A lot of boats today have a very tight engine compartment that causes air flow conerns and high air temp inside the engine box. You should install vents to increase air flow inside the compartment. If you read the engine manual on Mercury it will tell you the air temp inside the engine compartment must be kept under (I forget) or else the fuel can heat up and also the air is to warm for the intake stystem. You can look at the Mercury web site and get the details.