12volt supply

[John R]

Hi

 

Having surrouded my engine with a wooden cocoon I feel the need to supply some cooling for the alternator via a small 12 volt fan.

Can somebody help with where I can easily get a 12v supply from within the engine bay, perhaps from one of the alternators, that is only live whilst the engine is running.

 

Thanks in anticipation

[david and julie]

You don't say what type of engine you have but if it stops via the ignition key it may have a supply to the injector pump.

[SoJo]

Use a 12V fan from a computer,wired to any live when running.My Barrus Shire has a 12V feed next to the injection pump.

[RONNIE]

Hi

 

Having surrouded my engine with a wooden cocoon I feel the need to supply some cooling for the alternator via a small 12 volt fan.

Can somebody help with where I can easily get a 12v supply from within the engine bay, perhaps from one of the alternators, that is only live whilst the engine is running.

 

Thanks in anticipation

Hi can you come from the battery with a inline fuse and switch ,i did this on my kit car.

[Keeping Up]

You may be able to use the D+ connection on the alternator (the one which goes to the "ignition" warning lamp)

[John R]

You don't say what type of engine you have but if it stops via the ignition key it may have a supply to the injector pump.

The engine is a Beta 43. I will look at the injector pump area

 

Thanks

[Derek R.]

'Scuse me for nosing in, but the alternator should have a fan built in (if it's like any automotive alternator), it draws air through whilst running. Surely all you need do is supply an aperture to feed air to the alternator?

 

Derek

[david and julie]

The engine is a Beta 43. I will look at the injector pump area

Just to add that If its the type that has a push button stop the lead to the pump may not be permanantly live.

[John R]

'Scuse me for nosing in, but the alternator should have a fan built in (if it's like any automotive alternator), it draws air through whilst running. Surely all you need do is supply an aperture to feed air to the alternator?

 

Derek

You are correct the alternator does indeed have a fan but I have been recommended to supply forced cool air to the alternator now I have boxed the engine in simply to improve the life expectancy of the alternators.

[Ex- Member]

TBH a comp fan will make very little difference to the cooling around the engine, a simple hole at the opposite end to where the engine airtake is situated will cause a far greater air flow through the engine compartment than any comp fan ever would. Put your hand over the air intake and you'll see what I mean, in fact don't as the suction is quite fierce

 

If your engine is in a wooden cocoon your air intake will usually be on top of the engine, if a hole or ventilation slot is made at the lowest point possible the natural suction caused by the air intake will draw air from lower down where the air will be cooler. You might already have your air intake out side of this cocoon though which is where it should be, but if not you need to ensure your engine is getting enough air to run efficiently.

 

Remember your engine needs lots of air, starving it of air by cocooning it will result in poor fuel consumption if not adequately ventilated. This is why car engine air intakes have an air collection duct usually somewhere around the front grille to capture air rushing through when you're driving.

[John R]

TBH a comp fan will make very little difference to the cooling around the engine, a simple hole at the opposite end to where the engine airtake is situated will cause a far greater air flow through the engine compartment than any comp fan ever would. Put your hand over the air intake and you'll see what I mean, in fact don't as the suction is quite fierce

 

If your engine is in a wooden cocoon your air intake will usually be on top of the engine, if a hole or ventilation slot is made at the lowest point possible the natural suction caused by the air intake will draw air from lower down where the air will be cooler. You might already have your air intake out side of this cocoon though which is where it should be, but if not you need to ensure your engine is getting enough air to run efficiently.

 

Remember your engine needs lots of air, starving it of air by cocooning it will result in poor fuel consumption if not adequately ventilated. This is why car engine air intakes have an air collection duct usually somewhere around the front grille to capture air rushing through when you're driving.

[/quote

 

 

All the things you mention are the very things that concerned me during this project and I would be very interested in your comments regarding my solutions.

The wooden cocoon has gaps left at the base around the base plate where it is coolest to allow air to be drawn in to supply the engine. If this proved inadequate I intend to supply air to the air cleaner from outside via ducting but I am trying it first drawing air from within the cocoon to keep the induction noise down.

The fan I am fitting will be aimed at the larger alternator to supply cooler forced ventiation and the fan will be an 80cfm model which should supply more air than the engine needs at an assumed max engine speed of 2000 rpm. I can't decide whether to set the fan to suck or blow but intend to try both and measure the local tempreatue at the alternators.

