questions for a college design project

[Petros]

I know "going green" is the new popular theme, but there is something you should point out to your professor, and the class. The measure of the resource consumption is the total life cycle cost of any transportation system, if you consume more resources over the life cycle of the system to transport a given amount of freight (or passengers, etc.), than you have wasted resources.

For example, if the cheapest way to transport a ton of cargo is in a diesel powered freighter, than any other method, be it powered by solar, sail or recycled french fry oil, is a waste of resources.

So the "greenest" way to go is also the least costly (total life-cycle cost). Hybrid cars, methanol in gasoline, and other so-called green technology is not green since it consumes more total resources. The kind of muddled thinking that forces us to use these products is wasteful and harmful to the environment.

I say this as an engineer with 30 plus years of professional experience in a number of industries.

So putting artificial constraints on a design project, such as not using sails or existing practice, is a silly waste of time. It is not that we should not explore alternatives or push the envalope to improve efficiency, it is just wasteful to not consider all alternatives, INCLUDING existing practice.

[Stumble]

Well Petros,

while I agree with your premis this is a school project about more than simply designing a boat, so to that extent it is a reasonable restriction. However if it were my project I would make damn sure of my numbers then go back to class with a proof of why it is an impossible project, and the most ecologically friendly way to solve the underlying problem.


fcfc,

I am not sure about your order or the study, but I could accept that plywood is better than steel, I am not so sure about carbon fiber. The manufacturing process is insanely costly in terms of energy used due to the long duration high tempratures needed to make it.

[fcfc]

Originally Posted by fcfc

If you want to go electric and low cost, check ocean crossing rowing skiff. They are non sail boats that use the lowest energy to move.

Forgot to add they are somewhat "safe" for ocean crossing : they are allowed to cross ocean.

The propulsion system could be derived from propeller driven HPV (aka pedal boats, better the racing one, marathon style). They are again among the lowest power propeller driven boats, so are very focused on efficiency.

So the winning combination for low cost electric safe ocean crossing would be carbon fiber or plywood ocean crossing rowing skiff, with a propeller system derived from pedal boats. And all eletrically driven. That should go with 150watts to 300 watts systems (in fact, no more than long term human power). Would be very hard to go lower on cost.

Safety is there. These rowing skiffs are designed specifically for ocean crossing. (unsinkable, self rerightable etc ...)

Speed has been said not to be an issue.

Comfort has never been speaken of.


This would be about 3 time slower than a 22 ft sailboat on ocean crossing, but sail not allowed in your politically correct fashion driven game.

[Stumble]

fcfc,

the design brief also requires a 'yacht-like' design. While I agree with your theory, a rowing skiff doesn't meet the demands anymore than a sail boat.

[fcfc]

Originally Posted by Stumble

the design brief also requires a 'yacht-like' design.

The requirement are : a "low cost" "luxury" item.

Does it have any meaning ???????

Seems brain damaged teachers. Green, but not the most efficient, proven and reliable technology, ie sails. And low cost , but luxury.

[Submarine Tom]

Define "luxury"...

-Tom

[gunship]

An elevator on board?

[Petros]

Economy/Luxury boat: They serve Grey-Poupon mustard

[Tim B]

Ok, here's a thought...

You can use the sun to boil water. So, as with a solar power station, use the sun's energy to generate steam, then drive a steam turbine for propulsion.

Unfortunately, you'll only get about 12 hours of sun a day at best, so run a generator (off the turbine) during the day and store the electrical energy you'll need for night-time running. Run at high speed during the day (when you have the power) and at low speed over night (remember power=v^3).

Focussing the sun's energy may pose a small fire hazard, though. What the hell, it's a college project.

Tim B.

[Stumble]

Tim B,

The sun's power converted at 100% efficiency produces 1KW/m squared.

So to drive a relatiely efficient boat would require around 130 square meters of 100% efficient power generation. Assume for an instant that you want to provide any additional power, like run lights, power a refrigirator, whatever, now we are up to lets say 150 square meters...

Now reality says that in production level facilities on land with computer controlled systems they can get maybe 20% efficiency. So now we are up to 750 square meters of solar generation... Now this was based on the energy demands of a 64' powerboat... So if we don't want it to overhang the front and back... the solar aray needs to be roughtly 120' wide... Again there is no way of realistically carrying this type of system when the solar power is being used for propulsion.

[Submarine Tom]

You forgot about the giant magnifying glass hung from the helium balloon!

-Tom