Wind Driven Houseboat

Many folks will use a simple rule of thumb concerning propellers.

IN water 1 HP will produce 20 lbs of thrust on most boats , tho some will claim far higher theoretical numberrs.

In air the same HP will give 5 lbs of thrust , tho close to 7 is in theory doable.

An air propeller powered boat will need an outsized propulsion system to accomidate this .

My inshore dream cruiser would be a water propelled hover craft spud barge with self jacking ability.

Pull into shallow water , jack up 5 ft and watch the sport fish wakes pass below.

For the "no anchoring" areas , no problem the anchor would still be on board , the boat is aground , 2 black balls in the rigging.

FF

 

You can't use the same rotor for turbo charging and also propulsion. It won't work, at least not at more than 5% efficiency. Ie you will need 20 hours to charge for a 1 hour run. A very sophisticated, computer controlled cowl might improve upon this a bit, but it will cost a lot more than a complete houseboat ready to go. The fuel bill for a typical river houseboat is only a few hundred dollars a year. How will you recapture the expense with that fan. It must cost six figures to build and install along with a decent control system. Do you have a source for these fans?

The power you are using to supply each fan isn't enough. You need to generate a wind velocity that is several times greater than the ambient wind speed. Otherwise you power consumption will be entirely determined by the winds you encounter. It will also make it difficult to vector the thrust if you don't apply the power more densely.

If you were determined to do this, keep one eight footer as a turbine w/o a duct, and add a couple smaller pusher fans for propulsion. They probably need to make a stream faster than 100mph to be effective, but the aero guys could help with that more than I could. The good news is you can actually buy these components because they actually work.

Getting a biggish turbine generator to work on a boat has utterly defeated a whole bunch of fairly clever people. The unit will require active stabilization and computer control. Sounds silly, but it seems to be a very tricky problem to keep the thing pointed into the wind. The bigger the turbine compared to the boat, the bigger the problem. A VAT might work better in practice on a boat. Or use spuds instead of an anchor.

Wind turbine generator powering electric motor prop (in the water) has been built by several people, you should research these.

There remains a fundamental error in your conception. You must have wind to charge your batts. You can't just expect it all to go away when you want to operate the boat. Lets assume the wind velocity is the same when driving as when charging and the wind is either directly ahead or directly astern, which tends to be the case on rivers. If its on your nose, you don't want to propel by pushing on the wind. You always want to push on the slowest moving part of the environment you can access. Boats going upriver were poled or towed along a towpath for this reason, but rowed down river. A prop in the water is more versatile than an air prop because the flow velocity over the hull is much slower.

 

Perhaps you guys are right and I'll repost when oils $300+ per barrel. But I like the idea of being able to anchor anywhere you like and powering off the wind.
Air propellers are as efficient as hydro props.

 

Whenever I anchor,and almost everyone else,it is in a protected area with ...wait for it....the least wind and waves.

If there's enough reliable wind to charge there's going to be enough reliable wind to make big enough waves to stall you out. Imagine if the wind is coming from the direction you want to go.

How about you buy an old 3 hp Briggs motor,build a carbon prop/cowl,mount it on an old aluminum fish boat and tell us how it goes?

 

Maybe you're right but maybe I'd prefer to anchor further away.
Anyway it was just an idea and admittedly I didn't put a lot of thought into it.
It would seem the conclusion is you can't wind power a small floating house?

Colin
http://www.ww.xbug.ca/

 

So, comparing this idea to the Titanic turned out to be appropriate after all.

Blub, blub...

 

Not at all true, I'm afraid. The fluid that a prop works in makes little difference to its efficiency, any differences tend to come from other factors that impact on design.

I designed light aircraft before getting interested in boats, and you can get slightly better efficiency from an aircraft propeller than you can from a boat propeller. Aircraft props are more efficient than most boat props because they don't have to be compromised by being designed to stay clear of weed fouling and they don't have to deal with cavitation at relatively low blade loadings. A typical ordinary off-the-shelf small boat propeller might be around 50 to 60% efficient, whereas a typical off-the-shelf light aircraft prop will be around 60 to 70% efficient.

Sure, a prop working in air needs to have a much bigger diameter, and move a much greater volume of air, because air is around 815 less dense than water. This means that to get the same thrust a prop in air has to move more air at a greater velocity in order to match the thrust of a prop in water that's absorbing the same power.

