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Aberdeen
19th June 2008, 06:59 PM
In the beginning there was person power, followed by wind power, then fossil fuel power. There are some low powered electric motors out there.

But is anyone aware of developments towards solar powered electric boats that can get up and go..... ? not just your troll motors and the like doing maybe 5 knots down the Murray (if there is enough water to float a boat that is) I mean a boat that can go out to sea.....

Toymaker Len
19th June 2008, 07:58 PM
There is a full size solar powered ferry working in Sydney harbour out of Circular Quay.

Aberdeen
19th June 2008, 08:09 PM
Whoa !!!
Len, that sounds like one big boat, maybe a bit bigger than I had in mind... but seems like solar has or is being developed.....

Just looking at options for the next one.... like to cover all bases... and fuel is getting a bit expensive.... but then again I assume so would a solar powered engine with grunt :?

soundman
19th June 2008, 10:30 PM
There was some discussion about this on one of the fishing forums.

I think the first thing would be to have an efficient hull.

the other consideration is how much run time per day is expected.

there was a bit of napkin maths done & the consensus was that it could be viable for lake fishing, perhaps, whre you would travel to a location & remain there for an extended period.

the top or the roof of the boat would have to be wall to wall solar cells.

The big problem is the derating factors you need to consider, you never get the full rated output from a solar cell, unless you are just south of darwin in the height of summer, and you can only count on the equavalent of 4 full hour s of sunlight in a day.

traction or propulsion is a very high drain application.......

The viability would improve considerably if it was some sort of hybred machine.
charge from the mains, or from an onboard generator and use the solar as a sugnificant supliment..... that could be mage viable for an all day run.


I'd like to know "the truth" about this " solar ferry"......quite often these things arent as sucessfull as they are made to appear......do they charge the batteries from the mains at night?

cheers

Aberdeen
19th June 2008, 10:55 PM
Quite a valid point concerning the surface area that would be required to accomodate sufficient solar panels.... didn't think of that one straight up....

Daddles
20th June 2008, 12:16 AM
Don't forget the boat that did Adelaide to Stansbury a few years back by solar power - Mik'll know more about that. The thing with solar is the lack of speed, okay if you're into gentle cruising but not if you're into a Hartley with a monster outboard (I seem to remember some old git who fitted a 20hp outboard to a 10ft Hartley dinghy :oo:).

Personally, I think you're better off fitting a small diesel in a well designed displacement hull.

Actually, rescuing a 50's clinker cabin cruiser, tossing the clapped out Holden and fitting a 20hp diesel during the restoration would be the best thing you could do. I'll even tow the brute from my front yard to yours :wink:

Richard

Aberdeen
20th June 2008, 12:29 AM
Daddles,
No doubt Mik will come in at some stage with some info on that one... ?

As for a 50's clinker - wrong colour and I need a challenge not a life long hobby - besides waiting for someone to perfect bending timber with steam as the old girl has lots and lots of ribs that would need replacing :roll:

< Sad but back to work from tomorrow >

Daddles
20th June 2008, 12:46 AM
< Sad but back to work from tomorrow >

**points**
**hysterical laughter**

[\sympathy]

Richard :D

Boatmik
21st June 2008, 11:22 AM
Howdy Soundman,

I think your suspicions about the solar tour boat on Sydney Harbour are well founded - but it is still a step in the right direction.
http://www.evworld.com/article.cfm?storyid=107
The size of the cell area is small relative to the boat and when the sun is to the side only half the cells look like they will catch anything. What about when the sun is in the wrong direction so the effect of the sails could be in the opposite direction from the motors. Also the hull is not very optimised for low drag. No emissions - means shore power I very much suspect - particularly if they run at night too (tour boat!). If a sunny day gives the boat 5 knots on solar (with or without passengers!?!) only it ain't going to leave a lot for powering at night.

Light and simple and a low payload makes more sense in a solar boat.

Now to more modest boats...

The problem with going to sea for more than short periods is that you need to overpower the boat.

It might take only a few horspower on something light and slim and shallow ...

Can I say that again ... light and slim and shallow

And once more ... light and slim and shallow

... to keep it moving at an OK speed in good conditions. But going to sea means that you have to be ready for bad conditions too. And that means you might need HEAPS more power for extended periods - if you've spent time on the sea, you know exactly what I mean.

So the infernal combustion engine makes a lot of sense. However it can be in the form of a generator as Soundman suggested - and that is the solution for the Mundoo/Nomad.

