Fantail steam launches

I have been thinking. the best type of boat for what I need it for would be 12 ft long, hull depth 1.5 ft, width, 3 ft, flat bottom, and flat sides. Front will be slanting upwards looking from the stern, then it stops slanting upwards at 6 in. from the top of the hull, and that six inches will be FLAT. The whole boat will be FLAT. Would that be a good boat for a steam launch? I can't think of anything else that will work.
thanks,

 

(that won't break the bank)

 

I think your length is fine but your beam is to narrow. Remember it takes the same amount of time and money to build an ugly boat as it does a neat looking boat. You just need a flat platform for your equipment and engine but a hull you can trust out in a large lake when the wind comes up. Take a look at several (rowing boat plans) that could accept a small outboard. I say this as it could be a kicker engine or when you want to sell it, it (the hull) will have some value to others who might not want steam power. Stan

 

Again, how much "stuff" do you need to float? Do some simple math and figure out how many people (average 160 pounds), engine, tanks, plumbing, electrical, fuel, etc., you need to support. This is the basis for you calculations and hull form selection process. Double this figure, which will get you in the ball park. Divide this number by the weight of water (salt or fresh) and this is the amount of water you need to "displace", plus the weight of the materials for the boat itself of course.

Knowing a sealed box 12" x 12" x 12" square will provide roughly 62 pounds of floatation, you can calculate how may cubic feet of volume you need to float your boat. A 12' long, 3' wide box with no rocker, 90 degree sides and square ends will displace approximately 235 pounds with 2" of boat submerged in the water. If pushed down deeper to 3" immersion, then it will displace about 415 pounds. At 4" about 595 pounds. As you can see, you'll need a wee bit more boat and a fair bit more understanding of volumetric calculations. This is really simple stuff, very basic math.

 

I'm only going to use my boat in freh water, or as apex says, "sweetwater".
I have decided on 14 ft by 5 ft wide.
What did you say the min. bore was to push a launch?
thanks,

 

I have no idea what you're referring to, by way of "bore to push a launch".

Assuming a 14' LWL, the best speed you can hope for in your 14' boat is about 6 MPH. Again this assumes a displacement type hull.

A typical taped seam, partial deck, moderate rocker 14' x 5' boat will weight about 250 to 350 pounds (bare hull). This would be a 3/8" bottom, 1/4" sides, 1/4" decking and internal seating, bulkheads, etc. Now calculate how much stuff you need to put in it and you can figure out how much volume you need in the hull.

 

I was calculating his steam engine (the birthday gift) a few weeks ago. And came to the result, that we would need much more bore and stroke at agiven pressure, to propel a small boat. Do not remember the figures, right now. Think was about twice the displ. minimum.
Regards
Richard

 

Could one of ya give me a ballpark estimate how much weight a flatboat that is 8ft long, hull depth 1.5 ft, sides are flat, flat bottomed, (except 6ft from the stern it slants upward 1ft and stops 6 in. from the top of the hull). flat stern. Figure the hull weighs about 100, 150 lbs. width 4ft.
thanks,

 

Are we "alive" (awake)?
I can't build a steam launch in Nevada. We might move to Texas by this August though. Hopefully I can earn enough money to build the launch by the time I get there.

 

I have decided on the hull shape of my steam launch. The only problem now is whether I want a paddlewheeler or a propeller. If it was a sternwheeler, it could keep it's shallow draft, and float in about 4-5 inches of water no problem! ha! I could maneuver (that how it's spelt?) it where people are standing in about a little above ankle deep water if I had a sternwheel on it! no problem getting aboard, just beach it and let nobody gets wet. And now comes the problem of the whistle... I don't want a SHRILL whistle, I want a deep roaring whistle, like a steam train has... like this... http://www.youtube.com/watch?v=4P0wgjpoQDw DAMN! near busts yer eardrums! I was thinking about the whistle the second train has, a little lower pitched, at about 1:43. Now that is a SWEET sound.

 

Hi Mike,
maneuver was right.
I cannot open youtube (its censored in Turkey). A deep full sound steam whistle is a huge barrel and needs a lot of steam to make a noise! And, it is a very expensive piece of metal. Say, you should calculate some 2.000 to 5.000$ if you find a bargain. (a newbuilt will cost a bit more, cos its art and science to make a sweet sounding pipe, and the artists are all dead)

Regards
Richard

 

How is it possible you've decided on a hull shape, when you don't even know how much it will weigh or how you'll propel it? Paddlewheelers are about the most inefficient design going. You need two wheels to have reasonable steering control, each independently driven. Focus on what you need, then address the frills like whistles, once the major decisions have been made.

 

how much gear do you think I need par? I can't build a boat over 14 ft without breaking my bank! A 14 ft by 5 ft boat could carry at least 1000 lbs. All my steam engine stuff will weigh about 350 lbs altogether, the boiler, the engine, and the piping, safety valve...etc. And your right, paddlewheels suck. I stick with prop. How will I keep it's shallow draft though when using a prop?
thanks

 

I have no idea were you seem to come up with these figures, but you clearly need to do a good bit more studying on volumetric. A simple box, 14' long by 5' wide will have to sink at least 3.5" to have 1000 pounds (990 actually). This assumes the box doesn't weight anything.

Lets guess you can build this 14' boat at 300 pounds worth of material, then add the 350 pounds of engine, boiler, fuel reserves (yea, right), then add a crew weight of 300 pounds, not to mention related plumbing, electrical and other boat stuff you just have to have, like shafts, props, rudders, steering, controls, etc. all in the remaining 50 pounds you got left?

It's wonderful you have this desire, but there aren't any free rides. You have to do the calculations. Start with an accurate weight estimate, add crew, all the equipment, all the materials in the boat structure and anything you might carry aboard, including Pluto the well fed wonder dog. Also add in a reserve capacity for safety, then you know how big a hole in the water your contraption will make. Then you can draw up a shape that will support this, keeping in mind the safety margins you desire, the function of the boat, it's drive system, etc.

 

I won't have any electronics. too expensive. just good ol' simple boat.