[C320-list] ENGINE SPACE VENTING

[Ken Geiger]

 Just got back from a charter on a catamaran in Thailand, Andaman Sea.  The 2 year old cat had electric toilets.  One had recurring problems in discharging the waste.  The other thing I noticed is they probably moved a lot more water than what I would want my holding tank to deal with.  Northern Dream is a fresh water boat where managing the holding tank pump out is always a part of our cruise plan.  So electric is not for us.  

FWIW

Ken

 

 

-----Original Message-----
From: John Meyers <jcmeyers7 at gmail.com>
To: C320-List <C320-List at catalina320.com>
Sent: Sun, Mar 18, 2018 2:08 pm
Subject: Re: [C320-list] ENGINE SPACE VENTING

Just in case some of you may think electric heads are a joke......

www.defender.com/product.jsp?path=-1&id=2391500

On Sun, Mar 18, 2018 at 12:07 PM, Donald Lawson <dnclaws at aol.com> wrote:

> Graeme
> Best answer is to ask Catalina and get the final answer.
> I had some refrig work done and the fuel tank cleaned this winter.  Mechs
> crushed dryer hose, it was fine before that. Tried to fix it but it
> probably needs to be replaced.
> Also I really am going to install an electric head.
> Don
>
> On Mar 18, 2018, at 3:29 AM, Graeme Clark wrote:
>
> > Don
> >
> > Nothing in the data you have kindly transcribed for us states that the
> blower is specifically there to provide combustion air
> >
> > It clearly states that combustion air “may” be supplied by natural
> ventilation and that a blower may be provided simply to remove odours or
> improve working conditions. In other words extra ventilation is only needed
> if natural ventilation is insufficient.
> >
> > If natural ventilation on the 320 was insufficient and it was necessary
> to have the blower running whenever the engine was running then (a) it
> would state that in the C320 manual and (b) it would probably be hotwired
> to the ignition key so it couldn’t be left off by accident
> >
> >
> > Just saying!
> >
> > Graeme
> >
> >
> > Sent from mobile: please excuse typos etc.!
> >
> >
> >> On 17 Mar 2018, at 23:05, John Frost <john at frostnet.net> wrote:
> >>
> >> WOW! Actual facts that we can use. Great research job Don
> >>
> >> Thanks,
> >> John
> >>
> >> John C. Frost
> >> President
> >> Safety Engineering Services, Inc.
> >> 2627 Trailway Rd.
> >> Huntsville, AL 35801
> >> (256) 650-0335
> >>
> >> -----Original Message-----
> >> From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On
> Behalf
> >> Of Donald Lawson
> >> Sent: Saturday, March 17, 2018 5:14 PM
> >> To: C320-List at Catalina320.com
> >> Subject: Re: [C320-list] ENGINE SPACE VENTING
> >>
> >> Jeff & Graeme
> >> Rather than have a debate, I thought I would give all the data I could
> >> collect and let everyone make their own decision as to use/removal of
> the
> >> blower Some of you will have to convert to english/metric where I did
> not.
> >> Also, this is for a 3YM30 Yanmar only but I expect it applies somewhat
> to
> >> all diesels.
> >>
> >> This 66 cu in (1.115 l) engine needs air at about 50 cu ft/min at 3000
> rpm..
> >> Assumes a .9 volumetric efficiency for this engine (under 1000 hours).
> >> Older diesels are above or near .8.
> >>
> >> Per the Yanmar Installation Manual (not owners manual):  1) Maximum
> engine
> >> room Temp shall be 140 deg F (60 C) and 2) Minimum Engine Room
> Ventilation
> >> Fresh Air Exchange
> >>   (Ventilator Capacity) shall be 194 cu ft/min (5.5 cu meters/min).
> >>
> >> Per Yanmar Installation Manual horsepower decreases from 30 to 29, at
> rated
> >> rpm,  when temp at the fuel pump increases from 25 C to 40 C. Expect
> lower
> >> hp at 60C.
> >>
> >> Rule and Shurflo ventilators have about 250 Cu ft/min capacity with a
> 4in
> >> hose.  I think I have a 4in dryer hose crushed to 2 in.
> >>
> >> ABYC Diesel Ventilation Standard H-32, from 1987, states:
> >> H-32.4.
> >> PURPOSE
> >> These recommended practices and engineering standards establish
> requirements
> >> for ventilation of boats using diesel fuel.
> >> SCOPE
> >> These recommended practices and engineering standards apply to boats
> using
> >> diesel fuel only for electrical generation, mechanical power and
> propulsion.
> >> NOTE:  Ventilation requirements for boats using gasoline as fuel are
> >> contained in ABYC H-2, "Ventilation ofBoats Using Gasoline".
> >> DEFINITION
> >> Ventilation - The changing of air within a compartment by natural or
> >> mechanical means. Ventilation may be effected by dilution of
> contaminated