Does anybody believe the engine or gearbox need air cooling over and above there water cooling.

 

Many thanks for the help so far

[David Schweizer]

You do not say what output your alternator is, but I have a 55amp alternator on my engine which is totally enclosed in a steel box. There is a grille to the outside of the boat at the back of the engine box with a clear air space of 11 square inches. This is the only air supply, and it has been operating fine for the last 12 years that I have had the boat, and presumably in the boat's previous fifteen years.

 

The only aspect of my instalation which might be considered non-standard is the pulley ratio which is 3 to 1 rather than the more normal 2 or 2 1/2 to 1 ratio, which means that the alternator fan is running a bit faster than on some instalations. I am not an expert in these matters, but you may be worring about something that may never happen.

Edited March 14, 2009 by David Schweizer

[Ex- Member]

A decent fan like a 12 volt radiator fan from a small car on top of the cocoon drawing air from the base of the cocoon would be what might get enough air flow to cool the alternators, especially if the fan draws or blows air directly on the alternator. Also these fans are designed to operate in an engine bay and are quite cheap and easily available from a scrap yard. Drawing the air would be my first try depending on where the air will be blown.

 

A comp fan isn't really designed for that kind of environment.

 

Your air intake should remain inside the boat but not boxed in. You could extend the air intake to extract outside the cocoon, I would always advise a decent big air filter though. That's caused quite a debate on here previously as well LOL

 

 

You could also have a fan blade made up for one of the pulleys, even the alternator pully it's self. This of course would only run when the engine does but not very directional.

 

David has a point my alt is 3.5 to 1 and doesnt get over hot. I would put a thermonitor inside the bay when engine is hot and get a reading. Then do the same under your car bonnet. I think your Alt will be fine.

Edited March 14, 2009 by Julynian

[John Orentas]

Hi John.

 

Your alternator will have a perfectly adequate cooling fan built into it, all you need to do is to make sure there is a an ample supply of cool air available.

 

http://www.canalworld.net/forums/index.php...=si&img=920

[chris w]

The fan I am fitting will be aimed at the larger alternator to supply cooler forced ventiation and the fan will be an 80cfm model which should supply more air than the engine needs..............

80cfm is not that much. A 3-bladed Eco-Fan claims 150cfm and it's difficult to even detect a draught from those.

 

Chris

[Keeping Up]

80cfm is not that much. A 3-bladed Eco-Fan claims 150cfm and it's difficult to even detect a draught from those.

 

Chris

I make it that at 2000 rpm, 80 cfm should be sufficient for an engine of up to 2.2 litres. But I think you'd need a good deal more air than that for effective cooling as well.

 

I really struggle to believe Eco-Fan's claimed figures. I recently installed a small compuer fan in the floor behind my fridge, which claims to deliver 30cfm; you can feel the draught from it, whereas I've yet to feel any draught from an Eco Fan.

[alan_fincher]

................whereas I've yet to feel any draught from an Eco Fan.

 

So had I until I recently saw one on top of a Refleks stove..... Now that really does get them spinning, and you could pt your hand in front and feel hot air being pumped at you.

[aread2]

I've got a cocooned Beta 43. Its got an acoustic coccon around it, as supplied by Beta. The air is allowed into the coccoon through baffled slots at the alternator end. I would not advise ducting in the supply to the air cleaner as you'll be reducing the volume of air passing through the inside of the box. Our coccoon has a substantial six inch fan at the end of the cocoon opposite the alternators to remove hot air. There's a diagram on the Beta site here.

The fan is the square silver thing at the bottom left of this picture of the cocoon with the top off:

You can see one of the ventilation slots in the front end of the cocoon in front of the three alternators (engine, domestic, travelpower). In this picture you can see the outlet duct leaving the cocoon:

[Tony Brooks]

The engine is a Beta 43. I will look at the injector pump area

 

Thanks

 

 

Sorry for the delay, I have been away. Here is my take on what you ask.

 

Your engine is quoted as having a capacity 0f 1.857 litres. A diesel engine has a volumetric efficiency (how much of the 1.857l it actually draws in) of perhaps 75%. AT 1000 rpm there will be 500 induction strokes per minute so we get 1.857 x .75 x 500 = 696 litres per minute. That is equivalent to a stack of 140 x 5 litre oilcans or the contents of close to 1000 wine bottles.

