Origami HullThe Origami hull is a hull formed by folding steel into the shape of a hull. The hull plates are first butt welded to form a two large flat plates. Each of the two larger plates will be formed into one half of the hull from bow to stern. To form each side, darts cut into the plate and then is bent so the edges of the darts close together where they are welded. With both sides of the hull completed the side are brought together and welded down the keel.
Here is an example of an Origami Boat pattern for a single chine hull. You can download and print the large image of the pattern, then cut out the pieces and tape it together to see how the process works. See "Paul's 65ft Origami" for an example of how a large origami hull is built.
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Originally thinking in Aluminum it is ideal to get the plates wide enough to avoid as much welding as possible. In aluminum everything would be 3/8 inch except the pilot house which would be 1/4 inch.
Hull: 15 wide x 75 long x 2 sides; 16 plates - 8 x 20ft
Deck 16 x 70; 8 plates - 8 x 20ft
Bulkheads 8'x 16' x 5; 5 plates - 8 x 20ft
Keels 20' long x 2 deep x 2 sides x 2 keels; 2 plates - 4 x 20ft
Skeg & Rudder 15 long x 8 deep x 2 sides; 4 plates 4 x 20ft
Pilot House: 15 x 16 roof + 4 x 62' perimeter; 2 - 8 x 20 and 4 - 4 x
20
When converting to steel the wide plates are no longer important but steel comes off a roll so lengths up to 65 feet are available if you don't mind paying extra for the oversize truck to deliver them. If I could get 75 foot long sheets, it might be worth considering, but I choose 45 ft sheets because they fit on a standard truck and will allow the butt joints in the hull to be staggered.
The pilot house will still be aluminum on a steel boat; so to convert the aluminum sizes to steel I just took the square footage for all of the 3/8 inch plate which came to 5,120 and divided that by 6 ft, which is currently the widest steel plate available without having to pay extra and that comes to 854 feet. Divide that by 45 ft plates and it comes to 18.9, but 20 is a nice round number. In July of 2008 the price is 61 cents a pound delivered, plus tax. It would have been half that cost if we had purchased in January, but that is spilled milk.
In addition to plate we also need 1000 feet of 2 1/2" to 3" Sch40 for the bulwark and for rounding the corners. We chose to go with 3 inch. It's considerably more but I have bent 2 1/2" pipe and never bent a 3 inch pipe yet. Also 800 ft of 1/4 inch, 2 x 2 inch angle that will be used for ribs and stiffening the deck. We could go with 1/4 thick, 3 inch flat bar too, but I banging your head against the flat of an angle is much nicer that the edge of a flat bar.
CWT = 100 pounds
CFT = Foot
| Date | Qty | Description | Size | Weight | Weight Each | Price | Price |
| July 2008 | 25 | Steel - 3" Sch 40 Pipe | 42 ft | 7,959 lbs | 318 lbs | $6.25/CFT | $6,562.50 |
| July 2008 | 30 | Steel - 2 x 2 x 1/4 Angle | 20 ft | 1,914 lbs | 64 lbs | $58.5/CWT | $1,119.69 |
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We decided it was time to move the steel inside the fence on up on cribbing where it will be easy to access from the building pad. We learned some lessons about moving big plates of steel along the way.
The pilot house is about 16 ft wide and 20 ft fore to aft and will be constructed from 1/4" 5000 series aluminum in order to keep the weight down. The only trick is connecting the aluminum to the steel so that the aluminum does not corrode away. There are two basic approaches. The most popular is to completely isolate the aluminum form the steel with a water tight gasket and bolts that are insulated by nylon washers and sleeves where they pass through the holes.
The second approach it to bond the aluminum to the steel so that
the electrons can flow across the joint easily. When there is
no air or water gap between the two metals then the aluminum will
not corrode. You can not weld aluminum to steel in the
conventional manner but they can be explosion welded together in
sheets. You then buy a bar cut from the sheet and weld the
aluminum side to the pilot house and the steel side to the deck.
The only real problem is that explosive welding is not something you
can do at home and a 2 inch wide aluminum to steel bar will cost you
$62 a foot (Jan 2009).
Video on Explosion Welding:
http://crazymotion.net/explosion-welding/wldl6fIDGQ5EjAy.html
There is a chemical approach for bonding the aluminum to steel. Ultra Safety Systems makes a product called TefGel; www.tefgel.com. To use TefGel, you would dry fit the pilot house with a gasket made from butyl rubber or strips of fiberglass board. Then paint the steel, put the gasket and pilot house back in place and coat the inside of the hole, the bolt and nut threads as well as the washers with TefGel and tork it down. A fiberglass gasket will add a little more stiffness to the structure that rubber but they did not recommend any other sealer in the joint although it would not do any harm and would work to hold the gasket in place as stop leaks between the joints in the gasket. They recommended G-10 or FR4 epoxy fiberglass. A 1/16" thick, 12 x 48 inch sheet is under $30. TefGel is $22 for 2 ounces. And like the explosive welded interface you will also get a pilot house that will conduct a lighting strike on into the hull. I can see where it would be useful for all the other stuff that gets bolted on as well.
There is a highway bridge just blocks from the house that is 15 ft 8 inches. After that it's just utility lines. The pilot house as well as the forward and aft bulwarks will have to be attached after we are on the other side of that bridge. The mast will have to wait until we are at the Port of Catoosa; www.tulsaport.com. Then it's just 440 miles and 420 feet in elevation through 18 locks to the Mississippi and then another 600 miles to New Orleans and open water. The closest call we will have is the I-430 bridge in Arkansas which has it's clearance listed at 53 ft when the water is at it minimal level. Luck for us, the top of our mast is 52 1/2 ft from the water.
www.moonflowerofmoab.com -- A completed project with lots
of photos and documentation.
www.harderwoods.com/pipedocs.html Online Pipe Fitting
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