Is copper tubing going to break down in a marine use? Circulating marine water through a chiller box via coiled copper tubing…is there any reason you’d say this would not work to cool the water down?
IIRC, copper does not corrode to failure in marine water.
A drawback to copper tubing is that it can work-harden and crack from vibration. Recommendations are for seamless, annealed tubing with permanent flared connectors, and secure mounting. Old-time motorcycles used to use a loop in the line from the gas tank to allow some flexibility, but most people use a section of suitable rubber hose these days. The chilling water won’t be a fire hazard like a broken gas line, but if it has a through-hull fitting below the waterline, you could get a sinking feeling. A seacock on all through hull fittings is standard equipment.
If you come up with a compact, low-cost cooling system for the occupants of a boat, please feel free to share the design.
Copper and seawater get along OK. The U.S.S. Constitution has a copper-clad hull and AFAIK hasn’t sunk yet.
Of course, I’ll bet they make specialty alloys just for the purpose of running brine.