Larger boat feasible?

[Jstemwedel]

It has been nearly two years since I posted on this web site, but have been really busy so it seems like a lot less time. In previous posts I mentioned that I had purchased the Gartside #125 plans for a 23 ft. steam launch. Some responders commented that the design is very beamy (7.5 ft beam) and might provide for a rough ride in its intended operating area -- Lake Superior. I have not started constructing the boat yet, and have had time to mull over the comments. Am now thinking that it might be a bit too beamy, and have been considering going with a different design.

At the same time, I've been thinking of a larger boat... Currently considering a 30 ft tug with a length to beam ratio of about 3.6 (versus 3.1 for the Gartside design). I want the larger size for better handling of rough seas and more space for amenities. What I am wondering is whether or not steam is feasible for a boat this size. I estimate that it would need approximately 22 Hp (based on a 23 ft launch requiring 10 Hp -- 30 / 23 = 1.304 -- 1.304 cubed is 2.22 -- 2.22 x 10 Hp is 22.2 Hp. ). I have not seen any commercially available steam plants or boilers in this power range, and am afraid that compression ignition might have to be resorted to, even though that seems pretty dull.

[barts]

I'd consider historical power levels: 1 - 3 hp/ton for proper easily driven hulls. We're designing a 37' OAL 10k lb disp. steamer, powered by an engine w/ 10-20 hp, depending on cut-off. If you want interior space consider designs other than a tug. Look into a steeple compound (or uniflow, as we are doing) to save cabin space. Look for a design that permits a proper large prop - at least 24" for the boat you're considering. Consider the weather of your intended cruising grounds - is this a one, two or three season boat (four is impractical where you are)? What shelter do you need/want?

Remember, slow boats need large props and low rpms to be efficient. A 30' needs about 7.5' beam - 4:1 is the nice place to be, and a 30' x 8' OAW is readily trailerable.

- Bart

[Jstemwedel]

Bart,

Thanks for the feedback. The boat will have a longer and more spacious house that a typical tug, and a 28 - 30 inch diameter prop. The hull design to be a 1/3 scale 100 ft. commercial harbor tug design. It will be used from late Spring through early Fall (ice conditions and heavy weather limit operations in early Spring and late Fall, respectively). It will live at the local marina, which is in a small fishing village and not expensive. The boat is planned to be able to cruise at least 100 miles before refueling, which might be another limitation for steam. Have also considered having a 2-5 hp DC motor attached to the shaft with a pulley for auxilliary power on short trips when we don't feel like raising steam, or when departing the marina (to avoid belching soot on other boats).

Is there a uniflow engine commercially available, or will you hunt down a used one for your boat? What boiler will you use?

[barts]

Bart,

Thanks for the feedback. The boat will have a longer and more spacious house that a typical tug, and a 28 - 30 inch diameter prop. The hull design to be a 1/3 scale 100 ft. commercial harbor tug design. It will be used from late Spring through early Fall (ice conditions and heavy weather limit operations in early Spring and late Fall, respectively). It will live at the local marina, which is in a small fishing village and not expensive. The boat is planned to be able to cruise at least 100 miles before refueling, which might be another limitation for steam. Have also considered having a 2-5 hp DC motor attached to the shaft with a pulley for auxilliary power on short trips when we don't feel like raising steam, or when departing the marina (to avoid belching soot on other boats).

Is there a uniflow engine commercially available, or will you hunt down a used one for your boat? What boiler will you use?

A 5 hp DC motor will draw ~140 amps from 3 12V batteries. I'd plan on something closer to 2 hp. A 100 NM range is quite doable so long as you don't go racing and have an efficient boiler and engine.

I'm building a single cylinder uniflow of my own design, using a Detroit Diesel 149 CID cylinder liner and a weldment to form the cylinder. She'll have single beat poppet valves, shifting camshaft to effect three-position (5, 10 and 15%) cutoff; the engine is NOT self-starting by any means. The boat will use a Kitchen rudder so that the engine can continue running forward while the boat reverses or sits still; this will aid single-handing. I've considered a jog motor to start the engine; traveling any distance on battery power seems impractical. She'll burn either wood or diesel.

For those of you on pinterest, http://www.pinterest.com/weaverbarbie/steamboat/ has some musings and links from across the web from my wife and I.

