Hi yall, I have a question about a bizarre (and somewhat terrifying experience) i had today. I was fishing in a canal in southeast louisiana today, approx 1/2 mile wide with a very deep channel through the center, which probably planes out towards the sides which are surrounded by marsh and other smaller canals. I was having a great day of fishing and after one spectacular cast i happened to look up and see a huge freighter coming down the channel. I expected a large wake from the ship and it was too near to do any major maneuvering, so i kept my kayak near the side of the channel ( an ENOURMOUS mistake!!) While the ship was about 1/8 of a mile away all the water from near the sides began rushing out toward the ship. I was in about 4 ft of water which drained to the bottom in about 20 seconds. The force of the outrushing flow was greater than any undertow i have ever encountered. This is when i realized i was in serious trouble. My kayak rushed out toward the ship (which was at least 1/4 mile away) Soon a wave of returning water and ship wake (which was at least 2-3 feet above my head from where i was sitting in the trough, I would estimate it at 6-8 feet) was rushing back toward the bank, as i was rushed toward the wave. The outrushing water and inrushing wave collided to form a huge breaker which crashed right on my face. In my current state of terror i somehow managed to remain upright through the massive breaker and the slightly smaller wake waves which ensued. Everything under my deck bungies was washed about 2 feet up on formerly dry land, then returned when the water level returned to normal. I was soaked, and i am still picking dirt out of my teeth. I was very lucky to be wise enough to have my pfd and srayskirt on. My question is this- What force contributed to the outrushing water before the ship reached my location. I theorized that if anything the ship should displace water would raise the water level. Or could it be that the propeller acted as a vacuum of sorts that sucked water ahead of the ship by forcing it through the prop and displacing it in the form of a wake behind the ship? I am totally fascinated by this incident. After the ship passed i decided to call it a day and happened to notice another equally large tanker coming through the canal. I decided to hide in a side canal and paddled back about 1/2 mile into a canal and thought i could hide around a couple of bends. I was amazed to see the same effect occuring as the ship approached, I rushed back into the middle of the side canal and again faced some serious waves although not nearly as large. These were only 3-4 feet and did not break. I understand that the shape and break of the waves had to do with the depth of the water where i was. Thanks for any input. Robin Lovelock New Orleans. *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Gratytshrk_at_aol.com wrote: > > Hi yall, > I have a question about a bizarre (and somewhat terrifying experience) i had > today. [snip] after one spectacular cast i happened to look up and see a > huge freighter coming down the [narrow, shallow] channel. > [snip] While the ship was about 1/8 of a mile away all the water from > near the sides began rushing out toward the ship. I was in about 4 ft of > water which drained to the bottom in about 20 seconds. The force of the > outrushing flow was greater than any undertow i have ever encountered. [snip] Soon a wave of returning water and > ship wake (which was at least 2-3 feet above my head from where i was sitting > in the trough, I would estimate it at 6-8 feet) was rushing back toward the > bank, as i was rushed toward the wave. The outrushing water and inrushing > wave collided to form a huge breaker which crashed right on my face. [snip] > After the ship passed i decided to call it a day and happened to notice > another equally large tanker coming through the canal. I decided to hide in > a side canal and paddled back about 1/2 mile into a canal and thought i could > hide around a couple of bends. I was amazed to see the same effect occuring > as the ship approached, [snip] What you experienced was the "surge" portion of the ship's wake. In brief: that surge produces a minimal vertical excursion of the water's surface *when the water is very deep* (at least as deep as the "length" of the wave the surge forms in deep water). That's why you would not notice the surge if the ship passed by in deep water. OTOH, when the water is very shallow, the leading part of the wave (the trough) arrives first, and because its "ideal" form is impossible to maintain in shallow water, it "sucks" water back toward the ship, to help form *the crest* of the wave (which arrives just behind the trough). Because the water is too shallow to sustain the crest, a breaking wave is formed, similar to surf, and the wave becomes akin to what happens in a tidal bore. What happened to you is sort of a small scale version of a tsunami hitting a shallow, sloping beach. For more about waves (and beaches), chase down Willard Bascom's classic work, written for the lay person: Waves and Beaches, Anchor Books, 1980 (revised version), ISBN 0-385-14844-5. Out of print, I am sure, but in any good library's earth science section. A treasure trove of stuff useful for ocean paddlers, covering both waves on the water, and how coastal landforms are affected by waves. You'll be a better person, and have an improved sex life if you read this! <g> -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
