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Jul 10, 2019, 11:53 AM
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Hi Mitey, have you had a chance to maiden this boat yet?
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Jul 10, 2019, 08:30 PM
Registered User
Thread OP
Unfortunately, no. But it IS "done". I have everything hooked up, the impeller spins, the nozzle turns, etc etc. The only thing I haven't done yet is figure out a way to secure the batteries, I'm thinking double sided velcro would allow for adjustability but still hold tight. I also need to throw some grease in the grease port. Oh, and some flotation. But really, she's ready to rock.



I'm getting married next month, and I've been super busy getting all of that squared away... I'm sure the married men here know the gig. That, and the wife and I both bought brand new motorcycles 3 weeks ago, so any time we've had not working or planning the wedding we've been breaking them in. In fact, I just got done with the wife's 600 mile oil change.

We're heading up North to our hometown for about 10 days for the wedding, and my parents live on the bay, so I think I may throw the jet sprint in the car when we go and give her a little spin in the salt water. I've even got a "drivers stand" about 30' above the water :-)

This is low tide, at high tide the water comes up to the bulkhead.

Jul 14, 2019, 11:30 AM
Registered User
Thread OP
OK, last update before her first run I reckon. Still not sure when that will be, but here it is.

Grabbed some closed cell foam from work to use for flotation and stuffed some up front between the bulkheads. Flotation done.

Filled up the grease cavity with marine grease. Grease done.

Stuck some velcro all along the stringers, and some on the batteries. This should at least be good enough to dial in my CG before making more permanent battery hold-downs/mounts. Batteries done.

However, when filling up the grease cavity I noticed.... I think I installed the seal backwards. Damn. Getting all that stuff installed and lined up just right isn't the easiest thing in the world, but it looks like I'll be pulling the shaft and seal out and setting it back in the right way. I was considering adding a pin to my "test" (read, FDM, CA'd onto the shaft) impeller, so maybe this was Poseidon's way of telling me to get that done before I spin the impeller off within the first 30 seconds.

Maybe I'll fill the tub today and at least give her a little throttle to see what happens.



Jul 14, 2019, 12:23 PM
Registered User
Thread OP
Actually, I have a question. Every time I connect my batteries to my ESC, I get a big nasty arc on the negative terminal, and it's starting to get a bit black and nasty in one spot. Is there any way to mitigate that? I don't recall ever having that happen on my cars. Perhaps a capacitor somewhere?
Jul 14, 2019, 01:33 PM
Just Plane Nutts
AirDOGGe's Avatar
Try these: https://www.amazon.com/XT90-S-Female.../dp/B00RVM8U5W
\
Jul 14, 2019, 04:29 PM
Registered User
Thread OP
Thanks Air. Trying to avoid buying a new plug ATM, seeing as I just got this one soldered up. I'll stick it in the Amazon cart and save it for later though!
Jul 15, 2019, 12:49 AM
Just Plane Nutts
AirDOGGe's Avatar
Well, there's this method, though I have not put it to use myself to verify. It looks sound. Basically you connect the small aux wire with inline resistor first, THEN the main connector:

https://www.4-max.co.uk/grafix/AntiSpark1.JPG
Jul 15, 2019, 10:57 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Quote:
Originally Posted by MiteyF
Actually, I have a question. Every time I connect my batteries to my ESC, I get a big nasty arc ...
... Perhaps a capacitor somewhere?
Capacitor(s) will make it worse. It's the inrush of current into the input capacitors (big, coloured, barrelshaped) that's responsible for the spark

But, on the other hand ...

... "The spark is your friend" (CastleCreations).

No spark, then input caps are dead and rest of controller will soon follow (due to voltage spikes higher than batteryvoltage). Preferably taking plane down with it
Explanation
www.rcgroups.com/forums/showthread.php?952523-too-long-battery-wires-will-kill-ESC-over-time-precautions-solutions-workarounds


On the other hand, too big a spark is bad for connectors. Not to mention your nerves.
Solution: move the spark to a cheap extra sacrificial connector.
The extra/very thin wire will reduce current, no need for resistor, or choose resistor small enough to reduce spark but still visible/audible. You'll still hear a (weaker) spark as an ok signal/indication.

from
www.mgm-compro.com (professional) &
www.mgm-controllers.com (hobby)

Last edited by Ron van Sommeren; Aug 01, 2019 at 11:06 AM.


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