Electroshock Drowning – Prevention

Electroshock Drowning, Prevention. A few days ago I received and enquiry on my Facebook page (thanks Brian) asking about the possibility of testing for stray electrical current leakage in the water at marinas. To that end I thought that I’d talk that very subject in this post.  To make a long story relatively short it is possible to test for this but to do so requires specialized equipment. You basically need a Digital Multi Meter which is very sensitive on the low side of AC amps scale and it needs to be equipped with precious metal test leads.

Unfortunately these test results are  only good at the time of the test. In other words you could be ok  today and not tomorrow Unless you are testing every day or so which is probably not going to happen.

In my opinion,  prevention is  much better and a more practical solution to the problem than trying to continually monitor for any stray current leakage. The good news is that it’s not difficult to do just that. There is a devise on the market which is easily retrofitted to just about any boat’s on board  shore power AC electrical system. It’s called an Electrical Leakage Circuit Interrupter or  ELCI . It’s simply a high capacity Ground Fault Interrupter (GFCI) which breaks the circuit if it senses stray current leakage to ground or in our case into the water. You all know what a GFCI is. It’s that AC plug installed in our kitchens and bathrooms in our home that have the little red and black push buttons in the center. If the red button pops you simply press the black button to reset the devise. If it continually trips then you obviously have a problem which needs to be corrected.

To understand how these devises function we need to go back to our basic electrical theory which states that on a properly functioning AC (alternating current) circuit there should be equal current flow on both the hot (black) and the neutral (white) wires. Any current leakage on the circuit, however small will cause an imbalance in this current flow and the ELCI will automatically open and break the circuit.

The main difference between the ELCI and the GFCI are the current levels at which they trip at. The GFCI trips at 5 milliamps which is really too low for to be any use to us and  the ELCI trips at 30 milliamps. Enough to serve our purposes but not enough to be harmful. (Remember .6 amps AC = heart failure). The reason  that GFCI’s are ineffective for this is that all boats plugged into shore power on any one dock are electrically connected through the shore power grounding circuits and properly functioning boats will usually leak small amounts of current into the water, even under normal conditions. In most cases these current levels are too small to be of any concern. The problem is that they are cumulative (they add up) and can increase to levels, that while are still not dangerous can cause nuisance tripping of the GFCI’s and be a real pain.  This is also why, in North America AC power services at the docks rarely have GFCI’s installed. I understand that in other parts of the world GFCI’s are sometimes utilized on docks.

Ok back to the ELCI. Installation is relatively simple. In many cases the main 2 pole circuit breaker at the AC main panel can simply be replaced with one that incorporates the ELCI into it. Otherwise they can be installed as a stand-alone in the main AC feed circuit between the vessel shore power receptacle  and the 2 pole main circuit breaker at the on board  AC panel. They also are not costly, average  about $2-300 USD. Additional  information on the ELCI can be found at www.bluesea.com

In addition to the installation of the ELCI it is recommended that the on AC and DC grounding circuits be connected aboard the boat. This is easily done right at the panel.

Electroshock Drowning in Freshwater Marinas

Electroshock Drowning  is a topic in which myself and many others have been very vocal about these past few years and I have written about it many times in my magazine articles. It is a phenomenon which has been occurring in fresh water marinas, cottage docks and anywhere boats are moored and plugged into shore supplied AC (alternating) electrical current. It occurs when AC current, by way of faulty electrical wiring or appliances either on board the boat or on the dock leak current into the water and if persons or animals (yes pets and wildlife are susceptible to this too) are in the water nearby, the current travels through their bodies causing paralysis and even death.

Here is the equation: AC electrical power is supplied to boat shore power systems typically in the range of 15-30 amps   ……   .6 of an amp of electrical current is enough to stop your heart almost instantly if it travels through your body in an effort to reach ground.

How does this occur: It occurs when, through a wiring fault or a fault with an AC appliance allows stray current to  travel through the boats DC ground circuits which include underwater metallic components such as the prop shaft or stern drive. Think of your boat when plugged into shore power as similar to a hair dryer plugged in and floating in the bathtub. This in effect electrifies the water in the immediate vicinity of the affected boat. Anyone swimming nearby can be affected by this as the electrical current moves from the charged water to ground. If you remember your basic electrical theory electricity always moves from the source to ground and if your body gets in the way it will pass right through you and your heart.

