Requesting Small Sternwheeler hull design and analysis help

It's a standard style jon-boat hull. Used for shallow water all across the US. I'm just going to modify it, to do what I need it to do.

Since I'm doing it in plywood, I can leave the sides and built-in sponsons/wheel arms (for the paddle-wheels) and make the center transition upward, for clear water access to the wheels, like the Atkin design, but I have to add the low dead-rise, to get wiggle room for this mud, too. By the time I get through, she should do exactly what I'm trying to get her to do.

Since nobody is willing to run it on a computer design program, then analyze, I'm doing the best I can.

I figure my ancestors built boats, using rocks and fire. Surely I can do better than a dugout, or hide canoe.

 

Your assumption about the mud doesn't take into account a boat in this river and the water level fluctuations. I've seen it go from 20 ft of mud flat, to 20 ft of water, in under 12 hours and back to that mud flat in under 2 weeks.

At first, I picked hulls from sternwheelers and shrimp boats, that I know are shallow water types. With all of the griping, I gradually made my way around to a jon-boat. Simple to frame, simple to cut and simple to build. Since the pros aren't offering assistance in that area, just criticism, I've gone to a fairly simple concept on the hull, that will meet the criteria.

Safe speed is relative. Too little power will put her on the rocks, if the wind and current are against me. That said, I'm not looking to put her on plane, either.

As for outboards under boxes, I asked for examples and not a single one has been linked. Maybe I got the wrong conclusion that it doesn't properly exist... I would prefer video, with audio, to decide for myself.

I agree, electric drive is expensive. You may not get what you pay for, but you always pay for what you get. Up-front costs are high, but the benefits are 1)dependability, 2)low maintenance, 3)low energy cost, 4) once the equipment's paid for itself, vs purchasing fuel, the energy is free(solar). 4) silent operation. 5) no flammable fuels to mess with. 6) even if I run out of juice, the sun will recharge the batteries. Not instantly, not even in a day, but it will. 7) as I can afford them, I can buy more solar panels and piggy-back them into the system. Recharging faster. 7) I can have multiple, fully-charged battery 'packs' and actually swap batteries, if it becomes necessary. 8) I can use a backup genset, if necessary (back to using fuel, but it's an option), which I KNOW I can silence.

You're welcome to share examples of better hulls that I can build, as a carpenter. I can't even GET a pontoon hull through this area, which would limit function to about a 3/4 mile stretch. I'll stick with a relatively flat bottom, for shallower waters, thanks.

I've asked for assistance and gotten some, but mostly criticism, instead. It's a sternwheeler, for God's sake, NOT a speedboat. It's intended for a capacity of 1-3 people, for the most part, it's not a party-barge, either.

I asked about trolling motors for a reason. She's NOT intended to go on plane. 6 mph is fine. At least she'll be able to out run Michael Phelps...

 

indeed the Atkin do not has the stern submerged, but at water line, try asking yourself why

 

I already know why it comes upward to the waterline. It allows clear water to the rudders and wheel. There are plenty of examples of historic sternwheeler hulls as scale models, as real-world boats, and as designs for private building.

The wheel needs to be clear of the bottom, at all times, as well, or you damage the wheel.

As for Atkins not using the sponson/wheel-arm arrangement, they hang it off the stern and depend on the iron to support the wheel. Plenty of examples, either way. I'm in favor of having the sponson-type wheelarms, both for additional buoyancy and lower overall weight. If I chop the wood off at the transom, I have to replace it with something else. Most use either iron, or heavy timbers, to carry and position the wheel, if they do not have the wheel arms.

Otherwise, I'm not sure what you're talking about.

 

Here's a guy that built 3 versions of the "Showboat"...

http://www.philspaddleboat.com/#/

If you will notice, he uses a flat bottom, and his rudder extends below the hull. That's because he has a lake to run in, not this river with this clay/silt muck. Examples of sternwheelers with some dead-rise are out there. I'm through justifying it.

He also has taller cabin walls, at the sides, which have made his boat top-heavy enough that the 1st version was unstable, when someone climbed to the upper deck. The heavy structure, to support people at that upper level definitely hurt the stability. I also think the nearly vertical sides of the hull also hurt stability, but that's my opinion.

You can see how lowering the height of the perimeter walls of the cabin and using a mollicroft for headroom will move weight back to the center.

He has a LOT more freeboard than I think necessary, and also has it narrower, by 1'6", which will make further differences in the waterline and stability.

My plan is to make the entire thing wider, lighter and have less vertical height at the sides. I think he went over-kill on the structure and the excess weight hurt him.

He still maintains the wheel-arm/sponson design, which does add to stability and adds whatever additional buoyancy.

I also think his wheel looks too small, for the height of the structure, but that's more esthetics, than anything else.

I still think the jon-boat, with some added transition to the transom, is the right way to go. Short of someone drafting it up and running an analysis, I'll stick with what I have.

I did manage to find several alternative designs for the paddlewheels. That bears further thought.

At the recommended 2 lbs thrust, per 100 lbs of gross weight, the doubled 160 set up should cover it, right on up to hull speed. Using each with its' typical battery-bank, for trolling, gives about 48 minutes of constant use, at full power. Clearly, with a better compliment of batteries, she'll get far more run time.

Once I've gone upstream several times, I'll have a better idea of how far downstream I can go, before needing to turn around. Going upstream allows me to drift back, so, if I run low on juice, I can get back.

I also still think the 2 kW genset hybrid system is a key improvement over the straight battery setup, but nobody seems to be taking that into consideration, but me.

 

If you say that "I've asked for assistance and gotten some, but mostly criticism", then prove us all wrong by building it your way. What do we know? We are only shipwrights, professional seamen and naval architects.

 

So, show me which hull you think I should be building.

