leong

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About leong

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    Paddle Upwind
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    Male
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    Kayak racing, fishing and touring; road bike racing and touring; ski touring; swimming and fitness workouts.

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    Leon
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    Granowitz

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  1. Today I paddled to Mar-a-Lago to meet Japanese Prime Minister Shinzo Abe. I was hoping to demonstrate bracing and rolling to Shinzo and his lovely wife. I usually make the Mar-a-Lago trip alongside the ocean beaches of Palm Beach Barrier Island, but today I took the inside route (between Palm Beach and the mainland) because of the strong winds. This is a pix of Trump Plaza as I passed by it in West Palm Beach. Here are a couple of pix of the stinkpots I passed. Some people are really into conspicuous consumption. Here’s a pix of Mar-a-Lago from about two miles away. As I headed towards shore this Coastie came out to greet me. He was unaware that I was on the way to meet the Japanese Prime Minister. He said I have two choices: 1. Stay far from shore or 2. He’ll try out his bow-mounted machine gun. I chose no. 1. However, there’s a beach on Southern Blvd. that connects the Mainland to Palm Beach and he said it was okay to paddle there. So I did. Here are a few pix of Mar-a-Lago taken near the beach on Southern Blvd. I had a super fast paddle home (wind and tide pushing me) averaged 6 knots over the 8 nautical miles. At the end of the trip I parked my kayak along side of my Sunfish. Oh, did I mention that I never met the Prime Minister.
  2. Pru, A vector is a fancy dancy name for a line segment with a little arrowhead on one end. The rest is just commentary. Look here for a little more information. Luckily you won’t need tensors (they will really blow up your brain). Unless, of course, you want to blow up Kevin's brain. -Leon http://www.dummies.com/education/science/physics/what-is-a-vector/
  3. Excellent report as usual, Pru. BTW, it’s State Stage Fort Park.
  4. Rob and all, Just to remind you that the trip between Good Harbor and the end of Dog Bar is usually the roughest section of the circumnavigation around Cape Ann. But more important is that there are no takeouts (except, sometimes, at Braces Cove when there are no breakers). And, Joe, the area along Bass Rocks is very rocky and this portion of the whole circumnav is arguable the most scenic part. -Leon (who’s done the circumnav about a hundred times and is trolling NSPN from the Palm Beaches)
  5. Brian and Phil, I used 2 square feet because I used a large coefficient of drag. The extremely high hull speed (as you say) is not that high. I get my QCC700X to 6 knots (in still air and water) for short sprints. Max hull speed is just a number, not a hard speed limit. The Blackburn Challenge course is almost exactly 18 Nautical miles. The winning Epic 18’s and similar kayaks finish the course in 3 hours, or so. That’s an average speed of 6 knots for a long course. But so-called “max hull speed” of these kayaks is about 5.6 knots (1.34 time the square root of the water-line length of ~ 17.5’) But let all this go. Nothing good on TV so, instead of rerunning the test, I decided to prove my result analytically so there can be no questions on the values that I used (it’s good that I’m retired ). I also gave it a whirl on the water but couldn’t get the proper conditions today. See attached Mathcad worksheet for my analysis. Mathcad - DownCurrent-UpWind and vice a versa.pdf -Leon
  6. Phil, There is a lot of uncertainty in the necessary wind speed because of what to use for the frontal area in the air drag formula. I used a 2 square-foot area for the paddler and kayak. At 9 knots, the wind pressure is ½ pound per square-foot. So the force of the wind is 1 pound and, according to KAPER, that’s the total drag on a kayak going at 2 knots. But let that go. Suppose it does takes about a 20-knot wind to overcome the 2-knot current. Then, for case # 1, the drag increases to about 6 pounds and for case # 2, the drag decreases to about 9.5 pounds. So the qualitative result is the same; i.e. it’s still easier to paddle downcurrent/upwind than vice versa. In my experience in the inlet, it does seem like a 10-knot or so wind is enough to overcome the current. But, I don’t know the exact current speed or wind speed opposite to the current. Also, I don’t account for wind generated waves on the surface that might be moving opposite to the current flow. I think a key point is that a change in current speed costs a paddler more than the same change in relative wind speed. -Leon
