Some days Chrome and other days colors or black. Its not a stealth thing they must make a lot of racket going through the water . What with the displacement of the disc and the tight wire.
You can epoxie the cracks in the water jacket as long as there is no water getting into the Oil system. The system in my old boat used lake water in the block. The inside of the block was fine , no water getting into the base. Epoxied it up and ran it for years. "V" ed out the cracks and used the marine tech . to seal them up.
Just saw the picture , thats more than a crack
There are bolt on kits. You get the surge coupler , run brakelines to the axle and put calibers and discs on each wheel. Boatbandit.com had the kits. I have been thinking about doing it with my Islander , It has the same single axle as yours.
Uni-bit , or stepbit drill will drill the thin sheet metal with out catching and tearing. Put tape on the bit at the size you want to stop at to keep from drilling a size to big.
The Cortland line Store at Exit 11 on Rt 81 has mill ends of leadcore for 3$ a spool. They are 7 to 8 colors. All weights from 14# up to 60# . Just want guys to know
Most I/O's have a water seperator that has a port to tap into. I don't know what you have for an engine or tank setup. So its hard to help you more that that.
Maybe after awhile, you might better get what you need to have the kicker charge the batt. while your trolling. The solar chargers can't keep up with much of a load. To get one that would , it would be huge!! Plus you have to get the sun to shine