New propulsion sytems for ships

The search for alternative propulsion systems for pleasure craft will probably become far more urgent in the UK from November. Only commercial vessels will continue to pay reduced duty on red diesel, so that UK boaters will see the cost will rise to around £1-20 per litre from around 60 pence per litre.

Red diesel is a more polluting fuel that standard Ultra Low Sulphur Diesel (ULSD) for cars, and is therefore subject to a higher rate of duty. Currently, red diesel has a rebated duty rate of just 9.69 pence per litre, so boaters will have to shoulder the difference between 56.94ppl and 9.69ppl (47.25ppl) from November.

This means UK Boaters will be paying more than the cost of white ULSD from roadside petrol stations.

http://www.ybw.com/mbm/redalert/blog/20080128180647redalert_blog.html

This also means that the fuel vendor is handed the responsibility of differentiating between commercial users, who will remain legally allowed to use red, and leisure users.

http://www.mbmclub.com/auto/newsdesk/20080128134014mbmnews.html

The news came through today from HM Revenue & Customs, with the following wording: "Private pleasure vessels will continue to be permitted to use marked (red diesel) but at a rate for heavy oil, repaying the rebated duty via the Registered Dealers in Controlled Oils who will declare this to HMRC. An allowance for domestic use will be permitted."

Here is the sting in the tail. Using Straight Vegetable Oil seemed like a reasonable option, but HMRC's Dave Fitzgerald told MBM that it would become a criminal offence to use red diesel for propulsion without proof that you paid the full rate of duty. They dip your tank and find it's white, so the questions start. If you are buying white ULSD from a service station, you are buying a less polluting fuel and apart from the difficulty of transporting it to your vessel and you show proof of purchase, all should be well. You might even be praised for trying to reduce air pollution. OTOH, they might ask for the extra duty on the grounds that you should be using red diesel in your boat and you are avoiding duty by using ULSD. Don't laugh. Lawyers will tell you the practice in courts of law, not courts of justice.

The duty paid was originally only applicable to road vehicles and HM Customs also took their cut if SVO was in your road vehicle. Boats are a different case. SVO in boats could end up with higher duty than SVO in cars.

http://en.wikipedia.org/wiki/Straight_vegetable_oil

The tax harmonisation rules of the EU are responsible for the hike in duty which means recreational boaters will pay more for lower quality fuel and boats don't drive on roads. What next? If you put a wind generator and solar panels on your boat, invest in the EEstor technology and electric motors, then you sail everywhere, without using fossil fuels, the EU will find a reason to tax that as well.

I do have one message of cheer though. As the ice returns to Europe and the entire population of 450 millions or so pack up and move south, the Atlantic will freeze over and the hardiest amongst us will be able once again to walk to North America from Galicia living on the ice and chewing seal blubber, http://en.wikipedia.org/wiki/Solutrean_hypothesis

I am led to believe it's an acquired taste.

Pericles

 

Flapping wing propulsion

Could you help me to find more information about flapping wing propulsion?

 

The Hobie Mirage may be what you want.

http://www.hobiecat.com/kayaking/models_mirage.html

If not, there is much more to be seen at:

http://webpages.charter.net/rcgilmore/Illustrations.htm#MiscWaterPats

Perry

 

Do you have maths ability?

The simplest method is to assume a forced blade angle (this needs to be smooth changing to avoid high forces - sinusoidal) and then work out the angle of attack of the blade relative to the flow vector for the desired speed. From this you can determine the lift and drag on the blade using polar curves. You then need to resolve these forces in the direction of travel and also those acting against the driving force on the blade.

I found the best blade uses a torsion spring to control the angle and this gets more complicated to analyse as you need to consider the dynamics although if you make a really light blade that moves slowly you can neglect its mass so it is simply a force balance. This system works like a variable pitch prop so you can get really good acceleration. Makes a very good towing vessel because you sweep a large area at low angles of attack on the blade.

For a human powered craft running at a 1:1 ratio a NACA0012 blade that is 100mm long and 1m wide does a nice job. It is best to place the blade close as possible directly below the CofG to avoid pitching. Even then you can get natural frequency in the vertical direction if the boat is light. The attached video is around 7kph and is quite relaxed pace. Once over 8kph the vertical oscillation just gets pumped and I found 9kph the absolute top speed. Same boat will do 16kph with a prop. A heavier boat with larger water plane would not be so prone to bouncing.

The rotating action of the Hobie flappers does not produce the same degree of variation in the vertical force so they are better in this regard. Otherwise they are not very efficient. Although as good as a typical outboard prop.

An ideal oscillating foil can reportedly get up to 90% efficiency but I did not get values like this with a constant blade section. Something that can conform to provide an asymmetric blade might get that high as the Cd when relaxed will be very low.

I know a fellow who modeled a dolphin tail using a steel frame and a rubber insert. It was powered with a 90cc Honda motor cycle engine and mounted on the back of a tinny. The blade was about 18" across. It would plane. He once approached the beach and could not shut the motor down. The boat managed to work its way up the beach before he eventually got it shut down.

