Hello my name is XXXXX XXXXX will help you with your problem. Your problem is either that you have some blockage in your cooling system or one of your sensors is not working correctly. So best thing to start with is to verify if the sensors are ok. The sensors are located on the top of the cylinder heads , one on each head. When the alarm goes high, disconnect these sensors one at a time and see which one switches the alarm off. That will be thew one triggering your alarm. Replace this sensor with the other and check again. If the alarm goes high again, check if it is the same sensor ( which is now located on the other head) which has triggered the alarm. If yes then it is the sensor. If it is on the same side which triggered then you have some blockage on that side.

If on the other hand both engines are triggering the alarm them you might have the engines mounted high on the transom and it will pickup air while at high speed.

If you need more information let me know.

Noel