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Stumble · 23-01-2017, 13:21

Quote:

Originally Posted by buzzstar

Another side to the same story. Sails and sailing aside, what about water flow when the boat at anchor? We seem to discuss all kinds of anchoring ideas and problems. What about the generation of power (electricity) by using the forces that act on the hull and keel while at anchor? I have no particular ideas, but it seems the OP and maybe a couple of others might.

It is absolutly possible, you just need a very, very large prop for it to work. Flowing water has the same available power if it's the boat moving the water or the water movingly past the boat. The important question is the relative speed difference of the generator and the water.

If you anchor somewhere with a 5kn current modern hydro generators will produce a reasonable amount of power.

On the other hand I would never voluntarily anchor somewhere with 5kn of current.

captlloyd · 23-01-2017, 14:45

I don't know about the canting keel idea but I envision something between the anchor and the boat. Tremendous pulling force not really being utilized for anything. We may be straying from the OPs original question or not. As I originally stated before, there may be times when while underway with very strong wind conditions SOME sailors might be willing to trade-off a bit of speed for some power generation by some sort of hydro generator. The mind like a parachute must be open to function.

Kelkara · 23-01-2017, 15:08

Quote:

Originally Posted by captlloyd

I envision something between the anchor and the boat. Tremendous pulling force not really being utilized for anything.

Oh but it is being used for something!!! It's being used to hold your boat in place!!!

If you want to use some of that force for something else then you'll have to let the boat move e.g. drag the anchor.

SV Windrush II · 23-01-2017, 15:08

Whatever way power generation is used, it needs to be as consistent as possible and dependable.
Depending on a rolly anchorage would not be one of them I would think. Like one of the posters, I try to stay away from those anchorages. The other thing I have noticed through testing is that it takes a LOT of motion to generate any usable energy!
I have been working on a wave/power generator that attaches to the boat with a float and a pivoting arm so that it moves up and down every time a wave goes by the boat, (Or rocking back and forth) whether its moving or at anchor.
It has little drag because it rides on top of the water. and can easily hinge up alongside the boat when not in use or to clean it.
I cannot disclose all the details because of patent issues but I will update you as I get it developed.

**skipmac** · 23-01-2017, 15:22

Quote:

Originally Posted by captlloyd

Now you are talking. Tremendous forces generated from a floating object and the earth. (Bottom) I have seem many proposals of this idea, it has super potential.

But isn't it a cruiser's goal to avoid a rolly anchorage? Think I would rather run a generator than spend nights rolling at anchor.

**skipmac** · 23-01-2017, 15:28

Quote:

Originally Posted by captlloyd

I don't know about the canting keel idea but I envision something between the anchor and the boat. Tremendous pulling force not really being utilized for anything. We may be straying from the OPs original question or not. As I originally stated before, there may be times when while underway with very strong wind conditions SOME sailors might be willing to trade-off a bit of speed for some power generation by some sort of hydro generator. The mind like a parachute must be open to function.

Like the rolly anchorage, a situation where there is tremendous force on the anchor is not a regular occurrence and is to be avoided.

Hydro generators are not a new idea. They've been around for at least 40-50 years. Various designs have been tried, originally towed units, the most recent successful design is a unit that lowers like an outboard.

Hydro generators work but to get a lot of power they need to be big which means large forces, serious attachment to the boat, etc. No getting around the physics.

captlloyd · 23-01-2017, 15:31

Quote:

Originally Posted by Kelkara

Oh but it is being used for something!!! It's being used to hold your boat in place!!!

If you want to use some of that force for something else then you'll have to let the boat move e.g. drag the anchor.

No, the bow of the boat constantly moves up and down at SOME anchorages. And if you don't think it is generating a hell of a force, try a snub it sometime. And it does't have to move much to turn into mechanical power. Think of what happens when you try to start a chain-saw.

captlloyd · 23-01-2017, 15:37

Quote:

Originally Posted by skipmac

But isn't it a cruiser's goal to avoid a rolly anchorage? Think I would rather run a generator than spend nights rolling at anchor.

