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Hello, welcome to the K-designs mailing list. Firstly I'd like to get rid of some administrative necessities, and then introduce myself. Admin ------- Firstly, this list is for the discussion of K-designed sailing multihulls, those designed by Bernd Kohler. Normally this type of mailing list limits itself to the discussion of K-designed boats only and excludes for sale and wanted notices because they can overwhelm the list. However, to attract more people and find out who has which K-designed boat/sail no., the current charter includes advertisements of K-designed sailing multihulls for sale. This latitude does not include a particular piece of marine equipment. If you have a motor for sale, there are other, better, places to advertise. Secondly, I'm not responsible for how YahooGroups runs itself. Anyone worried about the YahooGroups should examine their Privacy Policy (last at http://privacy.yahoo.com/privacy/us ), and terms of service. Note particularly the terms of service which in part reads "Yahoo does not claim ownership of the content you submit...however...you grant Yahoo the following world-wide, royalty free and non-exclusive license(s) as applicable..." and then goes on to list things. So, if you have a world changing invention, don't tell us very much at all on Yahoo (but let us know by personal email :-) Thirdly, as moderator, I reserve the right to ban anyone who is not sticking to the charter (note that the Yahoo terms of service cover all the 'bad language', pornographic pictures, etc. so we don't need them in our charter). Ok, I think that's it. Anyway, if there's more, we can talk about it later - let's get into the content!! Personal I have been interested in multihulls for so long I can't remember when it started. While I subscribed to various multihull magazines, the cost of owning a cruising multihull seemed beyond my aspirations. Only in the last 5 years have I seriously investigated the possibility, and I have come to believe it is possible to own an reasonably priced Offshore Cruiser. I recently purchased the KD860 plans for building. I have never built a boat before, and have what I would describe as limited carpentry skills. I have sailed beach Cats, but never a cruiser. I have sailed on large and small monohulls and owned small ones. I am a former military aviator, wind influences on air foils has always been of interest to me. I am looking forward to the contributions of this group to further my learning experience of multihulls and K-designs in particular. Thanks Joining Us, Pat Ross pat@...

Hello Pat and all (when they come), Bernd told me about this group so here I am! I'm an amateur boatbuilder based in Matera, Italy. I'm 47 (almost 48, gosh) and I am a scientist (astronomer) by trade. I'm currently building the prototype DUO480, beacuse I needed a slightly larger beach cat than the DUO425 of which I had purchased a set of plans. The new boat is almost identical to her smaller sister except for a few details. Bernd has been producing the necessary additional drawings which he's been emailing to me as the are ready. I already drafted most of the pieces onto plywood and I'm ready to start cutting plywood. I will create a folder in which I'll put photos and comments during the contructions. If all goes ok, I have dreams of attempting a larger endeavour, such as the DUO800 or even the beautiful KD860.

Hello all, put me down for one DUO 480! I was just getting ready to order plans for the 425 but i was hesitating because i wanted something a little bigger. something i could have fun with single handed but also a cat that could carry 3-4 people. I've been a lurker of the K-design web site for awhile now and i'm glad to see finally a forum/group. Burk Sacramento, CA

Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the k-designs group. File : /SC 435/sc435-Croatia.wmv Uploaded by : g_kukurin <g_kukurin@...> Description : SC435 sailing video You can access this file at the URL: http://groups.yahoo.com/group/k-designs/files/SC%20435/sc435-Croatia.wmv To learn more about file sharing for your group, please visit: http://help.yahoo.com/help/us/groups/files Regards, g_kukurin <g_kukurin@...>

Would like to see another video when the wind is blowing! If possible, should show a view from the front and rear to observe bow wave and total wake. Cal

Hi, I'm Paul and I bought plans for both the economy cruiser and Eco7. I'm a big guy and the economy cruiser wasn't practical. (I play Santa at christmas and require no padding) I have been working on the Eco7 sporadically for a little over a year. Bernd drew up a set of antivortex panels for the Eco7. I like the simplicity of them and will be interested to see how well they work. This is one of 3 boats I am working on, the other 2 being a Bolger Super Brick and a Sam Devlin Winter Wren whose hull I am adopting from another builder. Obviously I like wood working as well as sailing, though for now sailing is limited to a pair of small dinghies on Lake Lanier (near Atlanta Georgia) until one of these beasts gets finished. Each boat as well as being very different in design is for a different purpose. The Eco7 and Winter Wren will live in the Ocean and the Super Brick will stay at Lake Lanier as a weekend retreat. Among my talents are videography and I am making video diaries of each of the boats which I will make available as they progress. anyway, that's who I am Glad to meet ya'll Paul

