Wheelnut

My Feedback: (81)

Hey guys,

First, thanks to SkR8Pn for sending me a pm.

I have had a lot of electric boats and I have done many mods successfully, but this jet boat is very alien to me. I reallly need to ask some questions.

I'm not sure what I really need to do. I mean, what mods does this boat really need to run decent without water coming into it.

1. What is the bearing mod for and where does the bearing go? I know the bearing has less resistance and will help the electronics run cooler, but does it also help keep the water out?
2. What is the sleeve mod and what is it for?
3. What's wrong with the stock shaft?
4. What is wrong with the stock coupler?

Thanks in advance for any help and remember pictures say a 1000 words[8D]

Soepahsonic

Hi everybody

Yesterday I ordered a NQD jet pump at Ebay and planning on putting it in a crackerbox.
I dont know if the hull is right for it nor do I know what length this hull shouldt be. I will build this cracker from scratch, so I can adjust the size of the building plans if needed. I know that the hull of the jet sprint/Tear into is about 44cm in length. I'm planning on using a watercooled 3200KV on 3s.
Now I have a few small question:

1. Can I build a cracker that's about 50cm in length max and use it with that setup ?
2. Can anybody tel me the exact diameter of the rim(?) of the nozzle ? Not the rudder nozzle but the part were the screws go in.
3. the exact height of the jet, without the bottompart. Basicly the red and green lines



That way I can determin the minimum height of the transom thus the scale of the cracker.

I hope I have made myself understandable for you guys
Thanks a lot for all the tips and trics so far.

Big salute from Holland.

Mick

seehuusen

Outrunner has more weight turning at a larger circle, hence it will always have more torque, comparing same specs to an in-runner
I don't have any experience with an outrunner, although I'd love to try one out sometime

Hey mate,

I did this exact sleeve mod, with pics on this page or the one before?!? In order to see the picture worth a 1000 words, you must also open your eyes LMAO I had to mate... hahaha

1. Bearing mod is a new-ish mod, only done a few pages back. It replaces the rubber grommit with a solid bearing, that supports the shaft a bit more than a rubber grommet. It does the same job, keep the grease in the shaft bore, to prevent water coming into your boat
2. The sleve mod ads a pipe into the original drive shaft hole, which is just drilled through the plastic of the jet drive. With vibration and what not, this hole has a tendency to get worn a lot, allowing the shaft to vibrate. The widened shaft hole allows more water into your boat, and the vibrations gives very bad thrust out of the jet drive.
ADDITIONALLY, the bigger hole, sucks air out of your hull, into the jet drive, and causes your prop to loose drive and prime... bloody annoying
With the sleve in place, you can glue in a longer copper pipe, which not only assists a lot with wear and tear, it also stabilized the drive shaft, giving A LOT less vibration
3. Nothing really, but in my case, I need one that is perhaps another 2-3 mm longer, so that it fits better with my coupler
4. Again nothing, you have to drill yours, and it's made from aluminium. I get a brass one, as it's stronger, and already drilled perfectly

I hope that helps, I'm off to eBay to make the order for all the new parts

Cheers
Martin

SkR8Pn

Hi Mick,

Can't help with the crackerbox dimensions

Red line = 34.5mm
Green line is just under 32mm, I measured off of 3 different stator housings and they ranged from 31.5 to 31.75....lol

SkR8Pn

inboxed again....lol

Soepahsonic

Thanks man !

That was really fast.
I have the dimensions of the cracker. Now I know I need at least 4 cm transom height. I scale the rest of the buildingplans accordingly to the transom.
If you like the crackerbox, you can downloadthe plansat powerpete.20megsfree.com/photo4.html

Again, thanks alot

Mick

SkR8Pn

No worries Mick,

Thanks for the link... Now i know what a Cracker box is....

If you get a chance, do a build thread. It would be great to see what you come up with!

Ja

spektrumFlux

great thanks for the explanation. :-)

what is the ideal operating rpm for Motor (Inrunner/Outrunner)?
when I browse thru HobbyKing Boat motor, all the motors listed are Inrunner, so does it mean Outrunner is not suitable for boat usage?
I notice those boat like Proboat ShockWave is using 1500kv motor on 3S Lipo, I thought we need like at least 4S Lipo to drive such lower kv motor?

meanwhile how does the number of poles on the motor affect the selection?

