> From: Chuck Holst <cholst_at_bitstream.net> <snip> > Bow and stern lines limit how far kayaks can move, and I > think this is, if > not ideal, still a very valuable service. My apologies since I haven't been following this thread - so this may have already been stated... I think the real value of bow/stern lines comes from not limiting forward/back movement, but from limiting up/down movement of the kayak. A _lot_ of stress is placed on the rack connections to the roof because of the long lever arm created when you strap the kayak to the rack. Pushing up or down on the end of your boat translates into a lot of torque where the rack meets the roof. Bow/stern lines limit the up/down movement of the boats. Since a single line can limit movement in only one direction, you need both a bow and stern line to help limit both. > Since I have never had the boats > and rack part in an accident, I think lines running to the > rack bars would > work almost as well as one running to each end of each kayak. I disagree - like I stated above, the value comes from limiting the movement of the lever arm created by strapping the kayak to the rack. I doubt there is much to stop a rack from separating when you are involved in a severe collision - there is just way too much force involved on those rack connection points. The fact that the kayak/rack is attached to the tie downs after the collision is just an added benefit from reducing the likelihood the rack will separate from the roof in the first place. Another thing that helps (or hurts) is the spacing between the rack bars. The closer together, the more affect the lever arm will have in trying to wrench the rack off your roof. On vehicles with a lot of spacing between the rack bars (such as a pickup with one bar over the rear of the cap, and one bar over the cab) they benefit less from bow/stern lines (but if you don't use them, you also lose the secondary benefit of having the boat tied to your vehicle if it does separate). There is a simple demonstration folks can do to illustrate this: Grab your favorite paddle (this will simulate your kayak). Place your hands about 6 inches apart on the shaft (this simulates your rack where it contacts your kayak/car). Have one of your kids grab a paddle blade and move it up/down. It will move easily (and in real life would wrench your rack off your car). Now spread your hands apart further and repeat the experiment. The further your hands are apart, the harder for your kids to move the paddle blade up/down. One final part of this experiment (for when boredom has really set in): Tie a rope to each paddle blade and stand on the center of the rope (simulating bow/stern lines). Make the rope taught and have your kids move the paddle blades again. It doesn't take an collision to cause a rack to roof failure. Wind, hitting a pothole, slowing down - all will cause a kayak to pitch up and down and possibly cause the rack to roof connection to fail. In a collision all bets are off. I bet most racks will separate when loaded when involved in any significant collision. What we should be trying to prevent is the rack and kayak from going airborne from just normal cruising. Woody *************************************************************************** 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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