Solar powered propulsion and low drag boats suitable for it

[b.o.a.t.]

Human pedal power? forget electric, help get the obesity rate down..

Some are thinking about these things.
http://www.foilkayak.com/faq/theory/

[ame="http://www.youtube.com/watch?v=U95UReP4mdo"]www.youtube.com/watch?v=U95UReP4mdo[/ame]


Then there's Paul Gartside's "Blue Skies" which rather appeals to me.
http://www.gartsideboats.com/catrow2.php#pedal

cheers
AJ

[Boatmik]

The bloke in the conventional kayak is barely trying compared to the superfit athlete with the too short paddle in the flying kayak!

Imagine doing that for a day!!!

More foil shenanigans for those who are interested
[ame="http://www.youtube.com/watch?v=j_z6hDLP9Go"]YouTube - hydrofoil-todd kyser[/ame]
[ame="http://www.youtube.com/watch?v=In8f0C_B9HA&feature=related"]YouTube - Human powered hydrofoil[/ame]
[ame="http://www.youtube.com/watch?v=b_5eMMkIOeo&feature=related"]YouTube - Learning The Aquaskipper[/ame]
[ame="http://www.youtube.com/watch?v=j_WKgcOiq2M&feature=related"]YouTube - Hydrofoil Surfing[/ame]
[ame="http://www.youtube.com/watch?v=1oyWMusaDTI&feature=related"]YouTube - Hydrofoil Windsurfing[/ame]

But all of the above are just toys that do one thing OK for short bursts compared to the day in and day out efficiency that racing Moths around a regular racecourse has created.
[ame="http://www.youtube.com/watch?v=8dx-OJhW3Bo&feature=related"]YouTube - 2006 International Moth World Championships - Heat 6[/ame]

Look at the way the world champion tacks just a year later - barely comes off the foils
[ame="http://www.youtube.com/watch?v=3BZwM2LDCb4&feature=related"]YouTube - Rohan's Foiling Tacks, Lake Garda, June 2007[/ame]

MIK

[Daddles]

But human powered craft aren't particularly green when you consider that the gaseous exhaust is a greenhouse gas

Richard

[Boatmik]

Speaking of gaseous exhausts ...

howdy Richard!

It only has an effect if you have to build an extra human being as a powersource. If you use one that is already in operation but relocate it then there is no nett effect.

MIK

[PAR]

I don't think we're anywhere close to utilizing human power, either directly or indirectly (like cranking a generator for example).

Until electric solves it's storage issues (they been saying it happen in ten years for about 40 years now) there isn't going to be any great gains for small craft.

Lagoon is offering hybrid drives (battery bank, twin electric motors, and diesel gen. set, with a shore power charger too), but haven't found the market very receptive yet. This is typical of new technologies. Most condemned 'glass boats when they first came out and the first metal boats were thought to surely sink at launch, ditto concrete craft.

Solar power (regardless of application) is only good for a few hours each day, then the energy storage issues comes back and bites.

Reciprocating to electric hybrids are the wave at the moment, but they aren't as efficient as straight reciprocating power plants in small craft.

Maybe turning the whole boat into a giant battery with electrodes along the bottom can solve the problem. Some are actually trying this, but unfortunately water isn't the best electrolyte even if salty.

This brings us full circle back to construction techniques, shapes and hull form devices. Light weight, easily motivated hull forms with steps, wings, air injection, vortice generators, maybe even transformable hull bottoms to suit different conditions and S/L ratios. Wings and other types of displacement reduction devices have a fair amount of development, dating back to the early part of the 20th century.

The oddball designers of the world will continue to stretch the envelope in pursuit of different paths for more efficient propulsion. I imagine Michael and I might be considered among this group, possibly begrudgingly.

On the subject of gaseous exhausts, I enjoyed a lovely one just a few minutes ago, though all four dogs did leave the room shortly thereafter. For a beasts that will eat their own vomit and cat poop, they sure are a finicky bunch.

[soundman]

I notice that the " solar ferry" is a " desirable hull shape", looks to me to be more of a "concept boat", if you get me.

interestingly, last week i helped a mate move his boat from the slip back to its mouring.

It was an eye opener.......I've known Dan since we were both spoty aprentices......I spent the next 10 or more years teasing dan about his boat that still wasn't in the water..he's had it in the water now for over 10 years & I hadn't seen it till the week befor last.

what is interesting to me ( and possibly to the average powerboatie) is the size of it and how little it needs to get it going.

This thing is no trailersailer, I don't remember how long it is 20 or 30 feet or something, but I do remember it weighs over 6.5 tonnes ( dan recons he'll make the next one lighter afterall it is his first boat).
so we have this thing ( a catamaran ) about the size of a small house.
Now I have seen it run under motor, without wind assistance do a genuine 7 knots by the gps.
what struck me is that there are two punny props being driven by two ten horespower motors.
Now considering this is not a light boat nor is it a cutting edge modern hull design, that gives some idea what can be achieved with a little power.

if you had a reasonably efficient slicing style cat hull, with reasonably light construction, it should be reasonable to push a 20" boat along quite briskly with 30 or 40 HP.

now if we had a couple of self furling sails for when the wind blows, a canopy covered in solar cells & a decent battery bank to match, and a smallish generator......all this to service a couple of electric motors.....it all looks quite reasionable.

so at the mouring you keep the batteries charged off the mains, you can motor very quietly out of the marina off the batteries.......as soon as you are clear and there is wind.... up sails & turn off the motors.......iff there is a favorable wind you can sail about for hours or days..... meanwhile the batteries are charging from the solar cells, there would be plenty of power for domestic uses & if the sun shines you are charging batteries.
If you are out for " quite some time" days, weeks and there is a spate of calm cloudy wheather you can start tye generator to charge batteries.

true hybred and far more cost effective to run that a similar size motor cruser.

just a thaught.

cheers

[b.o.a.t.]

