Hi Randy. I read you comment on kites and could not agree with you more. I wanted to investigate a kite for DOMINO and 6 mo ago did extensive research on the internet and only found a site that did kites for large commercial cargoboats.I emailed them and got no response. Now, thanks to your comment, I went back to that same site and found that they now seem to be doing kites for commercial boats. I have not had time to check the details, but, I invite you to check the following site www.kiteship.com Let me know what you think. Jean Pierre Dufour jpjdufour@yahoo.com www.dominocat.org power-catamaran-request@lists.samurai.com wrote: Send Power-Catamaran mailing list submissions to power-catamaran@lists.samurai.com To subscribe or unsubscribe via the World Wide Web, visit http://lists.samurai.com/mailman/listinfo/power-catamaran or, via email, send a message with subject or body 'help' to power-catamaran-request@lists.samurai.com You can reach the person managing the list at power-catamaran-owner@lists.samurai.com When replying, please edit your Subject line so it is more specific than "Re: Contents of Power-Catamaran digest..." Today's Topics: 1. Kite Sail for a power cat (Captain Randy Boelsems) 2. Re: asymmetric boards (Malcolm Tennant) ---------------------------------------------------------------------- Message: 1 Date: Sat, 17 Mar 2007 07:21:10 -0800 From: "Captain Randy Boelsems" Subject: [PCW] Kite Sail for a power cat To: Message-ID: <000f01c768a7$e5a9dc10$f219d74b@ARSLAPTOP> Content-Type: text/plain; charset="iso-8859-1" Hello all, My wife and I gave up the sailing cat world for power when our kids were born. Now that they are a bit older (and because of the ever increasing cost of fuel) I am thinking of going back to the blow boat side, part time, because I am not ready to give up the power cat that we love. I have been trying for several months to find out about kite sails for our power cat. I have tried to contact Kite Sail and Outleader (http://www.kiteship.com/outleader.php) but they do not respond to phone calls or emails. Does anyone have recomendations for a company that produces kite sails for power boats? We have a down wind run home from Catalina on a regular basis and a kite sail should suit us if we can figure out how to launch and recover the kite with out a mast. Randy Boelsems Gecko Gecko 1992 Euphorie 40 Power Cat Huntington Beach, CA http://geckoyachtcharters.com http://quickline.us ------------------------------ Message: 2 Date: Sun, 18 Mar 2007 10:04:15 +1200 From: "Malcolm Tennant" Subject: Re: [PCW] asymmetric boards To: "Power Catamaran List" Message-ID: <001c01c768e0$34509dd0$bb01a8c0@malcolm> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Bob Kupps. Dear Bob, If you go to Abbott & Von Doenhoff "Theory Of Wing Sections" you will find out more about wing sections [plan forms are another matter] than you probably ever wanted to know. You will find it is obvious as you look at the data for the airfoils that the asymmetric sections have a better lift to drag ratio ie: for foils of a given area, aspect ratio and percentage thickness the asymmetrical section may develop as much as 50% more lift for the same amount of drag. It may also do this over a greater range of angles of attack. So why aren't asymmetric section foils more widely used? Firstly foil sections, are usually used on keels which can't be easily raised and lowered which obviously means they are useless for a boat of this type. Secondly, they usually have to be able to be raised and lowered except on proas which often change ends to "shunt" [see Disco Volante]. This in fact is the crux of the whole issue- the raising and lowering of the foils. Early C-Class cats used asymmetrical foils and raised one and lowered the other when they tacked. They no longer do this, the gains were just not worth it. I have used asymmetrical foils on a number of trimaran designs [sylph, stinger,wild thing, flying circus] because on these boats the windward foils mostly come clear of the water,reducing the loads making them much easier to retract, when the boat tacks because they are located in the floats. They have occassionally been used on keel boats as dagger boards. In fact they are de rigeur on the various round the world race boats but these are racing boats that will often spend thousands of nautical miles on one tack and are prepared to expend the effort required to raise and lower them. And effort there is, lots of it. We had tandem dagger boards on the "Cordova". These were hydraulically operated and "chinned" themselves up and down in their cases. It was found that such were the loads when underway that there was not enough battery power to drive the electro-hydraulic unit that raised and lowered them. If you wanted to change the position of the dagger boards it was necessary to turn on at least one motor. So the owner very wisely decided to remove the daggerboards. In fact, we found that with the CS hull form, the dagger boards were not really necessary. The CS hull is very close winded by virtue of its shape. However if you will be operating in similar conditions to the Volvo boats, and your hull form requires the use of foils, it might well be worth considering them and installing systems that make them easily retractable. I was glad to hear that the 20% foil was a typo. It seemed more like a lifting body! I have used a number of different foil sections over 40 odd years and kept coming back to the good old traditional NACA0012 [I actually use a slightly thicker 13% section] for the rudders and a more laminar flow section, the 65-013 for the symmetrical dagger boards.Asymmetrical foils are usually 64A413 sections, or as close as I can get them without CNC 5 axis milling. Abbot & Von Doenhoff is one of the most heavily thumbed volumes in my reference library. I hope this helps with your decision making. Regards, Malcolm Tennant. MALCOLM TENNANT MULTIHULL DESIGN LTD PO Box 60513 Titirangi, Waitakere 0642. New Zealand. ph +64 9 817 1988 e-mail: malcolm@tennantdesign.co.nz www.tennantdesign.co.nz www.catdesigners.com ------------------------------ _______________________________________________ Power-Catamaran Mailing List End of Power-Catamaran Digest, Vol 25, Issue 9 ********************************************** --------------------------------- Finding fabulous fares is fun. Let Yahoo! FareChase search your favorite travel sites to find flight and hotel bargains.