Goodbye Key West - we left at 7;00 am |
A nice sunset after a rough day |
As I motored up the channel, my speed dropped to 3.8 kts, I thought there must be a heck of a current! A glance back provided a source of the problem - my dinghy had flipped over upside down in the high winds. It made a good storm anchor. Now the problem was how to right it?
An aside: Ann and I have five grandkids trying out the learn-at-home mode of acquiring knowledge. I suggest a home exercise in physics, after all, what else do they have to do? Let's assume a 9 x 4 ft square (we physicists love to approximate things, it's the technique, not the measurements) dinghy that's upside down. It has been dragged by a boat for some while which has resulted in a partial vacuum between the dinghy and the water it's immersed in. The soft dinghy provides a very good seal against the water. If you try to pull the dinghy vertically to right it, you will create even more suction - resisting your efforts to pull it vertically off the water surface.
Problem 1: Assuming a flat 9 x 4 dinghy with a rubber seal (the inflated tubes, 2 feet deep) against the water surface, how much force is required to lift the dinghy one foot (the dinghy weighs 120 lbs).
Problem 2: How would you propose lifting the dinghy to right it? Brute force or finesse? What method would you use and why?
Problem 2A - If brute force, how much is required?
Problem 2 B - If finesse, what technique would you use? Finesse is the essence of the solution, go for it but don't damage my dinghy! Describe the finesse technique in detail.
Problem 3: Depending on the technique, how much force would be applied to the point of attachment on the dinghy for righting and what would you use on Fleetwing for that force?
Answers will be graded and due at our Sunday Sherer meeting! (reward certificates will be given! - non-monetary! - learning is its own reward.)
4 comments:
Nice!
Well, certainly a 'insert adjective of choice here' start to your trip north. I was wondering about the little jocking on your Spot track just as you were poised to turn west into the anchorage area. NOAA Charts only show ~5ft in that area, Navionics Sonara a bit more. Looks like you're above 0 in tides on your ride in and through Friday morning when you leave. What kinda depths did you see? Did you just go to a hole you had stayed in before?
ScottnKit, you got it exactly right, of course. I removed your solution so the grandkids didn't see it, I may have been too late. I should have mentioned in the blog that it was a test for the kids!
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