Help needed with Academy Sea Dart

[beetleman]

Hello,

I'm fairly new in the RC boating hobby, which is virtually non-existent here in Israel (not enough lakes or ponds, too many wars...). I had purchased an Academy Sea Dart electric boat while on a trip in Dunedin, New Zealand. I've been trying to increase its speed ever since the maiden voyage...

I replaced the stock motor with a Tamiya Super Stock RZ, replaced the mechanical speed controller with a Futaba MC230CR ESC. I use a Venom 3300 battery. I even replaced the entire drive system (tube, shaft, prop) with a more durable one. I did this as I ruined the original plastic prop while running on hard weeds, and could not find a replacement (the shaft is 3mm). So I bought a more standard drive system (4mm) when I was on a trip in Paris, in the EuroModel store. Good thing I travel a lot!..

Although the speed has increased, I want more... The final effort I am willing to invest in this boat is where I need help.

The boat comes with a gear-down drive system. The ratio is 1:3 (I counted the number of cogs on the gears). I found out that this model's sister boat, the "Flying Fish" is identical except for a direct-drive system (no gear). Can anyone advise which would be faster by nature, say if both are built stock?

Since I only have trial-and-error as an advisor, I plan to remove the gear and scratch build an engine mount to accomodate the gear-less setup. Do I need different props?

Can anyone advise on this? Does anyone have experience with these boats? Any advice would be greatly appreciated.

Thanks!

[BoatDoc]

i don't know much about that boat. but i can say that you'll want some different props if you switch from gear drive to direct drive.

[beetleman]

Thanks BoatDoc.

Does anyone have any other input regarding my questions?

Thanks

[Tuslow1]

Do you have any pictures of the boat and of the setup? That might be helpful in giving the guys a better idea in what direction to start pointing you in. I wish I could help but I'm just learning myself. My answer would be "Go Brushless" but that isn't always the case, someone had a brushed boat that ran good enough to win a race against a brushless boat. So post some pictures if you can, I'm curious to see what it looks like..

[beetleman]

Ok, here are some images. Note the stock setup vs. the current hopped-up setup. I haven't got around to building the custom engine mount, so it is still with the gear box.

If anybody can advise to any of my quuestions (see the first post in this thread), I would really appreciate it.

Cheers

[beetleman]

By the way, the color scheme of purple and yellow was inspired by Vincent van Gogh's "Starry Night over the Rhone", 1888, exhibited in Paris, Musee d'Orsay :-)

[Ron Olson]

You asked me to so I looked. Consider that I haven't messed with an electric boat in a long time.
It's good that you got rid of the mechanical speed control as those have been known to catch fire. Next, I would take off the gear recuction unit and connect directly to the prop shaft. The gearbox will hekp it to turn higher-pitched props but the supplied prop shouldn't have any trouble being spun with that motor. The spot where the MSC sat could be cut off to slide the motor further back.

[beetleman]

Thanks Ron :-)

[beetleman]

I have now modified the boat to a direct drive. I removed the gear box and fabricated an engine mount. I also added a fan (yes, it is from an old computer CPU...). Looks simple, but it required a lot of trial-and-error. Will test the boat this weekend.

[Dongskie Pinoy]

Hi Beetleman!

Nice boat you got and great work you did converting it into a direct drive.

I saw the photo and was hoping you had not run the boat yet. I was pretty concerned over how you mounted the motor just right over the boat's plastic itself.

I am afraid this will melt your hull or the place where it is exactly mounted and disalign the whole motor with the shaft.. this can be disastrous...

A simple solution will be to wrap the bottom part of the motor (where the motor makes contact with the plastic) with a heat resistant material such as a asbestos film or an asbestos tape, this thing is available at your local hardware.

Your MC230 is limited down to 19turn motors, but due to the lack of ventilation inside the cabin, the ESC will heatup faster and sometimes will reach its maximum temperature and do a thermal shutdown even just with a 23turn motor.

A few tips to maximize your ESC are these steps:

- desolder the original wires and replace it with a 14guage wires
- change your battery connectors with DEANS plugs
- hardwire your esc wires to the motor (solder directly)
- install a 10,000mf / 16v capacitor in parallel to the esc to battery wires. This will lessen heat build-up in your esc.
- install a motor heatsink such as this:

http://www.3racing.com.hk/images/3RAC-MHS004BL.jpg

- be reminded that the fan shoud suck the air out of the motor and not blow air into the motor, this is because the motor's spinning armature creates a turbulence inside the can that blows air out of the motor can.
- you can also add a fan on your esc :)

Good luck!

[beetleman]

Thanks mate.

I did run the boat, and was amazed at the speeds it reached! The direct drive more than doubled the speed, almost tripled it. It really became a speed boat!

However, this came at a cost. The setup could not withstand the heat build up and after less than 2 minutes the boat stopped. My guess is that the ESC's protection mechanism kicked in. After a few minutes it came on again. I retrieved the boat and checked it. You could cook an egg on the motor, ESC, or battery! I had to let all cool for 15 minutes before the next run, which again lasted less than 2 minutes.

My conclusion is that I've heavily upgraded a boat that was not meant for upgrading. I agree with your comment about the engine location - it is sunk between 3 plastic walls with only the top exposed. This results in horrible cooling but there's no alternative as the motor had to be pushed down in order to align with the drive shaft (with the gear setup it was placed higher in the mount and in mid air, hence cooling was better). I'm glad it didn't melt down the plastic.

The fan is almost useless with the kind of heat that is generated, and I can't use a heatsink like you recommended because there's simply no room to stuff it.

I think that at this point it is time to move on to a new boat, rather than continue torturing this poor one... It has been a very educational experience though. I opened a new thread where I asked people for advice on which boat to buy. I'd be happy to hear your suggestions.

Thanks.

[peterpella]

[QUOTE=beetleman;2221655]Hello,

I'm fairly new in the RC boating hobby, which is virtually non-existent here in Israel (not enough lakes or ponds, too many wars...). I had purchased an Academy Sea Dart electric boat while on a trip in Dunedin, New Zealand. I've been trying to increase its speed ever since the maiden voyage...

I replaced the stock motor with a Tamiya Super Stock RZ, replaced the

RE

Hi there. This boat is really primitive. Few years ago i had almost the same problems as you now. I changed everything. My advice is: use standard Graupner 550 motor: let's say Speed 500 or Speed 600 ( however you need to make some bigger place inside to place that motor ) and 30 mm prop. If you need such items, go to Graupner and buy completely ready - made set consisted of motot, shaft, prop.

Peter