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 Boat Design Forums Coastal Cruiser

#61
01-24-2010, 04:21 PM
 Guest625101138 Previous Member Join Date: Jan 2007 Rep: 0 Posts: 0
Bert
There is nothing wrong with the wind turbine I have. The blades weigh 2kg. It will stand 60kt winds. It will produce about 1kW mechanical in 20kts. Can be locked to present negligible drag in heavy wind. If I ever set it up on a boat I will not let it weather vane but rather use a motor to control its angle to the wind similar to what I did with manually on the boat test. This allows it to be feathered completely.

Vertical turbines are much less efficient than the two bladed turbine I have. I doubt you could get a VAWT to drive a boat to windward as I have done with my turbine.

Efficiency is an important consideration for a turbine in this application. It should not be confused with the power coefficient.

Rick
#62
01-24-2010, 04:38 PM
 Fanie Fanie Join Date: Oct 2007 Rep: 2326 Posts: 4,254 Location: Safrica
KW you say ?

Power available in wind in Watt = 0.5 x air density x swept area x wind velocity^3

Air density = 1.23kg/m^3 at sea level
swept area in sq meters

If the swept area is 1.5m or ~1.8m^2 the power in a 16km/h wind is going to be about 100W

If the wind goes up to 32km/hr you will get around 800W

A 3m rotor in 16km/hr wind will give about 400W, increase wind to 32km/hr gets you 3kW

This is for the horizontal generator, I have no formulas for the vertical ones.

Look for adthyj... sorry can't remember what they call the darn vertical blade things but they are shaped differnt from your picture. They have two vacuum sides, one is on the side and one at the rear to enhance torque
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Fanie

Water ! Just gimme water !
#63
01-24-2010, 04:41 PM
 Willallison Senior Member Join Date: Oct 2001 Rep: 2366 Posts: 3,562 Location: Australia
Rick
I'm a little perplexed as to how you would build a 13 metre, stabilised monohull, with accomodation for 4, that weighs less than 1000kg. The propusion system would have to weigh...what... 200kg? Less the 80kg+ of your crew member leaves just 720kg for the structure....
Remembering that this vesel is to be trailered, so must be durable enough to be launched and retreived as such, not to mention the day-to-day use that a cruing boat must endure.
The calculations you cited were based on 1000kg with one person on board. What happens to the performance once you add the other 3 crew and their belongings, food and water?
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Will
Imaginocean Yacht Design
Logic will get you from A to B... Imaginocean will take you everywhere else...
www.imaginocean.net
#64
01-24-2010, 06:11 PM
 Guest625101138 Previous Member Join Date: Jan 2007 Rep: 0 Posts: 0
Quote:
 Originally Posted by Willallison Rick I'm a little perplexed as to how you would build a 13 metre, stabilised monohull, with accomodation for 4, that weighs less than 1000kg. The propusion system would have to weigh...what... 200kg? Less the 80kg+ of your crew member leaves just 720kg for the structure.... Remembering that this vesel is to be trailered, so must be durable enough to be launched and retreived as such, not to mention the day-to-day use that a cruing boat must endure. The calculations you cited were based on 1000kg with one person on board. What happens to the performance once you add the other 3 crew and their belongings, food and water?
You need to work through the design from scratch. It cannot be compared with a planing boat that has a huge amount of power by comparison and large concentrated loads at the motor plus slamming loads on the bottom.

Did you see the power required I posted above? The 4.5kW motor I have weighs 11kg. I have estimated 50kg for the mechanicals and electrics, which would also include a turbine if used. Lithium batteries weighing 100kg will give useful range - they are up around 100Wh/kg. Standard commercial solar cells for 1.2kW nominal weigh 70kg.

The red 8m boat that is scaled down boat of similar proportions weighed 54kg as a bare hull before fitout. With two on board and gear to be self sufficient for two weeks it has a total displacement of 420kg. It has 40kg of keel for stabilising rather than buoyant stabilisers. There are two lead acid batteries for instrumentation and other needs such as water making. It also has solar panels and wind turbine for all needs but propulsion. But the human engine operates at about 26% efficiency compared with 85% for electrics - so lots of food/fuel has to be carried.

