Conference unifix::sailing

    After a quick look in the local Yellows, I have one concern...
    
    Where do you get the tank refilled?  Plenty of propane dealers
    but no one advertising butane.  
    
    Otherwise, college chemistry tells me that you should get a hotter
    flame and therefore quicker cooking time than with propane or cng.
    
    Good luck, John W.

    Mien Frau -- REFUSES to use the Alcohol stove -- something about not
    liking invisable flames, etc....
    
    Our solution has been to use a fairly standard, high quality propane
    camp stove.    This has worked out very well for many years.
    
    As you said Propane/Butane are heavier than air and require some
    respect.  You want to store it where it does not get banged around and
    indeed can vent into the (moving) air if it should leak.
    
    Most of the portable stoves use cylinders vs the bigger tanks.  These
    are easier to store (a cut in some foam is great) & if one should leak
    it's 16 oz vs 20 lbs (i.e. safer?)
    
    Most motor homes etc... use propane so it is generally cheaper & easier
    to get.  The reason they use propane vs butane is it works over a
    larger temperature range.   Butane burns hotter than propane and makes
    an neat little stove; but, the difference in heat is not all that
    noticable for cooking.   At about 40 degrees F or less butane begins to
    remain more liquid (starts to freeze) & doen't burn as well (that's why
    cigarette lighters don't work as well in the winter - the wind puts
    them out more readily)  Propane however will burn nicely at quite low
    temperatures  (that's why I can Bar-b-Q all winter & Bar-b-Q's use 
    the propane)
    
    I would stick to a nice propane camp stove - some of them even store
    the cylinders inside the stove when not in use & are made to take the
    bouncing around of cars, etc...
    
    As long as it's stored outside in heavy seas you should be fine --
    just don't carry 156 cylinders -- 2 will last a full two week vacation 
    if used correctly & more can be had from almost any hardware, KMart,
    etc... as you travel
    
    
                            Happy cooking,
                                           Lou

    
    	Don't forget your worst case planning-
    
    	I brought my (?)-ane camp stove (read: little can w/ screw-on
    	burner) on an ultralight racer to squeak by the livability rules
    	of the race.
    
    	Anyway, afterwards, a detail-oriented member of another crew 
    	mentioned that the insurance company may not pay off a stove-
    	type accident as the stove was not permanently installed, nor
    	mentioned on the policy.
    
    	As a crew, I'd be more concerned about getting into the water...
    
    	It's always something.... to keep us from getting too comfy...
    
    	Anyway, I've seen what I think you're talking about. They seem
    	nicer than the old swing-stoves, and a nice, stuffable carry pack.
    
    	Hopefully the cans of fuel aren't too expensive...
    
    	Scott.

    Consider how you use your boat.  If it is just weekends and for short
    summer vacations propane or CNG will work fine.  If it is offshore or
    long trips I would go with propane as it is available world wide.  CNG
    is the safest choice but may not be widely available.  I sail in
    southern California and CNG is usually available at the fuel docks
    where you exchange your empty for a full tank.  I chose CNG for safety
    reasons.  I was a little surprised on the fuel consumption with CNG.
    CNG comes in a aqualung tank (very heavy) filled to 2200 psi.  I have
    found I get about a hours running time on the stove for every 100 psi.
    So I get about 22 hours per refill.  This is not a very scientific
    observation as sometimes we have both burners and the oven going.  The
    refill costs me $14 so I don't believe it is the most cost effective
    fuel.  I use less than two tanks per year so for me it's no big deal.
    Another consideration is the space necessary for the CNG tank and a
    very strong cradle and straps to hold it down.
    
    If I had to do it all over I would probably go with propane and deal
    with all the necessary safety precautions it requires.
    
    my 2 cents
    
    Chuck

This note is in reference to .2 & .3--

The Coast Guard has strict regulations pertaining to LPG/CNG 
usage aboard boats. So in addition to putting your insurance in 
jeopardy by using "camp stoves" you will also be at risk with the 
Coast Guard. You will have less trouble by using an approved device.

Joe

    
    The coasties approve/disapprove installations, not devices. My stove is
    plumbed probably no better than my gas grill, but the safety standards
    were met, so the insurance company ok'd it, sight unseen. 
    
    Whenever the bottle's open, so's every hatch in the area. Hopefully
    that's enough.
    
    What's for lunch?
    
    Scott.

My note pertaining to the Coast Guard was not intended to 
associate them with an equipment approval agency. But, they have 
established rules for LPG/CNG storage on boats in conjunction with 
the National Boating Safety Advisory Council. 

Back in 1985, the Coast Guard agreed to alter their requirements for 
the then proposed LPG/CNG storage locations on boats. They agreed to 
drop the requirement that LPG/CNG be stored above decks. This was 
done at the urging of the National Marine Manufacturers Association 
(NMMA). But, they required isolation between the interior of the 
boat and the gas cylinder. To my knowledge, the Coast Guard still 
requires a vapor tight (to the interior of the boat) locker that 
is vented to the out side of the vessel for cylinder storage as an 
alternative to storing cylinders above decks. 

