Engine Room Temperature

[firehoser75]

I am looking for advice and preferably experiences from those who have installed fans/blowers in the engine room to reduce ER temperatures.
Some background. I have read that engine room temperatures should never exceed 115 degrees F (mine have not) and that optimally the differential between the outside temperature and the ER temperature should not exceed 30 degrees F. So for example, if the outside temp is 68 degrees F and the ER temp is 105 degrees F, in theory your ER is too warm??
Also, having a cooler ER would benefit any installed items located there, for example battery chargers, inverters, batteries, solar controller, and even the engine alternator, hoses, etc.
My engine room temperature often exceeds the 30 degree differential and I am hoping to find a way to “cool” the ER without having to conduct major surgery like adding more holes, etc. Not going there! I have a Nordic Tug 37 with a Cummins 6BTA 330 hp usually run at about 50% throttle. My engine temperatures are excellent (checked with IR gun) and I freshwater flush as well as follow Tony’s advice dealing with the cooling system.

I am thinking about adding a blower (maybe even 2), but don’t want to go to the expense and trouble if it will not be effective. I am hoping for a reduction in temp of about 8-10 degrees F.
If I add blower(s), my goal would be to exhaust at least as much air as I may increase intake (don’t want to pressurize the ER possibly forcing gases and heat into the boat).

I have not experienced any operating problems associated with this higher than optimal temp difference, but I can understand the potential benefits (overall) of having a cooler ER.
Has anyone had experience with this (using blowers) with good results? If so, what brand/model of blower and where in the ER did you locate it (them)? As an experiment, I tried running a small (8-10 inch) 12v fan in the ER a couple of times and pointed it toward one of the ER vents. This usually resulted in a small decrease in temp (2-4 degrees F).
I use a remote sensor from a “home type” weather station to monitor ER temps. It is located about 2 feet below the ER ceiling. My ER vent openings are located just below the deck to hull joint on the sides of the boat.
Are blowers/fans a good or a bad idea? Should I just leave well enough alone (now operate with ER temps between 102 – 107 F but was hoping for always below 100).
Thanks,
Tom

Topic

[firehoser75]

Rob,
Yes, I am measuring the temperatures while underway and the temperature is usually slightly lower when there is a good breeze out there.
Tony, I will try measuring the temperature with the probe strapped to the air filter (I have your Envirovent installed). I do not run the generator while underway and would very rarely (if ever) run it after shutdown of the main.
Larry, that is interesting info regarding the wide range of temperatures you have seen at the various locations in the room.
My probe is just lying on top of the generator (gennie not running) which locates it about 2 feet from the ceiling on the port side of the boat near the bow end of the ER. The engine air intake (filter) is also on the port side, but it is about 6 feet away diagonally and about 1 foot lower than the probe. My ER vents are located on both sides of the engine room.
Do you think installing 2 blowers would help? Possibly one on the port with it blowing incoming air (ducted) down low in the ER near the air filter and the other located high on the starboard side exhausting air (blowers say 250 cfm)? Or, I am trying to solve an issue that really isn’t there?

[Larry Backman]

Some data I have accumulated

I have a single engine 36’ DE with a big QSM 11.

mY engine room has about 400 square inches of vents, no blower. I have 2 remote probes one on the forward bulkhead, one on the aft bulkhead. I also have an air intake reading on the engine.

Typically on a long mid summer run I have ambient air temp of 80, air intake temp of 90, aft bulkhead reads about 115 and the foreward bulkhead reads about 135.

There is no circulation on the foreward part of my engine room, but obviously good circulation on the aft part.

[Tony Athens]

Measure your temp with the probe strapped to the air cleaner with the engine at cruise power ( spec is actually at rated HP/WOT)..It would be typical for the temp to rise at lower/idle speeds. If you have a generator, when you shut down the mains, temps will also rise initially.

Tony

[Rob Schepis]

Are you measuring ER temp while out on the water or only after back at the dock and shutdown?

[Author]

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