There is also a problem with getting enough surface area for solar cells - the Nomad 3 has much of the roof covered. relative to displacement and low speed drag I would suggest it has more solar cells than the solar tour boat.

http://www.storerboatplans.com/Solarboat/Mundoo3murraycliffs.jpg

The break even point in power under solar only for the Mundoo is around 4 knots on an sunny day - an average sunny day - not a super hot sizzler. Now if we DOUBLE the amount of solar cells we can probably double the power but it will only increase the speed by about 40% - 5.6 knots on a clear sunny day and FLAT water and not much breeze. Four times the area and we get 8 knots in the same perfect conditions.

More wind, more sea and less sun ...

There is a capacity for getting a much lighter and simpler boat to have the same collection area by reducing the expectation for living space and ditching most of the batteries - that is my feeling for the best solution at the moment in terms of range and freedom of operation and seakeeping.

Consider that such a boat would go with with a 10 or 15hp four stroke high thrust outboard with its low fuel consumption for max speeds of 10 knots and a great ability to punch into a chop. That is what you are up against.

So the problem for boats is the small collection area. A multihull can have a much bigger collection area, but has more windage (wind drag) and multihull (and really the monohulls I am talking about above) performance is highly weight dependent - so loading them up with batteries doesn't make sense either.

However ... there are quite a few hire sailboats in the UK being supplied with Electric inboards using battery power.

There are lots of small simple boats using trolling motors.

Keep the boat simple and the drag down, supplement solar with a generator (one of the nice 4 stroke ones) and it starts to be an interesting equation.

Best wishes
Michael

Aberdeen
21st June 2008, 11:38 AM
Michael,
Thanks for that convincing input as to what one could expect from solar in boats...... looks like I'm still stuck with fossil power for the next one. Becoming a fossil myself I have discounted sail.... on a body physical sense.

I am pleased with your : "But going to sea means that you have to be ready for bad conditions too. And that means you might need HEAPS more power for extended periods -...........So the infernal combustion engine makes a lot of sense."
It might slow comments from Daddles on my last choice of motor :D

Boatmik
21st June 2008, 11:47 AM
BTW ...

The other way to look at it is to go through the same process as with the Mundoo/Nomad.

USe the boat on a river (less wind and waves).

And look to see how often shore power is available on your trips - the owners of that boat worked out that it would be daily. But they have found that they are much more independent than they thought as they are able to stop somewhere nice by the riverbank and mooch around and relax and HOLIDAY. And while they do that the batteries recharge.

Michael

Aberdeen
21st June 2008, 12:02 PM
My dream is a go-anywhere-boat...... river, lake, gulf etc.
I know how fast things can change out in the Gulf StVincent and believe in having good 'reserve' power available.... a versatile craft.....

The sea is where the heart lays.... be it local or possibly interstate on retirement.....

Boatmik
21st June 2008, 12:10 PM
Simple, basic, light, narrow, shallow, simple accommodation, minimum of gear. Minimum of on board electric use.

Aberdeen
21st June 2008, 12:12 PM
Simple is good Mik

While I'm at it... what are your thoughts on the use of Oregon in boats... seems lots of positives and a few negatives I've found on the web.
Reason being I've just come into possession of a reasonable amount of the stuff - straight and clear

Ply on frame 18' is the likely version to build next.

Boatmik
21st June 2008, 03:15 PM
There should be no criticism of Oregon (Douglas Fir) anywhere on the net for boatbuilding.

PAR and some other Nth Americans might have something to say.

In Trad building it makes quite nice planking - a lot of high quality Sydney boats were built in Oregon planking (quarter sawn) over spotted gum frames.

If it is not quarter sawn for planking then it can be difficult to sand flat as the dark parts of the grain are very hard to sand and plane. It is not a big problem with pieces for modern construction as the surface areas of gunwales, chine logs etc is usually quite small.

Oregon itself makes excellent high strength glued structures.

If you go the epoxy or other glued method - it glues really nicely and has excellent strength to weight.

If you are going epoxy gluing and epoxy coating ... even non durable timbers can give durable results - so no worries.

Only downside is that it can be a bit splintery - but at the same time that allows it to absorb huge amounts of energy when involved in an impact.

Nothing wrong with oregon at all.

Michael

PAR
21st June 2008, 07:32 PM
Douglas fur is a fine wood for boat building and used extensively. It does have finishing issues and is subject to checking, but has good strengh to weight and good rot restance.

How about a solar powered steam engine, driving a generator?

