Engine/Boiler Recommendation

[JonRiley56]

Hello All,

Just getting started on my project. I am going to be using a 22 ft. hull from a Tanzer sailboat. The sailboat keel has been removed. I will glass over the opening and add a skeg/keel to the rear to protect the prop and hopefully give me alittle more steerability.

I intend to deck the bow and stern and set the interior up after the fashion of a launch with seating around the bow and stern, two steering stations, one up front and one side steer. I live withina mile of the ocean and would like to be able to use the boat on saltwater.

Given the amount of weight I will add on the build out, and the weight of passengers, fuel etc. I could use help answering the following questions:

1. What size engine should I be contemplating ?

2. What size and type of boiler would be appropriate for the engine ?

3. What are the pros and cons of going with oil fired or wood fired ?

Thanks in advance for the help !!!!

jon

[barts]

1. What size engine should I be contemplating ?

The engine should be rated at about 2 hp per ton of boat displacement; a bit more
or less works fine. The Tanzer 22 has a displacement of about 3000 lbs, so 3 to
4 hp would work very nicely. Details on the Tanzer 22 are here:

http://www.msogphotosite.com/MSOG/pdfpage/tanzer22.pdf

I'd remove the keel or centerboard; the engine and boiler will help make up the difference.

I recommend a simple (single) cylinder engine for one's first steamboat; something of
about 2.5" bore x 3" stroke to 3" bore by 4" stroke would deliver your required power.
Getting the prop. sunk into the water enough may be hard; you'll want something about
16x20 to 18x22 [diameter x pitch] w/ the above engines.

2. What size and type of boiler would be appropriate for the engine ?

Something on the order of 20 to 25 sq. ft heating surface in a water tube boiler or
25 to 35 in a firetube boiler.

3. What are the pros and cons of going with oil fired or wood fired ?

Oil is easy and quickly put out if needed. Wood smells better and is more fun to be
around.... I'd set it up to do both; that way you can burn wood or oil in the same
unit....

- Bart

[steamboatjack]

Join the SBA or one of the US associations. The best answer to all these questions is in the SBA's new guide to steamboating.
Regards Jack

[JonRiley56]

Hey,

Thanks for the input ! I have sent in my check and membership form to the SBA, I have not gotten anything back from them yet. I am sure it will be on its way soon.

I am surprised that I can run with that low a horespower. I was guessing I would need a 5hp or better. As far as the prop is concerned, there is no shaft in the boat now so I will be putting in my own stuffing box, shaft etc. I may end up with the engine in front of the boiler with the shaft under the boiler platform to get a decent angle. Even then it may be "pointed down" further than I would like. I will have to do some measuring now that I have an idea of the prop size. For convenience at this point I am intending to have a large transom mounted rudder as opposed to one that is "inline" with the prop and contained in the skeg. It saves me cutting another through hole in the hull for the rudder post etc.

As far as the fuel situation goes for the boiler. Can I set up oil on one side of the boiler and have a fire door with access to a regular grate for wood across from it, or do I need to make the oil burner removable some how so I dont foul it with wood smoke etc ? It would actually be cool to be able to start the wood fire with the oil jets............... If I can leave the oil jets in, I could always have oil as a back up if I run low on wood..........say when I am steaming from RHode Island to France..........

I also want to set it up with a hot well and a condensing system. I have seen some info on people running the condensing pipe through the hulll and using the water to cool the steam. Again..........more holes.............. Could I set up with a couple of heat exchangers from a freshwater cooled I/O under the floor and pump cooling wather through them ? One hole to pick up the water, and one above the waterline to monitor the discharge and make sure I am cooling.

Sorry about the long post.............. I have a lot to learn.

jon

[barts]

I am surprised that I can run with that low a horespower. I was guessing I would need a 5hp or better.

5 hp will certainly work, but remember that these engines are driving large, slow turning propellers moving lots of water. This means that steam engines will make more effective use of their limited power than sailboat auxiliaries or small outboards. Large engines are easy to install - but the required large boilers and large fuel supplies much less so.
Sailboat hulls are easily driven, and unless your goal is to win races w/ others to the picnic spot (great fun I'll admit) I'd save weight and space for passengers or a wheel house or ...
As far as the prop is concerned, there ... post etc.

This makes perfect sense. One possible solution is to build a "well" on the bottom to permit the engine to sit down lower in the water. This actually works quite well and is reminiscent of the tunnel stern Sea Bright skiff designs by Atkins. People sometimes try to fit small props and gear them up; while possible this wastes power twice - once because of the losses in the bearings and speed-up gear, and once because the small prop is less efficient. Don't forget to balance the rudder somewhat as this affords much better turning performance w/ a propeller.

As far as the fuel situation goes for the boiler. Can I set up oil on one side of the boiler and have a fire door with access to a regular grate for wood across from it, or do I need to make the oil burner removable some how so I dont foul it with wood smoke etc ? It would actually be cool to be able to start the wood fire with the oil jets............... If I can leave the oil jets in, I could always have oil as a back up if I run low on wood..........say when I am steaming from RHode Island to France..........