 

The engine will be drawing that into the casing every minute so fitting a computer fan will be very like peeing into the cut. You know the level must rise but it is undetectable.

 

Reduce the air inlet you mention that is low down and fit a baffled inlet of at least 6 sq. in. clear area through the side of the casing just behind the alternator. The engine will ensure lots of cool air being drawn over the back of the alternator so the alternator fan can draw use it to cool the alternator. By all means duct this inlet from the outside air but do not make it undersiuze or otherwise restrict it.

[n.b.Goldie]

I've got a cocooned Beta 43. Its got an acoustic coccon around it, as supplied by Beta. The air is allowed into the coccoon through baffled slots at the alternator end. I would not advise ducting in the supply to the air cleaner as you'll be reducing the volume of air passing through the inside of the box. Our coccoon has a substantial six inch fan at the end of the cocoon opposite the alternators to remove hot air. There's a diagram on the Beta site here.

The fan is the square silver thing at the bottom left of this picture of the cocoon with the top off:

You can see one of the ventilation slots in the front end of the cocoon in front of the three alternators (engine, domestic, travelpower). In this picture you can see the outlet duct leaving the cocoon:

 

Surely if the fan is sucking air out of the box it will create an atmospheric depression within the engine box thus causing the motor to be starved of air (however slightly).

 

My own arrangement is similar to beta's but the blower pushes fresh air into the box and out of the (5) vents. Four of the vents can be closed if desired (in winter for example) or directed to atmoshere.

 

 

Edited to say:

p.s. why are the lock-nuts on your stern gland not tightened-up? There is a good gap between the adjuster-nuts and lock-nuts!

Edited March 16, 2009 by ditchdabbler

[Keeping Up]

Sorry for the delay, I have been away. Here is my take on what you ask.

 

Your engine is quoted as having a capacity 0f 1.857 litres. A diesel engine has a volumetric efficiency (how much of the 1.857l it actually draws in) of perhaps 75%. AT 1000 rpm there will be 500 induction strokes per minute so we get 1.857 x .75 x 500 = 696 litres per minute. That is equivalent to a stack of 140 x 5 litre oilcans or the contents of close to 1000 wine bottles.

 

The engine will be drawing that into the casing every minute so fitting a computer fan will be very like peeing into the cut. You know the level must rise but it is undetectable.

Surprisingly, 696 litres is only 24 cubic feet. So in theory a fan providing 80cfm should in theory be able to supply three times as much air as the engine needs. Not like peeing into the cut at all.

 

Whether it can actually do so is another matter altogether, especaly if air for cooling is what is actually wanted.

[fincaavellana]

Surely if the fan is sucking air out of the box it will create an atmospheric depression within the engine box thus causing the motor to be starved of air (however slightly).

 

My own arrangement is similar to beta's but the blower pushes fresh air into the box and out of the (5) vents. Four of the vents can be closed if desired (in winter for example) or directed to atmoshere.

 

 

Edited to say:

p.s. why are the lock-nuts on your stern gland not tightened-up? There is a good gap between the adjuster-nuts and lock-nuts!

I notice that you have a bell housing on the front of the water pump pulley, swap it for one with holes in as per a car water pump pulley and add a fan to the pulley no need to have a 12v fan, the engine will provide ventilation everytime it is running, cut a hole in your wooden box and vent it out through the vents in your hull one intake in front of the newly mounted fan and one outlet the other end of your box

 

Problem solved

[aread2]

Surely if the fan is sucking air out of the box it will create an atmospheric depression within the engine box thus causing the motor to be starved of air (however slightly).

 

My own arrangement is similar to beta's but the blower pushes fresh air into the box and out of the (5) vents. Four of the vents can be closed if desired (in winter for example) or directed to atmoshere.

 

 

Edited to say:

p.s. why are the lock-nuts on your stern gland not tightened-up? There is a good gap between the adjuster-nuts and lock-nuts!

 

The cooling air intake slots are pretty large - the intake on the diagram on the Beta web site is about a quarter of the ara of the slots on my housing - so I don't believe the vacuum in the cocoon is significant.

 

The pictures are from the engine installation so several things are incomplete. As well as the lock nuts being loose, the greaser tube is missing, the exhaust ends in the bilge and the ventilation outlet duct now goes to the hull at the bottom of the picture.