I trust you had a previous model and are now scrapping it ? I'm curious what the blower was.
The only way you want to move air is to pull it OUT of the engine compartment. Blowing air in may give you the smell of diesel fuel and possible CO. Here, the engine is shown kept in its Nike shoe box with an inch or two clearance around the engine.
I wired mine so that the oil pressure alarm switch activates a N/O relay to turn on the blower. Eliminates any additional load on engine when starting. The blower also shuts down by the loss of oil pressure. I didn't like the idea of walking away from the boat and hoping an OFF delay timer would shut down the fan after 20 - 30 minutes. If your at anchor and it didn't shut down while you're gone for the day, could be bye bye battery. I didn't bother with a thermostat either. Simpler is safer. I also used a DC/DC regulator to keep the fan from flying apart when the charging voltage hit 14.7V.
I switched from a Yellow Tail Blower to a Detmar blower after about 10 minutes of running. The Yellow Tail blower was so noisy I cut the wires to it after only 10 minutes into an all day outing. The Detmar was quieter but still noisy for another reason :
I had gone cheap and used aluminum dryer vent for the exhaust. It screamed like a banshee. A little more investigation and I installed :
Trident Polypropylene Blower Hose. Much quieter and it's stayed that way since 2012. The hose inside the engine compartment is still aluminum for temperature resistance.
A little pricy even back then but well worth it.
Heating the Great Outdoors.
