I was imagining it to be more along the lines of not abiding by the rules as to which side of the road you travel on versus speeding or going slow in a fast lane.
Either way, I agree that working boats deserve their space, and regardless of the rules, I'd rather let them do their thing... I'm here for enjoyment, not to tell some guy making a hard living that he is not following the regulations.
And it sounds to me that blowing 5 blasts with a whistle or horn will make you a target, not get to a solution.
The first question is: What this lobster boat identied itself as a Vessel Engaged in Fishing as defined by the Colregs.
If the answer is "Yes" then you (i.e., the sailboat) is the Give-Way vessel.
If the answer is "No" the next question to be asked is were both vessels in a channel or fairway.
If the answer is "Yes" then was the power vessels greater than 20 meters?
if the answer is "Yes" then the sailboat is Give-Way.
If the answer is "No" then the sailboat is Stand-On;
If the lobster boat did not identify itself as a Vessel Engaged in Fishing, then the sailboat is Stand-On.
If the operator of lobsterboat, for what ever reason, did not see the sailboat but could if he/she was standing in the appropriate part of the vessel, the lobster boat violated Colregs Rule 2,Rule 5 and potentially Rule 7.
If the sailboat was Stand-On and it did move without giving the lobster boat ample opportunity to Give-Way, then the sailboat is is violation of several Rules including Rule 7.
Suggested reading for anyone interested: Farewells Rules of the Nautical Road.