I had a similar experience to what Jack mentions, where my eTrex took a tumble in the water during a landing and subsequently the unit failed to work. I was able to get a refund, but it was still a hassle. ALSO: Garmin says the contacts (the ones used to hook the GPS to your computer) are gold-plated. If so, it must be about one molecule thick, since even without being submerged, but only coming into contact with salt spray, I found green corrosion coating the contacts. Before I knew they were (supposedly) gold-plated, I took a little screwdriver to scrape the corrosion off in the hopes of getting connection and probably scraped whatever trace of gold was on it clean off. Incidentally, does anyone know whether Garmin will send a replacement unit in this situation? Evan Woodinville, Washington >>>>>Date: Fri, 25 Jan 2002 23:11:55 EST From: JCMARTIN43_at_aol.com Subject: Re: [Paddlewise] Used Garmin eTrex??? > BTW, I have checked out the submersability of Garmin's unit by going for a > swim in the surf. I rinsed it in fresh water and it works fine. I now put it > in a baggy for surf launches and landings, but otherwise take it out and > just keep it in the pocket of my PFD. > Abandoning my lurk at the scan of eTrex! My luck with that unit was not as positive. Splashing with salt spray and probably some water shorted out the batteries and disabled the unit. Twice. I returned it to West Marine with all the corrosion intact, and suggested --- in writing --- that they not perpetuate Garmin's misstatement about "submersibility". They will admit that the unit will not work after submerence of virtually any kind, but, if you can find new batteries, completely dry the inside of the battery casing, and then get it back together during a severe attack of clapotis, you have no problem. See, Garmin will say, the electronics survive! BS --- it's false advertising, and they should cease and desist. An unbagged eTrex is a light paperweight once it's wet. Not worth the money. Just plain not worth the chance that it won't work when you really need it. End rant: resuming lurk. Two months to graduation. Jack Martin<<<<< *************************************************************************** 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/ ***************************************************************************
Had a pleasant paddle this afternoon, down the backwater of a small dam. Nice, easy mid-January inland paddle with a couple of friends -- a nice thing to do in a time of year that most years sees all too much ice, snow, and time spent on the computer rather than out in the big world. After the paddle was over, we were sitting on the back of his boathouse, taking in the sun and relaxing muscles too long gone unused, and one of us mentioned a guy that he'd seen or read somewhere that had used a Smoker canoe as the body of a Bonneville salt flats racer -- powered, I presume, by a honking V-8. Though there are days when I'd like to have had a little power in a canoe, this seemed a little much. I got to wondering, however, of the aerodynamics of canoes and kayaks at high speed, however. It's not such a dumb thing -- most of us have had our kayaks out in relative windspeeds of 100 mph or more, say, strapped to the rooftop rack, heading 70 mph down the highway into a 30 knot wind. Those reading from Germany, with no speed limit autobahns, may have had considerably higher relative windspeeds. Now, I will admit to having spent a few bad-weather Sunday afternoons sleeping through NASCAR races on the idiot eye. On the occasions that I have been awake for at least part of the race I've noticed that the announcers spend a lot of time talking about downforce, spoilers, drag, and other things aerodynamic. I suspect that the average kayak designer rarely spends much time thinking about spoilers on a kayak, but as I drove home I spent a little time visualizing what happens to a kayak sitting on the roof of a car at speed. My question, then, is fairly simple: to throw out variables, for the sake of disucssion, let's consider a car with a single kayak heading down a road, with dead calm winds. Ignoring the straps and such that hold it down, is the kayak generating upforce or downforce? My guess is downforce, and probably not an insubstantial amount, mostly because the area between the bottom of the boat and the roof of the car is going to present something of a venturi that Bernoulli's principal can grab hold of. But, there are complications, the biggest one being the wind being deflected upward from the windshield and hood of the car onto the underside of the forepart of the boat hanging out in the breeze. The boat is going to be affected by this, of course; under some circumstances, the upforce will raise the bow of the boat, increasing the frontal area and hence the drag, and the situation will worsen and the boat will do a backflip before you can say, "Did you remember the tiedown straps?" Let's remove some complications and reduce it to simplicity. Mount that boat on a rack on the back of a semi-trailer for the test, just to get rid of the upward force and try to get the airflow coming at it from directly in front. Make a special rack for the test, say, a pair of rods that would fit through fore and aft grab loops on the end of the boat, so the boat can move up or down as necessary without moving backward, and put some scales under the boat. Upforce or downforce? Little or lots? Why do you think so? I know this is a nearly useless question, but it's something to think about while facing the prospect that the weather is supposed to turn colder and it may be a while before I can get out again. -- Wes --------------------------------------------------------------------------- Wes Boyd's Kayak Place http://www2.dmci.net/wesboyd/kayak.htm Kayaks for Big Guys (And Gals) | Trip Reports | Places To Go | Boats & Gear --------------------------------------------------------------------------- *************************************************************************** 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/ ***************************************************************************