Yes, but it sure does'nt always turn out that way. Are you saying that you always anchor in a perfectly calm harbor? Not me, look, these ideas are not going to apply to everyone all of the time. Do you always have wind to sail?

buzzstar · 23-01-2017, 15:41

Once again I am less knowledgeable than most, but my understanding of the big plates sometimes used by powerboats in the roily anchorages are absorbing at least some of the power of the waves that could be used to produce electricity.. Would not doing the same to produce electric power have a similar effect, although perhaps to a lesser degree. I also want to know how those who discard roily anchorages so easily manage to find alternatives when most of us cannot, but would if we could.

topmast · 23-01-2017, 16:12

Reminds me of the push me pull you lever system I developed years ago for a pivoting hingedcentre board Letting the boat roll her guts out on downwind passage. Chains on the top inboard end pulled thru bicycle hubs to drive a geared up generator That's about all I can remember about it as I was pretty drunk at the time

Kelkara · 23-01-2017, 17:10

Quote:

Originally Posted by captlloyd

Think of what happens when you try to start a chain-saw.

Using the anchor to kick-start a stubborn diesel ... now you're on to something

.

hsi88 · 23-01-2017, 17:49

While we are doing a little "blue sky" analysis, I wonder if one could harness galvanic corrosion using the abundance of seawater flowing over whatever dissimilar metals were appropriate to generate electricity using some sort of electrochemical reaction or harnessing some form of generated magnetism using a steel hull or keel. I'm no scientist (obviously) but wonder what might be possible.

**skipmac** · 23-01-2017, 17:54

Quote:

Originally Posted by captlloyd

Yes, but it sure does'nt always turn out that way. Are you saying that you always anchor in a perfectly calm harbor? Not me, look, these ideas are not going to apply to everyone all of the time. Do you always have wind to sail?

No I don't always anchor in a perfectly calm harbor but anchoring in rolly, wavy, high current harbors is very uncommon for 99% of the boats. So uncommon that it would not be cost effective or generate enough power to justify the investment in time and money for a probably elaborate, custom made system that would generate a small amount of power a very small percentage of the time.

Much better to invest in a system that will work the majority of the time in real world situations and generate more usable power for the investment.

Scotty Kiwi · 23-01-2017, 18:03

I was involved in electric vehicle development for a Chinese company - marketing development, not technical.

Naive ("sophomoric" - great word!) suggestions from time to time would be along the lines of placing wind generation in the roofracks, handlebars etc etc to recharge the power supply.

The Professor of Aeronautics response (apart from disguised eye rolling) would be that such generation devices were (in the late 00's) around 30% efficient. There is always a cost of generating power. For these, a 70% loss in normal operation. Its OK to lose energy when going downhill or braking, but these times are relatively few. More importantly there were more efficient, lower cost, lower maintenance ways of harnessing that that loss than little windmills.

It seems all this is analogous to the OP's thinking. It makes sense that a similar 70% or so inefficiency percentage would apply to hull or tow hydro generation on a boat.

IMO any loss percentage at all puts paid to suggestions of hydro generating power for use in propulsion. But most boats would be very happy to sacrifice a tiny bit of forward speed on a long trip for the comfort of charging batteries to run lights, make a bit of ice. And where I am from there's normally too much wind, and the boat often has wind and water energy to burn. But I wouldn't want an in hull system that is permanently engaged, and therefore susceptible to weed growth, breakage, difficult to service.

The OP, as a novice, may consider how the Log on a boat (to record boat speed), works. It's a little water wheel, 6 paddle blades about 1cm sq, on the end of a through hull plug. To keep mine accurate, (in low weed growth fairly cold water), I'd have to pull it out every month, have a brief water spout inside the boat, replace the plug with a blank plug, scrape the weed off, put it all back, and then mop up from the water spout. Just another of the myriad of five minute jobs.

A similar but larger device could generate usable accessory power from water flow over the hull, in conditions where the inefficiency doesn't matter. But the maintenance? And my guess is there is more water flow away from the hull, not right next to it (this thought supported by the necessity to calibrate the Log). So the windvane system of a power generating outboard would be attractive to me. (I was reluctant to get a tow generator, as I was damn sure there'd be a day when I'd be too knackered and forget it, wrapping the thing around the prop when berthing (as done to the tender a few times).

There you go.