Multi-fuel boiler?

[87gn@tahoe]

I would imagine if it holds up to gasoline it *should* hold up to EVOO.

[RogerV]

Without commenting on the suitability of propane as a fuel in a steamboat, I thought that some of you might find this interesting: http://www.litecylinder.com/products.aspx The "Lite" cylinders are made of fiberglass with translucent panels in them that allow you to actually see the level of propane in the tank. Two of their features I think might be useful aboard a boat: they won't rust or corrode, and both vertical and horizontal tanks are available. They also weigh less than metal tanks, but are more expensive.

It of course depends completely on the boat and whether space is available, but I was wondering if one small ten-pound cylinder might be carried as an "emergency reserve."

[fredrosse]

The sidewheeler Margaret S. was a bare hull a few days before the last steamboat meet of 2010, and I had to install the boiler, engine, paddlewheels, rudders, and all piping within 6 days. That schedule meant that I had to put a burner together very quickly, so I abandoned the oil/wood/coal options and went to Home Depot, buying a large "Weed Burner" that uses a 20 pound (or larger) propane cylinder for fuel. The burner ($30 USD) is rated at 650,000 BTU per hour, more than six times my heating requirement, so it runs in a very throttled condition on the boat. The Propane has worked well, and I will probably stay with the Propane as the primary fuel. My only complaint is that the burner does make some noise (a roaring sound), and I have since gotten a set of cast iron burners from a domestic furnace (these are virtually silent) which I intend to install this winter.

I burn about 1 gallon of Propane per hour, and after about 1-1/2 hours of running, the propane tank is showing a heavy ice coating, due to the Propane boiling away. The boat is now fitted with three sockets to receive the standard steel Propane cylinders, and I can switch to another tank in a few minutes. I suppose, if necessary one could disconnect a Propane cylinder, tie a rope to the handle, and throw it overboard. Towing the cold propane cylinder behind the boat for 15 minutes will heat it up sufficiently to restore several atmospheres pressure to the tank. I have never had to do this, but I must switch tanks on longer trips.

Near Philadelphia the new 20 pound steel cylinders are $20 USD each, and the filling is about $16 USD each. They are readily available at many outlets, certainly more available than Dissel fuel. Anything other than the standard 20 pound steel cylinders is very expensive, and much less available in my area. There are 10 pound steel cylinders for about $50 each (empty), and fiberglass 10 pound cylinders cost about $80 each (empty). The 20 pound steel cylinders are universally used at exchange stations, whereas there is virtually no exchanging the smaller cylinders at almost all exchange stations.

[Lopez Mike]

Just to stir up the troops on a cold Winter day here on Lopez Island, I’ve been thinking about the comparative qualities of fuels. The figures being offered here and on other posts are sometimes difficult to interpret due to the fact that most liquid fuels are rated in BTU’s for a certain volume and the solid fuels are rated by weight.

So I sat down with my trusty HP48 and did some crude conversions.

Given 7.5 gallons per cubic foot and 33 pounds of dry fir per cubic foot, we get 4.4 pounds of wood per gallon times 7000 BTU per pound equals 30,800 BTU per gallon.

Now I can hear you all tuning up that wood isn’t measured by the gallon for obvious reasons. Mark Twain commented on stacks of firewood along the Mississippi stacked so loosely that you could throw a cat though them. So given my style of stacking scraps of wood, sort of heave them in there and hope for the best, let’s take a stacking efficiency of 50% as a worse case. Surely we can do better than that but I’m leaning over backwards to justify my wood fired boiler.

Now we are down to maybe 16,000 BTU per gallon. Hmm. Now we know why the first steam boat to make it across the Atlantic almost ate itself up to make port! They burned the pilot house and much of the deck, I believe.

But how are we doing for weight compared to oil, seemingly the highest density fuel mentioned? Let’s use six pounds per gallon and 139,000 btu per gallon. That gives us 23,167 BTU per pound.

How about propane? 91,000 BTU per gallon divided by 4.11 pounds per gallon yields 22,141 BTU per pound. So much for any advantage of oil over propane by weight.

We see that compared to wood at 7000 BTU per pound, oil and propane are still better. But not as superior as some would make out! With some efforts at stacking the wood carefully, many a wood fired boat has made it to its destination. And (this in the nose of the sniffer), with much less smell! Also, I’m not in the habit of buying wood scraps.

Now to throw another log in the stove and reread some Hornblower.

Mike