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Gas Jet Boaters

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Old 05-09-2010, 11:52 AM
  #276
Scott Schneider
 
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Quote:
ORIGINAL: Dana W

I ran the little sprint boat pretty hard today to see how the dog bone would hold up under pressure . Well the dog bone universal joint did fine however I sheared the KMB jet pump drive shaft off . The shaft steps down from 1/4'' to 5mm . That was the weak spot ( see photo ) Here is a short video of it running . http://rcuvideos.com/video/DaVette-Sprint-Boat . I'll make another boat and go with the Graupner Jet Pump .
Dana,
Bummer ... yea a lot of vibration going on at that connection. Unless alignment is dead on and runout dead even you got [:@]
have a new shaft cut without the step and work on the runout of the dogbone coupler to get it perfect.

Honestly tho, with the engine in A/V mounts and dog bone couplers needing perfect alignment, really not the ideal connection type IMO.
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Old 05-11-2010, 03:00 PM
  #277
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Default RE: Gas Jet Boaters

My weekends running was just carnage. took the boat to my auntys place who has a small river running through her property. its about 6-7' wide which is probably not quite enough when your doing 50-60k/hr. After seeing all the real sprint boats, they al get beaten up a bit. The biggest hole has gone right through and it only the pool noodle holding the wood over the hole. and a broken pipe mount

cheers
steve
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Old 05-11-2010, 05:04 PM
  #278
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Default RE: Gas Jet Boaters

Quote:
ORIGINAL: infinityteg

My weekends running was just carnage. took the boat to my auntys place who has a small river running through her property. its about 6-7' wide which is probably not quite enough when your doing 50-60k/hr. After seeing all the real sprint boats, they al get beaten up a bit. The biggest hole has gone right through and it only the pool noodle holding the wood over the hole. and a broken pipe mount

cheers
steve
Steve,
But did you have fun

See an RCMK in there now for power, how it run for ya ?
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Old 05-11-2010, 08:26 PM
  #279
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Default RE: Gas Jet Boaters

it was a blast. just not long enough.

the rcmk is great. just that little bit more power than the Zen has made such a difference.
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Old 05-11-2010, 09:05 PM
  #280
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Default RE: Gas Jet Boaters

I joined the deck to my hull today. It's coming along now. Starting to look like a jetsprint.

I've got a build thread going over at the Snikwah site.

http://modeljetboat.com/forum/index.php?topic=14.0

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Old 05-11-2010, 11:18 PM
  #281
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Quote:
ORIGINAL: infinityteg

it was a blast. just not long enough.

the rcmk is great. just that little bit more power than the Zen has made such a difference.
You running the 3 or 5 blade impeller ?


Quote:
I joined the deck to my hull today. It's coming along now. Starting to look like a jetsprint.
Work faster, more hours, late nights .... get er done
Lookin good
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Old 05-11-2010, 11:54 PM
  #282
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I'm limited to the setting time of the resin at the moment. Typically it's our first cold week as winter sets in so the times are a little longer. I need to go buy a heap of parts before I get much further too. I just got a quote from Bruce at Gizmo Motors for a few things I need & once I have the cash I'll fire that order off. I'll have to get Ken at Retallick Engineering to fabricate a nice stainless header for me to fit the boat & also make me a pipe to suit the 29cc head I plan on putting on there. I'll also get him to modify the 29cc head too.

This is one of 2 builds I am currently working on. I must admit, I'm putting more time into this than the cat. I should probably get onto the cat soon, I plan on racing that in a couple of weeks!

After i mount the backing plate for the skirt bracket, I might have a go at laying up the carbon for the rollbar. I'll need to make a mold for that though.
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Old 05-12-2010, 04:29 AM
  #283
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Default RE: Gas Jet Boaters

Scott
I made the mistake of only getting the 5 blade impellor. i wish i had of got both now. but the lil extra torque from the rcmk has made a world of difference.

Dicko
Builds looking good. ive saved all the pics for future reference
I made my cage out carbon. I only done the female mold though. i used 5 layers of carbon uni's. Im not sure on the weight of the fabric now though, it is strong as ever though. i just used some 18mm custom wood screwed into a u shape and car bogged the corners into a nice curve. then used brown packaging tape layed evenly for the molding surface. it wasnt hard to sand the very small ridges the tape overlap left.

cheers
steve
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Old 05-12-2010, 06:50 PM
  #284
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Default RE: Gas Jet Boaters

That's funny, I use packaging tape for a lot of my molds too. The resin just won't stick to it & it's easy to pop parts off!

I have the rough measurements for Craig's Swashdrive roll bar & will make a similar sized one out of carbon. I found that if you squeeze the excess resin out of the carbon you can get a much stronger laminate. I plan on using the mounting blocks Craig provided with the kit to mount the roll bar to. I will probably only have time to mount the jet unit today & I'll get onto the mold over the weekend.

