Interlake One Design Racing

The Secrets to the Wind of Grand Traverse Bay

A L O H A ! First of all, you are in for a real treat. Accomplished sailors such as Head of Quantum Sails, Ed Reynolds, who has sailed everywhere in North America a zillion times plus flies around the world to places like the Med & Australia coaching the likes of Russell Coutts, Paul Cayard & Terry Hutchinson, remark that “there is no better sailing than on Grand Traverse Bay.”

What is the rage all about? The sea breeze. A sea breeze combines with flat water (mostly). This sea breeze is generated by the fact that West GT Bay is 19 miles long with a max width of 4 miles that funnels down to 1.5 miles on the south end and an August water temp in the mid 70s. At the bottom of this tunnel funnel is an asphalt heat sink called Traverse City. Once the sun gets all those streets, parking lots and rooftops hot the tunnel starts to draw and the funnel picks it up. This is what the hard-corps call the “West Bay Doctor.”

Basically, there are two winds to consider. The sea breeze and the system wind. The question is, “Which wind will prevail.” The sea breeze starts showing fingers at 10:am. Blows 8-10 from the North to Northwest at noon and 10-13 at 2:pm. This direction produces 1-2 ft. waves that usually maxes at occasional white caps. The sea breeze begins easing down at 5:pm. Is noticeably decreased by 6:pm. And by 7:15pm is put to bed. A real nice evening breeze of 5 knots often fills in from 8 to 10pm. {If you’ll buy this, I’ve got a bridge up north to sell you!}

If there is a weather system coming through, the cloud cover will usually kill the sea breeze and the system will run the show. If the system wind is gentle or there is some sun, then the two breezes combine. Most often they deflect each other giving a third wind direction. Once in a coon’s age these two winds go head to head. Then things get really weird. This happened at the 2000 Great White Northerns on Saturday, at the final day of 2001 Nationals and once again at the 2003 Great Whites. I have never sailed or raced in it except during an Interlake regatta. Go figure.

Except for that weird thing, the prevailing wind that comes out of all of this is some kind of westerly. Usually SW or NW that peaks at 10-13knots at 2:pm. Since that leaves a short fetch the waves are usually a foot or less.

In fact, the wave conditions depend far more on wind direction than speed. The race area is at the south end of West Grand Traverse Bay. This puts us in the bottom of a horseshoe and thus we are protected from three directions: East, South, & West. Only a Northerly winds in the teens produce waves. GT Bay waves are not nearly as choppy as the Lake Erie’s because of the water depth, reduced traffic, and shore type. Grand Traverse Bay reaches 360 ft. in depth. The average depth in the racing area is 80-120 ft. The shore is almost devoid of seawalls and rocks. Instead you’ll find a gradually sloping sand bottom and beach that absorbs waves instead of reflecting them. Also, for some unknown and blessed reason the boating traffic has split itself with the majority of the motors on East Bay, and those mysterious canvas flappers on our side. Yea! What does all this mean: No confusing “washing machine” chop. Be careful if the wind is southerly because it is usually windier than it looks. 30 knots from the south has difficultly kicking up one footers.

I have never had a need to clear weeds off the centerboard or rudder. In fact when looking at the bottom some 20-30 ft below I’ve seldom seen weeds.

That’s as much as I can tell you. With the exception of the Great White Northerns, we always race in the evenings. The local Interlakers have little experience with afternoon wind patterns. We only see the Bay during the day as we drive around doing our business and we pray that what we see will last until the evening’s activities. The playing field will be level, fun, & beautiful.

This link will get you to a map & satellite photo of the area. Taps on top of the picture/map let you change modes and arrows are there to zoom in/out and navigate. It’s really neat to not only check out TC but the Manitou Islands, Sleeping Bear Dunes, and more.

Bob Sagan
Fleet 38 Captain

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