Engine bay ventilation

[Paul Gwilliams]

Good afternoon,

 

Reading through some of the threads, without pictures I must add, lips still move with the words but hey ho, there is mention of side vents for the engine bay for assisting cooling engines and alternators etc

 

Having a craft of weeny stature (30ft) with a 3 pot 20hp engine I was wondering if I should be looking at putting some sort of ventilation in. I was of a mind to use two inline fans and ducting or fans mounted on either side of the engine bay one on intake and one out

 

Mentioned this casually to SWMBO (love acronyms) and she's not to enamoured with the idea of cutting holes in sides of boats or was it me cutting holes.?

 

Her suggestion was to cut out vents on the engine cover board which after some thought I thought I could do that with two pieces of board, matching holes with a fine mesh as the filling.

 

We do have a tonneau cover and the likelihood of cruising whilst it's persistently raining is very unlikely.

 

Any thoughts or ideas greatly appreciated especially ones I can share with the memsaab.

 

Apologies for all the full stops. Yes they do indicate finality but snowflakes of the world get over yourselves ?

 

 

[Tony Brooks]

How does the gunwale (cat walk) join onto the supports for the cockpit floor. If its a vertical  section this usually vents into the engine bay on cruisers so you can put vents on the inside of the cockpit. It may make fitting the fans a more trouble though. How old is the boat? if its more then a year or so what makes you think you need vents? The engine draws in an awful lot of air when its running and gobbles it up. If you have no problems why fiddle?

[WotEver]

1 hour ago, Tony Brooks said:

... what makes you think you need vents?

This was the question I was wondering.  

[Paul Gwilliams]

Thank you for your responses. I'll leave well alone. Ain't broken so need to fix

 

Boat is a owl class so well over 10 years.

 

Just reading other threads about reducing temperature for battery charging and engine running. 

[WotEver]

6 minutes ago, Paul Gwilliams said:

Just reading other threads about reducing temperature for battery charging and engine running. 

Generally these are threads specifically about cooling the alternator, usually because they have by whatever means coaxed it into supplying more power. 

[Bod]

We have, on a Trad stern, a fan in the engine ole, which is thermostatically controlled, to draw out hot air from around the engine, and force it into the area above the engine covers.  There are two large filter covered holes to allow cool air in for the engine to breath.

Duct the warm air on to feet in winter, very cosy!  Not much of a problem in the summer. Remove the duct.

When the temperature reaches about 30 centigrade fan switches on, takes ages in winter, has been known to come on immediately in the summer, power is taken from the isolated side of the starter battery, so when the engine is done with, and the starter battery isolated, the fan stops.

 

Bod.

[David Mack]

Vent holes in the side of the hull are only generally needed for air cooled engines. What engine have you got?

[Tony Brooks]

Needed yes, but don't Piper fit fancy ones as standard?

[Alan de Enfield]

2 minutes ago, Tony Brooks said:

Needed yes, but don't Piper fit fancy ones as standard?

Our 'Hallmark Millenium' (1999) had a Mercedes engine and an 'air vent grill' on each side of the engine 'ole.

[David Mack]

45 minutes ago, David Mack said:

Vent holes in the side of the hull are only generally needed for air cooled engines. What engine have you got?

 

6 minutes ago, Tony Brooks said:

Needed yes, but don't Piper fit fancy ones as standard?

 

2 minutes ago, Alan de Enfield said:

Our 'Hallmark Millenium' (1999) had a Mercedes engine and an 'air vent grill' on each side of the engine 'ole.

 

But if you have a water cooled engine, and your boatbuilder hasn't already provided hull side air vent openings, then there is almost certainly no need for you to add them.

[Tony Brooks]

Just now, David Mack said:

 

 

 

But if you have a water cooled engine, and your boatbuilder hasn't already provided hull side air vent openings, then there is almost certainly no need for you to add them.

I agree with that.

[Bod]

46 minutes ago, David Mack said:

Vent holes in the side of the hull are only generally needed for air cooled engines. What engine have you got?

Vetus M414.

The vent holes are all in board, in the engine covers.

 

Bod

[Richard10002]

2 minutes ago, Bod said:

Vetus M414.

The vent holes are all in board, in the engine covers.

 

Bod

Vetus M414 here as well - keel cooled. Vent holes on the insides of the step down from the cruiser stern to the accommodation.

[Alan de Enfield]

2 minutes ago, David Mack said:

 

 

 

But if you have a water cooled engine, and your boatbuilder hasn't already provided hull side air vent openings, then there is almost certainly no need for you to add them.

I agree with that, but was really responding to the comment "generally only needed for air-cooled engines" so anyone with a water-cooled engine with hull side air vents did not worry something was 'strange' or 'wrong'

 

When every boat is different "never say never, or, always"

[PhilR]

1 minute ago, Alan de Enfield said:

I agree with that, but was really responding to the comment "generally only needed for air-cooled engines" so anyone with a water-cooled engine with hull side air vents did not worry something was 'strange' or 'wrong'

 

When every boat is different "never say never, or, always"

Our 1980 Teddesley has an air cooled Lister without any ducting through the hull. Inlet air supply is between the well deck and counter. Hot air outlets are by the steerers feet. In cooler weather I have warm feet. In summer I probably have sweaty feet! It isn't any noisier than through-hull vents ?

 

But I digress! I am sure the OP would have noticed symptoms of overheating if there was a problem. His engine must be getting enough combustion air and ambient cooling. 

 

 

[Jen-in-Wellies]

1 hour ago, Tony Brooks said:

Needed yes, but don't Piper fit fancy ones as standard?

Yes they do. CNC cut along with the rest of the steel work. No idea if it is plasma torch, laser or what that does the cutting, but just as easy to cut a fancy one as a simple one. They are there to supply combustion air for the engine. Cooling is by the skin tank. There is angled steel plate behind, open at the top, so the actual vent size is perhaps 9" x 1" each side. Alternators are built to work in vehicles, where the under bonnet temperatures can easily reach 80C plus when stationary. As @WotEver says, they only have problems on boats when people try and extract more power from them than they are designed for long periods of time. 

Jen

[Paul Gwilliams]

Thank you all for your input.

 

As this is our first NB it's been a steep learning curve.

 

Both our previous boats were grp with an abundance of grills / vents.

 

Our engine, a beta 20 is a new engine put in by the previous owner. So it's not the original engine as fitted when built

 

Haven't done a full days cruising but was concerned about the heat in the engine bay.

2 hours ago, David Mack said:

Vent holes in the side of the hull are only generally needed for air cooled engines. What engine have you got?

Beta 20

[system 4-50]

I am sure my engine (Beta 43) prefers to be hot when worked hard. Why else would my builder have installed these two panel heaters in the engine bay?

[Alan de Enfield]

7 minutes ago, system 4-50 said:

I am sure my engine (Beta 43) prefers to be hot when worked hard. Why else would my builder have installed these two panel heaters in the engine bay?

 

Me too - I have 2x 6 foot 375 watt tubular 'green-house heaters', they must be there for a reason.