Quote:
Originally Posted by
rustyredcab 
So, even if the lost ball is likely to be lost in the hazard, but not virtually certainly lost in the hazard, you play it as a lost ball? Lots of shots are not virtually certain to be in the hazard until you get there and the ball is not found. If the rough is also thick, do you play it as a lost ball instead of the logical assumption that it made it into the hazard? That would make every ball that is not clearly in the hazard, a potential lost ball instead.
Hi Rusty,
You understand the rule correctly! I should add good luck convincing your buddies they need to play the ball as lost. You may want to print out these two decisions to keep the fights to a minimum. 
26-1/1
Meaning of "Known or Virtually Certain"
When a ball has been struck towards a water hazard and cannot be found, a player may not assume that his ball is in the water hazard simply because there is a possibility that the ball may be in the water hazard. In order to proceed under Rule 26-1, it must be "known or virtually certain" that the ball is in the water hazard. In the absence of "knowledge or virtual certainty" that it lies in a water hazard, a ball that cannot be found must be considered lost somewhere other than in a water hazard and the player must proceed under Rule 27-1.
When a player's ball cannot be found, "knowledge" may be gained that his ball is in a water hazard in a number of ways. The player or his caddie or other members of his match or group may actually observe the ball disappear into the water hazard. Evidence provided by other reliable witnesses may also establish that the ball is in the water hazard. Such evidence could come from a referee, an observer, spectators or other outside agencies. It is important that all readily accessible information be considered because, for example, the mere fact that a ball has splashed in a water hazard would not always provide "knowledge" that the ball is in the water hazard, as there are instances when a ball may skip out of, and come to rest outside, the hazard.
In the absence of "knowledge" that the ball is in the water hazard, Rule26-1 requires there to be "virtual certainty" that the player's ball is in the water hazard in order to proceed under this Rule. Unlike "knowledge," "virtual certainty" implies some small degree of doubt about the actual location of a ball that has not been found. However, "virtual certainty" also means that, although the ball has not been found, when all readily available information is considered, the conclusion that there is nowhere that the ball could be except in the water hazard would be justified.
In determining whether "virtual certainty" exists, some of the relevant factors in the area of the water hazard to be considered include topography, turf conditions, grass heights, visibility, weather conditions and the proximity of trees, bushes and abnormal ground conditions.
The same principles would apply for a ball that may have been moved by an outside agency (Rule 18-1) or a ball that has not been found and may be in an obstruction (Rule 24-3) or an abnormal ground condition (Rule 25-1c). (Revised)
26-1/1.3
When is it Necessary to Go Forward to Establish "Virtual Certainty"?
Q.Rule 26-1 requires there to be "knowledge or virtual certainty" before proceeding under the provisions of the Rule. In the absence of "knowledge" that a ball is in a water hazard, is it possible to establish the existence of "virtual certainty" without going forward to assess the physical conditions around the water hazard?
A.In the majority of cases, in order for it to be reasonably concluded that the ball does not lie anywhere outside the water hazard, it is necessary to go forward to assess the physical conditions around the hazard. However, there are situations where there will be sufficient evidence that the ball is in the hazard to establish "virtual certainty" without anyone having to go forward to review the physical conditions around the hazard.
In the following examples, the conclusion that it is "virtually certain" that the ball is in the water hazard would be justified without anyone going forward to the water hazard so that the player would be entitled to proceed under the provisions of Rule 26-1.
· It is a clear day, with good visibility. A player's ball is struck towards a water hazard, which has closely mown grass extending right up to its margin. The ball is observed to fall out of sight as it approaches the water hazard but is not seen actually to enter it. From a distance, it can be seen that there is no golf ball lying on the closely mown grass outside the hazard and, from both prior experience and a reasonable evaluation of current course conditions, it is known that the contour of the ground surrounding the hazard causes balls to enter the hazard. In such circumstances, it is reasonable for the conclusion to be reached from a distance that the ball must be in the water hazard.
· It is a clear day, with good visibility. A player's ball is struck towards an island putting green. The margin of the water hazard coincides with the apron of the putting green. Both from prior experience and a reasonable evaluation of current course conditions, it is understood that any ball that comes to rest on the apron or the putting green will be visible from where the stroke was made. In this instance, the ball is observed to land on the putting green and roll out of sight. It is therefore concluded that the ball has carried over the green and into the water hazard. The player drops a ball in a dropping zone in front of the hazard, which has been provided by the Committee as an additional option to those under Rule 26-1, and plays to the green. When he arrives at the putting green, he discovers his original ball on the back apron of the green lying on a sunken sprinkler head. Nonetheless, in the circumstances, it was reasonable for the conclusion to be reached from where the ball was last played that the ball must be in the water hazard.
In the following example, it cannot be established that there is "virtual certainty" that the ball is in the water hazard without going forward to assess the area surrounding the hazard.
· It is a clear day, with good visibility. A player's ball is struck towards a water hazard, which has closely mown grass extending right up to its margin. The ball is observed travelling in the direction of the water hazard and it is known from prior experience that, with normal turf conditions, the ball would undoubtedly go into the water hazard. However, on this day, the fairways are wet and therefore it is possible that the ball could have embedded in the fairway and thus might not be in the water hazard. (New)