I'm working on just this problem now. Picture a parabolic mirror with a stellar tracking mechanism attached, with a boiler (very small) fitted at the focal point of the "collector". Steam is produced and drives a low pressure steam engine, say about 20 HP. The 20 HP engine is belted to a generator (around 12 KW) which powers the onboard devices, including a motor driven prop.

My use is for home generation of electricity, for selling back to the utility company, but it could be applied to a boat as well.

Of course tracking the sun as you change course is an issue, but not particularly difficult to over come. I have a source for a low pressure steam engine, which is the heart of the system. It has no crank case, nor any of the typical steam engine related parts, at least in a traditional steam engine format. The 20 HP engine weighs just a few pounds (yep, I couldn't believe it either, until I checked it out) and will begin to spin (no load) at about 2 PSI. It's very compact and doesn't make a lot of noise.

On the other side of the coin, you could develop a runabout with a 20 HP electric motor and drive it quite fast until you drained the battery bank. Capacity and storage are the big issues, as you've likely surmised, with this avenue of electric propulsion pursuit.

Aberdeen
21st June 2008, 07:42 PM
PAR
I like your thinking outside the square..... sad thing this way at the moment is a distinct lack of water :(, plenty of sun though.
Steam power.....has been around a long, long time.... great to hear that someone is looking at this alternative power.. well done.

As for my next boat - looks like I've discounted sail and now solar, oars are out (getting old and unfit with a crook back anyway).
Leaves me at Plan A - motor... likely a diesel stern drive subject to $$$'s

Run it until the power drains..... big downside of an electric boat - can't really run a long power cord when you are using it :doh:

Now back to working out the best way to cut my newly acquired Douglas Fir..... with the direction of the rings or against... my feeling is to go with them not across them.....

Happy sailing!

echnidna
21st June 2008, 08:19 PM
PAR, any more info available on the lp steam engine?

soundman
21st June 2008, 11:17 PM
I think mick is on the track with the idea.

I look at the boat in mick's post, the solar ary pictured would only be enough to provide enough energy for reliable domestic uses on the boat.

Just to get a bit of proportion
I can see what appears to be 6 x 80 watt panels... which could reliably be expected to yeild about 2.5kwH of energy per day which would drive a 5 HP motor for about a hour....it would be a usefull top up but you couldn't rely on it to get you anywhere and you would need about 1500AH at 24V to support that run time without stressing the batteries.

Now a a viable fishing platform
A lightweight catamaran with a hull typical of a small sailing cat say 14 to16 foot and 6 feet wide with a flat deck.
the solar cells would be mounted in place of a bimini canopy, it would be reasonable to mount 4 or 6 x 80 watt panels and still leave some casting room.
It would be viable to push that with a pair of largish trolling mottors.

the above would de entirely viable for lake & river fishing and would be passable in esturies.

Many of the stocked impoundments have restrictions on the use of internal combustion engines.

I think sail though has to make a resurgence as a practical rather than recreational propulsion method.
" I have a sail because it gets me there not because I want a sail boat" if you get me.

cheers

cheers

PAR
22nd June 2008, 12:31 AM
Here's a YouTube video of the engine, http://www.youtube.com/watch?v=ENsnutreEjQ

ian
22nd June 2008, 01:10 AM
Howdy Soundman,

I think your suspicions about the solar tour boat on Sydney Harbour are well founded - but it is still a step in the right direction.
http://www.evworld.com/article.cfm?storyid=107
The size of the cell area is small relative to the boat and when the sun is to the side only half the cells look like they will catch anything. What about when the sun is in the wrong direction so the effect of the sails could be in the opposite direction from the motors.Michael

here's a photo the ferry's solar cells can be angled to catch the sun
http://www.solarsailor.com.au/images/media/images/SS_TOPBACKCLOSE_LR.jpg

ian

Boatmik
22nd June 2008, 01:36 AM
Howdy Ian,

I understood how they can be moved - but thanks for the pic. However here they are far from optimum for the sun - look at the shadow - so they have decided to go for the wind to get thrust and pretty well forget about solar. The solar panels should be facing toward the top left of the pic (see the direction of the shadow) and note that the array on the port side of the boat can't be oriented toward the sun at all.

The best thing is to have the wind and solar elements separate so both can be optimum.

I think the main purpose of such a craft is that it hasn't been done before - and certainly not in a mainstream and commercial way - I think it is great from both of those points of view! And that it is visible each day in a one of the busiest places in Australia and it is so obviously different too - and that is the real value of those solar sails.

