Some perspective on fluid samples from a current surveyor and former yacht broker.
Although I take lots of fluid samples now and I think they can be a useful tool, people need to keep in mind that the real value is in trend analysis. Taking regular samples on a regular basis with the same number of hours on the fluid can tell you a lot about the health of the engine/gear. A single sample only tells you the current condition of the fluid and there are many, many variables.
When I was a broker I learned the hard way to tell all my new listings to change the oil/trans fluid and keep it clean until survey. Old oil at survey is a deal killer, as evidenced by the jumping to extreme conclusions on this thread. Most seem to read "elevated water, sodium" as reason to believe the vessel sank. I see no reason to leap to that conclusion.
The OP had the boat surveyed, so I'm sure the surveyor was looking for actual evidence of a prior sinking. The OP wrote "elevated" which is probably how the lab wrote it, and not "high".
High hours and lots of time sitting without changing the fluids is a guaranteed way to make an oil sample fail analysis. I saw it many times, old guy quits using his boat, had a bunch of hours on the oil, decides he's not going to change it because he's selling it. Boat sits on the market for a year, goes to survey and the oil analysis comes back with all kinds of things in it. Buyer usually freaks out, cancels the deal or tries to renegotiate heavily because of the results. 90% of the time though an oil change & putting 5-10 hours on the oil results in normal oil sample.
I once saw a twin engine boat that had oil samples pulled by the hull surveyor and by the engine surveyor, sent to 2 different labs. One set came back bad on both engines, the other set said they were fine. Probably because one of them scraped a little debris from the bottom of the pan.
My point is when a single oil sample comes back bad on a survey, take a deep breath, change the fluid, put some more hours on the gear, and resample. It's one data point, conclusions are best drawn from multiple data points that suggest the same conclusion. When an engine has been sunk it usually takes at least 3-4 fluid changes to remove the salt from showing up in analysis. If the OP's second analysis comes back fine after a change and running, then he's probably going to be ok.