I just tried out a 23 turn double motor that I installed in my Profisherman Bass Boat. I have 2 identical 7-cell NiCd battery packs that I'd just charged. One of them is new, the other a year old. I ran the new one first and everything was ok - run time normal, nothing too hot after, boat speed not noticeably different than with the stock motor. After half an hour I tried out the second pack. Right away something was wrong. The boat only had about half the power. I ran the pack down which didn't take long and noticed the plastic had melted away from one of the cells in the pack. At first I thought the problem was with the battery pack but now I'm wondering if the problem was something else which caused the battery to overheat. I measuered the battery voltages before and after the runs:

new battery before=9.93V after=9.02V
1 year old battery before=9.66V after=9.09V

Any ideas?

Another thing. The steering servo has stopped working but I think this is unrelated. At the end of the second run the boat was full of water. Maybe it will work again when things dry out.

Sometimes old battery packs do not hold a charge after awhile. I had a 4 year old battery pack witch was 1400mah. It was like yours, only I got 30 second runtime. I invested in some 1500mah packs for 9$ and now I get 10+mins of runtime.

Greg, If some cells get way hotter than the other batteries when charging or discharging, then you deffinetly have some dead cells. I have the same boat and I when I put a 23 turn motor in, I noticed a big difference, I was using a GPS, but it was still noticeable to my eyes that it was going alot faster. I have a Octura X632 that I am about to try out on it. I will let you know how that goes.

That makes total sense and also explains why the power was reduced from the get go with that battery pack. I'll know for sure when I run the boat again with the good pack.

I mentioned in my original post that the boat was not noticeably faster with the new 23 turn motor. However, I now realize that it was running with the nose low with more of the forward part of the hull dragging in the water. This is because the new motor is lighter than the old so the weight distribution has changed. When I make some adjustments to get the trim right I should get significantly more speed.

I have an Octura X430 prop that I'm going to try on it. I need to sharpen and balance it first though. I'll let you know how that turns out.

Just tried out the X430 prop after sharpening and balancing it. Unfortunately the water on the pond was still - not good for speed. Anyway I find it hard to tell how fast it's going by just looking at it. I don't think it was going any slower than with the stock 32 mm plastic prop though. The run time seemed a bit shorter than usual and when I brought it in everything was a bit hotter than normal although not really hot. This was surprising because I thought the smaller 30 mm prop would pull less amps, everything would be cooler, and I'd get longer run times. Perhaps the pitch of the X430 is greater than the stock prop. Also the drive dog had been tightened much harder on the shaft indicating the prop was putting more torque on it. I might try raising the motor slightly to reduce the drag of the lower unit.
GRK65, did you ever get to try that X632 on it?