> >> air, by introduction of fresh air, or by local exhaust of contaminated
> air.
> >> REQUIREMENTS -IN GENERAL
> >> a Ventilation Principle - Ventilation cannot be relied upon to remove
> all
> >> vapors that are pos- sible from the presence of liquid fuel resulting
> from
> >> fuel system failures or fuel spillage. (See ABYC H-33, "Diesel Fuel
> >> Systems") b Storage Batteries - Compartments containing storage
> batteries
> >> shall be vented to provide for the escape of hydrogen in accordance with
> >> ABYC E-lO, "Location and Installation of Storage Batteries".
> >> c Diesel Fuel Vapors - Due to the characteristics of diesel fuel and the
> >> closed nature of the diesel engine fuel system, neither mechanical nor
> >> natural ventilation, as prescribed for gasoline powered vessels, is
> >> necessary to remove diesel fuel vapors. (See ABYC H-2, "Ven- tilation of
> >> Boats Using Gasoline") d Removal of Fixed Gaseolls Fire Extinguishing
> System
> >> Discharge - Ventilation means shall be provided to remove the discharge
> from
> >> ftxed gaseous ftre extinguishing systems.
> >> e Combustion Air - Ventilating provisions and openings to the machinery
> >> space provided for supplying combustion air shall accomodate the air
> >> requirements required by the engine manufacturer(s) for each propulsion
> and
> >> auxiliary engine in that space. These openings may also function as
> means of
> >> providing natural ventilation.
> >> f Additional Uses of Ventilation - Power or natural ventilation is not
> >> required on a diesel boat, but may be used to control compartment
> >> temperature. power ventilation may also be used in the machinery space
> for
> >> odor control and personnel comfort while servicing equipment.
> >>
> >> Note c and e above.   Could not find the current standard without paying
> >> money, expect it to be unchanged?
> >>
> >> Based on the above the blower is not there to cool the engine but does
> >> exchange air for engine room cooling and combustion.
> >>
> >> Therefore I will:
> >> Continue to run my blower during engine operation per Yanmar's
> requirement.
> >> Change the dryer hose to something more substantial to keep it from
> being
> >> crushed when I work in the aft areas.
> >> Install an electric head
> >>
> >> Happy Boating
> >> Don Lawson
> >>
> >>
> >>
> >>
> >>
> >>> On Mar 15, 2018, at 2:09 PM, Jeff Hare wrote:
> >>>
> >>> Don,
> >>>
> >>> Per what Graeme said, that's how ours was configured as well from the
> >> factory.  For a bilge blower to really serve its intended purpose, it
> would
> >> have to suck air in and vent it outside, as it's supposed to remove
> residual
> >> flammable "gasoline" fumes prior to starting the engine to prevent
> awesome
> >> dockside entertainment.
> >>>
> >>> So, if you really run the blower when you run the engine, that probably
> >> only serves to validate the point that the engine gets what it needs
> just
> >> fine through many places like the front and aft engine cover cracks,
> all the
> >> places where hoses and bilge drain holes exist in addition to the pair
> of 4"
> >> holes.
> >>>
> >>> So, generally no need to sweat this.  To my knowledge I've never heard
> >>> of a 320 having overheating or efficiency issues due to the way the it
> >>> was installed by the factory.  On the bonus side, without the bilge
> >>> blower hoses clogging up the transom vent holes, your fridge might run
> >>> a little cooler.  :)
> >>>
> >>> There's really nothing stopping you from drilling another 3" or 4" vent
> >> hole near the existing ones to increase air flow except that you'd be
> hard
> >> pressed to show made any measurable difference.
> >>>
> >>> Cheers!
> >>> -Jeff
> >>>
> >>> -----Original Message-----
> >>> From: C320-list <c320-list-bounces at lists.catalina320.com> On Behalf Of
> >>> Graeme Clark
> >>> Sent: Thursday, March 15, 2018 5:20 AM
> >>> To: Catalina list <C320-List at Catalina320.com>
> >>> Subject: Re: [C320-list] ENGINE SPACE VENTING
> >>>
> >>> Don
> >>>
> >>> I may be being stupid, but cant see how running the blower improves the
> >> airflow *to* the engine? It sucj=ks air away from the engine and is
> pretty
> >> inefficnet at that according to Jeff). The suction from the air intake
> on
> >> the engine itself when the piston is drawing in air probaly exceeds the
> >> suction from the blower by a factor of about 50 at a guess.
> >>>
> >>> Only if your blower was reversed to pump air INTO the engine
> compartment
> >> would any possible benefit be accrued, surely?
