G'Day, I've come across a peculiar effect/illusion and would like to know if others have experienced it? Has anyone else noticed that sometimes when paddling into shore the sea seems to slope downwards giving the effect of paddling downhill? Almost as if the beach were in a slight valley! Also under these conditions the paddling seems easier as though one were indeed paddling downhill and yet there may be no significant waves breaking so it can't be swell. I've seen this effect both when tired and fresh. Would be glad to know if anyone else has experienced anything similar or has an explanation? All the best, PeterO *************************************************************************** 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/ ***************************************************************************
Hey Peter, Sloping water... now that's what I like! It makes paddling so much easier. Usually on the sea, I look for 4+ knots of long-wavelength "slope" (e.g. current), combined with 3+ feet of short-wavelength slope (e.g. waves). Of course, these conditions are much more common on whitewater rivers, which is where you will more commonly find me... ;) Last weekend in fact, I paddled down the deep, dark, rainforested SF Hoh River on the Washington coast, which has a steep gradient that is *very* obvious. But I digress... here is the answer you are looking for: I think you have witnessed the effects of surface tension on a grand scale. Ever seen how a drop of water "beads" up on a car windshield? Well, the ocean is beading up near the shore. And if you bought that, then I have some more great "facts" to tell you :) I think it is psycological. Your mind has decided that its personal frame of reference is more important than "outside" frames of reference (e.g. the shore). So therefore you perceive the shore as being "lower" or less important. This is not an uncommon thing, and I have experienced something similar while paddling in near-dark conditions on mirror smooth water. It felt like we were paddling on molasses and were working very hard to make barely any headway. In fact, we were smoking along at a high speed, but we didn't notice this until we passed some flotsam in the water that provided a reference frame. Given the utter lack of useful references, our minds had decided that we weren't moving and that we were working very hard. I wouldn't be surprised if something similar is happening to you. It was very interesting to observe a perceived change in physical effort from this illusion. Next time you feel that sensation, try to "break the spell". Do roll close to shore and keep your eyes closed for a while. Then open your eyes and see if your perspective reorients to something more logical. Cheers, Kevin ----- Original Message ----- From: "PeterO" <rebyl_kayak_at_iprimus.com.au> To: "Paddlewise (E-mail)" <paddlewise_at_paddlewise.net> Sent: Tuesday, November 27, 2001 2:04 PM Subject: [Paddlewise] Sloping sea illusion? > G'Day, > > I've come across a peculiar effect/illusion and would like to know if others > have experienced it? > > Has anyone else noticed that sometimes when paddling into shore the sea > seems to slope downwards giving the effect of paddling downhill? Almost as > if the beach were in a slight valley! Also under these conditions the > paddling seems easier as though one were indeed paddling downhill and yet > there may be no significant waves breaking so it can't be swell. I've seen > this effect both when tired and fresh. Would be glad to know if anyone else > has experienced anything similar or has an explanation? > > All the best, PeterO > > > > > *************************************************************************** > 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/ > *************************************************************************** > *************************************************************************** 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/ ***************************************************************************
I've noticed this illusion in places where the land is almost flat and sloping gently upward from the water surface. I attributed it to a false perception of the land as providing a true horizon and therefore the water was sloping downward relative to this falsely perceived horizontal reference. A similar illusion occurs at the many 'Mystery Spot' locations where the local topography is sloped in a way that fools our perception and can make it seem that water is flowing uphill. Of course, these sites generally also have deliberately distorted structures and slanted vegetation to enhance the illusion. Michael Daly wrote: > > From: "PeterO" <rebyl_kayak_at_iprimus.com.au> > > > Maybe its caused by a local variation in refractive index of air a > > few meters above the sea surface. Line diagrams suggest it might be, but > > would water laden air cause enough change to explain the illusion? > > The first thing I though of was refraction. The refraction may be a temperature, > rather than humidity, effect. Hot land, cool water - air temp low near the surface > and increasing with height. Thermally caused refraction causes mirages and > that's just a bending-around-the-horizon sort of thing, as your experience is. > I think refraction and vertigo-like effects on balance organs would be the first > two likely candidates. > > Mike > > *************************************************************************** > 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/ > *************************************************************************** *************************************************************************** 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/ ***************************************************************************
I've noticed this illusion in places where the land is almost flat and sloping gently upward from the water surface. I attributed it to a false perception of the land as providing a true horizon and therefore the water was sloping downward relative to this falsely perceived horizontal reference. A similar illusion occurs at the many 'Mystery Spot' locations where the local topography is sloped in a way that fools our perception and can make it seem that water is flowing uphill. Of course, these sites generally also have deliberately distorted structures and slanted vegetation to enhance the illusion. Michael Daly wrote: > > From: "PeterO" <rebyl_kayak_at_iprimus.com.au> > > > Maybe its caused by a local variation in refractive index of air a > > few meters above the sea surface. Line diagrams suggest it might be, but > > would water laden air cause enough change to explain the illusion? > > The first thing I though of was refraction. The refraction may be a temperature, > rather than humidity, effect. Hot land, cool water - air temp low near the surface > and increasing with height. *************************************************************************** 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/ ***************************************************************************
> Peter Rathman wrote > >I attributed it to a false perception of the land as > >providing a true horizon and therefore the water was > >sloping downward > This now reminds me of the effect you get when paddling down the Nahanni River downstream from the Virginia Falls. The cliffs on either side of the river show the layers of sedimentary rock slightly sloped relative to horizontal. This makes the river appear sloped. An optical illusion like those magnetic hills. Definitely a possibility with the right shoreline. Three candidate explanations - ready for a vote? :-) Mike *************************************************************************** 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/ ***************************************************************************
Mike wrote >Three candidate explanations - ready for a vote? :-) G'Day, I'ld vote for the false horizon optical illusion in which a sloping beach is interpreted by the brain as horizontal. The weather conditions reported, in which the illusion occurred, were so varied its hard to think there could be similar refraction effects in each case. As for vertigo, there was no sense of giddiness or sickness, but maybe! All the best, PeterO *************************************************************************** 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/ ***************************************************************************
> A perhaps related experience is the illusion that solid ground and > stationary objects are moving after watching whitewater kayakers on the > swirling water at Taylors Falls, a popular whitewater practice spot on the > Minnesota-Wisconsin border. > It's actually called the Waterfall Effect, and I'd bet that the ground etc. seems to be moving in the opposite direction from the water and kayakers... *************************************************************************** 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/ ***************************************************************************
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