waterproof connectors for the battery case and for the wires:
This is a 2" tube top from home depot - something like this for the battery tubes, with a hole drilled through then epoxied would be ok for D cell (10 in series, for a total of 12 volts, 17000 mah (milliamp hours, see below chart) and something like this waterproof plug might work
D CELLS: see this site for more info: http://www.allaboutbatteries.com/Energy-tables.html
Here is a PVC compression fitting, from this site, and a cool "make your own gaskets" package which could really help:
Molex has some connectors that are IP67.
Deutsch makes some cable mount connectors. Not sure of the rating.
For permanent connections -- IDEAL makes some wire nuts that are IP55.
3M has Scotchlok Butt splices (gel filled).
Another option for connecting wires would be an IP rated junction box.
All the connections could be made inside the box. Wires would enter
the box through a cable connector (e.g. Hubbell SEC50BA which is IP66 suitable).
IP rated connectors: I think we should go for IP68, truly underwater rated.
I shall look into this more:
This is very interesting too: on openROV forum:
Eric suggests Loctite Hysol E-90 FL
Just for reference, the marine grease and the marine epoxy i like best is:
I also find this silicon stuff super tough, the marine grease really effective, and the DAP urethane glue really good, but it dries hard.
Check out this guy's technique: Basically, he pours hot wax over the entire control unit for waterproofing!