipe laying last year. Hated it with a vengeance 
> ROV hookup and diving at the moment


I was an ROV Pilot/Tech many many years ago and then I made a full recovery  :Grin:

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## Spanners

I just sign their paperwork, make sure the lights are on and  point the finger to someone to make sure the noisy things in the bottom of the ship work  :Have A Nice Day:

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## longrange308

Selling any of the motors yet spanners?

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## Spanners

Have 3 waiting in wellie for when I arrive back from Alaska

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## Spanners

Have a low hour 215 horsepower fresh water engine available

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## longrange308

Price? And what's included?

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## Spanners

Motor loom ecu jetpump header tank bottle
44.x hrs. Fresh water. 
Pump prop and wear ring like new.

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## Spanners

Any things possible, but it'd be like a blown V8 in a mini

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## Spanners

130 would be heaps in a 3.3. 215 is excessive to say the least. 
I did have intentions to build a couple but have 1000 1/2 finished projects already. 
There are guys building hulls for nix almost. I won't build my next hull, will just finish it off. 
I'm just going to focus on intake pump and nozzle projects for now and maybe some wiring harness conversions

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## yerimaginaryM8

whats happening to the hull is it for sale?

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## Spanners

Steering cable due next week. Battery to mount and dash harness to lengthen, cover seats, make intake grate and its away.

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## veitnamcam

> Steering cable due next week. Battery to mount and dash harness to lengthen, cover seats, make intake grate and its away.


So sometime next year?

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## Spanners

> So sometime next year?


Lol prob
I fly out this weekend.
Maybe get it in the water this year.

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## veitnamcam



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## Snowgrass

Any update @Spanners? I had a look at a 3m WattsCraft today in his workshop. Pretty keen to get a kit he had there built up, then work away at fitting it out.

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## K95

Got two 3.76m wattcraft hulls with kawasaki 15F. Henry is good to deal with.

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## Snowgrass

Yeh he seemed a good bugger to talk to. I wasted an hour of his time today sussing out options. He's got a 3m kit there he'll do a good deal on if he builds the bare hull for me. Just trying to decide what motor to chuck in.

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## Nibblet

This one  :Have A Nice Day: 
Did you manage to complete?

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## yerimaginaryM8

Looks like it's for sale and it never hit the water??
https://www.trademe.co.nz/motors/boa...4927f594c3ce15

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## Sarvo

> Looks like it's for sale and it never hit the water??
> https://www.trademe.co.nz/motors/boa...4927f594c3ce15


What you recon its worth - be very good on the mighty Arawhata  :Thumbsup: 
Has it enough power ??

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## Spanners

Ive got another small boat with 80hp. Its spent a lot of time down the Arawhata 
110hp is heaps in a wee boat. 
Simply dont have time to finish this one so it needs to go as in a mates workshop. 


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## Sarvo

> I’ve got another small boat with 80hp. It’s spent a lot of time down the Arawhata 
> 110hp is heaps in a wee boat. 
> Simply don’t have time to finish this one so it needs to go as in a mates workshop. 
> 
> 
> Sent from my iPhone using Tapatalk


Heading down 26th - so will talk to the lad down under and see what he reckons
Has got one already - but its a sprint Jet and not practical - goes like a hurd of Turtels but only 2 seat and zero room for gear :-(

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## Sarvo

PS
What’s the fuel economy and general maintenance required etc etc

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## Spanners

To head up and back arawhata youll need 40l. End of the day gas is cheap lol
Id expect 100hrs on Motor before touching it 


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## Markgibsonr25

From the arawhata.

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## Markgibsonr25

> I’ve got another small boat with 80hp. It’s spent a lot of time down the Arawhata 
> 110hp is heaps in a wee boat. 
> Simply don’t have time to finish this one so it needs to go as in a mates workshop. 
> 
> 
> Sent from my iPhone using Tapatalk


I like mine with a bit more hp 587 detuned to 400 ish.

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## Sarvo

> From the arawhata.


Thats Honda I can see ??
That can't be 400hp ???

