went out last weekend with my 16' cape horn have a 2000 70 hp 4 stroke suzuki ran wot for 10 miles did some scalloping and starded back alarm came on temp light also rpms droped to 2500 or so. I stoped turned off engine restarted water stream was fine didnt seem hot went 6 miles or so same thing. new waterpump put in last dec has around 25 or so hours since.
check and or change thermostat and inspect water pick-ups for obstructions. Motor dropping back to 2500 r's is part of the failsafe components and is good to hear that it's working
Also keep in mind that the ECU can sense a rapid rise in temerature and set the alarm off before the engine actually overheats. It's refered to as a "gradient" temperature alarm. When you get the alarm, shut the engine of and restart it. If the alarm has stopped, then you had a "gradient" alarm. If it happens often than you have a t-stat or pressure relief valve problem. Also, if you're into a lot of seaweed, it can happen.