The original boat on this thread got to the detailing stage and the bare hull estimate was 250kg. I estimated 1100kg one-up for that boat but that was with lead acid batteries of 240kg. The stabilised monohull has more panel area but the main hull shape, being slender, has very small unsupported spans. The stabilisers are boxes with pointy ends and provide stiffening along the side of the cabin. So it has some nice structural features for inherent stiffness without going to heavy panels.

It might be 13m long but the total displacement with crew is 1t. There would be selective strengthening in wear zones and some solid floatation in obvious collision areas. But is is only 1t that is carving it way through the water - no slamming.

With hindsight the 8m red boat would have been better as a stabilised monohull but it was already fully detailed when the idea for the stabilised monohull with a cabin came along. It could have been built without the keel although the motion in a beam sea might not be as good.

By comparison with what Rob Denney is doing I am proposing a heavy boat:
His 15m proa with two separate hulls, joining structure and mast/rigging is looking like it will come in under 800kg.

If someone wants a design for a 13m solar boat detailed it can de done but it will cost and take time.

With the smaller day boat my main concern is keeping windage low so it does not get picked up and flipped by the wind.

Rick W
#65
01-24-2010, 06:25 PM
 Guest625101138 Previous Member Join Date: Jan 2007 Rep: 0 Posts: 0
Quote:
 Originally Posted by Fanie KW you say ? Power available in wind in Watt = 0.5 x air density x swept area x wind velocity^3 Air density = 1.23kg/m^3 at sea level swept area in sq meters If the swept area is 1.5m or ~1.8m^2 the power in a 16km/h wind is going to be about 100W If the wind goes up to 32km/hr you will get around 800W A 3m rotor in 16km/hr wind will give about 400W, increase wind to 32km/hr gets you 3kW This is for the horizontal generator, I have no formulas for the vertical ones. Look for adthyj... sorry can't remember what they call the darn vertical blade things but they are shaped differnt from your picture. They have two vacuum sides, one is on the side and one at the rear to enhance torque
The turbine diameter is 2.2m. May not look it in the video but easy enough to scale by length of the boat at 7.2m. Blades are 1.1m long and nominally 100mm chord. So I have blades with total area of 0.2sq.m sweeping 3.8sq.m.

Power in the incident air stream at 10m/s is 2.28kW. So CP for 1kW would be 43%. I could not get to that figure in the design as I am chasing efficiency not CP so it is less than 1kW but close.

Rick W
#66
01-24-2010, 06:47 PM
 Fanie Fanie Join Date: Oct 2007 Rep: 2326 Posts: 4,254 Location: Safrica
1kW in a 36 km/h wind, yes it is possible. A lot also depends on the efficiency of the rotor, if that is made to handle it.

1000W is a lot of power. The problems we sit with wind power generation is the limited max power because it is wind, the efficiency of the turbine and of course the wind speed.

If the battery gets fully charged (I assume you will use one) you have to either dump load (keep motoring or burn a big globe or heat water ) or have a regulator that can handle the now becoming high voltage from the rotor - or trim the blades out of the wind.

I can handle everything but when you need wind it's usually elsewhere, so take a fishing rod and make sure there are actually fish. The moment you drift into waters where fish are the wind will momentarily pick up. Out of the fishing area the wind will promptly die down From experience

Mmmm... when you dump load you can burn a 1000W little heater plate. At least you can have heated tinned food
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Fanie

Water ! Just gimme water !
#67
01-24-2010, 07:16 PM
 Guest625101138 Previous Member Join Date: Jan 2007 Rep: 0 Posts: 0
When I was testing the wind turbine I either had too much wind or too little.

The first time I took it out there were gusts over 70kph and it was frightening. I actually capsized the boat. The prop would churn the water white when it ventillated and lost grip as waves passed by. It would then bite and the boat would leap forward.

On the second test, when the video was taken, the wind was flukey and I had to give the turbine a spin to get it moving and increase the apparent wind. Once moving it did not need much to keep advancing.

From the first experience I quickly learnt why I need the ability to stop the turbine or feather it. The spider that allowed me to easily feather the prop was a result of that learning.

