Sailing Boat Engine Bilge Blower??? Use???

[Goudurix]

I have a 1991 Jeanneau 37ft bought second hand 6 years ago.
It has 2 large diameter flexhose pipes from the transom into the diesel engine compartment, a Yanmar 44 HP.
It has a typical Jabsco bilge blower inserted into one of these flexhoses, wired on the ingnition contact through a relay. The original one was dead and I replaced it by the same model (quite expensive and rated only 1.000 hours of service)
It is sucking out air from the engine compartment to a transom mounted exhaust, and wired to run continuously while the engine is running.

This replacement is now also "dead" and still have to measure it out. But before replaicng it I have some questions:

- why would it be there? No real need to exhaust fumes before starting as it is a diesel.
- why would it be wired to run continuously? Its normal use is a few minutes before starting?
- This boat was sailing the mediterranean in its early years. Maybe the blower was installed to bring more fresh air into the engine compartment to help it cool/have better performance with better fresh air supply? Should it then not be inserted so as to mump fresh air into the engine compartment?
- I have never seen it installed in comparable sailing boats in our climate zone (North-western Europe). How could it be useful?

• By having it independently switch-operated to ventilate the engine bilge in very hot outside conditions?
• To extract air from the engine compartment when running before the wind on engine to get any backflow of fumes prevented
• ????

Thanks for any help/recation


Merry Xmas & a happy 2012 with good winds



Jan
SY Goudurix
Belgium

[MacG]

Is it original or an addition by the former owner?

Most probably added to work as engine compartment cooler/refresher. I have seen it on small yachts before but not quite often. Personally I do not think that it is an original piece of standard equipment.

In large motoryachts 20 mtrs > yes, there is an extra ventilation quite standard to cool the high temperatures in relative small enginerooms. The bigger yachts, 40 mtrs > upwards have it as a normal standard item as the enginemanufacturers require a certain environmental temperature for full & continuous operation of the engines and generators.
That those blowers die that quickly is not that normal but might be by poor design or construction. Compare it with electric pumps, when of Taiwan or China quality they have a relative short live.

Theoretically it is no bad idea, although rarely seen on a sailing yacht.

[Goudurix]

Thanks MacG,

I don't know if you are a native french or dutch speaker - or english? Whatever I'll stick to english.
Difficult to know if it was added on but I guess so - the relay seems installed as an add-on, I cannot find anything in the boat's original (scarce) documentation, and I do not see it as included on the electrical wiring diagram.

The original blower and the replacement are Jabsco so a good brand and it was expensive. I don't have it's specs here but it draws 12 amps at 12V.

Indeed the specs sais about 1000 hrs of life time - these bilge blowers are normally intended to run a few minutes before staring a gasoline engine to exhaust any potential gasoline fumes.

On my boat wired to run when the engine runs.....

If meant to ventilate the engine compartment, I guess the way it was installed - extracting air from the compartment - it is creating a slight underpressure so that is not really helping engine performance.... Maybe I should try to see if the engine runs better (idle/high rev) when blower is extracting and when opening engine compartment? But it is "dead" now so cannot be tested this way...

May be meant to eliminate hot engine smells inside the boat, hence extracting air?

In the end I think I should have it wired through a switch and a relay rather then on the engine ignition switch - to be operated only when very hot outside and/or engine running for long time to get rid of engine smells?

Jan

[Hyprdrv]

Is the starting battery (or house batteries) located in the same space and is it a wet cell? Is it possible that there are diesel odors that are present when running and the PO was trying to suck them out? Is the bulge a wet one and it's there for humidity control? Just throwing ideas out there.

Steve in Solomons MD
Lagoon 410 SE

[colemj]

Probably mounted to remove engine heat from the boat. Did this boat spend time in hot climates or charter?

Mark

[Hyprdrv]

You were typing while I was posting.
Or add an adjustable thermal switch to activate the fan when temps. are above, lets say 100d.

Steve in Solomons MD

[MacG]

Hallo Jan,

Leuk je op dit forum te ontmoeten. Tegen het voorjaar verkas ik naar Blankenberge, dan zullen we elkaar zeker eens ontmoeten. Momenteel lig ik in Weesp.
Ik schrijf verder in het Engels voor de overige forummers.

I think the whole is wrongly wired/installed. And yes, Jabsco should be good. I think it is the wrong blower for the wrong purpose.
I have done long runs on the Med, although it can be hot midsummer, there is no real requirement for engine compartment cooling. Imho you can remove the whole thing and close the venthole. Extra engine cooling with outside air is in our area and climate no real issue. Saves costs of maintenance anyway.

[Goudurix]

MacG,

yes welcome to Blankenberge, close to our marina.


At least the 2 vent holes and the 2 flexhoses must be original. I guess there is no need at all to close theù and remove the flexhoses.

Jan

[Goudurix]

I have posted on the Jeanneau owners forum to find out if the blower was installed originally on this model.

