How to Determine Overlap

In order to determine whether or not boats are overlapped, you must look at their hulls, and their equipment in normal position. A few examples of "equipment in normal position" are

• rudders in their down and locked position,
• a retractable bowsprit when extended sailing downwind, or
• a spinnaker flying.

Some examples of equipment not in normal position are:

• a retractable bowsprit extended while sailing upwind,
• a spinnaker with sheets or halyards loosed, or streaming out while hoisting or dousing (or shrimping),
• a line trailing in the water behind a boat.

Equipment in normal position counts; equipment out of normal position does not.

Draw an imaginary line through the centerline of each boat. Draw another imaginary line perpendicular to the first at the aftmost point of the hull or equipment in normal position. If one boat (her hull and equipment in normal position) is entirely behind that second line, then she is "clear astern" and the other is "clear ahead". If neither boat is clear astern of the other, then the two are "overlapped".

Overlap on the Same Tack

Here is a diagram showing two pairs of boats on the same tack on a beat to windward. For each pair, I've drawn imaginary centerlines and perpendicular lines on the lead boat. Note that I've drawn the aftmost point slightly behind the hull because that's where the rudders are. The yellow boat is completely behind that line, so Blue is "clear ahead" and Yellow is "clear astern". For the other pair, the trailing boat is not completely behind that line, so the boats are "overlapped", and I've colored them both green.


I've drawn an equivalent diagram showing boats sailing a beam reach on the same tack. As above, Yellow is completely behind the aftmost point of Blue so Yellow is clear astern and Blue is clear ahead. The two green boats are overlapped.


And, finally, here's a picture showing same-tack boats on a run. I've drawn the boats as monohulls this time, because the program I used made it easier to show spinnakers that way. The interpretation is the same though. Blue is clear ahead and Yellow clear astern. Even though their hulls are not overlapped, their equipment in normal position is, so the two green boats are overlapped.


to be continued...