It also became clear that there is considerable benefit in decoupling the turbine from the prop through an electrical system. The turbine can be set up with a maximum power targetting routine irrespective of what the boat is doing if it is charging batteries. If the batteries are fully charged then the turbine would spin free or be stopped depending on circumstances.

Also if going to windward in a light breeze the boat has higher apparent wind so the windspeed is increased to something useful. On the other hand going downwind the apparent wind decreases. In that case it may be more economic to power the air prop as assisted propulsion to take greater advantage of the 3.8sq.m sail.

I figure using solar, wind and batteries as potential power sources it will be more consistent than sailing. I could do 4kts with pedal power if I needed to get somewhere and it was dead calm, dark and batteries were flat.

The challenge in going long distances at best average speed would be to aim for a steady speed consistent with the ability to recover the required energy from wind and sun while using the capacity of the batteries. A bit different to sailing but similar mental challenge of picking routes and times based on records and making the most of prevailing conditions during the voyage.

Rick W
#68
01-24-2010, 07:17 PM
 Willallison Senior Member Join Date: Oct 2001 Rep: 2366 Posts: 3,562 Location: Australia
Quote:
 Originally Posted by Rick Willoughby You need to work through the design from scratch. It cannot be compared with a planing boat that has a huge amount of power by comparison and large concentrated loads at the motor plus slamming loads on the bottom. Rick W
Huh... you would have thought they'd have taught me that when I did me design degree.....
Ok - lets work through this again....
Now you are saying that the total displacement, with crew is 1000kg
Seems I was a little optomistic with my powertrain weight... by your estimate it comes to 231kg.
4 crew, say 300kg, plus their clothing etc another...40kg
Food + water for a few days... a minimum of 50kg
It's a 'cruising boat', so I'm assuming that you will be cooking and...well...pooping on board, there's another 15kg, minimum.
Ropes, fenders, anchor, safety equipment would come to a minimum of another 30kg.
We haven't considered interior structure yet... berths, seating, etc, etc.. but we are already looking at well over 650kg.
Now, I'm not saying that you can't build a 13m shell that weighs around 300kg. I'm simply querying how you would propose doing so, and finishing up with a boat that can accomodate 4 people for several days, is practical, durable and that can be had for anything thar resembles a reasonable cost?
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Will
Imaginocean Yacht Design
Logic will get you from A to B... Imaginocean will take you everywhere else...
www.imaginocean.net
#69
01-24-2010, 08:19 PM
 Guest625101138 Previous Member Join Date: Jan 2007 Rep: 0 Posts: 0
Quote:
 Originally Posted by Willallison Huh... you would have thought they'd have taught me that when I did me design degree..... Ok - lets work through this again.... Now you are saying that the total displacement, with crew is 1000kg Seems I was a little optomistic with my powertrain weight... by your estimate it comes to 231kg. 4 crew, say 300kg, plus their clothing etc another...40kg Food + water for a few days... a minimum of 50kg It's a 'cruising boat', so I'm assuming that you will be cooking and...well...pooping on board, there's another 15kg, minimum. Ropes, fenders, anchor, safety equipment would come to a minimum of another 30kg. We haven't considered interior structure yet... berths, seating, etc, etc.. but we are already looking at well over 650kg. Now, I'm not saying that you can't build a 13m shell that weighs around 300kg. I'm simply querying how you would propose doing so, and finishing up with a boat that can accomodate 4 people for several days, be durable and that can be had for anything thar resembles a reasonable cost?
Scaling from what I have done before, the panel area is around 120sq.m including bulkheads. Without going into any detail design I expect the average panel weight around 3kg to be adequate. Lighter if CF was used. So basic hull about 360kg using glass.

Points of difference in terms of your weight calculations, I was basing crew on a family of 250kg. Water would be determined on lightest option of water maker versus carrying it depending on the length on board and ability to reprovision.