Actually thinking of solar and wind - wind seems so much more effective it almost seems silly to discount it - except as far as the sailing function really forces a compromise on the accommodation and payload.

Thanks for the pic.

MIK

Vernr
22nd June 2008, 09:38 AM
- so they have decided to go for the wind to get thrust and pretty well forget about solar.

....Ahh yes, but you could also argue that wind IS solar energy (in its simplest and purist form)..........so by utilising the combined effect of both wind and electrical energy (derived from the sun) it is still 100% solar powered!!

ian
22nd June 2008, 10:10 AM
Hi MIK
I posted the pic as a comparison to the one posted by you as.

panels flat on the roof aren't ideal for energy collection, but then again when the wind's blowing the wrong way they don't add to the drag

moveable panels can be optimised for energy collection, but could add to drag.

when looking for the ferry pic I came across a drawing of a boat with a rigid airfoil sail covered in solar cells intended for use on San Fancisco Bay. That might be the best of both worlds.
use the wind whenever you can and reserve the "solar power" for docking and when you need to go directly upwind.


ian

Boatmik
22nd June 2008, 10:38 AM
Howdy Vernr, I was about to write the same thing about wind being solar energy - but decided not to as it also is from the rotation of the earth and the interaction with the viscosity of the atmosphere.

Howdy Ian, I think you have put your finger on the problem of compatibility between solar and sail. For a truly optimum solution you need to make sure that one does not interfere with the other - maybe not completely possible but that is the right direction to go. This will also be true of the solid wing sail - though it is a great way to get lots of solar area on a smaller hull.

However wing sails are already hard to engineer to keep the weight down to tolerable levels and even a small wing mast develops huge amounts of drive.

Biting Midge has a story about not being able to slow down an ocean racing cat offshore at night because the modest wingmast was developing too much power ... after all the sails were dropped. And that is the upside of the boat in the pics above.

Not discounting any of it - I don't think people generally realise how far we have to go - which also means that there are huge improvements possible.

But I do think that there is a general tendency out there of forgetting that power is only half the struggle - the other part is to reduce drag - and that means heading toward boats that are lighter, simpler and possibly much smaller than we are used to (though there are some interesting scale effects which might put the kibosh on that). Then as solar and other technologies become more efficient and implementation becomes more effective then the boats can become bigger.

Best wishes
Michael

nickpullen
23rd June 2008, 03:59 PM
Reduce drag: How about a foil design? with the motor mounted in the foil at the bottom, to work as ballast? Something like a Moth, as Mik posted in another thread somewhere...

Loving these threads on here about inovation and differnet thinking, such as this one and the Timor one.

Good reading!

PAR
23rd June 2008, 05:14 PM
Michael has hit on it a few times and I'm agreeing, but will add with these relatively low power applications, optimizing the hull form is likely more then half of the equation.

In recent years I've designed a few low power displacement and semi displacement craft of various sizes. Some were to address the desire to propel a vessel without the need for big HP engines others to see how far I could take this.

I have a 33' houseboat design that uses a 30 HP outboard and travels around 20 knots. Most houseboats of this size would be restricted to displacement speed (about 7 knots) or require a few hundred HP to get up to 20 knots.

Of course this design is light, has over a 4:1 length/beam ratio, with a very efficient hull shape and design tricks to help solve some of the issues associated with low power, light and narrow hulls at moderate plane speeds.

Narrow and shallow as Michael put it earlier, is the ticket. There are other options too, but these two are the big mommas.

Efficient propulsion assemblies are available, common even, if the hull form takes most advantage of the HP on tap. Who wouldn't love to have a runabout that ran in the mid 40 MPH range with a 20 HP outboard, instead of a 150 HP engine.

At the turn of the 20th century, mechanical propulsion was reasonably common, but cumbersome. An example would be the torpedo boat "Dupont" designed by Nat Herreshoff. One of it's steam engines weighed about 19,000 pounds and produced 1,700 HP. This was 1897 and considered quite good. Now you can have the same HP with an engine that is 95% lighter. As a result the hull shapes used in the early days of prop driven craft were very efficient.

Designers have gone away from these hull shapes because fuel costs have been low and HP production moderate in weight. This permitted designers to make nice fat boats, which could sleep a small platoon. In fact the number of berths is the selling point, not how efficient the hull is.

