Mailport January 2014 Issue

Mailport: January 2014

DIY Rescue Magnet

There is no need to spend money on a “rescue magnet” when you can get one out of a discarded speaker. There is a permanent magnet in most speakers—it is part of what makes a speaker work. The bigger the permanent magnet, the stronger it is. Just tie one to a line or string, and you have a rescue magnet. I have three of them, and they are quite useful.

C. Henry Depew
Sisu 26
Tallahassee, Fla.

Next: Getting Practical

Comments (2)

DIY Rescue Magnet
I have found the best source for free magnets are the magnetrons out of a scrap microwave ovens magnets out of scrap computer hard drives.
Vic Lucas

Posted by: lvictorlucas | February 2, 2014 10:23 PM    Report this comment

Thank you Neal for your insightful comments.

We would totally endorse your ideas that the energy absorbing characteristics of the chain in a snubber/chain rode should not be ignored and we did make mention that the kinetic energy of a moving yacht would be 'shared' between chain and snubber. However we were trying to emphasize the elasticity of the snubber as our observations are that snubbers are simply not frequently used and when evident are both too short and too large in diameter to utilise their energy absorbing characteristics.

All chain rodes are frequently mentioned and illustrate the problem. Many who buy 'modern' anchors always comment that when they set their anchors the suddenness of deceleration when the anchor bites as the vessel drifts back on the wind is sufficient to knock over the unwary. Catenary never 'disappears' and even under benign conditions with still some 'sag' in the chain the suddenness of the 'stop' is sharp - basically the chain impact as if the vessel has hit a brick wall (or a very unforgiving rock on the seabed). Try the same experiment with the snubber attached - and it is possible to both stand upright and do so holding a generous glass of chilled chardonnay! Basically the nylon snubber absorbs the kinetic energy of the moving vessel better than does the catenary. But this needs to be checked - particularly as there is a move toward lighter (and stronger) chain.

Sadly with your comment, you have anticipated some of our further work. We intend, in the fullness of time to look at the effects of combining a rode of nylon and chain and comparing it with only nylon and only chain. We also want to look at different types (different manufacturers) of anchor plait - as we think there might be significant differences in performance.

'Anchor rodes' are a work in progress - we hope to quantify the answers to some of your questions in the future, in the meantime we are grateful we have provoked some insightful comment from you.

We might make one comment on bridles. If one arm of the bridle fails (usually with a sound like gunshot) then the other arm will take an increased load as the vessel with then lie at an angle to the wind and present a higher windage. We would strongly recommend that anyone using a snubber or bridle always has a spare, that snubbers are considered as consumables and that a snubber that is adequate upto, say, 35 knots will not be adequate at 45 knots and 'storm' snubbers should be part of the armoury.

With thanks

Posted by: Jonathan N | December 16, 2013 3:08 AM    Report this comment

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