The cost of the hull might be quite unreasonable to get the strength to weight it needs. Someone might choose to trade a little performance for lower cost. Until the detail is done I cannot be certain if it can be done within a 1000kg weight target. The process is iterative and I have not even done one iteration on a 13m hull. If the weight ended up at 1100kg it is still consistent with the concept. If it was 4t you would be better looking at a different concept - that was the question that lead into the current interest in this thread. Likewise if you wanted to cruise faster than 10kts in something trailerable you would probably take another path than a stabilised monohull. That is how Matt Marsh got to his trimaran; see posts #21 and 24 here:
Boxy, simple ~8 m electric powercat
It gives more insight into where a particular configuration has an advantage.

Rick
#70
01-24-2010, 09:10 PM
 Willallison Senior Member Join Date: Oct 2001 Rep: 2366 Posts: 3,562 Location: Australia
Ok - 3 kg/sq.m would allow for approx 12mm foam core (80kg/m^3 density) with 600gsm skins. Possibly doable, but pretty fragile. Of course, that doesn't allow for any tabbing, fairing, painting etc, which tend to add around 15% to the weight. Of course, the cost of the panels alone (assuming you can build the whole boat out of them) would amount to around \$25,000....
Building a cruising boat is going to be vastly more complicated than a day boat... as an example, facilities like the head have to be considered... in most parts of the country you will have to have a holding tank anll its associated complications. I haven't researched the smallest units lately, but I doubt whether a watermaker is a practical option on a boat that has very limited power available. The manually operated versions are emergency units only.

I realise this is just an idea of yours at this stage. I'm just trying to cast a dose of realism into the project....
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Will
Imaginocean Yacht Design
Logic will get you from A to B... Imaginocean will take you everywhere else...
www.imaginocean.net
#71
01-24-2010, 10:15 PM
 Guest625101138 Previous Member Join Date: Jan 2007 Rep: 0 Posts: 0
Quote:
 Originally Posted by Willallison Ok - 3 kg/sq.m would allow for approx 12mm foam core (80kg/m^3 density) with 600gsm skins. Possibly doable, but pretty fragile. Of course, that doesn't allow for any tabbing, fairing, painting etc, which tend to add around 15% to the weight. Of course, the cost of the panels alone (assuming you can build the whole boat out of them) would amount to around \$25,000.... Building a cruising boat is going to be vastly more complicated than a day boat... as an example, facilities like the head have to be considered... in most parts of the country you will have to have a holding tank anll its associated complications. I haven't researched the smallest units lately, but I doubt whether a watermaker is a practical option on a boat that has very limited power available. The manually operated versions are emergency units only. I realise this is just an idea of yours at this stage. I'm just trying to cast a dose of realism into the project....
The idea of a stabilised monohull makes a fast solar cruiser possible. The components for it are gradually becoming more practical and cost effective.

I would want a budget of about \$100k to start a 13m boat as a project. I do not have a full tally on the 8m red boat but I expect to do it from scratch and paying for all materials would be about \$30k plus labour. Although this boat has the best of everything. One of the real risks with this boat is suffocating because the ports and hatches seal so well it holds pressure. The vent should never be closed. It is a full ocean capable mini cruiser with two cabins and a food/storage locker:
A 13m version using the stabilised monohull form would have walkthrough head room. The cabin height in the pedal cruiser is set to allow bending forward in a seated position. Anything lower is not practical to live aboard. If you want to stand a hatch needs to be opened and, with two on board, it is is best to do it one at a time otherwise it goes to about 60 degrees roll before stiffening up.

Once built, a solar powered boat never needs fuel. I guess that is a carrot for some. Essentially the range is only limited by crew provisions. The wear and tear and ongoing maintenance would be small compared with a sailing boat. There is no need to leave the cabin to set sails.

You can get small electric powered water makers and they are quite efficient but don't expect to be having hot showers unless it is hot weather - maybe solar heater?? The manual watermakers will make about 4 litres per hour at easy level of exertion.

Your comment on realism is noted. The world is full of skeptics and there is some satisfaction in proving them wrong but I do this as a hobby and building a 13m boat is beyond my allowance for this hobby at the moment. I expect a detailed design for 13m cruiser with only solar could be done for around AUD12k if anyone wanted it. I have not got into all the bits for a turbine yet. Believe it or not there are no commercial maximum power point tracking turbine controllers for small turbines. So still technology gaps.