Joe

    re .7 Vapor tight lockers for LPG/CNG
    
    As far as CNG goes you would want it vented at the top vs. bottom
    vented for LPG.  On my Catalina 36 the CNG system was factory
    installed.  The tank is mounted in a cradle in the locker under the
    helm seat.  It is not a vapor tight locker just for the tank.  It
    drains to the bilge as far as liquids go.  There is a covered cowl vent
    at the stern rail that would allow CNG vapors to escape.  Catalina does
    put special vented lockers for propane.
                                                       
    Chuck

    RE: .-1
    
    For an Englishman unfamiliar with the term - what is CNG? I would have
    guessed "compressed natural gas", which would mean methane to me. Is
    that really lighter than air, so needing venting at the top of the
    locker? But then, if you have a hole at the top to let the gas out, you
    need a hole at the bottom as well to let out the inevitable rain/spray
    etc which is bound to get in! So maybe it's a little academic!
    
    Re: .-several (butane vs propane)
    
    I was on a charter boat a couple of years back in the Solent, one cold
    and windy weekend. Sunday morning, the skipper cooked his traditional
    "fried everything" breakfast. We were using all three burners and the
    grill. One burner was dedicated to boiling a kettle of water, which I
    used to pour over the butane bottle (mounted in a dedicated deck locker
    vented overboard :-)) to shift the ice off the outside of the bottle
    and warm the butane up enough so that it could vaporise and keep our
    breakfast cooking!
    
    - Brian

>> "compressed natural gas", which would mean methane to me. Is
>> that really lighter than air

Methane is lighter than air.  From high school chemistry:

Air is mostly N2 and O2.  Oxygen's most commong isotope has an atomic
weight of 16, Nitrogen's most common weight is 14.  This means that
N2 is 24 and O2 is 32.  Methane is CH4, Hydrogen's most common weight is
1, Carbon is 12.  This means that a methane has a mass of 16, less than 
either O2 or N2.  Since N molecules of any gas have the same volume at
STP, the lighther gas will be less dense, and rise.  Methane is thus
lighter than air.

F.

Times may have changed, but when CNG was introduced, they were making a 
big fuss of the fact you could store the cylinders belowdecks, providing 
there was some cabin ventilation -- an easier thing in a cabin than
elsewhere such as under cockpit seats, lazarette, etc.  Two advantages
cited were shorter plumbing runs, easier at-the-bottle shut-off, and
better corrosion control on the more-expensive bottle. 

They also offered a full East Coast listing of dealers, and suggested that
any inconvenience could be mitigated by purchasing another cylinder and
having it on hand as a spare.  ;-)

The main advantage touted, of course, was safety, as it's lighter than 
air.

BTW, butane is a smaller molecule than propane, and I *thought* butane was
also lighter than air, too, but not in common use due to its relatively
high boiling point (as mentioned) and relatively low heat value per unit
volume.  Chipped into my memory's sidewalk is:  

HEAT VALUE (H->L):   Propane -> CNG -> Butane -> Alcohol -> Sterno

MOLEC WGT (H->L):   Propane -> Alcohol vapor -> CNG -> Butane 

Corrections and qualification welcome; this is ancient recollection for 
me, and it's important to have the details right if you're making a choice 
based on them!  (If CNG is mostly methane, then it should be lighter than 
butane, right?)

Anyone recall the molecular formulas for these four?

J.

>Anyone recall the molecular formulas for these four?

In order of increasing molecular weight:

Gas		Formula		Molecular weight

CNG (Methane)	CH4		16
Nitrogen	N2		28
Oxygen		O2		32
Methanol	CH3OH		32
Propane		C3H8		44
Ethanol		C2H5OH		46
Butane		C4H10		58

I've never given this any thought before, but the numbers suggest that:

a) propane, ethanol, and butane will sink into your bilge

b) CNG will collect under your headliner

c) methanol will diffuse out through every opening, since it is roughly the
   same weight as N2 and O2.

Can anybody confirm this, or offer a better answer?

--RS

    So last weekend we went cruising with the little Butane stove...
    understand this is one of those models that has a spray can
    sized self contained butane throwaway canister...and it was
    great!  This is your kitchen stove packaged up 12 inches
    by 10 inches!  Push the button and the little sucker boils
    water in no time flat!  It worked well in moderate wind
    and put out at least the 7500 BTUs as advertised.
    
    Since the butane can be disconnected between uses, I store the
    burner unit down in the cabin, and the fuel canister goes back
    in my self-draining gas tank area...well away from anywhere 
    where the butane could leak into the bilge.