I would rather not try the bump to find out method. I can cut about an hour off motoring if I can clear the bridge. I have a 27' Catalina std. rig so I figure that I'm about 39' from the water to the top of the mast/antenna. Bridge clearance is 31" Mean High Water. Datum for MHW is 13.89 So I figure that I should be able to go under on a 4'tide or less? any ideas? Like I said I would rather not find out the hard way.
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Which Bridge?
David - which bridge are you thinking about? Tim Brogan April IV C350 #68 (was Inamorata C27 #6111) Seattle
David - which bridge are you thinking about? Tim Brogan April IV C350 #68 (was Inamorata C27 #6111) Seattle
Math
1. Mast height from waterline 39 feet 2. Bridge clearance at MHW 31 feet 3. Diff between 1 & 2 is th additional amount of feet in lowered water level required to just clear 39 - 31 = 7 feet 4. MHW less difference is the height of the tide required against the datum to JUST clear, so 13.89 minus 7 = 6.89 feet 5. To give yourself some clearance, a four foot tide would do just fine. Any questions, just draw a picture of the boat, the water and the bridge. Stu
1. Mast height from waterline 39 feet 2. Bridge clearance at MHW 31 feet 3. Diff between 1 & 2 is th additional amount of feet in lowered water level required to just clear 39 - 31 = 7 feet 4. MHW less difference is the height of the tide required against the datum to JUST clear, so 13.89 minus 7 = 6.89 feet 5. To give yourself some clearance, a four foot tide would do just fine. Any questions, just draw a picture of the boat, the water and the bridge. Stu
Fox Island
Tim, The Fox Island Bridge is the one I'd like to go under. I just found the datum info yesterday.
Tim, The Fox Island Bridge is the one I'd like to go under. I just found the datum info yesterday.
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