- Bart

[Jstemwedel]

The Kitchen rudder is very interesting. Its amazing that this is the first time of heard of it. The only drawback would appear to be a more complicated steering wheel and consequently potential confusion as to where the thrust is being directed.

[barts]

The Kitchen rudder is very interesting. Its amazing that this is the first time of heard of it. The only drawback would appear to be a more complicated steering wheel and consequently potential confusion as to where the thrust is being directed.

The reversing wheel is not necessarily part of the steering wheel, but the confusing aspect of the Kitchen rudder is that in reverse the steering wheel has reversed effect. Say you're going forwards in a starboard turn and you throw it into reverse. With a conventional rudder (ignoring poor performance, 'walking', etc. in reverse) the boat will more or less reverse its course. With the Kitchen rudder the reversed thrust will be vectored towards the port side of the boat. swinging the stern to starboard and the bow to port.

Needless to say, this will take a little getting used to. On the other hand, the reversed thrust acts as a very effective brake; I've read several anecdotes about 'stopping in a length and a half'. As can be seen in the video linked from the pinterest page above, boats with the Kitchen rudder are quite maneuverable. There's a narrowboat video on YouTube showing a very long canal boat turning in a tight circle using a Kitchen rudder.

We want to use a large 'box' keel on the Sea Lion to protect the prop, provide displacement w/ minimal wave making, insure 'beachability' and provide space for fresh water tanks that's warm enough not to freeze even if air temperatures are quite low. Such a keel can increase directional stability to the point of interfering with steering control in reverse. The Kitchen rudder acts as a stern thruster, much like one of those early outboards that reversed by the simple expedient on turning the engine 180 degrees in its mounts and should make maneuvering much easier.

The other aspect of the Kitchen rudder is that it allows the engine to run forward while providing either forward, none, or reverse thrust. This makes it much easier to single hand the boat. I'll provide remote throttle control in the pilot house, but otherwise the engine controls are needed only when stopping and starting.

- Bart

[Bob Cleek]

R.D. "Pete" Culler designed a number of very fine fantail "steam hulls" in the late '70's.









These are of his 24' launch, these being infernal combustion powered, although designed for a steam plant.

He has two other round bottomed fantail steam launches, a 32' and a '34', and a 34' hard chined fantail launch. The study plans for all of these are in Pete Culler's Boats and the lines, construction drawings and offsets for the 34' round bottomed launch are also in his Skiffs and Schooners (These books are available through the WoodenBoat Magazine online store or Amazon, etc.)

The 34' launches were designed to be open launches without pilothouses and with canvas dodgers, "Navy style." However, the pilot house on the 24' launch is easily scaled up to fit the 34'ers and a cabin is easily extended aft from that to provide a very nice cabin arrangement suited to the builder's taste.

These were designed in response to requests for a scientifically designed steam launch hull back when Bill Durham was publishing Modern Steamboats and Steam Launches and Culler discusses them in that publication. They are designed for traditional carvel planked construction, but could certainly be adapted for strip or cold molded planking, the latter being perhaps a preferable option if the vessel were intended to live on a trailer.

I believe copies of Culler's plans for these vessels are available through the Mystic Seaport library.

[Lopez Mike]

I love the lines. Of the hull, that is. With that little pilot house forward, it looks way out of balance visually. I would need at least a canopy from the stack aft. The way it stands, it looks like a lobster boat, not a pleasure launch. Of course it was probably intended to look like a lobster boat. Not to my taste.

This hull is now high on my list of possible hull replacements for Folly. I wonder how lightly it could be built with strip construction?

[barts]

This hull would need a fair amount of weight to sit down on her lines.

Mike, one of the guys down south has scaled up Otter's hull style. Pretty easy to build,
looks nice and you get a fantail stern. Also quite lightweight - Otter's hull is order 450 lbs.

- Bart

[Lopez Mike]

Yeow! I just chased down the specs on that boat. 4200 lbs. What are they building these craft from, purple heart or ferro cement? Are they building an ice breaker?

Granted, that is a total displacement number but I would expect to come in closer to 2000 with some attention to weight. My machinery weighs about 800-900 lbs. including shaft, wheel and rudder.

Perhaps I am misinformed but I have been under the impression that the required power for a given speed (staying down around the square root of the waterline length) is directly proportional to the displacement.