Join Date: Feb 2004
Thanked 0 Times in 0 Posts
Rep Power: 0
We religiously use snubber lines while anchoring on chain rodes. However, my primary purpose is to reduce the amount of wear and tear on deck hardware, as well as to dampen chain noise belowdecks, rather than to try and rectify any real or perceived shortcomings of inelastic anchor rodes with regard to overall holding power of the anchor.
Fortunately, protecting deck hardware from inelastic shockloading by chain rodes only requires a modest amount of elasticity. Just think of the clear difference between dropping a ceramic plate on a wood floor instead of a concrete floor. The wood floor must only have moved a few thousands of an inch...
Although it may be tempting to go to longer, stronger and more elastic snubber lines -- as evident from the discussions in this thread -- we should try to avoid creating what is know as a "kinetic rope" (more precisely a kinetic energy recovery rope - KERR) in the world of offroad wheeling and caterpillaring.
The purpose of a KERR, typically made of the same elastic nylon rope used for snubber lines, is to transfer kinetic energy delivered by the towing vehicle while the rope stretches, into potential energy that is going to be ADDED to the energy that the towing vehicle can deliver as soon as the rope is fully stretched.
There are some You tube videos, I believe, that show the awesome power of the KERR technique, e.g. when extracting battle tanks from the mud. The forces created should be intimidating to anyone who realizes that KERR ropes have at times pulled vehicles from the mud while leaving their wheels and axles behind. Also, a second belay line needs to be used in case the KERR line, or one of its hooks/shackles or attachment points break, since the resulting whiplash has at times catapulted hooks or shackles straight through radiators or even imbedded them in engine blocks.....
Perhaps you might argue that circumstances at anchor are very different. But, are they really.....? Some of us have probably experienced being trapped in an anchorage with substantial waves rolling in, or even breaking around us, with the bow of our vessel being driven back with great force. I submit, that under such wave-generated impact conditions (or even impacts generated by sailing wildly at anchor), the boundaries between KERR snatching and anchor snubbing are likely to be vague at best and nonexistent at worse.
If so, what practical consequences are there to be distilled for sailors?
(1) the elasticity of a snubber line (or an elastic anchor rode itself) is at best a two-edged sword; under certain conditions the destructive forces on anchor and deckware are likely to be amplified instead of reduced;
(2) therefore the minimum amount of elasticity necessary to control shockloading on deckware is likely to be the optimum choice; and
(3) under dynamic load conditions snubber lines should be treated with the same respect off-road recovery specialists treat their KERRs (i.e. one should keep one's distance and the rope should be replaced regularly).