Lead article in AABB out this week - "compressed air engines" by Robert Ayliffe.

Seems there's a bloke in France has built a real 5-seat car that will go 110kph & 300km on a charge. Has sold the whole thing to TATA in India.
(may be the death of the idea, might not - India's burgeoning oil consumption is one big reason for escalating prices. An engine which doesn't need it would be a hit in a country with 4 times the population of the US & no oil industry worth a damn.)

Another bloke in Melbourne is working on a compressed air rotary engine but hasn't built a car around it yet.

Compressed air outboards are being developed/available in Europe.

Looking at historical stuff, trams in France were driven by compressed air for close to 60 years in the 1800's.
Underground mining equipment including trains well into the 1900's.
Early torpedoes used compressed air as the only absolutely reliable & compact power source available in those leaky old subs.

Evidently it is possible to store a lot of energy as pressure - a lot more than I had thought possible. Rob postulates that a small compressor driven by photovoltaic or wind generated electrickery should be able to trickle charge enough air to drive most recreational craft useful distances. One could fire up a large hydrocarbon fuelled back-up for those times that demand exceeds stored supply.

I think it could be especially readily adopted by harbour ferries & the like - compressed air can be generated & stored at multiple sites & topped up frequently & quickly as required.

A proven technology with 21st century levels of energy conversion efficiency.
Rob goes so far as to muse on compressed air replacing electricity for many domestic appliances, with widespread energy self-suficiency.

He's wrong about air cylinders lasting forever, but with careful air drying before it is stored, they'll outlast batteries many times over & be less polluting to produce.

[b.o.a.t.]

if you had a reasonably efficient slicing style cat hull, with reasonably light construction, it should be reasonable to push a 20" boat along quite briskly with 30 or 40 HP.

Bolgers power sharpie cruisers have just this in mind.
Tennessee is a 29 footer cruises comfortably on just 10HP.
Idaho will do 30MPH on 25HP http://www.common-sense-boats.com/idaho.htm
Bolger's bantam is another multihull approach http://www.nauticaspect.com/Inhoud_EN.htm

Plenty of other boats - more or less boat-shaped - with same efficiency.

[soundman]

I have looked at both the "Fishcat" and the "sneakeasy" before too.

My main concern with the fishcat is that the single outboard has no hull in front of it to form the water for the prop.
This would have to result in a loss of prop efficiency and quite a bit of turbulence and such around the prop.

cheers

[PAR]

Ideally, you don't want anything in front of the prop, which is one reason the FishCat works so well. Any obstruction, including the lower leg of the outboard itself reduces propeller efficiency. You pretty much have to live with the lower leg, but if it can "swim free" like the FishCat's does, then you've gained considerably over more conventional designs.

The cavitation plate (correctly called the anti-ventilation plate) will control the "weak side" of the prop (where the blade tips are closer to the water's surface). There's no need to worry about "turbulence around the prop" . . .

[PAR]

After thinking about it last night, it might be possible the prop could suck in air, if it was riding in the converging wakes of the two hulls. The transom location appears too far forward for this to occur on FishCat and the two hulls are also likely too close together as well.

[Boatmik]

The cavitation plate (correctly called the anti-ventilation plate)

Wow ... another person who tries to use the terms correctly!!! Well done old chap!!!

My respect continues to flourish!

MIK

[soundman]

I was reading one of the outrigger sites.
This bloke was having problems with his new small honda, with the turbulence from the leg causing the prop to misbehave.
the leg was round and seems the manufacturer had assumed it wouldnt be a problem because there would be a stern in front of the outboard.

his solution was to fit a streamlining foil above the "anticavitation plate"

cheers

[Boatmik]

Howdy Soundman,

This is because the outboard was set up incorrectly probably due to limitation of the freeboard of the boat or a long shaft outboard had been selected rather than a short shaft.

There are two settings for an outboard.

1/ One is .. if there is no transom in the water the anti ventilation plate should be 25mm below the water.

2/ The other is, if there is a transom in the water then the anti ventilation plate should be 25mm below the bottom corner of the transom.

Clearly the boat in your example should have simply mounted the outboard higher to meet the first criterion.

Michael Storer

[PAR]

Outboard legs are specifically shaped to be hung in the typical location behind a big fat transom. The rounded entry performs well in this location, but if in "clean" flow it sets up a fairly big entry wave, which robs the prop of flow and usually introduces air as well.

In the old days, when I was a boy and outboard engines were limited in size and available power, we used every trick in the book to get more out of them. One very common trick was to "streamline" the entry of the leg. This usually required a fair amount of welding. We'd but a pointy nose on the lower gear case and add similar to the leading edge of the leg. Some of us (okay, I'll admit to doing it too) actually went to the bother of putting a foil shape on the flow directors and anti-ventilation plate. Most of use also increased the area of the anti-ventilation plate for added lift and a bigger "hole shot". This hurt our top end speed slightly, but we'd jump on plane faster, at lower speed and this extra jump was enough to win at drag race events, where top speed really wasn't realized, just how fast you can cover a 1/4 mile from a standing stop.

An anti-ventilation plate extension would probably help those finding issues with their multi hull or double ender mounted outboards. Though I suspect Michael is correct in that the engine is mounted too low or high for it's hull configuration.