Trial #2 I was looking in my attic for my next project and stumbled over my ABC Hobby Baltek. It's been in the attic for over two years and was never really finished. I did sail it once before with decent result (See trial #1) but it was time to finish it up and add it to my regular fleet. While finishing it up, I took the drive train apart for inspection. I found that the stock main gear showed a little bit of wear but everything else looked good. |  |
| I decided to try experimenting with water cooling the motor brushes and not use the normal cooling coils. I'm running the stock motor which is an 05 motor. I don't know the motor specs but it's labeled as an M&Y 700rst. n the previous trial, I noted that the motor did not get very hot on 7 cells so I was not expecting any problems with heat. |  |
| I got some new batteries I was itching to try, they where some 3000 ma NiMh 6 cell from radio shack. I had previously tested them on my discharger and found that delivered a little over 3000 ma at a discharge rate of 10 amps before dumping. Not bad, in fact I got lucky as I tried another set from a different batch ad they only would deliver 2400 ma under the same conditions. I was initially surprised by the speed of the boat, especially since this is essentially stock with a plastic propeller to boot. |  |
| A quick check of the hull after running for a few minutes proved that the boat was water tight. |  |
| I did a couple of close passes and saw a stream of after coming from the cooling exhaust so that was working. On my Super Hawaii, I did not get the same result so I happy to see this working. |  |
| I ran the whole battery pack down until my homebuilt ESC started cutting out. One of the features of it is that it will begin to pulse once the cut out voltage is reached so you know when it's time to bring it in. On opening it up, I found that the battery pack was fairly hot and that the motor was cooking. It would cause drops of water to sizzle as they touched the casing. So much for just cooling the brushes! |  |
| After I let the motor cool, I was ready to try again. This time I changed the propeller to an Octura X442. The plastic propeller provided good speed but more is always better, right?! |  |
| With the new propeller and new battery pack in place, it was time to test the boat again. I did not notice any increased speed with the new prop but I did notice that it start porpoising a good bit and I thought I noticed a bit of cavitations but this may have been due to picking up some pine straw in the prop. The water cooler also stopped working with this propeller. Oh well, the X442 is a poor choice for my setup and I immediately changed back the the factory propeller. |  |
| The boat turned well and tightly. It would spin out if you tried a hard over turn at maximum speed. I never looked like the boat would roll over however. |  |
| When the boat was up on plane it ran straight and true but if power was reduced a little bit or the prop picked up a piece of pine straw, the boat had a tendency to lean to the right, the same side as the motor. |  |
Trial #2 Conclusion The boat ran well and was faster then I thought. The motor did get much hotter then I like. I don't know why it didn't during the first trial but it's a problem that needs to be addressed if I'm going to continue using high capacity batteries. I'll add a cooling coil and see if the stock water pickup can supply enough water pressure. I may also try some other props but I'm pretty happy with the stock one. |  |
