Effects of not running an engine compartment fan?

[LongRange]

So there I was rummaging round and learning about the Volvo D2-75 in my 2005 Dufour 455 GL which we purchased last May, when I realized the fan which is meant to ventilate the engine compartment is simply NOT CONNECTED

The fan is located near the rudder quadrant, low down at the back of the "equipment space" between the two aft cabins. It is bolted neatly and securely in what looks like its rightful place, with a ~12cm air conduit running all the way back to a grille near the upper middle of the transom, and there is even a little etched plaque affixed nearby with "engine ventillateur" or something similar in neat font. It all looks thoroughly professional... except for the fact that the wires are not connected.

I am rather certain that they have never been connected either, because the insulation is stripped off in that flawless way that suggests a machine did it, and the individual wire strands are all impossibly neat and parallel, as if they have never actually been connected to anything. Nearby are the two power leads, looking straight, brand new, and uncrimped.

I would never have seen any of this had I not stuck a mobile phone in an awkward place to take a photo and see what is down there.

There are another two bigger ~15cm diameter vents leading to openings on the transom, but they are not fan-forced - just passive large diameter hoses with their inboard ends sitting loosely near the engine block.

How common is it to run such engines without an electric blower? I think it has been this way since it was new in 2005, and I see no reason not to connect all up and have it work, but I am interested to know to what extent this is risky.

Thanks for all advice.

[rwidman]

There is no fan in my boat's engine compartment and no indication that there was supposed to be one. The engine runs fine.

If you can contact the boat's manufacturer, do that. If not, try to contact other owners and see what they have in their boats.

Your boat has been running this way for twelve years with no problems so I wouldn't be in a big rush to change anything without a good reason.

[Pete7]

Some times we run ours, some times we forget. Actually if you put your hand in front of it, there isn't much of a breeze given the 4 amps it uses never mind the noise it makes. Also our diesel is quite capable of pulling in air through the bilges etc. Far more important are there use if you have an inboard petrol engine to remove fumes before starting.

Pete

[ramblinrod]

Originally Posted by LongRange

So there I was rummaging round and learning about the Volvo D2-75 in my 2005 Dufour 455 GL which we purchased last May, when I realized the fan which is meant to ventilate the engine compartment is simply NOT CONNECTED

The fan is located near the rudder quadrant, low down at the back of the "equipment space" between the two aft cabins. It is bolted neatly and securely in what looks like its rightful place, with a ~12cm air conduit running all the way back to a grille near the upper middle of the transom, and there is even a little etched plaque affixed nearby with "engine ventillateur" or something similar in neat font. It all looks thoroughly professional... except for the fact that the wires are not connected.

I am rather certain that they have never been connected either, because the insulation is stripped off in that flawless way that suggests a machine did it, and the individual wire strands are all impossibly neat and parallel, as if they have never actually been connected to anything. Nearby are the two power leads, looking straight, brand new, and uncrimped.

I would never have seen any of this had I not stuck a mobile phone in an awkward place to take a photo and see what is down there.

There are another two bigger ~15cm diameter vents leading to openings on the transom, but they are not fan-forced - just passive large diameter hoses with their inboard ends sitting loosely near the engine block.

How common is it to run such engines without an electric blower? I think it has been this way since it was new in 2005, and I see no reason not to connect all up and have it work, but I am interested to know to what extent this is risky.

Thanks for all advice.

Proper engine compartment ventilation is important for the following reasons:

1. Prevent carbon monoxide poisoning. The blower is installed to create a negative pressure in the engine compartment. Passive air vents supply make-up air to the compartment. This negative pressure ensures any air leaks between the engine compartment and occupied living space, flow into the engine compartment. If the engine exhaust system develops a leak, the carbon monoxide by-product of combustion (also known as "the silent killer") can fill the engine compartment. Without proper ventilation, this can enter the living space and kill the occupants. This may sound over-dramatic, but this is very, very, serious stuff.

2. Without proper ventilation, the engine compartment will be warmer than design intent. This can cause premature failure of components, and reduce alternator performance. If the battery compartment is in communication with the engine compartment, battery life may be reduced. This can also elevate the cabin temperature, via radiant heat transmitted from the engine compartment.

In summary, it is not really possible to have too much engine compartment ventilation, and insufficient ventilation can be a bad thing on a whole lot of fronts.

That being said, if the wiring system is faulty, nobody in an arm chair over the internet can advise if it is safe to just "connect it up". If you are not sufficiently familiar with marine electrical systems to verify the wiring safety before connection, it may be wise to hire a "sparky" to check it out for you.

Some may suggest you gamble and just connect the wires. However, their skill set could be significantly different than yours, and it is not their boat to gamble with. If there is an unknown short circuit, or you accidentally create one, and the wiring is not connected to proper over-current protection, you could easily set the boat on fire. If you feel confident in your knowledge and skill to prevent such an event, have at it, else, call in a pro.

[Tkeeth]

It's more of an issue for gasoline engines than diesel. Engine compartment fans are designed to remove fumes so no explosion occurs in the event of a leak. I run the generator compartment fan and engine just to help keep the heat out of the cabin. Covered in Title 33 CFR, Sections 183.601–183.630 states for gasoline. Generally it is applied to all engine compartments, so if gigged on an inspection, this is the rule.

