You want curious, check this out:
Never had a doubt as to the foul play MO but have read only a little. Most interesting the lack of detailed follow-up and 'through' the entire investigation. (Am wondering if this is end of chapter; or 'end of story'. All to ask - is there more here, that gets closer to the truth of the 'who' of this?)
If Wheeler's death a 'hit'; and so designed to look like 'pathetic happenstance'; will we ever get close to the truth of his death? (All signs, of course, point to NO.. .)
This mystery is as perplexing as it is tragic; and certainly for none more, than his family. And not so great for others, who may at least feel, so threatened and forewarned.
The road there was to a pier for an oyster packing house which burned in the early '60s (iirc on the date), the old Rock Point Post Office should have been just up the hill about 150 meters, there was a store, made of the same concrete across the road which burned (as many older historical buildings at Rock Point did) about 15 years later.
I grew up in that area, on the water.
Yes, a small craft can be filled with an incredible amount of sand, depending on the tides and waves involved, in a short period of time.
I saw no mention of having asked what the wind direction was (onshore or off), wind speed (The Wicomico is about 2 miles wide there, and if from the southeast, the fetch (distance the wind has blowing over the water to generate waves) goes all the way to Westmoreland VA, a distance of over 12 miles, and certainly enough to generate some significant waves--especially on a falling tide.
That kind of wave activity can fill a beeached, beam on to the waves 16 ft. rental boat (The kind they used to rent the tourists over at Captain John's) half full of sand in just a few hours (4-5) if the conditions are right.
I'm not saying there aren't questions about Mr. Colby's demise, there, just that there are places in the 'evidence' that could be filled in to make the scenario tighter or might leave it open to question.
The question I would ask the author is one of who and why.
But I think we need to look toward Texas for the answer to that question.