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## Markgibsonr25

> Thats Honda I can see ??
> That can't be 400hp ???


Sure is

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## Markgibsonr25

Boost + the occasional use of ethanol it can do more

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## veitnamcam

> Boost + the occasional use of ethanol it can do more


Literage/boost/and internals please.

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## cambo

I know of a K24 powered race car that has over 500hp.  It's NA but he's boosting it soon with aims to get over 1000hp

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## Markgibsonr25

> Literage/boost/and internals please.


It would take a while but in short fully forged internals 9.5 :1 pistons,running 12-14psi boost,Variable with more programmed to come on when vtec comes on about 5000rpm.Flex fuel sensor for ethanol content, Dont really use ethanol much anymore as new motor seems more than enough for this little tub.7" southern two stage jet

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## longrange308

So the unit and motor combo are working all good now?

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## Markgibsonr25

> So the unit and motor combo are working all good now?


Took a while to sort but yes.

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## Tommy

K series hondas have sooo much potential. Even the vanilla 24a is good for something like 350hp without touching the head, even though everyone gets excited over the k20a(r). And there are fucking shitloads around, so not a major major if you kill a standard one (24, I'd cry if I killed a 20r hahaha). In an application like a boat, even better: more availability of bits that will work ex usa, and the yanks go mad for them. Not that it's a problem basing on a standard factory motor: Drown it, rev bash it, whatever.... So long as every second Auckland housewife has a crv/accord and can't drive for shit, there will be loads of spare engines available

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## Markgibsonr25

> K series hondas have sooo much potential. Even the vanilla 24a is good for something like 350hp without touching the head, even though everyone gets excited over the k20a(r). And there are fucking shitloads around, so not a major major if you kill a standard one (24, I'd cry if I killed a 20r hahaha). In an application like a boat, even better: more availability of bits that will work ex usa, and the yanks go mad for them. Not that it's a problem basing on a standard factory motor: Drown it, rev bash it, whatever.... So long as every second Auckland housewife has a crv/accord and can't drive for shit, there will be loads of spare engines available


True in some points the k24a has a few negatives over the a2 if you are going to boost.What i have found in my real world testing is standard motors with boost dont last.I think all these claims on the net of 500hp on a s/h block straight out of a car may work in the short term but not for long.I think drag racing and jet boats place different demands on the motor for longer.Hopefully I wont need a spare motor after building this one for a very long time

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## JoshC

Cool man, unreal power to weight ratio


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## cambo

Went for a blast in a mini boat in the weekend. Bunch of guys in a few boats went out for a play up the Waimak.
4 minis with ski motors/pumps and 1 4.6 with a big V8. Couple of the minis had the supercharged Kawasaki ultra motors with a few mods. 1 was over 350hp.Sounded amazing. 
The boat I went in was a 3.8 Hydro with a Kawasaki 15F. Even with 4 of us in, it went well. 
I'd love to give 1 of these minis a crack. Maybe use a Honda k series motor though with a Scott unit

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## cambo

@Spanners has you got the boat finished yet?
Would love to see some pics of it

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## Spanners

Sold the boat. Brought another, swapped + cash for current boat. 
Its 3m (9ft) with Seadoo spark engine and one of my pumps i make in it. 
Goes really well




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## Mathias

> Went for a blast in a mini boat in the weekend. Bunch of guys in a few boats went out for a play up the Waimak.
> 4 minis with ski motors/pumps and 1 4.6 with a big V8. Couple of the minis had the supercharged Kawasaki ultra motors with a few mods. 1 was over 350hp.Sounded amazing. 
> The boat I went in was a 3.8 Hydro with a Kawasaki 15F. Even with 4 of us in, it went well. 
> I'd love to give 1 of these minis a crack. Maybe use a Honda k series motor though with a Scott unit


I saw some pix of that, a mate who was on the trip sent them to me. He had the Jetech with the supercharged Kawi in it.

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## yerimaginaryM8

Spanners what are the "pumps I make" ASPCNC intake + other bits or is this you SACO WaterJet Drives - Home ?

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## Spanners

Stainless pumps for Spark




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