Lots of us out here on the West Coast start w/ wood and switch to oil; the trick w/ starting w/ oil is that it needs to be sprayed somehow. Remember that the flame from the
oil burner is quite vigorous and will want to play against a stainless, ceramic or wood fire target. Many boats here place the oil burner and fire door on the same side of the boiler.

I also want to set it up with a hot well and a condensing system. I have seen some info on people running the condensing pipe through the hulll and using the water to cool the steam. Again..........more holes.............. Could I set up with a couple of heat exchangers from a freshwater cooled I/O under the floor and pump cooling wather through them ? One hole to pick up the water, and one above the waterline to monitor the discharge and make sure I am cooling.

Remember to fit a float valve operated bypass - this makes condensing operation quite simple and avoids the need for close manual regulation of the boiler feed pump. Internal
condensers work, but requires another pump and more mechanism. Almost all of the boats out here use the keel condenser method of just piping the exhaust through the bottom of the hull. Keep in mind that if you silver solder (or TIG weld) a plate to a piece of piping for a through-hull, you can bed that plate against the bottom of the hull w/ 3M 5200 and it's not going to leak or come off.... On my single cylinder I don't even bother with a vacuum pump; the engine just forces the condensate out via back pressure. If you're set on using an internal condenser, you'll need twice as much surface area as the external kind since cooling water flow is more limited.


- Bart

[JonRiley56]

Hi Bart,

Thanks for the quick response !

There is no floor in the hull now so I can set things up anyway I see fit. I will be running PT stringers and side supports and building from there.

Given the need to get to the fire box and ashpan (if I use wood) on the boiler I assume I will have to have that on the deck, although I guess I could have a bit of a well for the boiler, not as low as the engine but lower than the deck. It would keep the center of gravity lower.

Can you explain the condensation idea a little more. What I think you are saying is that I can take the exhaust steam as supplied by the engine, route it through a pipe that goes sthrough the hull to be cooled by the lake/ocean water and then back into the hull and into a reservoir of some kind. Also, the steam is just being "pushed" by the engine exhaust pressure through the condensation pipe as opposed to being pulled off of the engine by a a vacuum pump and pumped through the pipe. Is that correct ?

If so, what happens at the "other end" of the pipe ? I assume water will collect there. Is there enough head pressure from the steam to push that water up through the hull and into the hot well, or do I need a pump there to move it ?

I am also unfamiliar with "balancing" a rudder. Can you elaborate ?

thanks !

jon

[fredrosse]

I have converted a fiberglass sailboat to electric power (so I could run with the steamboats while my sidewheeler was building). After cutting out the centerboard well and fiberglassing in a propeller shaft tube, I mounted "Bilge Keels" on the exterior of the hull, which gives good steering stability, and greatly reduces rolling in a typical sailboat hull that has a round bottom. These are made from aluminum angles, on my 14 ft boat I used 2" x 2" x 1/8" angles, your boat should probably have 3" x 3" x 3/16" angles. The bilge keels are bolted through the fiberglass hull, into wood engine/machinery mounting stringers that are mounted on the inside of the hull. This gives a strong setup with minimum work. The wood interior stringers should be bedded into fiberglass mat, or 3M 5200. The bilge keels should run about 1/2 to 2/3 the hull length, terminating near the stern. The interior stringers can run further forward, and will make a good mounting base for boiler, engine, floors, etc.

For efficient propulsion you need a big low speed propeller, the diameter should be about 10% of the hull length, with a pitch somewhat larger.

[JonRiley56]

Hi Fred,

The bilge keels are a great idea ! I will definitely go that route. The hull I am going to use curves up a fair amount in the stern so I dont know how far back I will be able to take them. I will have to take a closer look at it in the day light. They might also provfide some protection for my condenser piping since I dont have a keel onder the midline of the boat.

jon

[barts]

Can you explain the condensation idea a little more. What I think you are saying is that I can take the exhaust steam as supplied by the engine, route it through a pipe that goes sthrough the hull to be cooled by the lake/ocean water and then back into the hull and into a reservoir of some kind. Also, the steam is just being "pushed" by the engine exhaust pressure through the condensation pipe as opposed to being pulled off of the engine by a a vacuum pump and pumped through the pipe. Is that correct ?

This is correct; the trick is that you want the exhaust to enter at the highest end of the pipe and then drop down; this keeps ample space in the condenser for the condensate.

If so, what happens at the "other end" of the pipe ? I assume water will collect there. Is there enough head pressure from the steam to push that water up through the hull and into the hot well, or do I need a pump there to move it ?

There's plenty of back pressure; a few PSI is ample to force the water up into the hotwell. If you like to run her out of the water, of course, a bypass is needed.

I am also unfamiliar with "balancing" a rudder. Can you elaborate ?

http://en.wikipedia.org/wiki/Balanced_rudder

- Bart

[fredrosse]

You can get more details about the conversion of a sailboat hull to moderate power at http://groups.yahoo.com/group/electricboats/
Get the file "Building an Electric Javelin" .

Now that I have a steam sidewheeler, I no longer need the electric boat. I am thinking of making the Javelin into a fast steamer, something with over 10 shaft horsepower, capable of about 15 knots. I would prefer to use a 17 foot Thistle Hull, but I already have the Javelin, converted to propeller drive.