The Steamboating Forum

I've been interested in hobby steamboats for quite a while and finally have an opportunity to purchase a turn-key steam launch that would work for me. I am very comfortable with the hull, the motor, the expertise of the seller and his setup. The only grey area as far as my research is concerned is knowledge of the Benson Mountain boiler. It is a 46 sf unit built in 1999 and installed in 2000. Benson Mt. doesn't seem to be in business anymore and I can't find much information on that boiler or it's design.

Can anyone provide useful info on this boiler and it's expected service life?

Hi Centurion,
Welcome (maybe) to the wonderful world of steamboating. I had a Benson Mountain boiler of the same specifications you describe. Mine was also built and installed in 1999. I had no issues with the boiler, it is very free steaming, clean burning and relatively low height which helps a lot with stability and good forward vision. I ran it in the Catawissa, an Elliott Bay hull, for eleven years and loved it. My wife fires it when we are out together, the fire door is set up facing forward. She has no problem keeping up steam and with good dry wood can gain on pressure at full throttle. Eleven seasons of use and the tubes are still in good condition. I replaced it in 2011 to try an improved design that is very similar but shorter shell with shorter tubes and taller firebox and 28 square feet of heating surface.

If you buy the boat and are confident about the other features I would not hesitate over the boiler, it is a very user friendly, stable steaming and forgiving piece of equipment.

I don't know where you are, but if you can get to Lee's Mill for the meet that starts September 10 and runs through September 20 you can see several boilers of the Benson Mountain build as well as the "Mark II" version in steam and talk to their owners, a word is worth a thousand pictures in this case.

Best of luck, best regards, Steamboat Mike.

Steamboat Mike wrote:Hi Centurion,
Welcome (maybe) to the wonderful world of steamboating. I had a Benson Mountain boiler of the same specifications you describe. Mine was also built and installed in 1999. I had no issues with the boiler, it is very free steaming, clean burning and relatively low height which helps a lot with stability and good forward vision. I ran it in the Catawissa, an Elliott Bay hull, for eleven years and loved it. My wife fires it when we are out together, the fire door is set up facing forward. She has no problem keeping up steam and with good dry wood can gain on pressure at full throttle. Eleven seasons of use and the tubes are still in good condition. I replaced it in 2011 to try an improved design that is very similar but shorter shell with shorter tubes and taller firebox and 28 square feet of heating surface.

If you buy the boat and are confident about the other features I would not hesitate over the boiler, it is a very user friendly, stable steaming and forgiving piece of equipment.

I don't know where you are, but if you can get to Lee's Mill for the meet that starts September 10 and runs through September 20 you can see several boilers of the Benson Mountain build as well as the "Mark II" version in steam and talk to their owners, a word is worth a thousand pictures in this case.

Best of luck, best regards, Steamboat Mike.

Thanks for the feedback. It was valuable and I appreciate it. Your reply prompts some questions, though. A forward facing fire door? As a newbie, how does that work when you're alone?

Secondly, 28 sf on an Elliott Bay hull? I'm certainly no expert but that seems small for that hull.

Thirdly, what is a "Mark II" version. Is that for an updated Benson Mountain boiler? If so, I've been under the impression that Benson Mtn. is no longer in business.

I am hoping to be at Lees Mills. The vessel I am interested will be there. I might just take it home with me.

Hi Centurion,

The fire door facing forward works very well when I am out alone. The fire box is quite large, as a result the fire needs tending every 45 minutes or so. It is not difficult to toss in a couple of chunks of wood then. I have two steering stations and the hydraulic steering holds a setting while I am occupied with fire tending duties. The best thing is that when I have company it gives them something to do while under way.

As to 28 square feet of heating surface........I have always suspected that it is not the total square feet of heating surface that is important, it's just a number. The more important things are the quality of the heating surface, the firebox volume and circulation of water inside the boiler. The firebox volume is critical for good combustion andheat transfer since if there is not good combustion there is not good radiant heat to transfer to the firebox wall. The firebox does the greater part of steam generation, the tubes are mostly serving as conduits to get the spent gasses out of the firebox to the stack. A square inch of firebox surface is much more effective than the same square inch in a tube. Almost all of the effective heat transfer is done in the first 6 inches of the tube, after that the temperature difference is not great enough to do much good. The heat transfer is also conduction rather than the much more effective radiant transfer in the firebox. Good circulation in the firebox water leg is necessary to take advantage of the heat being radiated on the fire side and passing it to the water. All of these features the Benson boiler has.

This leads to your third question. The Mark II is in quotes because it is what I humorously refer to the present boiler that is in my boat. It was not built by Benson. It was built by Paul Boshan, a boiler builder in Carson, California. The boiler that resulted is virtually the same as the Benson but with a shorter outer shell and a slightly taller firebox. This resulted in shorter tube length. The idea that the first part of the tube does most of the work seems to be borne out by the fact that the stack temperature is not appreciably higher than the longer tubed Benson predecessor.

When you get to Lee's Mill, look me and the Catawissa up, we can talk at length about the relative merits of the boilers and you can see how it all works.

Welcome aboard, best regards Steamboat Mike.

Every 45 minutes? I'm impressed. If I didn't feed my boiler for 45 minutes there wouldn't even be coals left.

With volatile stuff like cedar 2 x 4 ends I am stuffing that hole every five minutes. With seasoned fir, every ten minutes might do. I don't see enough hardwood out here on the West coast to have any serious experience with it.

This is all when running fairly hard with a Beckman VFT-30 feeding a 3 x 4 single. When I'm doofing around at lower speeds things are somewhat less onerous.

Heading for Olympia, WA for the tug boat races and to haul bodies and toot the whistle. The tow boaters used to turn up their noses at my boat so I scrounged up a 3" towing bit. They grumble and make sarcastic remarks but seldom refuse a chance to go for a spin.