Coastal Cruiser

Well, sounds like you're almost on to something there. That would be a direct wind to water transfer.

 

PS

This is what I found about "solar powered boats"

Note: This article first appeared in Electric Boat News, volume 18 number 4 (Winter 2005/06)
TECHNICAL REPORT
ELECTRIC POINTS: “WHAT IS A SOLAR BOAT?”
In the seventh of a series of short articles on technical aspects of electric boating,
EBA Technical Officer Paul Lynn discusses solar-powered boats and proposes a
new measure of performance, the Solar Boat Index (SBI).
An eye-catching new craft, furnished with solar photovoltaic (PV) modules, arrives at an
electric boat rally. Onlookers naturally assume she is “solar-powered”. But what exactly
does this mean, and how might we quantify the performance of a boat that uses sunlight
for propulsion?
There is no easy answer. The viability of solar propulsion depends on the amount of PV
carried, the motor power needed to achieve cruising speed, the intended pattern of use
and – of course – the amount of local sunshine. In this article I should like to examine
these factors and propose a quantitative measure, the Solar Boat Index (SBI), to indicate
the comparative performance of a wide variety of craft.
The nub of my proposal is that any boat which, on average, derives 1 hour per day, or 7
hours per week, of summer cruising from its PV modules deserves the accolade “solarpowered”.
Most users confine their boating to weekends, and 7 hours of weekend
cruising is widely regarded as a reasonable amount for an electric leisure craft, whether
solar or not. And I shall show that the criterion is met, in English summer conditions,
provided the boat’s peak PV power is at least equal to one third the power required by its
propulsion motor at normal cruising speed. This, in turn, will lead to a definition of the
Solar Boat Index.
To illustrate the argument, let’s consider a boat having 0.5kW peak of PV modules,
mounted horizontally, and a propulsion motor that requires 1.5kW to drive the boat at
normal cruising speed. According to the above proposal, this boat will just meet the
criterion of being “solar-powered”.
How much energy do the modules produce? Using arguments similar to those in EBA
Information Sheet No.2 on Solar Photovoltaics, in the summer months May to August in
England, 0.5kW of PV may be expected to deliver an average of about 1.5 kWh per day
of usable stored energy to the boat’s batteries. And since the motor needs 1.5 kW at
normal cruising speed, this solar input will clearly allow an average 1 hour cruising per
day, or 7 hours at the weekend, assuming adequate battery storage.
But what is “normal” speed? I should like to suggest 5 mph (8 kph), the speed limit on
the river Thames, for boats based on rivers and lakes; and 4 mph (6.4 kph), the speed
limit on the English canals, for barges and other canal boats. Most people would probably
agree that these are realistic, and enjoyable, speeds at which to travel.
I now propose the following Solar Boat Index (SBI):
SBI = 3 (Ppv)/(Pm)
Where Ppv is the peak power in watts supplied by the PV panels, and Pm is the motor
input power required to give a cruising speed of 5 mph (6.4 kph) on rivers and lakes, or 4
mph (6.4 kph) on canals. I have included the factor 3 in the definition so that a boat
giving an average 7 hours of weekend cruising in England, which is just “solar-powered”,
achieves an SBI of unity (1.0). This is easy to explain, discuss, and remember.
A further advantage is that a boat’s SBI value equals the expected number of cruising
hours per day provided by its PV modules. For example, a boat with SBI = 2 gives an
average 2 hours per day of solar cruising at “normal” speed.
Let’s take some more examples of solar boats, this time real-life ones. My own catamaran
Solar Flair, which completed the first solar voyage along the non-tidal Thames in 2003,
has four 75W PV panels, giving Ppv = 0.3kW, and needs about 0.55kW of motor power to
travel at 5 mph (8kph) in calm water. Her SBI is therefore equal to 3 x 0.3/0.55 = 1.64
(which, I note with relief, is comfortably above unity). The catamaran Collinda, in which
Malcolm Moss made the first solar voyage across the English Channel in 1997, has a
more impressive SBI of 2.8 making her well and truly “solar-powered”. And Cedric
Lynch’s canoe, often seen running at unlikely speeds in weak sunlight, manages an SBI
of 4.3. This one will be hard to beat!
We should also consider the local climate. Data for England should also apply reasonably
well to countries such as Germany, Holland, and the northern half of France. A boat
based in the south of France might get an additional 30% from its PV panels in summer,
and one based in Spain or Australia perhaps 50% more. Such variations, as well as
different patterns of use in different climates, should be taken into account when
interpreting SBI values.
Finally, a few words of caution. An SBI value can only be an approximate indicator of
performance because of the uncertainties surrounding the solar climate and a boat’s
pattern of use. I therefore recommend that SBI’s should only be quoted to 2 significant
figure accuracy. And we should avoid saying that a boat based in England and having an
SBI of, say, 0.80 is definitely “not solar-powered”, or that one with an SBI of 1.2
“definitely is”. A little flexibility is required. With such provisos I launch the SBI upon
uncharted, but hopefully unruffled, waters.

