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Old Dec 29, 2012, 02:13 AM
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Is this a good setup DTRC Boat

I have a Dtrc Cat (E36 ) aprox 800mm long the esc is 120amp
Not sure what the brand of motor it is but i think its a 3674 and 1620kv
batterys
2 x 7.2 volts 4900amps in series

New to boats and would like peoples input to the above to setup
thanks
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Old Dec 29, 2012, 06:09 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
5,120 Posts
Hi Dazzer,

Welcome on the wet side!

The only cat with this dimensions I could find is this one:
http://www.dtrcmodel.com/Productsview.asp?id=44
Is this your boat?

The seller offers little more info, so if you would be so kind to show us some pictures and list what goodies came with the boat, we could comment on that.

Judging by the pictures on the site, it's a stunning looking hull, most likely made from vinylester and rather underpowered with a 3674 1620Kv motor on 12 cells NiMH(?).
On 14,4V (really, are you running it on NiMH?), a 1620Kv motor will give you barely 21.000 rpm at the prop under load, which is at least 10.000 rpm shy of what most cats this size have.
Running the motor on 6S Lipo would be a nice set-up, provided the motor and ESC can handle it.

This version is clearly a beginners set-up.
Whitout having seen it run and with pictures of the bottom, it's hard to say if upgrading is worthwhile.

If the silicon tubing is routed like in these pictures, you'll have the infamous 'half motor' cooling, the outlet has to be on the highest point to avoid trapping air in the motorcooler:
http://www.aliexpress.com/store/prod...305221944.html
If the motor is indeed a Feisuda, it's a two pole motor that requires a perfect cooling to avoid overheating.
Change the tubing prior to running the boat!

If the motor is a Feisuda, it's either a 3660-1620Kv or a 3674-1660Kv, see the data on the site:
http://www.fsd-motor.com/en_productview.asp?id=311
As usual, the Chines can't copy data very accurately...

Regards, Jan.
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Last edited by pompebled; Dec 29, 2012 at 06:27 AM. Reason: Addition.
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Old Dec 29, 2012, 05:17 PM
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Joined Dec 2012
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thanks for your reply
Yes that is the boat
Running it on 2 x 2s 7.2 v 4900mAh in series (LIpo Batterys)
I dont think the motor is anything great the esc blew on the second day not sure why running the above battery setup maybe wrong
What motor and esc would you reccomend for this boat ??
Thanks for the info on the cooling will change that asap
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Old Dec 30, 2012, 07:02 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
5,120 Posts
Hi Dazzer,

'Long distance diagnostics' are always difficult, you'll have to provide us with lots of info and pictures to get answers that apply to your specific situation.

Regarding the ESC blowing up; without knowing how you ran the boat, this can be anything, from a few drops of moisture getting inside the ESC (did you tape the hatch shut to avoid water ingress?), to running the boat long stretches at half throttle (to get the hang of it...).

Running these set-ups at less than full throttle is lethal for both motor and ESC, they'll overheat and die.

Did the boat come "RTR", or did the manual specify that you had to program the ESC prior to running the boat?

If you still have warranty, make use of that and ask for a replacement ESC, even a '120 Chinese Amps' ESC should be able to handle the 3674 Feisuda.

You see, your six lines answer raises more questions than answers, elaborate, elaborate!!

Pictures, pictures, scans of the manual, etc, ect...

Lipo batteries are 3,7V a cell, 2S lipo have 7,4V, hence my confusion with 6 cell NiMH packs, which are 7,2V (1,2V per cell).

Regards, Jan.
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Old Dec 30, 2012, 05:15 PM
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HI Jan
Thanks for your responce
First time i ran it was about half speed for about 2min then from at point was full power .
Yes i taped the cover down each time i changed the batterys there was a little water .
Setup of the boat is a little strange right side is esc middle is battery then left side battery I guess this is because of the 2 blade prop .... it does handle ok and turns tight Name: 20121231_071833.jpg
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i have 4 x 2s 5000 lipos i would like to stay with thease until i need to replace them ...

motors should that be around the 2200/2800kv and the esc around 180amp
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Old Dec 30, 2012, 05:17 PM
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forgot this one Name: 20121231_072049.jpg
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Old Dec 31, 2012, 07:20 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
5,120 Posts
Quote:
Originally Posted by dazzer2161 View Post
1) First time I ran it was about half speed for about 2min then from at point was full power .
2) Yes i taped the cover down each time i changed the batterys there was a little water .
3) Setup of the boat is a little strange right side is esc middle is battery then left side battery I guess this is because of the 2 blade prop .... it does handle ok and turns tight.
4) I have 4 x 2s 5000 lipos i would like to stay with thease until i need to replace them ...
5) motors should be around the 2200/2800kv and the esc around 180amp
Hi Dazzer,

By the numbers:
1) You may have damaged the ESC in those first two minutes, going to full throttle will have cooled things down sufficiently, but starting up for the second run may have been the final blow.
I use Chinese ESC's too, but I always open them up prior to running them to check if all Fets have physical contact with the watercooler.
As an example a picture of a 100A Mystery ESC; the dull spots are where the Fets actually touched the cooler...

You can imagine that running the ESC without sanding the Fets into one plane, the only response from the ESC, when full power is applied, will be 'poof'...

2) Did you pull the flexshaft after every(!) day of running the boat, drying it and re-grease it?
Due to the windings of the flexshaft, the grease will dissappear while running, leaving room for water to get up the stuffing tube.

