Propane...

[Godot]

Item 1: My new Bayfield has a propane cooking system. It used to have a propane water heater, too; but I didn't find it worth the trouble and removed it (eBay, soon). Propane works, it is convenient, it is already installed, it is staying (for anyone thinking about talking me into kerosene or alcohol). The tank lives outboard on the stern pulpit.

Item 2: I've been so frustrated with a phantom drain of amps in the boat, I decided to redo the entire electrical system. It is now much improved (and almost done). I've used modern, properly sized boat wire everyplace. I've broken circuits out into a couple different panels. I have a battery monitor. I'm happy. Or at least I was...

The problem: I finally got around to hooking up the xintrex S-2 (preexisting) propane sniffer/solenoid control to house power this past weekend. As expected, the solenoid burns about one amp, which is totally acceptable. What is less acceptable is the propane sniffers (one in the bilge, one in the cabinet directly under the stove) burn around .5 or .6 amps. Now, given that you'd think that the sniffers should be turned on whenever the boat is occupied (and maybe always, depending on your philosophy), I find that the 12 amp-hrs or more a day, just for monitoring, to be an overly serious drain on my limited battery (and charging) capacity. THIS is clearly a big contributor to my phantom battery drain.

The solution: As far as I know, sniffers are not required equipment. However, they do seem rather prudent. I'm thinking of wiring the Xintrex control/sniffer system up to a spare switch on the circuit breaker panel. I figure a decent compromise might be to throw the switch whenever the valve on the tank is on. When I'm well done with whatever cooking I'm doing, I could close the manual valve, and kill the Xintrex at the panel. This has the advantage of saving some electrons and giving me a third place to kill the propane if necessary (at the xintrex control panel, at the tank, and now at the electrical panel). It has the disadvantage of losing full time monitoring.

I post looking for the opinions of those who may be seeing something that I'm missing. I think with the tank at the rail, the solenoid at the tank, and the new propane line entering the hull through a vapor tight fitting, that I'm covering the important safety bases. Am I missing something?

[Captain Smollett]

Not an "expert opinion," but just some faceless guy on the Internet, but...

That seems like a good strategy to me.  So long as you have the tank off, and "know" that it really is off (that the solenoid works...is there positive feedback for that?), I personally don't see a reason the sniffer needs to be on when the tank is off.

Or, maybe consider perhaps leaving the sniffer on for a bit after the tank is closed...just to account for any gas in the line.

Or, maybe rig a single switch to operate both the solenoid and the sniffer?

I'm going on a limb with a SWAG, but my 'gut' tells me that most propane accidents are probably from leaving the tank on all the time and/or not properly ventilating the tank installation itself.  

Also, I think leaks rarely 'develop' in a good system.  I'd also SWAG that most leaks occur after working on the system/lines without proper leak detection...but I really don't know this.  Would love to hear of a real first hand story of a propane system not leaking one day then leaking the next.

Like yours, my tank is completely outside the boat; so long as the tank is off, there really should be no way to get dangerous build-up of gas inside.

[SalientAngle]

sniffer at lowest point in bilge below waterline would seem prudent, maybe on timer, just $0.02, cheers

[Godot]

sniffer at lowest point in bilge below waterline would seem prudent, maybe on timer, just $0.02, cheers

Sniffer one is currently in the bilge sump (not at the lowest point...I don't want the thing covered in water!). Sniffer two is under the cooktop which sort of makes sense as that is the only place in the boat where a propane connection is made. The current system will draw more than 12 amp-hrs a day from the battery (currently a 90 amp-hr group 24, but soon to be upgraded to a pair of group 27s). Recognizing that it is undesirable to have the battery drop below 50%, and that getting that top 10% of capacity can be a challenge, the battery really only has a useful capacity (without unduly stressing it) of 36 amp hours. The sensors will use a third of that capacity up every day.

A timer, while possible, would be a pain to implement. Especially considering the sensors aren't exactly "instant on" and take a few minutes to warm up. Not to mention, it always alarms (by design) during the self test phase of bootup. (can you imagine the alarm going off every thirty minutes or so?).

As a point of comparison, my "chartplotter" (a glorified mounted GPS maybe a little bigger than a typical handheld) uses somewhat south of 3/4 of an amp if the screen isn't at max brightness. These sensors alone are using just slightly less juice than the GPS. Prudent, maybe;  but I'm not sure it is practical to keep it running all the time.

I figure my solar panels might be generating 25 amp-hrs a day (they aren't hooked up yet, so I'm making some guesses based on anecdotal evidence from other sailors...4-20 watters will be installed on the dodger). The sensors would use up HALF of my daily solar capacity.

Basically, while half an amp doesn't seem like much, it does seem to add up pretty quickly in real terms.

