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.

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® 

 

Moisture Meter Facts and Myths

Moisture Meter Facts and Myths

Moisture meterOur continuing discussions on various aspects of the marine survey and some of the logistics involved in getting it done provides us with a perfect lead in for this a discussion on moisture meters. It’s been a while since we discussed these little guys and since moisture readings can be one of the more confusing of the items noted on a survey report let’s see if we can dispel some of the myths bandied about surrounding these infernal little devises. I say infernal with a bit of humor thrown in because in all reality as a surveyor I have to admit that I have come to rely on the data that they present, but only when in the hands of an experienced operator.

First of all let’s take a look at where the moisture meter originated and how it happened to wind up in the hands of marine surveyors and fiberglass repair professionals.          The moisture meter was originally developed by the lumber industry to assist in the scaling and grading of wood. Early versions were all of the analogue type and each had 2 sharp pins extending from the end of the meter’s housing which the operator pressed into the wood and the reading was displayed by the needle on the meter. About 20 or so years ago the meters lost the sensor pins which were replaced by a sensor pad on the body of the meter which was simply  held against the subject matter and the display produced a reading. This improvement allowed the meter to be used on various materials such as drywall, stucco and yes fiberglass. It wasn’t long before any marine surveyor serious about their craft had one of these guys in their tool kit. By the way the pin type meters are still in use by the lumber industry. Since no formal training or instruction was provided on how to interpret the information produced by the meter (remember they were mainly for use on lumber) many different approaches to the meters usage and data interpretation surfaced and became commonplace. Luckily since then most experienced surveyors have become proficient in their use but there remain many myths and confusions that still surround the use of these devises.

The first comment that I would like to make is that incorrect usage of the moisture meter has probably been responsible for more unnecessary repair and bottom jobs to fiberglass boats that all other diagnostic methods combined.

Secondly the moisture meter does not actually measure the moisture content of the substance. In actuality it measures the electrical conductivity of the material in question.

The theory is that since water is a conductor of electricity, the more moisture contained in a substance the higher the reading will be. This reading is then displayed on the meter, usually as a percentage.

This brings me to my next comment. Moisture readings should NEVER, NEVER be interpreted as, or reported as a percentage. My answer is always “as a percentage of what?” Here’s why. All fiberglass resins all have some level of moisture in their core makeup, some more and some less. Unless the surveyor was present on the day that the boat’s hull was popped out of the mold and if he was able to take moisture readings at that time, put the information on file for 15 years or so or until the next time the hull’s moisture levels were measured there is no way that percentages have any bearing on the resulting information. I still come across survey reports that report moisture levels as a percentage.  Add to that the fact that a boat hull’s make up is actually a combination of resins, gel coat (which is actually a thickened, pigmented resin) spun glass re-enforcement (of various configurations) and possibly a core material (balsawood, closed cell foam or plywood). Then add a few coats of anti-fouling paint and we have enough to seriously confuse any self-respecting moisture meter. This where the experience factor of the operator comes into play. The moisture meter is in reality a very simple devise to use. You place the sensor pad on the substance in question and read the display. That’s the easy part. Trying to understand and interpret what the meter is telling us is where the difficulty sets in.

The next question that arises is how deep into the substance can the meter actually read? Moisture meter manufacturers make claims and I don’t want to say that they are false but it appears that any meters depth of accuracy, again will depend largely on the substance being measured.

Does anybody notice a pattern developing here? The point that I’m trying to make is that there are usually more variables in the use of a moisture meter than there are absolutes and interpretation of the readings is the real key. I have taken moisture readings on hundreds of boats over the years have to admit that I still do not have it all figured out but I have learned enough over the years to know when to question the readings and investigate further by other methods. I see moisture meters being offered for sale to boat owners at retail outlets and when I’m questioned as to whether they are a good investment for any boat owner my answer is usually no. In most cases what happens is that inexperienced meter operators are easily confused by any or all of the issues listed here and they wind up calling someone such as myself to re-examine and make recommendations.

Taking moisture readings in ambient air temperatures below freezing is also a bad idea and since I have mentioned this previously many times in this column I won’t go into it here.

One thing that the moisture meter does do very well is to prove the positive, this is if a substance is dry the meter will show it easily. Its when the readings are elevated that the confusion sets in.

So I think that you can see that while the moisture meter is in reality, is a simple devise to use there’s a lot more to it and accurate interpretation of the data is the real key.
Reprinted From “The Seaworthy Surveyor” Ontario Sailor Magazine

Original Article By David Sandford AMS® 

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