3) If the boat runs well with the factory set-up, there's no reason to change it.
The fact that the boat 'handles well and turns tight' makes me suspect it's relatively slow, about 30 mph would be my guess, judging by the rpm under load.
Well dialed in, this type of hull should have no problems reaching 60 mph (at least).
The picture is too blurry to be sure, but I suspect the prop isn't sharpened; a dull leading edge causes an impressive roostertail, a sign of energy not propelling the boat forward and also causes propwalk.

When a cat runs at full speed, the turns are wide, at the penalty of a flip, when you attempt a narrow turn.

You can add a few miles to the topspeed when you sharpen the trailing edges of the sponsons at the end and at every step.
Sanding the running surface dull (sand lengthwise!) also adds to the topspeed and improves handling.

4) Running this size cat on 4S and have a fast boat isn't the best way to go about it; the current will soar and you'll need a big ESC to be able to handle that, also the runtime will drop, unless you use parallel packs to compensate for that.

5) Motor suggestions:
- with 35000 rpm under load a rather 'hot'set-up:
http://www.hobbyhot.com/LEOPARD-Boat...ess-Motor.html
- With 30000 rpm under load at the low end of 'cat revs', possibly creating torque issues due to the large prop required to get up to speed:
http://www.hobbyhot.com/LEOPARD-Boat...ess-Motor.html
- the cheaper HK variant:
http://www.hobbyking.com/hobbyking/s..._Inrunner.html
- With 33300 rpm under load a medium suggestion, due to the shorter can less torque, which may limit your propchoice:
http://www.hobbyking.com/hobbyking/s..._Inrunner.html

All these motors are four pole, which is a big step up in terms of torque and cool running, compared to the two pole motors like the Feisuda and Feigao motors.

Please take notice of the fact that I'm not a fan of low Voltage / high Amps set-ups, which the motors listed above are on 4S.

Running a higher Voltage with lower Kv motors is much easier on batteries and ESC.

You may get away with the T-180:
http://www.hobbyking.com/hobbyking/s..._Boat_ESC.html
But, depending on your motorchoice, the spikes in motorcurrent can (and will) be well over 200A when getting out of the hole and accelerating out of turns..., keep in mind that you may have to invest in something like this:
http://www.hobbyking.com/hobbyking/s...ooled_ESC.html

In which case you'll also need a UBEC as powersupply for the servo and receiver:
http://www.hobbyking.com/hobbyking/s...Reduction.html

Regards, Jan.
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Old Jan 01, 2013, 12:48 AM
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Joined Dec 2012
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Hi Jan

Thanks for all the info

Based on the my batterys 2 x 7.4v 5000 in series for the above if i decide to start with new batterys
1/ What battery setup would you use ???
2/ What motor would you use in your battery setup???
3/ What esc would you use for the above ???


Regarding the boat flex sharft yes i remove it and grease it each day i use it ,But didny check it when i got it.
4/ Is the UBEC supply power to the servos ,because the ESC dosnt have an onboard BEC???

5/ What would you recommend for a prop ????
6/ What voltage and amp etup would you run ???

Sorry for all the questions im just new to the boats

Regards
Darren
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Old Jan 01, 2013, 02:11 AM
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Australia, VIC, Blackburn North
Joined Feb 2011
825 Posts
Hi Dazzer,

If that was my hull, I would've used my current Genesis setup.

Swordfish 200A, Leopard 4082 1600kv, Octura X440/3 Prop and two 6S (22.2v) 4000mAh 40C (can't fit 5000's in my hull) in parallel giving 8000mAh.

I'm planning on trying the Swordfish 240 and changing to 2 x 4S in series (8S, 29.6v) for some high speed runs.

With the last set up, I'll still be able to run on my current battery setup (6S) without changing ESC.

Yes, UBEC is to power servos when ESC doesn't have one.
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Old Jan 01, 2013, 05:53 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
5,120 Posts
Hi Darren,

Not knowing your budget, (I am a budget boater myself) an adapted version of Mozzyrocks' set-up will get you running much faster without investing lots of money:
- Motor: your stock 1620KV
- ESC: the Hobbyking T-180
- Lipo: preferably two of the biggest capacity and C-rate 6S lipo's that will fit in the hull, wired in parallel.

With 32000 rpm at the prop (which needs to be sharpened and balanced, prior to running those high revs!) and once the boat is dialed in (strut height, propangle, CoG ect.), you'll be pleaseantly surprized how quick it'll run.

Things to do on the hull:
- sharpening all trailing edges
- sanding the running surfaces dull (600 grid)

Regards, Jan.
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Old Jan 02, 2013, 05:13 AM
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Thanks for all the info guys

One last question Regarding props mozzyrocks your prop is 3 blade ?? so woundnt 2 blade have less drag in the water so there for be quicker ??? Oris my way of thinking wrong
Thanks
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Old Jan 02, 2013, 09:19 AM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
5,120 Posts
Hi Darren,

As a rule of thumb, when the size is the same, a two blade is more efficient, as the blade surface is bigger.
The threeblade 'sounds' faster, as there is one blade more per revolution hitting the water.

Testing with identical boats shows that the twoblade draws less amps, yielding more runtime.

Having said this, the shape of the prop, the pitch and degree of sharpening can make or break your performance.

A dull twoblade will always perform less than a sharpened threeblade...

Regards, Jan.
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Old Jan 03, 2013, 05:04 AM
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Joined Dec 2012
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THanks for all the help going to replace the ESC and motor, Prop ans start to sand the hull Batteyrs do you think this batterys are any good
http://www.hobbypartz.com/77p-sl4000-6s1p-40c-6666.html
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Old Jan 03, 2013, 05:06 AM
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Would have 2 of thease in Parallel price seems good
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