 

Hi Marco,

The 105Ah batteries I have weigh 35kg's. To make up 1500Ah (~1500W for one hour max !) would require 15 of them at a wopping 525kg's.

I'd be carefull of 'articles' written by some. People have all kinds of weird ideas about power and especially electrical power and it's capabilities.

Some think a battery is an unlimited capacity device that will store unlimited power as long as you keep on pumping it in.

So if you charge the 12V 65Ah battery at 60A for 5 days that is 120 hours then you should have 60 x 120 = 7200Ah.

Hence the motor draws 30 A then surely you can go for 240 hours... Right ?

RIGHT


I always say to people take the exersize bike and put a generator on it's hind wheel, then paddle just to keep the 25W TV going for 15 minutes

People have no clue how much only a 1000W is.

 

I know enough about materials that I can get very low weight but it comes at a price. Whether the high cost of expensive materials can be offset by the low weight needs a few optimisation loops.

The boat would need to be getting up to 16m or more before you could think of separate sleeping cabins or it would be boxy and that adds wind resistance.

Going longer with the same target speed allows heavier displacement. So it scales up well.

Rick W

 

Hi Fanie...yes, you are probably right and I count myself among the ignoramus on solar power.
However that small article only tries to define what a solar vessel is, as opposed to an electric boat with some form of solar assistance that after a few hours a week out at sea will have to come back to port to plug in the grid to recharge, or carry a very long lead.
From the post of this thread it seems the builder is trying to build a purely solar unassisted self sufficient boat with its only source of power being turbines and solar cells. That is what I understood anyway.
My observation is that the turbine will work ok with favourable wind whilst on the way and will work against it badly with the wind from the wrong direction...plus the surface needed for pure solar propulsion is probably disproportionate for the size of the boat.
But like I said I am no expert so I may well be wrong on the solar cell count. I know I am right on the turbine account though.

 

Have a look at this video clip and explain what is going on:
http://www.youtube.com/watch?v=CCN2MlbVJG0
You might think of it as perpetual motion but I know it as basic physics. Power in equals power out plus system losses.

Windage on a streamline cabin on a boat of this size is less than my body presents to the wind. Same thing for a proportionally larger boat.

The ability to sail directly into the wind is well known and many have done it on water and land.

Rick W

 

ahhh... yes, but with increased length and displacement comes increased wetted surface and power requirements. There ain't no free lunch here. Increased length for a given displacement will generally see improved efficiency as the reduction in wavemaking drag will more than offset the increased wetted surface.

In terms of the weight, I'm skeptical as to the viability of the project...full stop. Like you, I haven't gone to the trouble of doing detailed weight estimates or structural calcs, but nothing you've described to date makes me believe that you can engineer a 13 metre cruising boat, in even the most spartan of terms, that will come close to making your 1000kg target. I will happily be proven wrong, of course.... but what's the sense in suggesting such a thing, in any serious sort of way... to go to the trouble of making a 3D model of it, unless you've done even the most preliminary of weight calculations?

 

Solar cells are only about 24% efficient, but consider that it is in bright south african sun, for about 8 hours per day here, and if the solar panel is pointed correctly at the sun. There is about 1000W of energy in a sq metre of healthy sunlight.