[MacG]

Originally Posted by Goudurix

MacG,

yes welcome to Blankenberge, close to our marina.


At least the 2 vent holes and the 2 flexhoses must be original. I guess there is no need at all to close theù and remove the flexhoses.

Jan

You could but it is no requirement. I remember there is something in the CE rule saying that engine compartments must have a way of ventilation. So you better leave the situation as is with a powerswitch for off/on separate from the ignition/start key. With a general engine use of 150 hrs/annum you have some 6 years of potential use if they run parallel to the engine.

In this case there are more solutions possible.

[DeepFrz]

I assume that the blower is 12 volt. If so you should be able to dismantle the motor and replace the brushes and clean the commutator. If you want a longer lasting motor/blower assembly you would need to install one with an AC motor at least a continuous duty blower like this 4000 hr rated Jabsco blower.
Jabsco 4 Flexmount Continuous Duty Blower - ITT Jabsco 35770-0094 - iboats.com
or this 10,000 hour unit
http://www.hodgesmarine.com/Jabsco-4...35770-0092.htm

[The Boat Galley]

As to purpose, we actually added a somewhat similar blower to our boat and as Colemj said, it was to remove engine heat from the engine compartment in the tropics. There were other air vents in the engine compartment, and this served to exhaust the hot air and pull cool air in. Engine ran several degrees cooler but -- more importantly -- it kept the area inside the boat near the engine compartment noticeably cooler. We would run the fan while the engine was running, but also about 10 to 15 minutes after shutting it down to bring cool air into the engine compartment.

[Goudurix]

Originally Posted by DeepFrz

I assume that the blower is 12 volt. If so you should be able to dismantle the motor and replace the brushes and clean the commutator. If you want a longer lasting motor/blower assembly you would need to install one with an AC motor at least a continuous duty blower like this 4000 hr rated Jabsco blower.
Jabsco 4 Flexmount Continuous Duty Blower - ITT Jabsco 35770-0094 - iboats.com
or this 10,000 hour unit
Jabsco 4" 250 Cfm Flexmount Heavy Duty Blower - 12v

Deepfrz, it seems that what I have now is your first link (DC250). It is exactly the same current draw and fuse recommendation of 15A.
Will try to open up the blower and check the motor.

Jan

[lancelot9898]

When I had my Tayana 37 built one of the options was an engine room blower which I had installed. Not sure how useful it is and I rarely turn it on. On really hot days after I turn the engine off, I will run it for maybe 10 minutes just to remove the heat from down below. Not really sure how effective it is since when I put my hand by the exhaust vent there is really not much air flow.

[svHyLyte]

Originally Posted by Goudurix

I have a 1991 Jeanneau 37ft bought second hand 6 years ago.
It has 2 large diameter flexhose pipes from the transom into the diesel engine compartment, a Yanmar 44 HP.
It has a typical Jabsco bilge blower inserted into one of these flexhoses, wired on the ingnition contact through a relay. The original one was dead and I replaced it by the same model (quite expensive and rated only 1.000 hours of service)
It is sucking out air from the engine compartment to a transom mounted exhaust, and wired to run continuously while the engine is running.

This replacement is now also "dead" and still have to measure it out. But before replaicng it I have some questions:

- why would it be there? No real need to exhaust fumes before starting as it is a diesel.
- why would it be wired to run continuously? Its normal use is a few minutes before starting?
- This boat was sailing the mediterranean in its early years. Maybe the blower was installed to bring more fresh air into the engine compartment to help it cool/have better performance with better fresh air supply? Should it then not be inserted so as to mump fresh air into the engine compartment?
- I have never seen it installed in comparable sailing boats in our climate zone (North-western Europe). How could it be useful?

• By having it independently switch-operated to ventilate the engine bilge in very hot outside conditions?
• To extract air from the engine compartment when running before the wind on engine to get any backflow of fumes prevented
• ????

Thanks for any help/recation


Merry Xmas & a happy 2012 with good winds



Jan
SY Goudurix
Belgium

Jan--

The Engine Room Blowers were/are standard issue on the Jeneau and Beneteau as the engine compartments are fairly tightly sealed. The flex hose to the blower itself is/should be led to the upper-most area of the engine compartment to extract hot air and discharge it off-board. The two static flex hoses should be led to the bottom of the compartment to admit cooler external ambient air. The cooler air ensures the greatest efficiency of the operation of your engine while the blower also discharges odors of hot oil, diesel fumes and the like, ensuring the accomodation remains more livable. You will likely find a material difference in the performance of your engine--fuel burn rate--absent the blower functioning. We did. The overall longevity of the engine is also enhanced in a cooler operating environment.

The blower can be rebuilt, as it is usually the brushes that wear out, provided that the shaft bearings on the roter remain intact. Our experience was/is that about 3000 hours pass between break-downs although that is based on the engine hour meter. As we have a separate circuit by which we can activate the fan while the engine/ignition switch is off--to discharge heat after having run the engine for awhile--we likely had another several hundred hours on the blower.

FWIW...