Running Engine Blowers

It depends on the boat (diesel boats). If the engine room stays salt free with them on at cruise, I run them all of the time when the motors are running to keep engine room temps lower, which helps keep interior temps lower also. If it brings salt in while running with the blowers on, I'll leave them off and only run them when doing non-planing speeds to keep the engine room cooler and after shutdown to cool off the engine room.

Some of the newer boats have air/salt traps. One company I remember was called T systems that some mfgs used or could install after factory.
Some others have coarse plastic or alloy mesh. All of these systems required an over board drain and required rinsing (to get the salt off).
Then the plain air box with a drain. Still needs rinsing.
Most blowers usually draw air from the ER and blows it out. Making the air traps/filters do it's work.

I prefer not to run them during operation; not only more hours on the equipment, but a fan for bad things (fire) that some boats to this day still do not have blower shut-downs.

As commented above, Diesels draw lots (LOTS) of air naturally, let them draw what they need. When not running and your still on the ship, turn the blowers on to help the comfort in the living spaces.

Good blowers are nice when you have to pull maintenance or access the ER.

I've been on boats that all they are was noise makers and never moved the heat (or any air) out at all.

That's them. Not heard that company name in a while. Well,,, I'm not in those old shoes anymore either.
Glad they are still up and doing well.
Thx

Cabo also used Delta T

Blowers usually pull air out of the ER, they don't bring it in so they shouldn't bring salt in.

The 70 footer I run has large AC blowers which I only run after shutting down the engines to extract the hot air out and reduce temp in the ER. In our case there are quite a bit of electronic stuff in the ER like battery charger, water maker, etc... So every degree counts.

As someone else mentioned, if you don't have blower shut down tied to the fire system running them underway isn't a good idea as in case of a fire they will suck the agent out.

Anything in the owners manual? Response from a factory reps phone call and hard copy of the company's theory of operation?
Without any higher authority,,, Leave them off while running. On when you dock after a run or have to go in the engine room.

Is there not some engine benefit to having them run while under way?
There is so much air sucked in by the engines while running. I cant see anything but a load on its power supply and time on the blower motor for not much (if any) benefit. .

Well, the cooler the engines intake air, the denser it is and the more power you derive from it. Would 3-5F make enough of a difference to notice, who knows. You never know why manufacturers install what they install. It could be to cool the engine room as quick as possible after the boat is docked in case you need to work on it.

I managed a 63' Hatteras MY, around a 2003 a long time ago and it had 2 air conditioners in the engine room. The owner had the factory install them in the build because he liked to do his own maintanence and tinker in there and wanted it cool, they weren't for use while the motors were running.

It depends. If the engine room air intakes are large enough then even C32 engines can get the air they need without any sort of engine room blower. One way is to run at cruise and see if there is any suction/vaccuum on the engine room door when you open it.