It has been raining on and off for the last few months here, so solar is not the hottest power topic.

I have 6 x 1A 12V solar panels on my roof I've been monitorring for some time. The power output of these 6 panels seldom comes any where near 6 Amp. In clouded conditions the output is only a few hundred mA.

On a boat the panels are never situated just perfect, so you wil only get a part of it's capacity IF the sun is up, and cooking.

The other drawback solar's have is their sheer size if you want anything usable from them.


I would highly recommend anyone going to sea with solar panes and batteries a s power source to take an alternative energy source...
The little Ryobi power generater I have can supply 800W continuous for 6 hours on a few liters of fuel.
How many weeks can I power the generator for the price of one big solar panel

 

I have little doubt it can be engineered. I have seen a lot more engineering in my life than most to have the confidence to say that.

Rick W

 

Have you looked at the video yet? Still think you are right?

Rick W

 

Hi Rick, yes I have seen the you tube videos. I still don't think they can go against the wind.
If that would be possible, then electric cars would have a turbine on the roof
to recharge the batteries and we all know that is utopic.

A turbine can only convert a fraction of the force of the wind into power to turn the prop and ... go against the same wind. However all the rest of the force of the same wind, (forget the boat resistance factor) the component of the force that does not turn the blade, is transmitted to the frame of the tubine to the boat and the total balance is negative. What you see in the video is an electric boat that is using the electricity stored in the batteries to go against the wind (if that is in fact what we are watching, and I can not tell which direction the wind is coming) and is generating some energy from the turbine in the wind yet LOSING a lot more from keeping that thing up there. If you had two equal boats both with charged batteries both into the wind, one with no accesory supply and the other with turbines. When going into a head wind the one without turbine will go further. Guaranteed.

That going into the wind with turbines is the modern version of the perpetual motion machine. Just think about it. I am not being contentious.

http://www.youtube.com/watch?v=IzGCYaJbf0A&feature=related

Here is another one, and I still say that even that million dollar cat CAN NOT go against the wind and be powered by it at the same time. That is baloney

 

Majority of boats have a single source of power. Some have a major source and an auxiliary. A solar/wind boat has two completely independent sources of power having unlimited supply. As long as you can capture it, it will be available at some time.

As a last resort I could hold around 4kts in a 13m boat under my own power. A great advantage of an easily driven hull. There is no boat that can guarantee 100% reliability. It could fouled fuel or broken mast or the myriad of other things that can go wrong in any boat.


Rick W

 

Yes they can The reason for that is the prop like you see in Rick's video has gain, ie the prop speed can exceed the wind speed. A little spinoff...


I agree Rick, but I think the difference is that the wind and solar resources are a bit unreliable due to weather conditions, ok sometimes. Most sailboats do have the little iron horse for backup, and it is easier to see if the fuel tank is full or not. Batteries full or empty are kind of difficult to see.

I've been out fishing when after a few hour's the batteries go on strike for no reason at all - after I thought they should be fully charged.

 

maintenance costs

Rick, you have mentioned that with the solar boat you don't need fuel. What I'm wondering is to what extent this would reduce the overall cost of cruising. What I'm thinking is that if you could install a perpetual motion machine for an engine but you had to replace it every hundred miles, you haven't really gained much. Do you have a feel for the relative ongoing costs for solar and wind vs. diesel? For example, how often do you need to replace the bearings on a wind turbine? How often will it get destroyed by wind and have to be replaced? How often will water get into the electronics of the turbine or the solar sells and require replacement? How often do you have to replace the batteries? Things like that.

 

I am not thinking about it. I was doing it in that clip. It is not perpetual motion. The turbine and prop do not have to be particularly efficient to do it but low efficiency limits the boatspeed to windspeed ratio.

It is just gearing. If I replaced the propeller with a winch connected to a wind turbine through a reduction gear could the winch pull the boat into the wind? The only difference with a propeller is that there is a bit of slip in the water.

They have wind turbine powered vehicle races in the Netherlands now:
http://www.youtube.com/watch?v=nBm6DU_t9i0&feature=related


Rick W