In previous fuel cost spikes and shortages, the industry just rode the thing out and got back on their horse when discretionary spending increased again. I suspect the same will occur this time around, unless it's a prolonged event. I don't see major design trends changing in the next 5 years or until fuel prices (in the USA) reach $8 per gallon. At this point, new designs will be required or all but the most divested boat builders will fold up their tent and go home.

The point is, we have propulsion systems in place that are efficient, but designers or more importantly, marketing departments from the major manufactures, are developing very inefficient hull forms. This will continue for several years while they wait for the market to rebound. Additional efficiency improvements to conventional propulsion will come, likely accelerated by the latest fuel cost dilemma, but don't hold you breath for production craft, until inventory and tooling costs are recovered.

Custom yacht design and of course commercial design efforts have made great strides, particularly in the last two decades, as far as efficient hulls and propulsion systems. If you compare a 1950's vintage freighter to a new one, they aren't even close. The new boat is safer, easier to operate, much more cost effective at it's task, much more maneuverable, recovers it construction cost more quickly, delivers it's cargo faster using much less fuel, etc., etc., etc. In fact, modern hybrid propulsion systems, used on these types of ships, have all but eliminated the need for tugs in and around port. The key is, those commissioning a new vessel must desire these traits. The pleasure boat market currently doesn't, but might in the near future.

In the small, pleasure, production boat market, material advances and improved drive systems will eventually couple with better hull forms, but it's an industry that traditionally has had to be forced to implement these sort of changes.

I remember the first 'glass boats. Most builders stood on the side lines and watched the few who dared with this untested material. These first craft were highly engineered, considering what little they knew about the resins they employed. Once all the manufactures jumped on the band wagon, they continued to build boats in the same mentality, which was a very heavy layup (just in case). These manufactures didn't reduce their laminate schedules until the dark days of the late 1970's and early 80's when yacht sales fell though the floor and you couldn't give them away. To stay afloat as a company, they actually started to engineer structures again, this time with an eye at reducing their building cost by saving materials. This lead to other resins, new techniques, different fabrics (some good, some not so much), but in general better products came out of it, once the mud was kicked from the boots of the industry.

Sorry about the rant . . .

Boatmik
23rd June 2008, 05:19 PM
Not a rant - a Gem Paul.

I learned a couple of things in there - so cheers.

MIK

Boatmik
23rd June 2008, 05:31 PM
Howdy Nick.

YOu look at the way the efficient foilers are going - the lightest, simplest boats possible.

It would be quite possible to have a cool bicycle foiler type thing if it was kept very light - so again we end with a battery restriction. Maybe if a battery and motor doesn't weigh too much more than a sail and rig on a Moth then you could get it to fly in an efficient way - but those bits don't weigh much on a moth and the electric thingies are heavy as are the batteries.

Can you see the pressure to have the smallest possible person driving the thing?

As soon as we are looking for a Jockey to increase speed or range it is not really a viable boat for the rest of us.

PAR might have his own magic to share here...

Paul???

Best wishes
MIK

nickpullen
23rd June 2008, 07:40 PM
It would be quite possible to have a cool bicycle foiler type thing if it was kept very light


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

b.o.a.t.
23rd June 2008, 08:15 PM
Human pedal power? forget electric, help get the obesity rate down..


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

www.youtube.com/watch?v=U95UReP4mdo


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

cheers
AJ

Boatmik
23rd June 2008, 10:56 PM
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
YouTube - hydrofoil-todd kyser
YouTube - Human powered hydrofoil
YouTube - Learning The Aquaskipper
YouTube - Hydrofoil Surfing
YouTube - Hydrofoil Windsurfing

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.
YouTube - 2006 International Moth World Championships - Heat 6

Look at the way the world champion tacks just a year later - barely comes off the foils
YouTube - Rohan's Foiling Tacks, Lake Garda, June 2007

MIK

Daddles
24th June 2008, 12:34 AM
But human powered craft aren't particularly green when you consider that the gaseous exhaust is a greenhouse gas :oo:

Richard

Boatmik
24th June 2008, 02:30 AM
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
24th June 2008, 09:31 AM
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
24th June 2008, 11:10 PM
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:D..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:D 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.
28th June 2008, 06:07 AM
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.
28th June 2008, 06:46 AM
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
28th June 2008, 11:01 PM
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
29th June 2008, 11:58 AM
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
30th June 2008, 02:18 PM
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
3rd July 2008, 08:11 PM
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
3rd July 2008, 11:43 PM
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
4th July 2008, 01:24 AM
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
4th July 2008, 05:01 AM
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.