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Dubb
12-18-2001, 07:38 PM
The plans for the Shellback Dinghy I'm building outline how to correctly rake the mast. However, the mast is actually perpendicular to the DWL, so I'm assuming that "rake" in these terms means in relation to something else. But I don't really understand rake anyway; if it is to ensure proper sail shape, doesn't that assume that the wind is always blowing parallel to the surface of the water? And also, how much does getting the "rake" just right matter in this boat -- or any boat for that matter? I'm having a hard time getting the rake just right in this boat, and I'm wondering if it really matters.

blisspacket
12-18-2001, 08:46 PM
my understanding of rake comes from experience in cruisers. Raking the mast aft will move the center of effort aft, and bring it closer to the center of lateral resistance of the keel, thereby reducing weather helm.

In a dinghy where body weight changes rake considerably, it does seem like a moot point. But if you follow the designer's notions, you get the performance and and appearance he is after.

You have only to watch a sailboarder playing with the extremes of rake to gather many of the implications.

John B
12-18-2001, 09:06 PM
Raking the mast aft is usually a fix to induce MORE weather helm or to reduce lee helm.
Or for a jaunty look.

PugetSound
12-18-2001, 11:37 PM
The actual reason for raking a mast aft is quite logical. It is to prevent tripping of the boom when on a broad reach and the boom is rigged way out. By raking the mast aft just a little bit and keeping the boom level (when amidships) the boom actually rotates up a little bit as it goes out to the side and thus doesn't trip on the water quite as easily.

[This message has been edited by PugetSound (edited 12-18-2001).]

TomRobb
12-19-2001, 10:36 AM
It also looks cool http://media5.hypernet.com/~dick/ubb/cool.gif

blisspacket
12-19-2001, 07:53 PM
thanks John B, you're spot on with your correction.

John B
12-19-2001, 08:01 PM
When Waione was in her bermudan cruising form up to 3 years ago I played a lot with rake trying to get what I thought was the right helm balance to mke her go to weather. I had 1 metre of rake in at one stage( on a forty foot hoist).
I solved the problem eventually by adding a vast amount of sail area to the main.... 400 ft up to 610 ft when we changed the rig to gaff.
Now you can tell that I achieved my objective by the bulging biceps and strained and stressed expression on my face.