According to Amazon.com the book Dave refers to is out of print; however, I have them running an availability search. Will let the list know what they come up with. Jim Tynan Pike Road AL ~For more about waves (and beaches), chase down Willard Bascom's ~classic work, ~written for the lay person: Waves and Beaches, Anchor Books, 1980 (revised ~version), ISBN 0-385-14844-5. Out of print, I am sure, but in any good ~library's earth science section. A treasure trove of stuff useful ~for ocean ~paddlers, covering both waves on the water, and how coastal landforms are ~affected by waves. You'll be a better person, and have an ~improved sex life ~if you read this! <g> ~ ~-- ~Dave Kruger ~Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Robin, I can't explain the physics but can tell you that the same thing happened to a ship thousands of times your size (the S.S. New York if I recall) when the Titanic started out from port. The ship was ripped from its moorings and thrown out into the bay, nearly causing a collision. The same effect is used to trigger certain types of anti-shipping mines, like those the Navy put into Haiphong harbor about 30 years ago. I have not found any advice in any of the kayaking books regarding safety in a channel when large ships are around except to keep out of their path. I was wondering about this as I kayaked down the Westpoint Slough with a heavily laden ocean barge moving ahead of me on a parallel course, at roughly my own speed. Should I attempt to pass it, stay even with it, pull in directly behind at a safe distance, surf its wake, or what? jerry. jerry. At 10:24 PM 10/12/1999 -0400, Gratytshrk_at_aol.com wrote: >Hi yall, >I have a question about a bizarre (and somewhat terrifying experience) i had >today. I was fishing in a canal in southeast louisiana today, approx 1/2 >mile wide with a very deep channel through the center, which probably planes >out towards the sides which are surrounded by marsh and other smaller canals. > I was having a great day of fishing and after one spectacular cast i >happened to look up and see a huge freighter coming down the channel. I >expected a large wake from the ship and it was too near to do any major >maneuvering, so i kept my kayak near the side of the channel ( an ENOURMOUS >mistake!!) While the ship was about 1/8 of a mile away all the water from >near the sides began rushing out toward the ship. I was in about 4 ft of >water which drained to the bottom in about 20 seconds. The force of the >outrushing flow was greater than any undertow i have ever encountered. This >is when i realized i was in serious trouble. My kayak rushed out toward the >ship (which was at least 1/4 mile away) Soon a wave of returning water and >ship wake (which was at least 2-3 feet above my head from where i was sitting >in the trough, I would estimate it at 6-8 feet) was rushing back toward the >bank, as i was rushed toward the wave. The outrushing water and inrushing >wave collided to form a huge breaker which crashed right on my face. In my >current state of terror i somehow managed to remain upright through the >massive breaker and the slightly smaller wake waves which ensued. Everything >under my deck bungies was washed about 2 feet up on formerly dry land, then >returned when the water level returned to normal. I was soaked, and i am >still picking dirt out of my teeth. I was very lucky to be wise enough to >have my pfd and srayskirt on. My question is this- What force contributed to >the outrushing water before the ship reached my location. I theorized that >if anything the ship should displace water would raise the water level. Or >could it be that the propeller acted as a vacuum of sorts that sucked water >ahead of the ship by forcing it through the prop and displacing it in the >form of a wake behind the ship? I am totally fascinated by this incident. >After the ship passed i decided to call it a day and happened to notice >another equally large tanker coming through the canal. I decided to hide in >a side canal and paddled back about 1/2 mile into a canal and thought i could >hide around a couple of bends. I was amazed to see the same effect occuring >as the ship approached, I rushed back into the middle of the side canal and >again faced some serious waves although not nearly as large. These were only >3-4 feet and did not break. I understand that the shape and break of the >waves had to do with the depth of the water where i was. >Thanks for any input. >Robin Lovelock >New Orleans. >*************************************************************************** >PaddleWise Paddling Mailing List - All postings copyright the author and not >to be reproduced outside PaddleWise without author's permission >Submissions: paddlewise_at_lists.intelenet.net >Subscriptions: paddlewise-request_at_lists.intelenet.net >Website: http://www.paddlewise.net/ >*************************************************************************** > *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
> I was having a great day of fishing and after one spectacular cast i > happened to look up and see a huge freighter coming down the channel. I > expected a large wake from the ship and it was too near to do any major > maneuvering, so i kept my kayak near the side of the channel ( an > ENOURMOUS mistake!!) I haven't experienced this kayaking yet, but where I grew up in FLorida I do remember large freighters coming up the river where my dad used to take me fishing. It was as if someone pulled the plug as the water pulled way off the shore. And then as the ship went by, the water would all come rushing back in. Pretty cool as a kid, and I would have never thought about it as it applies to kayaking if you hadn't brought it up. I never thought it was related to the wake though, I always figured it had to do with the amount of water being sucked through the props. Ya learn something new every day... Woody *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
http://www.nrct.go.th/HTMLpages/king/EnglishPage/barge/barge.html *THE ROYAL BARGE* is people powered and might just cause some of those weird currents on small channels. 'It has a displacement of 20 tonnes and will carry 50 oarsmen.' check out the paddlers in the last image. bye bye bliven *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
In a message dated 10/13/99 2:51:59 PM Pacific Daylight Time, woodardr_at_tidalwave.net writes: << I never thought it was related to the wake though, I always figured it had to do with the amount of water being sucked through the props. Ya learn something new every day... >> That was my theory as well, especially since the water receded about 1-2 minutes before the ship passed my location and therefore before the wake approached. I guess we were both mistaken. Thanks for the response everyone, and keep an eye out for the freighters! Robin *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
Thanks to whoever recommended "Waves and Beaches" by Willard Bascom. It is, as reported out of print, but I was able to get a copy at the local public library and am enjoying it already. *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
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