From - Mon Mar 10 13:18:05 1997 Received: from beasley.cisco.com (beasley.cisco.com [171.69.2.135]) by cheerios.cisco.com (8.6.10/8.6.5) with ESMTP id MAA22032 for ; Mon, 10 Mar 1997 12:10:12 -0800 Received: from bolero.rahul.net (root@bolero.rahul.net [192.160.13.1]) by beasley.cisco.com (8.8.4-Cisco.1/CISCO.GATE.1.1) with SMTP id MAA01148 for ; Mon, 10 Mar 1997 12:09:59 -0800 (PST) Received: from waltz.rahul.net by bolero.rahul.net with SMTP id AA28860 (5.67b8/IDA-1.5 for ); Mon, 10 Mar 1997 12:09:56 -0800 From: Randy Devol Received: by waltz.rahul.net (5.67b8/jive-a2i-1.0) id AA12796; Mon, 10 Mar 1997 12:09:56 -0800 Date: Mon, 10 Mar 1997 12:09:56 -0800 Message-Id: <199703102009.AA12796@waltz.rahul.net> To: cliff.sojourner@cisco.com Subject: Blade Runnings 8 X-Mozilla-Status: 0001 Content-Length: 3244 >From TRIFOILER2@aol.com Thu Oct 10 21:11:54 1996 Received: from emout03.mail.aol.com (emout03.mx.aol.com) by bolero.rahul.net with SMTP id AA12284 (5.67b8/IDA-1.5 for ); Thu, 10 Oct 1996 21:11:51 -0700 Received: by emout03.mail.aol.com (8.6.12/8.6.12) id AAA07847 for randyd@rahul.net; Fri, 11 Oct 1996 00:10:34 -0400 Date: Fri, 11 Oct 1996 00:10:34 -0400 From: TRIFOILER2@aol.com Message-Id: <961011001033_1145135293@emout03.mail.aol.com> To: randyd@rahul.net Subject: Re: Blade Runnings Volume 7 Status: R In a message dated 96-10-04 14:14:46 EDT, you write: << Here is another way Trifoilers are very different from most boats. I think I understand how a Trifoilers behave when overpowered. (Dan, correct me if I am wrong!) The leward foil must provide upward lift to keep the boat upright. At the same time, the windward foil must pull down to keep the boat from tripping over the leward foil. However, the amount of lift needed from the two foils is very different. Since drag is a linear function of lift, there is much more drag from the leward foil than the windward foil, which tries to turn the boat downwind. At speeds lower than 25 mph the rudder can easily keep the boat on track, but at higher speeds, the rudder rides higher, and rudder aeriation (air getting sucked down the trailing edge of the foil) both work to disable the rudder, which makes it unable to keep the boat sailing in a straight line. >> Hi Randy, I am glad you had a great day of sailing and have some friends in the area to go play with. To answer your question about your theory, which is a good one, but; I don't believe so. You are very close. Greg and I have noticed that when the rudder suddenly requires a major amount of helm to maintain a straight course, it is caused by one of two problems. 1) 90% of the time it is caused by ventilation on eighter main foil or even sometimes the rudder. The way to tell if this is happening, is look at the wake in the water. If there is a lot of white foam or a huge white rooster trailing off behind a foil, then there is your problem. I can always hear the extra noise of water falling. So I know which way to look. Now, how to correct for it. Sometimes just letting the fences do their job works. If the problem is really severe, you may have to let out the sails or round way up or down to reduce the side loads to get the water reattached. Then your good to go. This has been a factor of concern for us because as you can tell there is a loss of streering control. 2) Debris. If seaweed or a clear plastic bag gets wrapped around only one of the main foils. This causes the boat to suddenly deaccelerate and requires helm adjustment. This is usually not as bad as ventilation unless the debris is really big. Even ventilation causes the boat to slow down, so if the boat feels like it is going side ways, and no signs of white water, pull over to a complete stop upwind and backup for a few yards to clear the debris. Hope this helps next time you notice it. Feel free to pass this along to others on your mailing list Hobie Trifoiler factory boys. Dan