The Steamboating Forum

I'm not going to be able to begin construction of a model until after we finish the move towards the end of this year, but that just means there's no reason I can't have the design mostly drafted by the time I can start.

I tried to make the numbers below as precise as possible, but of course, being only preliminary calculations, I'm sure the numbers will change over time, and given the unique hull lines, it's entirely possible that attempting any calculations using data from more traditional launches is folly. At the very least, I'm doing something along the lines of thinking about the design, and working on Excel for the first time in months. That being said:

I gathered some data on existing boats (I can post the spreadsheet), including length, beam, displacement, speed, and horsepower. The numbers and ratios vary wildly with material and cabin layout, but the highest numbers I have for a wood hull are:

Emma, 346" (28'-10") length, 87" (7'-3") beam, 8,800 lb. displacement. That works out to about 25 pounds displacement per inch length. I am thinking that ratio will be a bit lower on my boat:

Emma's wood cabin runs almost the entire length of the boat, and while Fitch's paddle system requires wooden superstructure along the entire length as well, I do not think this will weigh quite as much as a fully-enclosing cabin would. Also, Emma's hull is higher off the water.

The average with similar designs is very nearly 21 pounds displacement per inch length. I will use this number for now.

I would like to make the hull 30', but would settle for as low as 25'. At 21 pounds per inch (252 pounds per foot), a 30' hull would weigh 7,560 pounds; a 25' hull, 6,300 pounds.

Using David Gerr's formula for hull speed (posted in the thread "Hull Speed Calculation"), V = 1.24*L^1.433 / D^0.311, we get:

V = 1.24*(30^1.433)/(7,560^0.311) = 10. miles per hour hull speed.

Of course, I very highly doubt I'd be able to reach hull speed with Fitch's propulsion method, but it doesn't seem like I'd be fighting a "slow" hull - she'd take whatever I could give her. The original boat is said to have cruised at 7 to 8 miles per hour, so my number seems within the realm of reason.

So, these are the numbers I've got so far. I'll see about sketching the hull lines at some point.

- Brenton

Building a 30 foot boat is about 3x the material and labor as would be required for something closer to 22 foot length. Also the larger hull would be difficult to trailer. I would think something like a 22 ft x 5 ft hull, 1 ton displacement, making 4.5 knots with 2-3 horsepower maximum. If the early “Indian paddles” arrangement is to be used, 30 to 50 RPM to direct drive the side mounted paddles.

If the later Fitch design is wanted (stern “Duck Paddle” type), then engine speed could be higher, as that boat had a chain drive with a drive ratio between engine and drive shaft. But keeping engine speed down in the range of 40 to 60 RPM would provide better “eye candy”.

Have a look in this forum’s “FAQ” section to get an idea of engine and boiler sizing.

As far as hull design goes, I would recommend the freeware “FREESHIP” or “DEFTSHIP”. It worked well for me in designing the Margaret S. hull. Good luck getting started.

As I look more and more into hull-building and designing, I realize that I do not want to build or design a hull.

As far as pre-made hulls go, so far I see the Compromise 21 or Rose 20 from Beckmann Boatshops, or the Elliot Bay hull as viable options (the gunwale should probably be relatively flat near midships in order to give room for the superstructure and connecting beams for the paddles).

- Brenton

A really good way to "get a feel" for hull, etc. is to look at the specifications for a large variety of boats. To that end I would suggest you visit the Northwest Steam Society website at: http://www.northweststeamsociety.org - on the "home" page select "projects &c" from the navigation buttons on the left and then select "boats". There are over 60 boats in service and operated by NWSS members. Each has its own page and relatively full specifications are listed. This permits comparing all the different permutations without accessing a multitude of websites - also a narrowing down of criteria, simplifying hull, etc. selection.

Hull design for early US steamboats was pretty basic. Although Fulton's North River was designed by Fulton who made full use of the British Navy's advanced (for the time) ship design, the hull was essentially a flat bottomed "skiff" 150' LOA, 13' wide and of 2' draught. The sides were completely vertical and parallel with no curvature to the bottom, and both the bow and the stern (at and below the waterline) were tapered at 30 degrees. Fulton's calculations were such that the boat met the required speed.

If you want to do some steamboating in California: The Sacramento Delta - B&W Steamboat Meet will be held the last weekend of September (Sept 27 - 29 2013) in Isleton, California. There's usually 10 - 15 boats and some people who will not think you're bonkers in the attendees: Dick Venerbeck, Ed Haas, Bart Smaalders, Wes Harcourt to name four. Information from Phyllis Blaine, 408-354-7128, steamit@oldtimetech.com

Tell 'em Ron Fossum sent ya.