At 06:46 PM 1/27/02 +0000, Wes Boyd wrote: >Had a pleasant paddle this afternoon, down the backwater of a small dam. >Nice, easy mid-January inland paddle with a couple of friends -- a nice >thing to do in a time of year that most years sees all too much ice, snow, >and time spent on the computer rather than out in the big world. > >After the paddle was over, we were sitting on the back of his boathouse, >taking in the sun and relaxing muscles too long gone unused, and one of us >mentioned a guy that he'd seen or read somewhere that had used a Smoker >canoe as the body of a Bonneville salt flats racer -- powered, I presume, >by a honking V-8. I just recently saw a picture of this. I think it was the latest issue of either "Sea Kayaker" or "Canoe & Kayak" magazine. *************************************************************************** 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/ ***************************************************************************
>>>and one of us >mentioned a guy that he'd seen or read somewhere that had used a Smoker >canoe as the body of a Bonneville salt flats racer -- powered, I presume, >by a honking V-8. I just recently saw a picture of this. I think it was the latest issue of either "Sea Kayaker" or "Canoe & Kayak" magazine.<<< C&K, the latest issue.... I wish I could come up with a reference, but I remember reading something a few years ago wherein a paddler kept track of his gas mileage with his canoe on the car. The gist of it was that gas consumption was always greater, but decreased the further back the bow was in relation to the windshield. If the bow stuck out too far then it interfered with the slipstream from the windshield. Wasn't there a message on Paddlewise last year in a discussion of tiedowns regarding bungies? In one the writer said that he once tied his sea kayak down with bungees and someone behind him saw the kayak lift right up off the brackets and 'float' above them... If this boat were upside-down then the flow-generated forces would have pressed down on the car with at least the equivalent weight of the boat..... Joe P. *************************************************************************** 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/ ***************************************************************************
Wes wrote: [Re: aerodynamics of a sea kayak in transit on a roof rack:] > Let's remove some complications and reduce it to simplicity. Mount that > boat on a rack on the back of a semi-trailer for the test, just to get rid > of the upward force [from a car's windshield] > and try to get the airflow coming at it from directly > in front. Make a special rack for the test, say, a pair of rods that would > fit through fore and aft grab loops on the end of the boat, so the boat can > move up or down as necessary without moving backward, and put some scales > under the boat. Upforce or downforce? Little or lots? Why do you think so? I'll take a SWAG at this, from the perspective of a sometime aeronautical engineer wannabee and longtime model airplane flier. (Impressive credentials, eh?) I'd say it's close to a wash, mainly because while the main airfoil (the hull) is shaped to provide a downward force (aka "downforce") the effect is weak compared to what a NASCAR racer develops because they exploit a variation of the ground effect, using a path that is very close to the ground. In addition, the deck of the kayak is airfoiled, also, to produce some upward force ("lift" in airplane terms), albeit not to the degree the hull is airfoiled. Finally, the beam of a kayak ("wingspan" if it were a true wing) is so small much of the effect of the moving air would be to form non-lifting vortices spinning off the sides of the yak. (This is one of the reasons long wings are more efficient than short wings.) I don't want to do the experiment of driving down the road at highway speeds with my yak untethered in its cradles to see if it would take off, but a friend did, at 35-40 mph. Result: it had not moved a shake when he pulled over to the side of the road. He was shaking, however, at the prospect of what might have happened. The bottom line in this may be that variations in sidewind and buffetting from passing semi-trailers have more upset potential than the "aerodynamic" effects of yak airfoil. Strap (and bow- and stern-tie) that baby down. Nobody needs a 17-foot fiberglass projectile impaled in the windshield! -- Dave Kruger Astoria, OR not an engineer, either *************************************************************************** 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'm driving from Florida to Maine in June. My fiberglass Kajak Sport Viking will be on top of my VW Van. ...on kayak cradles, with tie-downs to the van front and rear. ...with cockpit cover. The question is: "Should I wrap the whole boat up with something to protect it from sun, wind, and other?" It may be on top of the van for a month. Marinell *************************************************************************** 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/ ***************************************************************************
