This is my first post. I have a Mercruiser 351 260hp on a 24' Airslot. When I run it with the earmuffs hooked up while on the trailer it initially does not have any white steam/smoke? coming from exhaust. About five minutes in white steam/smoke starts to emit from the exhaust. The risers get hot, but I can still place my hand on them for about five seconds before I have to remove it. During this time my temp. gauge still reads cool with the needle still in the yellow before the green. I notice that the area where the water exits the lower unit is strong on the port side, but only spits out on the starboard side, but at times will become strong. While under load in the water the temp gauge raises to just before redline after about thirty minutes of 3/4 throttle but does not go into redline. Just trying to figure out if the steam/smoke is normal or not and if running just below the redline is also normal. I should also add that while under load and the gauge just below redline if I throttle down the gauge also goes down almost immediately. Thanks for any replies.