Thanks.

wyattroa

Anyone know a good place to off load these boats? I have two, one new in a box never opened that was shipped to me stock and the other with new esc, motor, and servo that was not setup.
Robert

swervyn

would skr8pn be ondabeach by any chance?

SkR8Pn

Lol your the second person to say that... That bloke is near you fella's i think.. I'm Northside Brisbane.

swervyn

Lol, Taswegian here so long way from me! Your couplers looked very familiar is all. Anyone had any experience dealing with him or buying any of his stuff? am seriously thinking of putting all my running gear in a new hull (as I have managed to butcher 2 hulls , so far!)& for the $10 or so extra than a new nqd, itwill save me the cutting out hassle plus the deck & hull (i assume) is seperated which will make life easier to fit out. Plus it actually looks pretty good stuff! really like his roll bar set up

SkR8Pn

Lol, yeh thats bit off on where i thought you were. My couplers are made from blank 6061 and can be balanced. The other ones are re drill stock couplers from the nqd,

seehuusen

hehehe, it was the grille pieces that got my attention

The blank hull, in clear plastic, would be great to try out
Has anyone seen the non-jet version, e.g. blanked out jet drive, using a rudder/ flex-shaft/ prop setup?? Pretty bloody quickQ

[quote]ORIGINAL: SkR8Pn


Lol your the second person to say that... That bloke is near you fella's i think.. I'm Northside Brisbane.


[/quot

seehuusen

found the video

SkR8Pn

Lol, first time i saw that style grate was back in 09, i think it was a canadian (aye) that did it. It was a really sweet sprint..

Man thats quick with a prop..... notice the jetdrive with a rescue bar going to save it.....lol cool vids

Started repairing my hull. Glued all the cracks, thought i only had one.....found seven lol. The pic makes it look new again but in person.... well, i can think of a four letter word to describe it. Now onto the cage.

seehuusen

WOOOT WOOOT!!! Get the boat ready so we can take it out for a bash Anyone else in the Brisbane area?

nice cage mate! What did you make it out of? I assume you just melted the length, bent them, and screwed in the separation pieces?

seehuusen

parts have started to arrive for my new Jet Boat build

Wheelnut

My Feedback: (81)

FYI,
This boat is in stock
http://www.xenonproject.com/rc-boats...jet-p-291.html

Ratrunner

1, yes it's possible that now that the cut off is set up, you are not drawing as much and therefore not charging as much.
remember that most manufacturers rate the capacity of a pack at 1C discharge rates and they go to 3.0V per cell when testing.
i use 3.5V cut off for my lipo's, so i dont get near the numbers that they claim.

higher amp loads usually mean less capacity available for use.

2, also possible (in fact probably the main reason for the reduced capacity)

3, there are heaps of better chargers out there than the accucell 6 and it's clones.
it realy depends on how much you want to spend. my charging set up cost a bomb, but im not likely to ever need to upgrade.

4, you can and will cause puffy batteries by using cheap low C rate atteries in a high demand setup like a jet boat with a 120A ESC.
even my 2200 nanotech 2S packs get very warm and puff a little during discharge in the boat. and they are supposed to be 35C (70C burst)
and my boat has the 35A seaking ESC in it.

Jason.

seehuusen

Thanks for that mate!! It all made sense, and it seems that all is as I suspected
I'm glad to hear about the lower usage of mah in other peoples R/C gear by setting the cutof V

Oh OK, cool, coz my 3S 2200mah battery gets warm too, not puffy, just slightly tighter/bulgier

The coupler for my new boat arrived yesterday, man, 4mm is big compared to 2.3mm shafts LOL This is going to be fun!!

Cheers
Martin

Ratrunner

yeah, when i said puffy, i didn't mean it's totally puffy, just that you can definitely see a little swelling, and it's very warm after a run (about 5.5 minutes)

Jason.

seehuusen

same as mine I'd say

seehuusen

left the jet boat sitting on the back seat, then a day later, flipped the whole seat down... Now I've got no roll cage I'm not sure if I'll just use the one off my new boat, or if I will make one like skR8Pn...

seehuusen

something fun arrived in the mail
Thinking of a big-jet conversion... not sure yet though... was it Cornwall RC Boats that had the Graupner jet? Might need to go have a looksie