Given the following quote from one of the articles on the incident.
"It was my understanding that a fairly large power boat ran up over D.J.'s stern and threw him into the water. Warren Hathaway was below decks. He scrambled up, the boat was taking on water," Mr. Kenney said. "D.J. probably didn't even see it coming."
If the powerboat was going fast enough to run up and over the stern of the sailboat, it was probably going fast enough that avoiding it might have been fairly difficult. COLREGS Rule #6 says:
Every vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and conditions.
In determining a safe speed the following factors shall be among those taken into account:
(a) By all vessels:
(i) the state of visibility;
(ii) the traffic density including concentrations of fishing vessels or any other vessels;
(iii) the maneuverability of the vessel with special reference to stopping distance and turning ability in the prevailing conditions;
(iv) at night, the presence of background light such as from shore lights or from back scatter of her own lights;
(v) the state of wind, sea and current, and the proximity of navigational hazards;
(vi) the draft in relation to the available depth of water.
(b) Additionally, by vessels with operational radar:
(i) the characteristics, efficiency and limitations of the radar equipment;
(ii) any constraints imposed by the radar range scale in use;
(iii) the effect on radar detection of the sea state, weather and other
sources of interference;
(iv) the possibility that small vessels, ice and other floating objects may not be detected by radar at an adequate range;
(v) the number, location and movement of vessels detected by radar;
(vi) the more exact assessment of the visibility that may be possible when radar is used to determine the range of vessels or other objects in the vicinity.
Given Rule #6 and the fact that the powerboat was clearly overtaking the sailboat, and the speed differential involved, I see the powerboat as being primarily responsible. In many ways, this is a very similar situation to the Clear Lake one, where an irresponsible powerboater clearly was traveling at an unsafe speed and is primarily at fault for the death of a person on the sailboat.
We don't know exactly how fast the power boat was going, but if it was going fast enough, there might have been little or nothing the sailboat could have done to avoid the collision.
Granted, visibility in this case was greater than that of the Clear Lake incident, but doesn't that mean the powerboat should have had MORE TIME to act to avoid the collision, yet failed to do so.
Bluntly put, gross negligence on the part of the powerboat is the reason people died in both cases.