No we use them on our fleet of trucks, the problem with trolling is, you don't have the volume of water moving, it's warm but not enough volume to make the difference, installing a boost pump would make up for it. My tiara has closed loop cooling, so I have a different application. Mine would use coolant, and it would be plenty warm, if I was to tee into mine, I would tee into the hot water tank section. Sent from my SM-G900V using Lake Ontario United mobile app