Rick W
#72
01-24-2010, 10:24 PM
 Willallison Senior Member Join Date: Oct 2001 Rep: 2366 Posts: 3,562 Location: Australia
I think you need to define just what you mean here by cruiser. In the current context, one man's cruiser is another man's coffin..... A boat that simply a longer version of the 'red boat' would certainly conform to many's idea of the latter!
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Will
Imaginocean Yacht Design
Logic will get you from A to B... Imaginocean will take you everywhere else...
www.imaginocean.net
#73
01-24-2010, 10:42 PM
 Guest625101138 Previous Member Join Date: Jan 2007 Rep: 0 Posts: 0
Quote:
 Originally Posted by Willallison I think you need to define just what you mean here by cruiser. In the current context, one man's cruiser is another man's coffin..... A boat that simply a longer version of the 'red boat' would certainly conform to many's idea of the latter!
It is a scaled version in ALL dimensions and slight larger dimension in height than straight scale to get 2m head room. It would have similar accommodation to a 10m light to moderate displacement yacht. It would have form stability better than most 3m wide planing hulls. Power is an order of magnitude higher than what can be achieved with human power.

I guess another man's cruiser is a noisy, smelly gas belching tub to yet another.

Rick W
#74
01-24-2010, 11:12 PM
 Willallison Senior Member Join Date: Oct 2001 Rep: 2366 Posts: 3,562 Location: Australia
Quote:
 Originally Posted by Rick Willoughby I guess another man's cruiser is a noisy, smelly gas belching tub to yet another. Rick W

Ok - so you're not envisaging Mum, Dad and the kids all sitting in a row to eat, sleep and...well...the other thing....

Some proper preliminary calculations should prove interesting....
__________________
Will
Imaginocean Yacht Design
Logic will get you from A to B... Imaginocean will take you everywhere else...
www.imaginocean.net
#75
01-24-2010, 11:12 PM
 Marco1 That's lunch right there Join Date: Oct 2009 Rep: 240 Posts: 136 Location: Sydney
Quote:
 Originally Posted by Rick Willoughby I have been putting my ideas for a coastal cruiser into a viewable format. An image is attached. It is at an early stage of development. Length is 14.7m, overall beam is 1.6m, WL beam 1.14m and displacement 1t. It has a 1.2kW wind turbine and 5 X 200W solar panels. There is 9600Wh of battery storage, I am planning on a 48V system that will give peak output of 4.74kW. This should give maximum speed of 12.4kts. Daytime cruising using storage, wind and solar should be at 10kts requiring 2.3kW. Overnight cruising using wind and solar for running and charging through the day and batteries at night requires 1.15kW to do 8kts. There is enough accommodation for two people overnight and will be roomy enough for four during day cruises. Performance calcs are based on two on board. It seems a practical concept. Should take about AUD25k to build and equip it. The hull is in three pieces so this will make it easy to transport and reduces the area needed to build it in. Any comments on experience with large solar panels, deep cycle batteries and small wind turbines will be appreciated. Rick W.
Rick, on the topic of turbine to generate electricty... I am sure you are aware that the wind energy required to turn the turbine is much more than the energy produced or you would have the perpetual motion machine.
Your turbine can only capture the force of the wind in the little circle occupied by the blades, yet the vessel will catch the force of the wind on all it's body...including the turbine who transmits the unused force component of the wind onto the boat. There is no way that the little electricty generated by the turbine can compensate, let alone give a positive balance of energy when going against a head wind.
So your tubine will only work if you have wind in the same direction of travel or close to it and will need to be shut down and yet its structure will still work against you if you are navigating into the wind. The only way you can have a wind turbine on a boat is if you could fold its structure completely down and away when the wind is not favourable and put it up when winds are with you, much like a sail.
Your turbine will work for you when at anchor like the solar panels but not as well underway.

I don't have the time nor the know how to challenge or support your calculations on solar panels, but I remember a time I was interested in solar cars conversions and my first thought was for a commuter car to go to work and back and sitting in a carpark in the sun to recharge. However my idea was short lived when I realised that the whole day in the sun for a car covered in solar panels would have given me power for something like 20K. Better than nothing but not worth the expense. I hope your figures are better than that.
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