-----Original Message----- From: Dave Kruger [SMTP:dkruger_at_pacifier.com] I don't want to do the experiment of driving down the road at highway speeds with my yak untethered in its cradles to see if it would take off, but a friend did, at 35-40 mph. Result: it had not moved a shake when he pulled over to the side of the road. He was shaking, however, at the prospect of what might have happened. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I wouldn't deliberately make this experiment, either, but it happened to my wife and I by accident after she was interrupted while putting her kayak on the car after dark. After about 15 minutes of conversation, I told her it was time to go home. So we got into the car and started off. We drove at least two miles down city streets, making a couple turns and stops before we got onto the freeway. Two miles later at about 55 mph, I mildly commented that the bow of her kayak was moving around a little more than usual -- no more than an inch or so, though. "Ohmygod!" she said. "I forgot to strap it down!" I immediately slowed down to 50 mph and took the first exit we came to, which was at least another three miles, then drove three blocks before I could pull over. Sure enough, not a single strap. The boat, a Romany 16, was just resting on the cradle. We strapped it down well before driving the last couple miles home, feeling very fortunate it was still with us. Chuck Holst *************************************************************************** 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/ ***************************************************************************
Speaking as someone who has done a lot of aerodynamics reaseach in the past, inculuding wind tunnel tests, I would say you most likely would get a lot of lift from a kayak on the roof of a car. The "up" flow field from the front, hood and windsheild would cause large vortexes to form off the gunwales causeing a lot of lift. This would occur either way you mount the kayak [right side up, or upside down]. You also can not ignor the effects of the rack or straps since these could have a large spoiler effect, disrupting the flow. There would be no effective down force on the car from the "bernulli" effect between the car roof the the kayak, whatever low pressure that occures in this space would have equal and opposite effect on the roof of the car, as the kayak, cancelling each other. More likely the rack would totally spoil this flow any way, and since it is not contained the low pressurre area would just draw in air from the sides, causing more lift generating vortexes. The vast majority of the effect would be drag, very noticable on smaller cars in terms of fuel economy. As well as in cross winds. Perhaps dangerouly so in very light cars. I carry my lightweight skin on frame kayaks directly on the roof with a thin foam pad, with bow and stern lines, and at least one circumference strap. This reduces the drag, and the lift, as much as possible and does not affect the fuel economy much. This is much less expensive than a rack, and you are not as likely to drive off without securing the kayak. Peter *************************************************************************** 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/ ***************************************************************************
In a message dated 1/28/02 3:55:40 PM Eastern Standard Time, owner-paddlewise_at_paddlewise.net writes: > Date: Mon, 28 Jan 2002 11:56:53 -0500 > From: "Marinell" <marinell3_at_home.com> > Subject: Re: [Paddlewise] Question for the engineers > > I'm driving from Florida to Maine in June. > My fiberglass Kajak Sport Viking will be on top of my VW Van. ...on kayak > cradles, with tie-downs to the van front and rear. ...with cockpit cover. > > The question is: "Should I wrap the whole boat up with something to protect > it from sun, wind, and other?" It may be on top of the van for a month. > > Marinell > Marinell, I trust you're going to stop and visit with me on your way north, so I can reciprocate your hospitality. Hank *************************************************************************** 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/ ***************************************************************************
Wes Boyd wrote 3 days ago (Iīm late with reading): > My question, then, is fairly simple: to throw out variables, for the sake > of disucssion, let's consider a car with a single kayak heading down a > road, with dead calm winds. Ignoring the straps and such that hold it down, > is the kayak generating upforce or downforce? I donīt know, but I remember a story my friend George told me last year. Some time ago, theyīve got a VW, a high volume vehicle known as a gasoline loving car. Once George and his wife checked out on a long tour (with the VW) down to Italy, that the VW needs less gasoline WITH the boats loaded on top, then WITHOUT boats on it. Crazy... maybe itīll help you, Wes. They told the "gasoline-effect" to VW, but nothing happened. Thatīs all. But several times when I was "on the road" with a nice looking seakayak on the top, the car behaves "better" in some way, than without boat. Canīt explain it nearer, just a feeling. my 2 cents paddle safe and long Jochen *************************************************************************** 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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