Thrust is a pretty meaningless figure, unless the speed at which that thrust is created is given. For example, I could design a propeller capable of delivering a static thrust that was extremely high, and yet which absorbed only a small amount of power. However, as soon as that prop started moving through the air its thrust would drop off very quickly, and the power it would absorb would increase. The same is true of props in water, a tugboat will probably have a prop optimised for a high bollard pull, but this will then mean that its efficiency at any reasonable speed will be poor.

As an example of how thrust is meaningless without velocity, take a look at these two examples:

1. A prop has a thrust of 1000 N at a velocity of 3 m/S (about 225 lbsf and 5.8 kts). It is delivering a power of 3000 W (as P = T.v at a constant velocity) so with 70% prop efficiency the engine would need to deliver about 4285 W (~ 5.75 hp).

2. A prop has the same thrust of 1000 N (~ 225 lbsf) but the boat speed is now 1 m/S (just under 2 kts). The prop is now delivering only 1000 W, so if it has the same efficiency of 70% then the engine only needs to deliver about 1428 W (~ 1.9 hp).

So, for example 1 the prop needs three times the power for the same thrust as for example 2, which illustrates why using thrust to describe power, without referring to boat speed, it flawed.

I've designed, built and tested a few props, as have others who are working on efficient boat propulsion, and the overwhelming evidence is that aircraft-shaped props used in water on boats are very much more efficient than traditional boat-shaped props. It's fairly easy to get an 80% efficient boat prop by shaping it like an aircraft prop. The big downside is that they collect weed and rubbish and are less robust, so they don't make for a practical solution for most applications.

 

Anybody who can come up with an air propulsion for boats will get my support,I don`t want any greater draft than 8 inches and nothing dangling under the hull.A boat to spend a lot of time on would be great if it can go anywhere,even slowly preferred.Nothing worse than bouncing across bumpy. water

 

Isn't isn't the correct assumption, though admittedly, it's not an easy thing with current technology, materials and costs.

Houseboats, by their very nature, aren't the best shapes to make particularly aerodynamic. If you could sink the house down into the hull a bit, you can lessen the Winnebago on floats look, but more importantly it's windage. Of course, draft now becomes an issue, but accepting trade offs is what yacht design is all about. With reduced windage, you can use less power, as you don't have to over come as much from a contrary breeze.

Next on the list would be hull form efficiency. The large rectangular shapes most enjoy in houseboats is about the worst you can employ. If you can live with (wait for it) more trade offs, in regard to how the accommodations are arranged, you can stretch out the layout and get a much better shape. This easier to propel shape, permits more reduction in propulsive force necessary.

Now that you've optimized the above and below water shapes, you can address propulsion units. Fans aren't especially efficient at moving boats. The blades themselves might be really efficient, but you need to move so much air, that your power consumption goes way up. Just look at a regular airboat, of which we have many in my neck of the woods. You bolt a 300 HP, small block Chevy to a jon boat, attach a prop and you get 30 MPH, with about the most skittish steering you can imagine. Now take the same jon boat and hang a 300 HP outboard on it and watch what happens.

Simply put, I think sails would be a much better option than fans. You could employ ducted fans for a modest improvement, particularly if vectored, but you'll still just eat lots of watts. If you employ a small inboard or outboard with the sails, you could continue in lulls and calms for very little.

It doesn't take much energy to push you along at relatively low speeds. If you just accept (another trade off) that you can't afford more then 8 MPH (assuming about a 30' LWL), then your propulsion will be small, economical and easy to live with. Sailboats discovered the world at these speeds and most passage makers also travel at these displacement speeds. It's only when you get greedy, that you have to pay dearly for propulsion.

Lastly, a houseboat is a perfect place for PV panels to live. You can generate quite a bit of electron flow, with the typical expanse of a houseboat roof. Houseboats as a rule eat lots of electrons. Of course, you'll need to store some for night time, but energy use on a typical houseboat would need a very careful look, to make it practical.

In short I don't see why you couldn't have a wind powered (mechanical backup) houseboat, but the problem(s) need to be addressed and well thought out.

