What is the HP needed to drive a 20m x 3m 40MT boat at 13kph?

I appreciate all of the thought which has gone into these questions. With your help, it seems that there is a space for a single container boat, but as several have pointed out, that might not be the most efficient. I need equations or software to be able to run the numbers and let the math point the way. I have installed FreeShip and can say that I don't know how to go from boat dimensions and displacement to energy required to maintain a given speed. Can anyone help advise me or even point to another free tool/set of equations which I can use to generate the data I need? Thank you.

 

There are some simple equations, eg by Derek Kelsall, that reflect basic relationships between length, displacement, speed and required power. They are useful for comparing otherwise similar designs under similar conditions, but they do not give exact values. For more subtle dependencies, such as the wave impedance on the volume distribution, there is simply no formula - what remains is experience, simulation, and calibration of the simulation using physical tests.

When it comes to simpler simulations, michlet is a great tool and easy to use. You can use it to determine the friction and wave resistance of a given hull quite well, or have it optimize for a given speed according to your own constraints. You can find a download somewhere here in the forum.

Beyond that, it gets a LOT more complex and difficult.

One of the most widely used CFD tools is OpenFoam [1] - but that is software for a very general field analysis and manipulation - CFD, electromagnetism, structural mechanics, finance ... which means that you have to specify very extensively and very precisely WHAT you actually want to simulate - that's hundreds of parameters spread across dozens of configuration files.

There are some tools that make this task much easier - one of them is CfdOF [2]. This is a workbench plugin for freecad - you describe your problem - CFDOF chooses the right solver - you specify geometry and boundary conditions - CfdOF offers them to you in dropdown lists appropriate to the problem and solver and writes them to the right places, and regulates the cooperation of all components involved (geometry setup, meshing, solving, postprocessing ...).

As I said, it makes the work much easier - but you still have to get deep into CFD in general, the mathematics behind it, and the peculiarities of the software used - the learning curve is quite steep. How it is done "right" is shown, for example, by this study of a KCS hull on a supercomputer [3].

For naval engineers and naval architects, this generic approach is rather slow and error-prone - that's why there is some commercial software that is specifically tailored to these requirements - others know more about this than I do.

In the open source area, I discovered the very interesting approach InsightCAE, which offers a workspace for various ship-specific simulation setups [4]. Unfortunately, I have not been able to try it out yet. The company behind it, SilentDynamics, offers the development of customer-specific extensions of this simulation environment in order to largely automate the complex workflow [5].

[1] OpenFoam Website
[2] CfdOF GIT Repository
[3] Ship Resistance Computations using OpenFOAM
[4] InsightCAE Dokumentation
[5] SilentDynamics Website

 

@ropf - Thank you for the equation. Between that and the British canal boat data I have some numbers.
So far what I have:
This is in comparison to $0.10 per ton per mile for trucks in the US.
I ran two scenarios on with solar panels on top and the other without.
I assumed:
$0.12/kwh
Cost of Capitol - 6%
Depreciation - 5%
$1/watt for solar panels
5 hours of solar a day
1000w/m^2 for solar power
Manufacture cost less battery $150,000

Still need good battery numbers, Work them into the price & weight calculations.


As we can see, solar is helpful, but when it comes to battery capacity demands, it can be very helpful.

 

I still think there is a huge disconnect between what you see this boat looking like size-wise and what it needs to be in reality. A one-trailer-sized boat won't meet your speed or range desirements; but a conventional landing craft sized for about 4 trailers can - almost. You're looking at a boat about 130 feet long and 25 feet beam. They weight about 170 tons empty and burn about 40 gph at 12 knots. Typical installed power would be around 1000 hp. You might be able to buy a 70-year-old one and refurb it for a million bucks. Fuel economy on a per-mile basis is a bit less than that of four semis, and the route distance will probably be greater than just roading the trailer. And you'll want to be able to break even at about 1/2 utilization.

 

I'm looking at a way to decrease the cost of transportation for the specific purpose of helping the Midwest and South take advantage of the movement of the manufacturing base away from China back to North America. If it isn't roll-on/roll-off new ports will need to be built which means political action. Basically, it would never happen...

Thanks all. I've made a lot of progress and your input has made this far easier.

 

And Battery costs.
Total on left
$/m/t on right.
Still need to account for weight
1k miles range @7Knots is ~20% cheaper than trucking. That probably isn't going to happen.
500 mile range @2.5knots is ~63% cheaper... That might.
A couple more revisions on the numbers and then it is time to talk to customers. (Walmart, Costco, Amazon & US Transportation Command)

Also comparing shipping from China to New Orleans @ $0.002 - $0.004 per ton per mile & 11,796 miles = $24 - $48 per ton & 29 days.
From Memphis to New Orleans @ $0.037 per tom per mile & 500 miles =$18.50 per ton & 7 days.
Materials from Memphis just received a $5.50 - $29.50 per ton discount and a 22 day faster supply chain.
That is what I'm looking for & that really helps reindustrialize the Midwest & South.

You guys rock. Thank you so much!