Solar powered propulsion and low drag boats suitable for it

[PAR]

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]

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

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]

PAR, any more info available on the lp steam engine?

[soundman]

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]

Here's a YouTube video of the engine, [ame="http://www.youtube.com/watch?v=ENsnutreEjQ"]http://www.youtube.com/watch?v=ENsnutreEjQ[/ame]

[ian]

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


ian

[Boatmik]

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]

- 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]

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]

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]

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]

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]

Not a rant - a Gem Paul.

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

MIK

[Boatmik]

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]

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..