Cheers
Jason

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Old 05-13-2010, 07:58 AM
  #285
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Default RE: Gas Jet Boaters

I came up with a solution . With what little drive shaft I had left on the pump I managed to find a round collet with set screws for the 1/4" pump shaft . I put a square drive collet on the engine . I installed a square drive flex shaft and now I'm good to go .
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Old 05-13-2010, 10:28 AM
  #286
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Quote:
ORIGINAL: Dana W

I came up with a solution . With what little drive shaft I had left on the pump I managed to find a round collet with set screws for the 1/4'' pump shaft . I put a square drive collet on the engine . I installed a square drive flex shaft and now I'm good to go .
Much better set up


Quote:
infinityteg .... I made the mistake of only getting the 5 blade impellor
Reason I ask is because I have both and been running the 3 all along, but also running the RCMK Evo top end may have the power on hand for the 5 ?
Running the 3 acceleration is instant like a light switch and rpm is @16K ....
*So how snappy is yours with the 5 blade ?
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Old 05-13-2010, 02:17 PM
  #287
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Default RE: Gas Jet Boaters

well dana i dont think youll have a problem with the flex shaft set up. mine and scotts has held up like that now for a while.

scott
without being able to compare the three blade with the 5 im not too sure of the difference. I find the accleration of the boat very good. While running the Zen in it turning you could hear revs drop off a little but it is definitly not as noticable with the EVO.

cheers
steve
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Old 05-19-2010, 12:34 PM
  #288
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Default RE: Gas Jet Boaters

Hot dang !! .... found better performance, better intake loading and overall less blow outs and odd behavior with some intake mods !!
Added an intake bubble made from a tea spoon then attached just ahead of leading edge on intake. A bit deeper angles on intakes leading and trailing edges done as well. Together hull is working great as is without the C/G changes I though it needed

On smooth water now boat will run WOT without proposing what so ever, turns under full power generally brings a one point turn without loosing suction. Go crazy on steering and throttle boat will still unhook and do table top spins for giggles

Will post a few pics of the mod later tonight .....
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Old 05-20-2010, 12:00 AM
  #289
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Default RE: Gas Jet Boaters

Here is what the mods look like
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Old 05-20-2010, 10:06 AM
  #290
Dana W
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Default RE: Gas Jet Boaters

Interesting However I didn't have any porpoising with my CG moved back .
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Old 05-20-2010, 02:24 PM
  #291
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Quote:
ORIGINAL: Dana W

Interesting However I didn't have any porpoising with my CG moved back .
Dana,
I know likely a crutch fix for the forward C/G, but had to try it out.
But runs just great now, maybe the C/G will make it even better !!

** So with yours, what C/G % were you able to set yours up at ?
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Old 05-20-2010, 09:35 PM
  #292
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Default RE: Gas Jet Boaters

I did what you suggested 27% .
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Old 05-20-2010, 11:22 PM
  #293
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ORIGINAL: Dana W

I did what you suggested 27% .
Fair enough
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Old 05-23-2010, 12:28 PM
  #294
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Default RE: Gas Jet Boaters

Dana W,

here's the pics, this is a 40x15 inches warehouse hobbies jetski hull. thanks


jul
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Old 05-23-2010, 02:26 PM
  #295
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Quote:
ORIGINAL: wave waker

Dana W,

here's the pics, this is a 40x15 inches warehouse hobbies jetski hull. thanks


jul
Well that's very cool
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Old 05-23-2010, 02:29 PM
  #296
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Default RE: Gas Jet Boaters

Cool. that'll be an interesting project
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Old 05-23-2010, 07:19 PM
  #297
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Default RE: Gas Jet Boaters

WOW , I didn't know they where making a jet ski . I'll look into what pump they're using .
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Old 05-23-2010, 07:45 PM
  #298
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Quote:
ORIGINAL: Dana W

WOW , I didn't know they where making a jet ski . I'll look into what pump they're using .
Tony made a few of them in the late 80's and into the 90's. He still has the molds but I don't think they sold very well.
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Old 05-24-2010, 11:34 PM
  #299
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Default RE: Gas Jet Boaters


Quote:
ORIGINAL: Dana W

I ran the little sprint boat pretty hard today to see how the dog bone would hold up under pressure . Well the dog bone universal joint did fine however I sheared the KMB jet pump drive shaft off . The shaft steps down from 1/4'' to 5mm . That was the weak spot ( see photo ) Here is a short video of it running . http://rcuvideos.com/video/DaVette-Sprint-Boat . I'll make another boat and go with the Graupner Jet Pump .
I've been thinking about building a boat like this for a long time. Would the KMB hold up long-term to a Zen/RCMK? I had a KMB drive a few years ago but never used it & sold it. I remember paying WAY more for it than they seem to go for now.

Would the KMB would be ok just for playing around? How much more are the Graupner drives & what kind of extra performance to you get?
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Old 05-25-2010, 05:53 AM
  #300
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Default RE: Gas Jet Boaters

Hey everyone

Im just about to get started on a gas jet boat build and have been following this thread thought it was time to say hey

And im looking for a bit of advice everyones input would be appreciated

Currently looking at getting a hull 780mm long 350mm wide

Running a RCMK or Zenaoh gas engine

A 2347 49mm impellor diameter graupner jet unit  [ would rather a swashdrive  ] 

How do you think this will all stack up together?

has anyone been running this unit in there jet boat cant seem to find much info on it
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