There are no pontoon boats on this stretch, because they can't get in and out. They're also too deep, for the same deck area of a jon-boat, or Lafitte Skiff. Not to mention they make ugly sternwheel boats.

Flat-bottom? I've watched this muck glue one flat-bottom boat down and suck it under, with the next rise of the water. I need a shallow-water, not-quite-flat-bottom hull.

The only other hull I know will do that, I believe you would laugh at, in this thread, if not the forum, even though it's possibly easier to build, than the jon-boat, may be even better suited to the area. Wouldn't matter that, instead of the typical 1/4", I would be skinning it in 5/8" ply and covering in the epoxy/fabric. The shape is common to a lot of small sailboats, just have to nearly double the beam and stretch the hull slightly, still has a low dead-rise, is even lower to the water than the jon-boat, and makes the transition up to the transom, with no further modification...

Make those adjustments and the finished hull should weigh in at under 700 lbs., and still draw only about 9" water.

That hull is a sneak box.

Show me what you think I should use.

 

I think you should start by using simply paper and pen. Write down all you want and figure out where the conflicts are. Wishful thinking does not take any part of the process. Things either work or don't. Then calculate the cost of the things you want and see if there are conflicts with your budget. If there are, modify the list and start again.

 

rogulf @ yahoo. urogulf @ yahoo.
JL Frusha

The stern submerged is not just a problem of the wheel: it is also a very important problem of resistance at hull speed. More resistance means more KW to move the boat.
So if you want a boat also hybrid electric, the resistences of the hull are the first problem.
You can not expect to have good performance at low speed with a hull of speedboat.

For your project I suggest this geometry:

 

Thank you.

I wasn't aware that the submerged stern was a problem, but I've been trying to describe the same design problem, for another reason. The rise to the stern allows better water flow to the wheel.

Jon-boats do double duty. Often, they are used as pole boats, or with oars. I picked that, because of the extreme shallow water capacity. Same can be seen with the Laffite Skiff. Most homemade jon-boats deal with less than 25 hp. Some only use a trolling motor. Since they ride so high, they are easier to plane, which may be why some may think of it as a speed hull. Mostly it has to do with how far forward the rise to the bow.

My max width is 7'6", to fit a US trailer. Anything significantly smaller is going to hurt the cabin space, anything wider will need extra permits...

Those side pontoons would tend to limit the ability to rock loose, side to side. Basically, as deep as the muck is (I've been waist-deep in it, just launching a canoe and a kayak), I really need to be able to rock back and forth over the keel, but a deep keel is also a problem.

I don't know why there seems to be an aversion to, or problem with, a jon-boat hull. I can't go flat-bottom, but a jon-boat is a slow, shallow water hull, directly descended from punts. by moving the angle to the bow further back, they've decreased the speed to plane and to go faster, on commercial versions. Essentially I need a broad, flat-bottom, with a shallow 'V', instead of a purely flat bottom boat, with a slope to the stern, to get water back up to the wheel, rather then dragging it around the hull.

This hull is almost right... The 'V' is too deep (by maybe 1/4 to 1/3), and there's no transition to the transom.




This hull shows the transition to the wheel... but doesn't have that 'V'.



I figure a 3-in-20 slope 'v', with dead-rise to the sides, in place of the flat-bottom, should solve the problem. That comes very close to the jon-boat hull that everyone doesn't like, and says is a speedboat.

If it looks like a speedboat hull, that's not my fault. Speed is the opposite of what I'm working at. If the hull is capable of speed, it doesn't matter, but I need as close to a flat bottom as I can get, and still be able to rock side to side, if she's grounded. That rise to the transom works for me, there, too. As long as there's water at the drive system, I can put here in reverse and rock, to get water under the hull and back out.

Another thing going for me, with the electric trolling motors is that I don't HAVE to buy the high-dollar toy. I can get several used motors and either use their bracket, or make my own. 80 lb thrust units aren't the most common, but I saw one for under $80 on ebay, a couple of days ago. Those around 60 lbs thrust are more common. I've seen bolt-on triples, too, It's the total thrust I need, not necessarily a pair of $1,500 units.

I may be crazy, and often sound like it, but I'm not as dumb as the arguments make me sound, either. With a shelf, behind the stern, like the Lafitte Skiff, I could convert a couple of lower-units to electric and put them there, between the hull and wheel. Either way, I get away from a complex reduction drive-train. Save several hundred bucks here, and put that toward quality batteries...

I can put rudders and monkey-rudders/flanking-rudders on, for steering. That steering technique is as old as sternwheel boats, and it works.

 

Max width is 8'6".
http://drivinglaws.aaa.com/laws/trailer-dimensions/

 

This can help explain my point. It's an extremely shallow draft, low deadrise hull, with the ability to pole the flats, or use a big motor to go fast.

5" draft, flat deck, nice and low to the water,...
(perfectly legal, too)

I don't CARE about the big motor... If I wanted a speedboat, I'd be asking for help to build a speedboat.

http://newwaterboatworks.com/page13/page13.html

Put a big enough motor on a concrete slab and it too can be a speedboat

 

Thanks! Been a number of years since I saw the 7'6" rule. I guess they changed it. I just figured it was a solid rule, as good as set in stone. I'll take extra width ANY day!

 

http://www.txdmv.gov/motor-carriers/oversize-overweight-permits/texas-size-weight-limits

Well, damn...

That 8'6" is max trailer width. Gonna take a long trailer and a longer ramp, to put a flat-bed over the smallest wheels... :/

Still need space for the bunk rails, too...

 

Still digging, but closer...

This was posted by member lewisboats, 12 years ago...



This hull is almost exactly what I've been trying to describe. Add sponsons as wheel-arms, and carry a plate just above the waterline for the electric motors...