Protection at Anchor

A few cruisers have contributed to this discussion. Please email us if you have any comments on this subject.

Sent to noonsite by David Peppiatt, 28 April 2009.

New Zealand is the home of the “electric fence”; a simple device guaranteed to keep the most obstreperous bovines at bay.

It seems to me that a very good form of defence against boat-invasion, while at anchor, would be to install a Kiwi electric fence.

Unless the invader(s) come aboard via parachute or pole-vault they will almost assuredly have to grasp some part of the vessel’s taff-rail wires\supports to get aboard.

A 10,000 volt, Kiwi electric fence, wired into said rails, will bounce the biggest and the best invader straight into the water.

All you need do is warp the electric fence material (polyprop fabric strip with imbedded wire) around each level of your vessel’s fence and bingo!

Imagine Herbert The Horrible coming alongside, in the dead of night, presuming you’re easy meat. He reaches up, ever-so quietly. Both hands get a grip on what he thinks is just a boat rail. Boom! Herbert learns what Kiwi bulls have now known for years….Never mess with a Kiwi electric fence!

Better yet, they run off a clutch of D-Cell batteries, unless you want to give Herbert a real shot at the Guiness Book Of Records for the greatest leap backwards since Mao came to power…to do that you wire it into your main battery.

This defence system can be left in place and simply switched off until needed. It’s corrosion-free and largely maintenance-free.

You can wire up fences, alloy booms and mast, rigging, you name it. It has a self-returning earth so anything metal, to which it is attached, will be live, live, live.

Even better yet, it cannot be deemed a man-trap because it cannot kill.

There are various simple bits of electronics you can add to a Kiwi electric fence.

For example, when Herbert The Horrible gets his first taste of 10,000 volts; ergo, he just earthed the system….the electronics, noting a voltage sag, can switch things, like lights, sirens, EPIRBS, you name them.

And so while his mates are watching Herbert do screaming splash impressions….and they know not why on account of electric fences aren’t devices freely advertised at “Pirates 101″…. your entire vessel lights up like Christmas Eve, your sirens are screaming and, most importantly, you get a heads-up that something is going down.

It’s about then that you get to come out pointing your own gun at the intruders…..presuming they have enough fortitude to stick around after the last few moments’ events.

I’m suprised nobody has ever considered such a simple, yet elegantly deterrent, deterrent to boat-invasion.

Further suggestions sent by Gregory Sandness, 3 July 2009

Subject: Electric Lifelines & sizzling pirates
Some years ago I purchased a set of floats for an airplane I had from a couple who had not only wired an agricultural electric fence charger to the lifelines of their 20 metre ketch, but also that of the main genset as an alternative for hostile waters when a “fence charger” might not answer. The (would be) intruder could grab the first lifeline without effect, but the moment they grabbed the second… the circuit would be complete and the happily idling genset would thence growl with the load/resistance placed upon it. Capt. Nemo would be proud I’m certain.

Further Ideas and Questions from Robert Jones – 28 June 2012

Subject: Kiwi Electric Fence Chargers
The electrified rail option is a good one. I will be constructing similar on the trawler we are purchasing. Retiring to the sea from a lifetime of farming and ranching, I have been installing and using “New Zealand” style electric fencing for livestock management since the technology came to the US in the early ’80s.

Most of the fencing on our current ranch is high tensile wire connected to an electric charger imported from NZ ( The theory behind all of the chargers of this sort is that they store and pulse high voltage (low amperage) electricity. When, and only when, the animal (or human) completes the circuit, they receive a “shocking”, non-lethal, pulse that surely is an effective deterrent. While maintaining, or travelling too close, I have, accidentally, received this shock many, many times.

The good thing is that, if your rail is metal, even chrome, you do not need to rap the nylon fence material around it. Because the rail is already conductive, you would simply need to tap the hot lead from the charger to the rail. The complicated part is designing the ground system. A must. Dealing with livestock, the ground is accomplished through the animals direct contact with the actual ground. On the charger end, the ground stake can be next to the charger and connected to the ground lead of the charger. The actual ground will complete the circuit with the hot wire at great distances. Another method, is to run two wires, one hot and one a ground. With that method the animal will only get a shock when they touch both wires at the same time.

That is where the boat installation will get complicated. Where to run an isolated ground circuit so as to have the assailant touch both to complete the circuit and receive the shock. The ground must be isolated because the charger will go dead when the circuit stays closed. That is what makes the system not start fires or kill. You could run the ground to the water, but it would only effect swimming assailants. A boat would isolate. You could also hand lines from your boat with the integrated wires, but the person would have to touch both.

I would love to hear other ideas of how to set the trap to close the circuit. Thanks for the forum!!

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