Solar-Powered Motor

[AtomicPhil]

Has anyone tried using a solar powered motor? i was reading up on people who uses solar powered cars and even boats. the boats goes slow compared to the car though . also some youtube videos. so i was thinking if there a way to make or get a motor to use solar energy to run. it helps when theres not enough wind and you need some boost. im not experianced in sailing at all yet. but would like to hear some opinions.

[Alexei]

Whatever that is you're smoking, please hold on to it for about 8 years. I'd like a puff when I'm done in the Navy.

Well, maybe not.....



Point is, all those silly solar cars and what have you are experimental, bare bones, and generally not ready for commercial prime time. Sure, they're fine for some demonstration or some rich guy's lark, but that's about it.

Solar is a great supplemental power source, but for propulsion you just can't get enough energy out with current technology to make it worthwhile on a practical level. Someone correct me if I'm wrong (Gord?).

Unless you're deliberately working to develop a new product or conduct some form of research (as opposed to just wanting to have fun on your sailboat), I'd stick with what's known to work. You'll spend a lot of cash, time, and frustration chasing all these fads and newfangled promising-the-world gadgets, but you'll probably not accomplish a whole lot.


My $.02


-Alexei

[cal40john]

Making poor assumptions, let's say I use 20 HP to move my 40 footer near hull speed in relatively calm conditions. (I know it doesn't convert directly and you can probably get by with a smaller electric motor.) That's about 15 KWatts. Bright sunny day figure 1 KWatt/m^2. So 15 m^2, or 135 sq. ft., or a little under a 12 foot by 12 foot panel if you had perfect conversion of all sunlight during the brightest part of the day.

Grabbing a random 80 W panel, I get a little more than 20x20 feet for current efficiencies.

$3-$5 / watt, $45000 at the low end. If we ever see the new $1/watt panel, $15000.

Add more panels for less than perfect sun, morning, evening, battery charging for night motoring, etc.

John

[David M]

There is only so much energy in a square meter of sunlight and solar panels are around 20% efficient, 40% at best. For it to work, I think we would have to find the technology to attach solar panels directly to the sails in order to have enough surface area to make it economically and practically feasible. Battery technology will also need to be developed which has a much higher watt-hour/kilogram storage capacity so we will also have propulsion at night without weighing the boat down with hundreds and hundreds of kilograms of batteries.

As old as wind power is, its still the best thing going without having to burn fossil fuels.

We just don't have the technology yet. I think we will someday though.

[scubasteve]

Boat engines run at much higher loads then cars due to drag, wind, current, sea state and power loss through the running gear. Not practicle at this moment in time.

[Rhosyn Mor]

perhaps we shall see the day when someone can produce a wind powered boat, wind power is so much more powerful than solar.....

[David M]

I was thinking along those lines as well but did not want to be the smart alec to say it.

Having both onboard in case the other fails is really the best of both worlds still. Atomic's original question is still an excellent question.

[witzgall]

Electric boating is happy and well for many users. If you want to get into the scene, join the Electric Boats Yahoo group.

Concerning a wind powered boat, you already have one. Look up....

[AtomicPhil]

Oh thanks for the information. gives me an idea if this works or not. well this site so far has many good infos.

[GordMay]

Originally Posted by Rhosyn Mor

perhaps we shall see the day when someone can produce a wind powered boat...

Indeed!

[sailtotrail.com]

Jeez AtomicPhil, that's a ridiculous idea! Unless maybe you're the guy in this video who demos his sailboat navigating out of the harbor via electric propulsion that's recharged by regeneration, solar, wind, and/or shore power.

Since sailors got along with zero non-wind propulsion up until diesel engines (let's not get into steam) became available in the last 100-ish years, it doesn't seem that unreasonable to rely on wind 99.9% of the time and just using the electric motor to cozy up to the dock. Granted, I'm not usually in a big hurry to get back to the office when the wind dies to begin with.

A quiet boat with one less fragrant, dirty-burning liquid on board sounds like nirvana to me. The battery array required is a definite negative, but I like the trade-off. And... *cough* I'm sure it isn't even close to cheap. (looks like the system in that video is either $3995 or $5494 without the batteries)

Okay, okay... maybe I'm defending AtomicPhil less than I am my own obsession with this technology. You got me.

Wow! That Yahoo group is nuts. Almost 12k posts with almost zero organization of the threads.

[s/v Jedi]

About the weight of the batteries: for mono hulls, it can be used for ballast when the batteries are put low. We have our house batteries in the keel sump and they are officially part of the ballast.

cheers,
Nick.

[sailtotrail.com]

Originally Posted by s/v Jedi

About the weight of the batteries: for mono hulls, it can be used for ballast when the batteries are put low. We have our house batteries in the keel sump and they are officially part of the ballast.

Good call.

I referred to the smell and general nastiness of fossil fuels, but I also momentarily spaced out on both the weight and space saved by not lugging around fuel. At 7lbs/gal that can add up pretty quickly if you have even semi-significant tankage.

[s/v Jedi]

Engine + full fuel tanks is 2.3 tons on Jedi...

ciao!
Nick.

[SURV69]

Please consider this scenerio . . .

No wind(meaning no wind to motor against)

No speed(meaning 0.0 knots forward movement

Sunny day

Why is it(so it seems), that movement by motor is always considered in terms of maximum speed, or something close to maximum speed?

In this scenerio ANY SPEED would be more than 0.0 knots and many years ago I read a book(don't ask me which), that referred to "natural" speeds of boats.

The "Natural" speed being referred to was the speed a boat could maintain in calm waters on a windless day with "almost" no force being placed against it.

Beyond this "natural" speed, the power curve rose sharply in order to move the boat faster than the natural speed up to the hull-speed, at which time useable power reached it's usefulness.

If I rememebr right the "natural" speed for my Venture 25 was about 1-1/2 knots, or almost 2 mph.

2 MPH is an alfully lot faster than 0.0 knots.

SO, considering the original question, I wonder how much power a trolling motor would draw to move a sailboat at about 2 or so MPH and if that power draw could be sustained by a decent sized solar panel?

Keep in mind that my scenerio involves absolutely dead air and need for very slow speed.