CAT 32 Aftercooler removal and test..why?

A lot of Cat owners are questioning the maintenance schedule. My manual for 3406E and C15 engines updated 4/15/2015 states aftercooler clean and test at 15,000 gallons, or 1,000 service hours, or 2 years calendar time. Replace every 6000hrs or 6 years. Not sure if the same as the C32. I question this because of what you stated, low hours over the 2 year clean and test period. Average time for recreational use is way less than 1000hrs. in 2 years. Was told by a Cat mechanic the warranty program was the reason for the schedule. Adds a lot of expense when you amortize cost for cleaning and replacement over 6 years. You need to check for updates on your Cat maintenance schedule, it maybe different than original.

I find a lot of engine shops, all brands not just Cat, will get into a routine of recommending bundling services together that may not exactly match each engines requirements. The most common I've heard is a 2yr/1000 hr service that cleans and/or replaces everything that salt water runs through. Getting the service manual and reading it along with having good notes on past service is a good way to stay on top. Often times mechanics are dealing with customers who are very behind on service and they do indeed need everything done at once to catch up.
It's a hard job to go to the owner and lay this out. I remember one time getting out all the books and having them turned to the maintenance pages as I was making notes. The owner asked what I was up to and then we started looking at it all together. Our discussions went smoother once he started to realized the scope and requirements of keeping a boat in good condition.
I also remember getting a major service done on generators while we were in Mallorca. The invoice was staggering. A replacement generic plastic coolant overflow tank was over $150 (after converting from euros). In the US I could have bought it for under $10 at the auto parts store.

If your aftercoolers are original, have them pulled and CHANGE them with new ones. CAT recommends changing them every 6 years. I've seen them fail, once even on a 3 year old yacht with the new style C32 aftercoolers and causing a rebuild. I don't think I'd inspect/pressure test them every 2 years, I WOULD just pull them every 6 years and replace them with new ones.

I would never let salt water in any engine,genny , again. I would use a interstage heat exchanger . I been thinking how to incorporate a Stainless steel hull bottom also to reject all the heat . IMO The only salt water running into the boat is for the water maker or too interstate heat exchangers.

You would need more surface area than that. Essentially the entire bottom of the boat. I'm thinking 50 to 90 foot luxury planning boats with high horsepower engines, duel generators, and enough AC cooling capacity to keep your ice cubes from melting on the hottest day.
While I believe retro fitting is possible, every one would be a one off build to match the total btu load. It would be much better to be fitted into new hulls already sized correctly for the btu load of production boats.

Interstage heat exchangers are another option.

Sucking in Salt water and pumping it through a engine then out is the KISS way.

Refrigerants are another possible solution as they absorb heat , move it , then reject it easily.

Using it too little is as bad if not worse than using it too much. At 83 hours per year it would be cheaper to charter.

That's all well and good if you're interested in an 8 knot boat. Most people aren't and a keel cooled system will not work on a yacht or sportfish.