APPLES AND ORANGES
Nov . 9, 2000 Dear John, There is more confusion surrounding the ballast/ displacement /stiffness issue than perhaps any other factor in sail boat design. I'm not going to try to teach you all about it here, the questions are just to complex. Having saidd that you should be aware that if you are going to make a meaningful comparison between two boats your going to have to do more than look at displacement and draft to conclude one boat is going to be more tender than another. Unfortunately I don't have any stats on the French boat your referring to, but I would suggest that you need to look at displacement / ballast ratio, sail area to displacement ratios, and more esoterically, prismatic co-efficents to really get an idea if one boat is going to be stiffer/faster/wetter than another. Don't assume that the lighter boat is more tender, it may have a more efficent ballast to displacement ratio than the heavier boat even though they have the same draft. Sail area, center of effort, center of resistance, hull shape etc. are all important factors in these issues. Don't let the uninformed persuade you that a heavier boat is always stiffer than a lighter boat, because it just isn't so. For example old cruisers with massive displacement inefficently placed frequently rolled like logs in a seaway, where lighter displacement modern boats carry there sail area much more efficently. If you want to read a really knowledgable essay on this topic check out Tom Waid's site, The Voyage of The Bellatrix, or Skeine's Elements of Yacht Design. All I'm really saying is that you want to make sure that your comparing apples to apples. If you really want to find out if the boat is tender in reality make a simple test: take the boat for a sail. Get her properly trimmed in a moderate wind (15 knots or so) going closehauled under full sail and then decide. If she heels more than about 25-30 degrees I'd probably say she's tender. 20 to 25degrees is about right for me. Anymore than that and the decks start getting too wet for She Who Must Be Obeyed's peace of mind. Obviously there is not much point in academic discussions when a real world test can answer your question for you, and the owner should be happy to take a potential buyer for a sail, although I suspect things are getting a little frosty up there Montreal ! I hope this helps. Brian Pickton @ BeneteauOwners.net, aboard The Legend, Rodney Bay, St. Lucia