Another point that you need to be aware of is that this occurs mostly in fresh water situations, much more so than in salt water. This is because salt water is a better conductor than fresh water and any current dissipates rapidly after it enters the water. In fresh water it remains at a concentrated level in the immediate area surrounding the boat. And when you take into consideration that the high salinity levels of the human body actually make it a better conductor than the water itself, just by being in the water we actually provide the best path for the current to move to ground.

This is a very brief overview on how this can occur and is occurring. I will have much more to say in future posts. For more on this I invite you to visit a couple of websites dedicated to this phenomenon.  I will add them to my links page as well.

http://www.electricshockdrowning.org/    This site is operated by Kevin Ritz who has a very deep connection to this issue.

http://www.boatus.com/seaworthy/magazine/2013/july/electric-shock-drowning-explained.asp       A very good article by Boat US which offers a very good description on how to inspect for electrical leakage aboard boats.

http://www.boatingmag.com/how-to/electric-shock-drowning-prevention      More good information.

FRP Deck Repair, Rosborough 28 Part 2

Just a quick update on our Rosborough FRP deck repair. We decided that some additional cross bracing was necessary and we added that in addition to cutting and fitting of the plywood panels. All components will be liberally epoxy coated proir to the final installation and since its early spring here we may have to wait for the temperatures to warm a bit.

Rosborough 28 deck repair

Cross Bracing Installed. The side supports are a “starboard” like mateial and the braces are hardwood.

Rosborough 28 deck repair

The plywood panels cut and fit.

 

 

 

Hull Re-Core on a Fiberglass Sailboat

A while back I was asked to perform a pre-purchase, condition and valuation survey on a fiberglass thirty-five foot sailboat. In all fairness even though the manufacturer is no longer in business I won’t mention their name. Lets just say that it was a Canadian built boat, manufactured in the early eighties and not many were built.

As I usually do I began with an inspection of the hull exterior surfaces starting with the below waterline areas. A visual inspection showed many layers of flaking bottom paint, blisters half the size of my fist and almost every type of bottom issue that you can name. My moisture meter registers its maximum reading at 99 and at that point a red light flashes. The red light was flashing for a good portion of the time and there were very few areas on that I would consider normal moisture levels for a boat of this age. Sounding the hull was more like tapping a hammer on a leather arm chair that a fiberglass boat hull.

To make a long story short the buyer was able to negotiate a very attractive purchase price and the boat was moved to a local fiberglass repair firm for a complete bottom laminate re-core.

The original hull construction was a balsa cored fiberglass sandwich structure which had over time taken on a considerable amount of water. The pictures and text below show the repair process.

This is the hull with part of the exterior laminate layers and the balsa core removed. The edge of the balsa can be seen in near the middle of the photo. The white material is dry fiberglass which is something you should never find inside a fiberglass laminate. It’s obviously been this way since new.

FRP Hull Re-Core1

This is some of what was swept up on the floor after the balsa was removed. Lots of black rotten wood and even more dry fiberglass.

FRP Hull Re-Core3

This is the bow area with the new balsa core installed. The blue material is a core bonding compound specially formulated to bond the core to the inside fiberglass laminate layers. The gap at the bow will be filled with solid fiberglass and resin. No balsa will be used here.

FRP Hull Re-Core 4

The new core with the exterior fiberglass laminate layers completed. At this point the hull will be given a preliminary sanding and then the fairing material will be applied.

FRP Hull Re-Core 5

Now the fairing compound has been applied and next the hull will be sanded smooth in preparation for the final epoxy barrier coat. Next the new fiberglass will be allowed to out gas (cure) before the final epoxy barrier coats and the antifouling are applied. The boat will then be ready for launch

While complete bottom re-core jobs like this are rare, this proves that they can be done. All it takes is money. By the way the price for this job was in excess of 25 K.

 

Reprinted From “The Seaworthy Surveyor” Ontario Sailor Magazine

Original Article By David Sandford AMS® 

 

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