Here is the lineplan I came up with in DELFTship (it's not Revit or Solidworks, but it's not AutoCAD 1997 either). My line of thinking is that if I am going to build a hull myself, it's going to need to be simple, rugged, and stable (I can pretty it up after it doesn't sink), especially given the superstructure that it will have to support for the paddles.

The design below reflects about the extent to which I would be willing to go as far as hull complexity; something along the lines of what others above have described - flat (perhaps angled, but still straight) plywood sides, meeting at a flat plywood bottom. Of course, I'll take whatever performance I can get out of it (it is good to do things well), but if I were pushing for speed I would have stuck with traction engines (or perhaps stationaries) /sarc.

Buying a premade hull would mean finding one with the appropriate shape, size, and price. Nothing is technically impossible (I've heard you can fold a piece of paper nine times, if it's the size of a small building and you use a forklift), and I'll keep looking.

The important thing is that I've got a lot of time yet before even moving to Phoenix, so I won't be able to start constructing even a model until at least next year, and I'll have plenty of time to work out the details.

I'll keep up with the planning of the project as things go along, so at the very least, everyone will get to enjoy the anticipation ("You'll see it's all a show, you'll be laughing as you go..."). i imagine there is a reason no one has built a working full-scale Indian Paddle mechanism, and I'm sure it will take support from the whole steamboating community.

To that end, I am planning on attending the Great Delta Steamboat Meet this year with my father (contacted the Blaines last weekend) so I can get a close-up look at the design and construction of the hulls (my boatbuilding experience consisting of participating in a Nail-and-Sail two years ago, this will be the newest element for me), and, of course, the power plants.

- Brenton

Brenton
A couple of comments:
1. You will want to kick the bottom up in the stern unless you are planning a plaining hull,which I doubt. Start 5 to 6 frames ahead, and end with the bottom at or a little above the transom. This will keep you form dragging a mass of that will boil up arount the stern, and leave a little more room for the prop.

2. If you are going to be building with plywood you will need a hull form that consists of developed surfaces. These are surfaces that bend in one direction such as flats, cones spirals and cylinders. This is not intuitive, but the frames will be curved as you move toward the bow as well as the stem where the sides meet. It's been a while since iI have played with Delft, but I think it ha a developed surface mode tha makes this easy to see.

Simple skiffs are often built with only three molds, the stem, transom, and one in between. Depending on the flare to the sides and the spacing the plywood will go where it wants, and the desired frames can be paterned and fitted to it. Modeling with some poster board can be a big help in visualizing this.

Good Dreamn & Good Steamn

Dave

Brenton
My first comment should have read: Starting 5 to 6 frames ahead ending at the transom with the bottom a little above the waterline.

Dave

Dave - thank you for the pointers. I will be overhauling the hull design as a result of information I've since gained. Prop clearance will not be an issue with the Indian Paddle design (seen here: http://upload.wikimedia.org/wikipedia/c ... ped%29.jpg). The developability feature is a real help in DELFT.

New progress:

After doing some research on riverboat hulls of the period, I came across the Durham Boat, used from (sources vary) the early/mid 18th to early 19th century.

http://www.davidhanauer.com/buckscounty ... 006_03.jpg

The Durham Boat is essentially an elongated batteau; relatively flat sides, flat bottom, double-ended. Some claimed only 20" displacement when fully loaded with pig iron.

They were the main cargo hulls along the rivers, usually poled along (rowed in deeper waters) by three to six men. Size reports vary; the standard size seems to have been 60', but much shorter hulls were and have been built.

At any rate, this is the type of ship Washington used to cross the Delaware to get back at the British for putting tacks in the colonists' tea (or was it so that the colonists wouldn't have to pay for anymore taxis?).

An accurate reproduction would require strip-planking, but the lines seem fairly easy to replicate in DELFTship (no drawings to speak of). If that doesn't work, the Washington Crossing website lists the two shops responsible for building the boats currently used at the park (http://www.ushistory.org/washingtoncros ... durham.htm).

See also: http://durhamhistoricalsociety.org/history2.html.

- Brenton

Two hours in DELFTship later, I have two versions of the Durham boat hull - a historically accurate, strip-planked replica, and a simplified, 3-chine plywood version. I will probably fair the lines a bit more, but they're mostly where I think I want them to be.

Brenton
I see what you're wanting to do now. On the developed hull I would suggest a single chine vee bottom with the sides extending a little below the waterline at mid length, and a slight warpped bottom that will let the chine rise at each end. Also a curved plywood surface has inherently more stiffness than a flat one.
Your round bilged hull looks sweet, and would make a nice strip plank project.

A boat building rule of thumb is the length of time to complete the project will be proportional to its number of parts.

Strip plank many parts--plywood fewer parts.

Dave