Liem Bahneman <liem_at_starfleet.com> wrote: >> I'm not a kayaker, but I found your topic while searching for information about this exciting, yet terrifying effect known as the Drawdown and Surge. We were boating on the Columbia River about 4 miles downstream of Longview WA. We beached my father's boat and were playing on the beach. We noticed a huge cargo ship steaming up river at what had to be at least 35 knots. It was moving so fast that when it came around the bend about a mile away, it was _leaning_. >> I know that section of the Columbia and have paddled it several times. I am pretty sure I have camped and lunched on the beach in question. A couple of observations: 1. 35 knots is excessive. Large cargo vessels do not attain such speeds on the Columbia for sure, and I doubt many are capable of that speed on the open sea. 20 knots would be a maximal figure and 15 knots is a common maximum speed on the Columbia. Looking at the bow wave of the container ship in question, I'd guess that ship is travelling at about 13-15 knots. 2. I have experienced the drawdown/surge effect many times, and it is more entertaining than threatening except when the bottom configuration focuses its effect. And, that's what happened to Liem's party. I do not want to minimize the hazard of these surges, but Liem's numbers are suspect, nonetheless. I have never seen a drawdown/surge with an eight foot excursion. All the ones I have seen maxed out at about 3 feet, with maybe the odd four-footer here or there. In any case, even a 3-4 foot excursion is dangerous if you do not anticipate it. Many beached power boats on the Columbia have been slammed around by them. What makes them really nasty is that they cause a long horizontal displacement of the water's edge on a shallow beach, which could catch little kids unawares and knock them down, with injuries certain and a drowning a possibility. They make the usual ship's wake look puny. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Wed Aug 06 2003 - 16:07:44 PDT
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