Rick W.

 

flapping wing propulsion

Thank you for prompt reply but I mean about flapping wing located in tunnel with rectangular cross section.

 

Same maths apply so use the same approach.

Is it intended to recover power or deliver power.

Rick W.

 

You did originally state that the unit was for propulsion. The only reason it would be in a tunnel is to reduce induced drag and this is almost insignificant if you use a high aspect blade. The wetted surface of the tunnel would be a performance killer. It would add a lot more drag than it reduces. Hence no point in using it.

Rick W.

 

Vladimir & Rick:
You're probably way ahead of me on this, but have you reviewed the MIT Robotuna paper published 1994 in Scientific American?
http://www.sciamdigital.com/index.c...LEID_CHAR=6F9D6AB7-76D4-4F7B-9DBE-BBD09ED4066

see also:
http://web.mit.edu/towtank/www/Tuna/Tuna1/tuna1.html
http://web.mit.edu/towtank/www/projects.html
http://www.rbbi.com/folders/tech/product/penguin.htm
http://www.robotic-fish.net/index.php?lang=en&id=robots

 

Yes. There are a few papers around on oscillating foils but they are actually easier to model than a propeller. At any point in the stroke the whole blade has the same foil conditions. My model determines data at each degree of rotation for a bit over one cycle.

The fish modelling is really another dimension because they aim for vortex recovery from the body flexing to the tail to gain efficiency. I just ended up with very high aspect blades that have low induced drag so losses are low in the first place. My widest blade was 4ft and was just over 3" long. I ended up with preferred aspects around 10. Even 4 is OK (similar to attached) but you can feel the benefit with the higher aspect blade.

I gave up on trying to mimic nature with the oscillating stuff after a fellow pointed out that there is nothing in nature that mimics a shaft and bearing. Forced me to consider the virtues of rotating foils - otherwise known as props. You do not see many modern aircraft with flapping wings instead of props either although there are some good models around.

Rick W.

 

Stephen
Did you hear the cost of the robotic Koi in the video. USD256k. It would be nice to have that money to throw at some ideas I have.

I experimented with all sorts of flapping mechanisms. I admire the Hobie system because it overcomes the main disadvantage of the large vertically oscillating blade. Still no where near as good as a prop though.

There remains one aspect of nature that has yet to be bettered and that is the reduction in drag through surface texture, surface films and surface damping that evolution has concocted. The advantage of smooth surfaces is regularly over estimated. I am certain there are cost effective ways of reducing viscous drag but I am yet to find one.

Rick

 

"The California law firm of Kabateck Brown Kellner LLP filed a class action lawsuit this week.

About a decade late.

Those wishing to run on ethinol free fuel only need to go to the airport for fill ups.

By Law aircraft fuel does not contain Ethanol.

Its nice and clean and can take a years storage with addatives.

FF

 

Some news from SkySails:
"Hamburg / Haren/Ems, 3 July 2008. The latest measurements made aboard the cargo ship “Michael A.“ demonstrate how the SkySails-System delivers far more than five times the performance per square meter of sail than traditional wind propulsion systems. With the help of the wind, the 160 square meter kite generates up to 8 metric tons of tractive force – this approximately corresponds to the thrust of an Airbus A318 turbine engine. Depending on wind conditions, ships in the future shall be able to post fuel savings of between 10% and 35% using this auxiliary propulsion system. “Our own measurements show that we were able to temporarily save far more than half the fuel by deploying SkySails in favorable wind conditions,” reports Gerd Wessels (37), managing partner of the Wessels shipping company based in Haren/Ems, adding that “alternatively we were able to increase the ship’s cruising speed from 10 to 11.6 knots with the help of this towing kite propulsion.” The innovative and environmentally sound wind-propulsion system retrofitted aboard the 90 meter long multi-purpose cargo ship “Michael A.“ has been undergoing pilot testing in European waters since the end of 2007."

(bolding is mine)

More at: http://www.skysails.info/index.php?id=64&L=1&tx_ttnews[tt_news]=107&tx_ttnews[backPid]=6&cHash=094576f9d8

Cheers.

 

Guillermo,

According to the "Telegraph", Cornish fishermen are planning to rig sails on their boats. http://www.telegraph.co.uk/opinion/main.jhtml?xml=/opinion/2008/07/20/dl2003.xml

Perhaps the SkySails System will interest them. I know a couple of them.

Regards,

Perry

 

Good for them for seeing it sensibly. I'd love to see the skipjacks return to the Chesapeake Bay, the Deadrise Powerboats are good looking boats but nothing can beat the images of the old sail powered oyster fleet.

 

Perry,
I think the SkySails is still not ready for commercial fishing applications. Some further research has to be done to that end, in my opinion, and it will not be useful for all kind of fisheries. But the time when we'll see wind powered fishing vessels will come again, probably sooner than later.

Cheers.