Hi everybody, My name is Wolfgang, german multihull sailor, living in Brasil on the island of St. Catarina( about latitude S27?30??)At this moment i?m in the fina fase of building a DUO425, which is my first boat building experience. and what an amazing experience it is - i just love it. So i?m very pleased about the founding of this group and hope for interesting discussions and idea sharing. Fair winds to you all Wolfgang

Charles, I was able to translate your site by right clicking and using ghe Google Page Translator. Very nice site. Thanks for letting us know you had that set up. http://pages.globetrotter.net/leblancc99/blog/weblog.html Pat

I would like to use the forum to share practical building experience. We (my wife and I) built 13 boats so far. Lets talk about sanding. One of the works which have to be repeated often when working in the wood/glass Epoxy system and even more so when working with foam sandwich system. The most important tool is a very good sander. Epoxy gets thermoplast again above about 75 degree Celsius. Which means, when you use an ordinary oscillating sander which vibrates 20000 times or more a minute and the wrong sanding paper, the only effect you get is clocked sand paper. So which sander is the best for this ? We use a linear sander which has a 5mm rotating movement and a rotation speed between 2000 to 6000 revolution. As sanding paper we use Aluminum oxide paper (grain 85 and to finish 120). This sanding paper will not clock as easily as normal sanding paper. It last about 8 times as long also. By the slow rotation of the sander the Epoxy will not get thermoplast . This machines work whit almost no manual pressure. The are not cheap but worth every penny. The relative new orbital sanders are not bad also. But you have to hold them absolute parallel to the working surface. Otherwise you get immediately marks which have to be filled again. Preparing a perfect putty will help also to easy the work. This will be a story for an other time. Cheers Bernd

I would like to use the forum to share practical building experience. We (my wife and I) built 13 boats so far. Lets talk about sanding. One of the works which have to be repeated often when working in the wood/glass Epoxy system and even more so when working with foam sandwich system. The most important tool is a very good sander. Epoxy gets thermoplast again above about 75 degree Celsius. Which means, when you use an ordinary oscillating sander which vibrates 20000 times or more a minute and the wrong sanding paper, the only effect you get is clocked sand paper. So which sander is the best for this ? We use a linear sander which has a 5mm rotating movement and a rotation speed between 2000 to 6000 revolution. As sanding paper we use Aluminum oxide paper (grain 85 and to finish 120). This sanding paper will not clock as easily as normal sanding paper. It last about 8 times as long also. By the slow rotation of the sander the Epoxy will not get thermoplast . This machines work whit almost no manual pressure. The are not cheap but worth every penny. The relative new orbital sanders are not bad also. But you have to hold them absolute parallel to the working surface. Otherwise you get immediately marks which have to be filled again. Preparing a perfect putty will help also to easy the work. This will be a story for an other time. Cheers Bernd

Hi Wolfgang No question is stupit, only answers can be. Linear sanders are also called flatbed sanders. The look like the ordinary oscillating sanders, but work with an excenter for a greater hub. And this makes all the difference. One of the manufacturers is Festo on Germany Cheers Bernd

hello, I'm going to order the DUO 425 plans and i want to get an idea of the costs of the sails, masts etc. Can anyone tell me the size of the windsurfing sails used on these boats? Is the boat balanced around the older triangle style rig or the newer rectangular style rig? or both Thanks, Burk

Hi everybody, There?s one thing i?d like to understand better about the asymetrical hullshape. Easy to understand that this hull shape generates a lift, thus improving windward performance - if you fly the other one. With two hulls both in the water this effect should be zero. Yesterday i acidentally found the page of one boat called g-cat 5.0 This boat features very sharp symetric hulls and these guys tell us, that hull asymetry is symply a myth, proven by their boats performing better or at least equal to any concurrence. They also claim that their hullshape produces less wake, thus generating more efficency and speed, which sounds pretty logical. Well loking at the underwater part of our hull, i?m strongly reminded of some kind of full keel, monos used in the old days. If windward performance is created like that, than the underwater ship should in fact show a very sharp profile. Well, maybe the master can iluminate us on this topic. Cheers Wolfgang

Cause for Celebration today. Its the International Talk Like a Pirate Day. If you need any help here's a couple of links to give you a hand. www.talklikeapirate.com www.talklikeapirateday.com www.yarr.org.uk Keep to the Code!

