Hi Raven,
I can understand your uncertainty about going brushless. (I was in a similar predicament about 4 years ago!)
But they do provide plenty of benefits for model submarines - reduced space and weight being two.
The Hobbyking route is more technically risky but will probably be cheaper.
I would go the Mtroniks combo route again, I think. (I don't have any links with the company other than as a satisfied customer!) Have a look at this link:
http://www.mtroniks.net/prod/Boat-Speed-Controls/G2-Hydra30-System.htmGetting the right motor and prop combination is always a little hit and miss but you can do some "tweaking". In order of difficulty:
- Try direct drive with the existing prop. Do an "in-bucket" test and measure the current (if you can) or run time.
- If the current is still too high (much more than 5 Amps say) change the prop or take some pitch off. (You can sometimes twist blades.)
- Still too high, put in a gear reduction. (3:1 works for me)
Some of my experienced sub enthusiasts go straight to direct drive and make changes to the setup on the brushless ESC but it sounds to me that you need a more "out of the box" solution to get you started with brushless.
David