  7. Brian, You might want to change your answer based on the following hints: A wind speed of approximately 9 knots against a kayaker has a force of roughly 1 pound and that cancels the 1 pound water drag on a kayak in a 2-knot current in the opposite direction. Case 1: Say you paddle with the current (against the wind) with a speed over ground (SOG) of 4 knots. Then the relative water speed is 2 knots; (4 -2). Also, the relative air speed is 13 knots (9 + 4). Again, at a relative water speed of 2 knots the water drag is 1.00 pounds. Also, the air drag at 13 knots is 2.29 pounds. Thus the total drag you have to overcome is 3.29 pounds (1 + 2.29). Case 2. Instead, say you paddle against the current with the same SOG of 4 knots. Then the relative water speed is 6 knots (4 + 2). Also, the relative air speed pushing you is 5 knots (9 – 4). At a relative water speed of 6 knots the water drag is 11.91 pounds. And the force of the relative air speed of 5 knots pushing you is 0.34 pounds. So the total drag you have to overcome is 11.57 (11.91 – 0.34). Therefore, unless I made a mistake somewhere, I believe the example demonstrates that it’s easier to paddle downcurrent/upwind then vice versa, at any speed (not just as you approach hull speed). My actual paddling experience is consistent with this answer. Also, as you approach hull speed the exponent in the approximate exponential formula for water drag grows larger than 2.0. Also note that it’s less than 2.0 at slow paddling speeds. I validated this using John Winter’s drag program, named Kaper. Note, in a program I wrote I got answers consistent to the two cases at lower speeds. The examples were just easier to present. One mistake I think you made is assuming that both wind resistance and hull drag are the same exponential functions. Yes, to a first approximation, the water drag function is sort of like Dw = W*s^2 and the air drag function is exactly Da = A*s^2 (where s is speed and A and W are constants). But, because water is much denser than air, W >>A so a small change in s changes water drag much more than it changes air drag. The water drag values are from keelhauler.org/khcc/seakayak.htm and the air drag values were calculated from the standard air drag formula like the one published here https://www.grc.nasa.gov/www/k-12/airplane/drageq.html -Leon
  8. A Winter Brainteaser Almost daily I paddle through the Palm Beach inlet going to and from the ocean (no, I haven’t met Trump yet and I keep away from Mar-a-Lago when the Coast Guard is patrolling). The current in the inlet is generally about 2-knots and sometimes the wind is in the opposite direction. In fact, sometimes the wind exactly cancels out any drifting of my kayak; i.e., the current drifts me west at 2-knots and the wind pushes me east at 2-knots. So here’s a brainteaser. Under the non-drift conditions above, which is easier (less exertion) to paddle: upwind/down-current or vice versa? Give reasons for your answer. -Leon
  9. Nick, have you given up on the J-racks?
  10. 1. Shoulder and triceps exercises for the long term. 2. If you can lift the kayak onto your shoulder tilt bow (stern) into Jhook in front of you to take half the weight and then tilt stern (bow) into Jhook behind you.
  11. When Lisa and I trained in the Concord River she sometimes didn't wear a PFD because it inhibited her rotation. She felt the difference but I don't think we ever timed the difference. There was always at least a 1-minute difference between our 8.6-mile runs (probably due to wind). She also hates to wear a wetsuit for the same reason.
  12. You could argue that a sea kayak is a pretty good flotation device too, as long as the hatches don't flood.
  13. http://www.jerusalemonline.com/news/world-news/around-the-globe/watch-great-white-shark-breaks-through-divers-cage-24220
  14. Wow, I'd rather be in a sea kayak with a bombproof roll.
  15. Josko, When Olympic sprint paddlers switched over to wing paddles their speed increase was about 2%. But they’re paddling in close to laboratory conditions (short distances with no waves). But variability of ocean conditions on different days might cancel any noticeable differences between two types of paddles. So don’t feel bad if your “faster” paddle blade isn’t always the faster paddle blade on a different day. -Leon