Yes, I got that foam from Dennis Love, from the Elite RC Boat group on Facebook.
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Cool, I have not tried it in a heavier electric yet. Gas boats so far it works great.
Made the maiden run today on the JetChopper 30. Leak test went well so we buttoned her up and sent her off. A quick test to make sure the cooling lines were flowing and my son stabbed the throttle. We started out with a Graupner 442 2-blade. I have the COG set at 33% (10" from transom) and she for sure running wet.
Datalogger showed:
Max Amps: 77.23
Max Watts: 1143
Max RPM: 28,571
Average Loaded RPM: 26,500 (Seems a little low, might come up with not plowing water?)
GPS Speed: 30.2mph
Max ESC Temp: 87.2
Max Motor Temp: 68.4
This is an SSS 3674 - 2075kv 4-pole motor on 4s
Stinger and trim tabs all set to neutral
I think setting the COG back to 30% at 9" should be my next step.
I also noted that while the motor and esc were cool, the water is very cold in my pond, and the water flow coming from the rudder pickup was not to my liking so I will add the second pickup.
I also have a slight alignment problem as I can hear the flex hitting the stuffing tube. I'm going to swap in another motor coupler to see if that helps at all, if not I might need to adjust the set screws on the motor mount.
JC30 2075KV 4S G442 Prop 3-31-17 Gauges.JPG
JC30 2075KV 4S G442 Prop 3-31-17 Temp Chart.jpg
JC30 2075KV 4S G442 Prop 3-31-17 Amps Chart.jpg
JC30 2075KV 4S G442 Prop 3-31-17 RPM Chart.jpg
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
A friend of mine built a Jetchopper 30 with a Leopard 3674 2200kv on 4s, I only saw it run a few times. But it did run very wet with its bow down, he had no trim tabs on the hull so not that causing the problem. I don't know where he had the cg set but worth checking if theirs any hook in the hull.
The hull does have quite a bit of hook in it, noticed it as soon as I received the hull.
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Although quite rare their are some hulls with built in hook, the Seaducer monos for one. Seaducer tell you that this hook is built in on purpose & not to take the hook out. But not sure on the Jetchopper hulls whether any hook is just a distortion in the hull that should not be their. I would email the guy that makes them & ask if the hook should be their rather than just filling the hook out first.
On the Jetchopper 30 website are the build & set up instructions, it states. The hook near the transom shall be grinded off to make a near perfect straight line, try moving your cg back first though. If that dosnt improve things I would look at filling the hook in the hull.
Mine has a hook in it also. As did the first one I built up years ago. I filled the hooks in the first one. it was a much better boat then.
Kenny, as suggested above, move the cog back & raise your trim tabs up to well above level to make sure they are not pushing the nose down too. Maybe put a slight positive angle in the strut too, if it is still running wet. If all that fails then as Martin suggests, you will need to fill the hooks.
See the danger. THEN DO IT ANYWAY!!!
https://forums.offshoreelectrics.com/...hp?albumid=319
https://forums.offshoreelectrics.com/...hp?albumid=320
Will try those suggestions. What would I use if I end up deciding to fill the bottom?
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Just for rookie clarification, a "hook" is an imperfection in the bottom of the hull? I'm envisioning it as a depression followed by a ridge just before the transom.
Vac-U-Tug Jr (13mph)
Yes, it's basically that the bottom of the hull is not flat, I'll take some pictures later.
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Yes a hook is a distortion in the hull bottom where the distortion is concaved, this sucks the hull down to the water. You can also get a rocker distortion in the hull which is which is the opposite to a concave, which causes the hull to porpoise.
Hooks & rockers also apply to both monos & cat hull running surfaces.
Pics of the hull bottom
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NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Tested the boat yesterday with the batteries moved as far back in their trays as possible, basically almost touching the motor mount. Results were nearly identical in Amps, Watts, Temps, Speed and the hull was still running wet. I did swap out a spare motor coupler and that has solved my noisy cable issue, I guess I get what I pay for from ebay. I ordered up a new Aeromarine coupler to try as well.
So I dove into tackling the hook issue on the bottom of the hull. Sanded with 80 grit paper and cleaned with denatured alcohol. Mixed up some bondo and covered one side of the hull. Will try sanding down smooth tonight and see if I need to reapply or I can start on the other side.
20170403_214837.jpg
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NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Did you check this thread for tips?
https://forums.offshoreelectrics.com...ht=jet+chopper
I've consulted Tony (Propperchopper) and Paul (785boats) as they have both built this hull. Paul indicated in his build thread filling the hook inproved his wet running hull. I have yet to adjust the stinger from neutral to positive, but if most boats have a flat transition to the transom, then that's what I want. I can adjust from there, just glad I started testing now before I went to paint. Mine is running a quite a bit "wetter" than Pauls:
https://www.youtube.com/watch?v=V7mp...ature=youtu.be
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
You're in good hands then. Would suck to do all that work to find out its not going to help. AC Model boats are another group that has a hook intentionally built in.
2nd coat of bondo on the Chopper hull, this stuff is pretty easy to work with, about the consistency of toothpaste. Sands pretty well, on the first coat I knocked down all the high spots and with the ruler noted that I still needed to build up some areas.
20170404_220815.jpg
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Looks like it's going to be table flat soon enough. A quick shot of black or gray spray paint over the bondo will let you see your progress and high/low spots a little easier while sanding. They call it a guide coat in the auto body world.
Vac-U-Tug Jr (13mph)
Wrap the sand paper around a flat block of wood when sanding to get a nice flat surface on the bondo.
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Looking good.
Nearly time for the water.
See the danger. THEN DO IT ANYWAY!!!
https://forums.offshoreelectrics.com/...hp?albumid=319
https://forums.offshoreelectrics.com/...hp?albumid=320
Was trying to decide if I leave the hull white and go with accent colors, or go all green? I decided to try the colored stripe instead, I'm liking the choice so far.
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NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Some more progress on Color
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NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
I decided to paint the Sonic Lime Green and Gray outline on the nose instead of the decals I hav placed there, more to come.
20170416_182322.jpg
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Added some detail to the hatch and re-working the bow section with paint, much happier now, should be able to clearcoat this baby soon!
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20170420_211914.jpg
NEVER SATISFIED RACING
Fine Design 32 V-Hull 4082+6s
Looks good .
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