> >>>
> >>> Just a thought
> >>>
> >>> Graeme
> >>> #366
> >>>
> >>>> On 15 Mar 2018, at 04:26, Donald Lawson <dnclaws at aol.com> wrote:
> >>>>
> >>>> IMO.
> >>>> When I rebuilt/ replaced my engine(s) I learned a lot about the
> Amount of
> >> air a Diesel needs to run.  It needs a lot of cold air to run
> efficiently.
> >>>> I run the blower while the engine is running, not to cool the engine,
> but
> >> to ensure that I provide the engine with enough cool combustion air.
> >>>> I agree with Jeff that the blower is not used for cooling the engine
> >>>> although I don't quite agree about better paths of air for engine run.
> >>>> My aft cabin mattress pretty much precludes that. HOWEVER If you
> >>>> removed the hoses there may be enough SQ area of opening to get rid of
> >> them.  Will do the math and get back to ya'll, but I seem to remember a
> 3in
> >> dia hole is enough for a 2GM20.  We have 2, so may not be an issue.  I
> will
> >> rid myself of them in the future. I pretty much crushed them working on
> the
> >> fridge anyway.
> >>>> Don Lawson
> >>>> #1104
> >>>>> On Mar 14, 2018, at 4:35 PM, Jeff Hare wrote:
> >>>>>
> >>>>> Not to be critical of anyone's answers, because it's great to bounce
> >> these thoughts around to help refine your logic, but seriously don't
> >> over-think this.
> >>>>>
> >>>>> The engine doesn't need cool ambient air to keep it cool, that's what
> >> the raw water heat exchanger is all about. Otherwise they would not put
> it
> >> in an insulated box with a couple lengths of dryer hose.  It also
> doesn't
> >> need any duct work to feed it air to run because there are SO many
> better
> >> paths for hull-cooled bilge air to get into the engine that it's simply
> a
> >> non-issue.
> >>>>>
> >>>>> If you really believe that the blower reduces the heat in the aft
> cabin
> >> with the stock hoses, awesome, but it really doesn't.  No way you're
> moving
> >> that much heat out through those crinkled half crushed hoses with our
> anemic
> >> blower. LOL!  You'd have to run the blower till the engine block cools
> down
> >> quite a bit to make any real difference or it'll just reheat the air
> again.
> >> By then someone sharing the mooring field with you would have launched a
> >> torpedo at your boat because of all the racket that thing produces.
> >>>>>
> >>>>> If you really want to help remove any excess aft cabin heat, I'd
> suggest
> >> that you open the aft cabin access door at the foot of the bed and aft
> >> cockpit locker above the fridge compressor and let convection take
> over.  If
> >> you really wanted to use hoses for some reason, you'd need 4" smooth
> wall
> >> hoses that have fewer bends and a more powerful blower to actually get
> any
> >> reasonable airflow.
> >>>>>
> >>>>> I'm pretty certain that the blower and the hoses were only installed
> to
> >> satisfy outdated requirements for a bilge blower (which diesels are
> exempt
> >> from now in the US anyway).
> >>>>>
> >>>>> Cheers!
> >>>>> #809   stay'n hoseless  :)
> >>>>> -Jeff Hare
> >>>>>
> >>>>> -----Original Message-----
> >>>>> From: C320-list <c320-list-bounces at lists.catalina320.com> On Behalf
> >>>>> Of John Meyers
> >>>>> Sent: Monday, March 12, 2018 3:23 PM
> >>>>> To: C320-List at catalina320.com
> >>>>> Subject: Re: [C320-list] ENGINE SPACE VENTING
> >>>>>
> >>>>> John
> >>>>>
> >>>>> If thing for convection to work you may need one of the openings to
> be
> >> connected to a hose with one end lower than the one without a hose. The
> one
> >> with the hose will let cold/fresh air in when the hot air rises to the
> vent
> >> without the hose.
> >>>>>
> >>>>> John Meyers (The other John M)
> >>>>>
> >>>>> On Mon, Mar 12, 2018 at 10:08 AM, John morrison
> >>>>> <sail-ability at sympatico.ca>
> >>>>> wrote:
> >>>>>
> >>>>>> I attended a surveying seminar on the weekend, and for those who
> >>>>>> may not know ( I didn't) diesel engine spaces do not require forced
> >>>>>> ventilation in order to pass a survey. You may want to have it for
> >>>>>> other reasons as has been mentioned in this forum. I intend to
> >>>>>> remove the vent hoses from the cowls and let the space vent by
> >> convection.
> >>>>>> The cowls are high up in the stern so warm air should exit pretty
> >>>>>> well, we'll see  how that works. When the hoses are attached the
> >>>>>> cowl holes are blocked and hot air from the engine, fridge
> >>>>>> compressor, cannot escape; unless of course the blower is r
> >>
> >>
> >>
> >
>
>