 

It's easy enough to do, but not a very practical solution for low speeds and high thrust, as the prop diameter would need to be pretty big to get reasonable efficiency. Most air boats run with props that are way too small for best efficiency (just for practical reasons), so need masses of power, plus they make a lot of noise because the small prop needs to spin so fast, too, not my ideal way of propelling a boat.

Something like the prop on Decavitator (http://lancet.mit.edu/decavitator/), which was a large diameter, turning pretty slowly, would work pretty well on a low speed shoal draft boat. Coupled to a quiet electric motor and it might make for a peaceful way to explore the shallows, free from the risk of prop fouling.

One problem is trying to size the prop, as many conventional propeller performance simulators run into problems when you get down to the sort of relative flow velocities that are typical for a big, slow turning, low velocity prop. As others have found, you need to go back to first principles to determine the L/D at each prop station to optimise such a prop, and that gets pretty tedious when you're doing it iteratively to get the best mix of diameter, pitch, planform and rpm for a given requirement.

 

PW,have you considered a scow? It'll be cheaper and easier to build,get you more interior space,and should get you a shallower draft as well.

BTW that is a decent layout and idea for a houseboat,I happen to admire the vintage mini houseboats from the 60's and 70's.

 

A 28' 2" LOD houseboat that is efficient and sips fuel at a very reasonable rate, power 10 to 30 HP outboard.



A 33' 2" LOD of similar breeding.



Of course one is flat bottom the other V, but both are efficient compared to typical houseboat offerings from production manufactures and most plans houses.

 

For two 8' shrouded fans @ 30% efficiency in a 15 mph wind you get about 900 watts of power.
So it’s less than 1.5 days to supply 30 kw.
Stove and oven are propane powered.
LED lighting and laptop computers use very little power. At home I use a TV card on my computer to provide video entertainment.
The overall shape of the boat is based on the idea of getting the most space as well as a stable platform for the fans at the lowest building cost.
I note that our ancestors roamed the planet in square riggers without satellite navigation and weather reports nor the ability to go up wind. This boat can spin on it’s axes as well as being able to move in any direction given that the fans can be rotated 360 degrees.
I haven’t done all the math as far as max. speed vs. power available but I would avoid going upwind on a windy day for any length of time.
Jack post at all four corners might be useful while charging.

 

I know you are really into this idea, but a set of sails would do the same thing more efficiently for less money. Just a thought. But, if you want to build an experiment because you enjoy the process, by all means.

 

Oh dear, Please do some cost benefit sums... How much is a pair of 20 to 30 hp outboards?

MEASURE all your electrical energy consumption and add up the numbers - it will be more than you think...

How much for 32 AGM batteries ? - - as you DO NOT want standard wet lead-acid car type batteries in the bilge area emitting H2 looking for an opportunity to Explode?

Batteries buried in bilges, how are you going to service and maintain the batteries?

When one battery goes dead or shorts out internally, how are you going to test and replace that battery?

Batteries in parallel are not good for high load situations as the monitoring circuitry can become quite complex... (a dead cell severely impacts on power available)

Remember, batteries should not be discharged below 50% to assure reasonable life / endurance and reliability...

How are you going to charge the batteries on a windless day?

When the wind and tides prevent forward movement - - what then ?

Have you measured the output of the fan driven generators over a day on average over a long trial covering all seasons?

How many KWH and what is the minimum wind-strength necessary to recharge, if all batteries are at 50% and bring up to 100% - - A MEASURED & PRACTICAL ANSWER, AS theoretical is not enough because the wind is not theoretical nor constant....

I can think of better use for 2 tons of batteries - (that would give me at 10 knots on both diesel 20hp saildrives about 4000 nautical miles or more)... The AGM batteries I use for nav (Autopilot, radios, computers and maritime requirements add up to fairly heavy demands) and house are Au600 a piece... Your 32 batteries, if similar to mine = Au$18,200.00 and with a hard life as prime propulsion batteries may need replacing after 5 or less years... - - - - Most live-aboard cruisers find that they are anchored up 80% of the time, usually ashore exploring the local culture and customs as true "Flaneurs" - - - - Houseboats, one could expect 95% anchored.... Is there value in going electric whan compared to outboards?

Dream on, do it - document a great success and I will apologise - But I know it will have major issues and am confident I will not need to offer anything but condolences as the project is presented...

Well done PAR (post 27) - rep is sadly on hold