This may sound crazy, but I wonder if we couldn’t take advantage of the planar structure of modern ADCPs and mount the whole thing external to the hull rather than have to machine and weld in an expensive sea chest and coffer dam to house the ADCP as we do today? It would be less costly and potentially easier to service if necessary.
I’m thinking specifically of the 38 kHz ADCP, which is roughly 1 m in diameter and weighs roughly 210 kg in water. That’s a lot for sure, but if outfitted with a suitable flotation collar it could be made slightly buoyant for handling in water. Divers could then guide it to its location along the hull. Once in place the collar can be removed (or not depending on design approach?). Even better, since the ADCP will not experience great pressure perhaps the body could be 3-D printed or made of carbon fiber epoxy instead of marine brass; this would reduce its weight enormously. It could be attached magnetically or bolted to the hull. Power and communications would go through a wet-mateable plug in the hull. The massively parallel communications cable used today would have to be serialized to reduce the number of pins. Just a thought.
To justify such a redesign would of course require an identifiable market = perhaps that is something Science RoCS can help develop? In any event this suggestion is one of many possible approaches to improved coverage of ocean currents from merchant marine vessels. See my January 15 blog.