FEDERAL LAW:
183.610 Powered ventilation system.
(a) Each compartment in a boat that has a permanently installed gasoline
engine with a cranking motor must:
(1) Be open to the atmosphere, or
(2) Be ventilated by an exhaust blower system.
Permanently installed with regard to an engine means that it is securely fastened to the boat’s structure
and the necessary wiring, piping and controls are connected and secured to the boat in accordance with
the applicable USCG regulations. See Title 33 CFR Part 183, Subpart I, Electrical Systems and Title 33 CFR
Part 183, Subpart J, Fuel Systems. The use of the term “permanently installed” is to highlight that the
engine is not portable or easily removed from the boat and to differentiate it from “portable equipment”.
The term gasoline engine with a cranking motor is used to indicate that the gasoline engine can be
started from a location that is remote from the compartment where it is permanently installed. An engine
without a cranking motor (starter) requires the presence of a person at the engine location in order to
start the engine. Presumably, any dangerous conditions such as liquid fuel or vapors being present at the
engine location would be detected by odor and/or sight and remedied before the engine is started.
This section of the regulation addresses boats that have a permanently installed engine with a
cranking motor in a compartment. To comply with the regulation one of the following alternatives
must be satisfied:
1. The compartment must be open to the atmosphere, as defined in 183.605.
2. There must be an exhaust blower system installed to ventilate the compartment in which
the engine is installed. An exhaust blower system consists of one or more blowers with
ductwork and terminal fittings attached to the ducts.
TO COMPLY WITH THE LAW
• Is there a gasoline engine permanently installed in the compartment?
• Does the gasoline engine have a cranking motor (starter)?
If you have answered NO to either of the above, see 182.620, Natural Ventilation.
If you have answered YES to both of the above, then you must answer YES to one of the following:
• Is the compartment open to the atmosphere? See 183.605 for requirement.
• Is there an exhaust blower system? See 183.610, (b) through (f), for requirements.
9
183.610 Powered Ventilation
FEDERAL LAW:
183.610 Powered ventilation system.
(b) Each exhaust blower or combination of blowers mus

[David M]

A well designed boat will have adequate ventilation where it is not necessary to run a ventilation fan all the time when the engine is running.

A well designed boat, and a boat that meets ABYC standards in the US, will also have a ventilation fan for venting the bilge before starting the engine.

[Sailmonkey]

We run a fan at all times the engine is running, not to benefit the engine, rather to benefit the humans. The blower pulls heat and hot “smell” out of the engine compartment so the salon doesn’t suffer from heat and hot engine smell.

The engine doesn’t care......the alternator cares a little, but not much.

[David M]

Actually, there are standards for the air temperature inside the engine compartment versus the outside ambient air temperature. A temperature delta had to be met. Cummins would not warrant my engines if those standards were not met. This had to be under passive ventilation conditions....meaning not powered ventilation.

It makes sense because one should not have to be dependent on a cheap exhaust fan working in order to use one's engine(s) for hours at a time.

There should never be leakage of engine room gasses into living spaces. This includes the potential for carbon monoxide poisoning reasons, in addition to other reasons. One should not have to rely on an exhaust fan to prevent this from happening. Something is wrong with your passive ventilation system if this is the case.

[Bjorn_O]

Diesel engines do not need ventilation. The air consumption of the engine is sufficient.
Gasoline engines MUST have a fan, due to the explosion risk.

[rwidman]

Originally Posted by David M

....... A well designed boat, and a boat that meets ABYC standards in the US, will also have a ventilation fan for venting the bilge before starting the engine.

Only if it is gasoline powered. A diesel engine is not required to have a fan for venting the bilge.

[SecondBase]

I would add to Rod's excellent advice - time invested installing carbon monoxide detectors is well spent. Inexpensive protection of your life.

[David M]

Originally Posted by rwidman

Only if it is gasoline powered. A diesel engine is not required to have a fan for venting the bilge.

It's true, under federal law for Diesel recreational vessels, powered ventilation is not required.

ABYC requires it for Diesels as does federal law require it for all USCG inspected vessels, gas or Diesel.

Keep in mind that it is possible to have other dangerous or flammable sources of vapors in a bilge, even on a Diesel boat.

So you feel lucky?

[Sailmonkey]

Originally Posted by David M

There should never be leakage of engine room gasses into living spaces. This includes the potential for carbon monoxide poisoning reasons, in addition to other reasons. One should not have to rely on an exhaust fan to prevent this from happening. Something is wrong with your passive ventilation system if this is the case.

Been on many sailboats lately? show me more than one that excludes engine spaces from accommodations. Our 40 year old boat has a door in front of the engine, but for all intents the engine is sitting in the same hull that is occupied by the humans, as are thousands out there.

[boatpoker]

Originally Posted by David M

ABYC requires it for Diesels as does federal law require it for all USCG inspected vessels, gas or Diesel.

The ABYC part of your statement is not true.
1. Attached photo is a snip from ABYC H32 Ventilation of Boats Using Diesel Fuel.

2. CFR. Title 46, subpart K (uninspected vessels) specifies powered ventilation for gasoline powered boats only. I do not have the"inspected vessel" standards but I'd love to see the reference.

[Cheechako]

It's fairly common to run without a fan with a diesel. However all mine had fines. I wired the fans to a manual switch so I could choose to use it or not. After a long motoring session I often left the fan on while anchored for 10-15 minutes to remove heat from the engine room (in the tropics)
If those passive vents are set up right, the "chimney effect" will draw a lot out on it's own.