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® 

Marine Survey Inspections and Reports

We haven’t discussed marine surveys in a while so here goes. It’s late winter here in Canada and as we head into spring we ramp up into the busy season for us marine surveyors. I thought that a few posts on the processes of the marine survey inspection might be in order.

A Marine Survey is an objective report on the condition and value of a particular vessel paying close attention to the structure, installed systems, sails, rigging and motive power components. Survey reports are subject to the condition and accessibility of the vessel at the time of the survey. This is an important statement because the state of the vessel, as presented can affect the depth in which the surveyor can go to test and evaluate the vessel and its installed systems. For example a hull inspection cannot be performed without the vessel being hauled from the water. Electrical systems cannot be tested without charged batteries on board or available shore power.

When performing inspections test methods used by surveyors are usually of a non-destructive nature. What this means is that the vessel in question will not be disassembled by the surveyor for access to systems or components. If minor disassembly is required such as the removal of an electrical distribution panel the owner may be asked to sign a release absolving the surveyor of any issues that may occur as a result of his or her actions.

Hulls and decks are inspected visually for condition and structural soundness. In the case of fiberglass or wood construction moisture levels are verified and measured by percussive sounding and electronic detection.

Electrical and electronic systems are tested by powering up only when authorized, and providing power is available. If not visual inspections of all accessible wiring, fixtures and equipment are performed.

Plumbing systems are inspected for leaks and wear evaluations are based on visual inspections and reported life of the components.

Mechanical systems, engines gearboxes etc. are inspected for leaks, static functionality and overall general condition. If possible the engine may be started and certain dynamic run up tests will be performed.

Interior joinery is inspected for appearance, condition and structural soundness.

If the mast is stepped at the time of the inspection, rigging and spars are inspected from the deck only. For a thorough inspection arrangements should be made to de-step the mast. Sails should also be made available for a full inspection as well.

A pre purchase situation starts with all of the above and may also include a full engine and drive evaluation. Engine compression and oil pressure may be checked. On gasoline engines spark pugs may examined for telltale signs of problems such as oil consumption and internal component degradation.

At this point a sea trial will facilitate a running inspection of all spars, rigging, sails and loaded run up and tests of the all motive power components.

Survey reports should be subjective, concise, detailed and include pictures that not only indicate problem areas but also give a good general description of the vessel being surveyed. The report should deal with appearance and cosmetic issues only when they affect either vessel value or safety related issues. Current safety standards and regulations should be quoted where applicable. Although many vessels were manufactured before current standards were put into place and compliance may or may not required by law it is always good safety practice to ensure that any vessel is maintained as close to current standards as possible. Insurance providers may require compliance with certain current standards as well.

Reprinted From “The Seaworthy Surveyor” Ontario Sailor Magazine

Original Article By David Sandford AMS®


Finding a Competent Marine Surveyor

Just a few comments on how to find and hire a competent marine surveyor. This may prove to be more difficult that you might think. Here’s why.

Currently in most countries marine surveying is an unregulated profession and as a result marine surveyors come in all shapes, sizes and in varying degrees of knowledge and expertise. So how do you find a good one? Here are a few tips.

1-Look for surveyor with recognised credentials or accreditations. There are many supposed certifications out there but in my opinion (and the opinion of many insurance companies) there are only two. The Society of Accredited marine Surveyors ® (SAMS®) and The National Association of Marine Surveyors (NAMS Global). Also look for a surveyor that is a member of, or better yet standards trained by the American Boat and Yacht Council (ABYC). This important because the ABYC have re-searched and written almost all of the marine construction and safety standards currently in use today. Boat manufacturers, Transport Canada and the United States Coast Guard listen to these people and any surveyor worth his or her salt needs to be current on all of this. ABYC affiliation is the only way.

2-Ask to see a sample of their work. Examine it and decide if it will provide all of the information that you will require.

3-Compare pricing. Surveyors of quality and integrity will show similar pricing. Any significantly lower or higher should be held in question. Cheaper is not always better.

4-Last but not least consult your insurance company about the surveyor that you plan to hire. If they won’t accept the surveyor’s work there’s not much point now is there?

I can’t stress enough how important this aspect of the process is. I come across survey reports every year that are an absolute joke. This is not the time to cheap out on a surveyor with inferior skills and expertise. It will probably cost you more in the long run with possible unnecessary repairs and modifications than you saved by hiring an incompetent individual.

Here’s a point to keep in mind if this all takes place during the winter months.

When ambient temperatures are below freezing any moisture contained in fiberglass structures, such as boat hulls and decks freezes as well. During the freezing process crystallization of the substance will occur. This adds small air pockets which make electronic moisture detection virtually impossible. Also because the substance is frozen it becomes very hard rendering percussive sounding tests useless as well. It is for these reasons that I do not recommend the surveying of fiberglass boats when the ambient temperatures are below freezing.

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