Hi Wolfgang I will come back to this issue when I am back from holiday in 11 days. Very short, why do you think aeroplans have a-symmetrical wing sections ? Because the produce more lift as a symmetrical section for the same angle of attack. We can translate this very simple to hulls. A-symmetrical hulls produce at a lower angle more trust against the windforce. So the point heigher to windwards. You right, the effect is cancelt out when parallel to the water surface. An angle of about 3 degree to the lee of the boat is sufficient to counter the sail force. The transom turbulence has nothing to do with symmetrical or else. The exit angle of the hull on the transom is the criteria for this. The lower the angle the lower the turbulence (suction) on the transom. Of course there is more to it, but enough for today Cheers Bernd

Wolfgang opened a discussion on the assymetrical hull shape of some of Koehler's designs. "Paradude" and Bernd are both correct in what they wrote. What they doesn't mention is why this works for a catamaran. When the wind attempts to blow the boat sideways, it also heels the boat. That presses the leeward hull deeper into the water and raises the windward hull. Thus, the hull with the airfoil shape that works best in holding the boat against the wind is the one that is immersed the deepest. This hull form was used extensively in the 1950s and 60s, notably by Rudy Choy with his elegant Pacific catamarans and by Hobie Alder with his Hobie 14 and 16. What these hull shapes allowed was high performance hulls that didn't require keels or boards to sail very well. During that same period, others on the East Coast US and the UK were favoring semi-circular (sort of) hulls that had lower drag but required keels or boards to go to windward. If you accept the idea of the survival of the fittest, it looks as if the semi- circular folks won out. The debate was documented in AYRS bulletins during that period. However, that doesn't mean that other forms aren't used. Kohler uses the assymetrical vee (rather extreme, I think), the trapezoid and the multi-chined shape that approximates semi-circular. His designs appear to compromise some performance for building ease. Cal

Hi Everybody, I would like to keep and accurate log of those who are on line that have plans or have completed a K-design boat. To help me get this organized please tell me: 1. Your name that you wish to use on this group site 2. The Model name of the plans that you own, or the Model Number of the boat you have completed. 3. Purchase date of plans 4. start date and completion date of vessel 5. The Sail Number or Hull Number, since they are the same 6. You or the vessels location. So for me it is: 1. Pat Ross 2. KD860 3. Sail Number 51 4. Purchased Plans Aug 28, 2006 5. Have not started building vessel 6. Location: USA - Pensacola, FL Thanks for you help. Pat Ross

Hi everybody, thanks for responding to my mail. Seems clear to me that on a small asymetric cat, like the duo 425, the system works allright, meaning you want to fly the windward = 100% effect. On a bigger vessel, like the Kd860, Pat will build, the last thing you want is a hull airborne. So here we have only a narrow strip that outdoes the contrary effect of the other hull. Well, that might very well be true in relatively calm waters. If you are out in the atlantic in 5-6m waves, you?d have a hard time to tell what?s up and what?s down, believe me. I think, a very important fact for the windward capability is how much lateral resistance the hulls offer to leeward drift...Keels and daggerboards simply work like that. A narrow hull shape will have a deeper draft as let?s say a round bottom vessel, but hopefully with less wetted surface. One might say, that sharp-cut hull have their keel/daggerboard incorporated in the design. cheers Wolfgang

Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the k-designs group. File : /duosail7,1.skp Uploaded by : o_alemao2003 <o_alemao2003@...> Description : You can access this file at the URL: http://groups.yahoo.com/group/k-designs/files/duosail7%2C1.skp To learn more about file sharing for your group, please visit: http://help.yahoo.com/help/us/groups/files Regards, o_alemao2003 <o_alemao2003@...>

Hi folks, if you don?t have it already, i?d like to recommend a fantastic, very easy to use 3D design program. With sketchup you can visualize your ideas in the easiest imaginable manner. Two versions are free for download, the free version, which is somewhat limited in possibilities and the pro-version, that?s limited by time. That?s the one i cracked last year, before google bought the company. Key generators can be found on the internet. The downloads for the program and other stuff are at www.sketchup.com They also offer free interactive tutorials. It would be very helpful to exchange ideas and solutions in this group. i?s also useful, before you start your next project. I did it before starting to build the 425 and by now already have the Duo800 in 3D. It?s a little like model building, leading to better and faster understanding of the 2D plans. Cheers Wolfgang