So, given the criteria I outlined in the original message, I just don't see a significant benefit, safety or otherwise, to leaving it running all the time. I can see the use of having it power up every time the boat is occupied (via the battery switch) if the boat is only occasionally used (especially with the motor topping off the battery at the beginning and end of every day trip). And I can see its' use in a boat with a large amount of storage and generating capacity. I'm just having a hard time justifying it in a small cruising boat (even if I'm only cruising for a week or two at a time, currently).

[s/v Faith]

Might contact the mfg.  I suspect the most common arrangement will be to only have the detectors on when the solenoid is open (when cooking).  If properly installed the solenoid closes off the system to the boat when it is off.

Propane is certainly worthy of respect, but not necessarily the fear some seem to have.  I do recommend one of the combo co / fire detectors though... Would install that at least.  Good to have below for a variety of reasons....

[Godot]

I have a CO detector.

The manual for a next generation system suggests that the sensors should be on whenever the boat is occupied.

[Captain Smollett]

I have a CO detector.

The manual for a next generation system suggests that the sensors should be on whenever the boat is occupied.

That's the simple minded answer.  What else are they going to say?

Propane: If the tank is closed, what good does it do to have the sensor on?

CO: If the hatches are wide open, and/or no combustion below (consuming O2 and emitting CO), what good does it do to have the sensor on?

The manuals are written for the lowest common denominator. They don't want to get sued...someone with a sensor installed but not using it coming back on them.

Hundreds of thousands of boats are "occupied" each year without such sensors installed.  Installing a sensor does not automatically make being on the boat with it turned off more dangerous.

Another thing to remember is that though propane itself is heavier than air, the ethyl mercaptan odorant added to it is lighter than air.  If you have a bad leak, the kind that can fill your boat up to explosive concentration in an hurry, you WILL smell it.

I think like many things we discuss here on sailfar in regard to 'safety,' we have to be careful not to let the hype machinery take over.  Propane requires some handling precautions - as does any other combustible fuel.  But it's not the bogey man waiting in the dark with will and intent to kill us in our sleep.

[Godot]

The CO detector was listed on the survey, therefor became an insurance requirement (darn BoatUS).  I don't have a smoke detector onboard (and the survey didn't mention it, therefor the insurance doesn't require it); but I probably will install one. It would be trivial to wire it into the CO detector circuit, although a 9-volt unit might be cheaper (Defender has a Xintrex-Fireboy smoke detector that is supposed to be suitable for marine use for $12.99). They are very cheap on the electrons.

I tend to agree with Capt Smollett on the sensors and think I will wire the boat up the way I originally mentioned (control/sensor panel to a dedicated circuit on the electrical panel) and use it as required. If the required juice was similar to the smoke/co detectors, or if I had significantly more battery capacity, I'd leave them running all the time as a Best Practice; but battery capacity is limited, and the value seems limited as well. They will certainly be running whenever the gas is on. They have to be, as they are powered by the same panel that controls the solenoid. I'll probably just plan on leaving the switch on for a few minutes after I'm done cooking just to feel good; but I'm not sure I see any real advantage.

[rorik]

...but I really don't know this.  Would love to hear of a real first hand story of a propane system not leaking one day then leaking the next....

The closest I had to a leak when I did have propane was noticing rub marks on the supply hose where it went through a bulkhead to get to the stove. There was no grommet in the hole as it wouldn't fit over the end fitting and stay on the hose and I hadn't found a substitute for a grommet yet. Granted, it may have taken years to get to a point where it would actually develop a leak, BUT...
Thinking about that rub mark, along with watching video of a boat in a not too distant marina burn to the waterline from a fuel fire (IDK if propane or not), and a few other considerations, made me nervous enough about a fuel that is heavier than air that I switched to kerosene.
One bonus is that it also reduces my 12volt load.
Not trying to make anyone switch away from propane, just my thoughts...

[Godot]

The closest I had to a leak when I did have propane was noticing rub marks on the supply hose where it went through a bulkhead to get to the stove. There was no grommet in the hole as it wouldn't fit over the end fitting and stay on the hose and I hadn't found a substitute for a grommet yet. Granted, it may have taken years to get to a point where it would actually develop a leak, BUT...

I cut the old propane hose out, and I got to tell you that the hose was pretty tough. That said, I have these vapor proof thru-bulkhead connectors that should stop any errant rubbing at the penetrations. I think I'll be ok.

[rorik]

I never saw those connectors before now..... thanks...

[CharlieJ]

..
Thinking about that rub mark, along with watching video of a boat in a not too distant marina burn to the waterline from a fuel fire (IDK if propane or not), and a few other considerations, made me nervous enough about a fuel that is heavier than air that I switched to kerosene.
-------
Not trying to make anyone switch away from propane, just my thoughts...

Welcome to the luddite camp :D Kerosene is all I've used since 1975 ;)


Well, I DO have a butane one burner, but the stove of choice is still kerosene -only I use 100T% Mineral Spirits instead

my converted (was propane) Sea Cook- making coffee in Mississippi Sound, and at rest