Dezincification

Dezincification can be recognized by the metal colour, shine and texture. In the image below, for example, the section of a bronze propeller blade with distinctly dezincified areas, recognizable by their pinkish colour, can be noticed. Black areas are rests of antifouling paint. White residues are housings of tubular worms and barnacles.

Dezincification can be limited to the surface or may well extend into the metal body.

The marks on one of the dezincified areas on this prop blade have been inflicted by the surveyor’s pocket knife tip. Blows by the pocket knife in the sound areas, in contrast,  have left no marks whatsoever! Dezincification compromises the bronze metal’s mechanical properties significantly and will lead to failure of submerged metals and, if left undetected, to heavy, subsequent damages. Usually, dezincification will slowly develop over time, but this is not a firm rule: A short circuit somewhere on board may lead to a quick failure of one fitting over short time, say few days.

For example, a short in a recently replaced deck light on one spreader may lead to power the mast, which, over the forestay may put the bowsprit’s waterstay under voltage. As a result the waterstay fitting starts to dezincify. This example is a real case and it required a lot of effort and wit to narrow down and eventually find the shortened deck light.

If one dezincified metal appurtenance is identified in the submerged hull, one should inspect the vessel for further damages, including damages to metal bonding and undesired galvanic shorts to one or the other metal fitting. A galvanic corrosion survey with a reference electrode may be required.

The author of these lines distinctly remembers the failed skin fitting on his own boat, which he plugged with his finger until somebody around heard him shouting for help….

Fair winds.

dezincification, prop blade, antifouling, tubular worm
Dezincified prop blade

Gloss Measurement

Gloss Measurement of Paints and Gelcoats on Boats

Gloss is an important aspect of our visual perception of objects. Boats are of no exception.

Surfaces with high reflectance are perceived as glossy, shiny or lustrous, whilst less reflective surfaces are perceived as semi-gloss or matt.

Gloss measurement of yacht's finishing
Gloss measurement of yacht’s finishing

The gloss of a boat’s beautiful cosmetics may deteriorate with UV, applied chemicals, saltwater and regular wear and tear during her life. Also, the gloss of a newly applied coating (paint or gelcoat) might be of question.

At marineSOLUTIONS, our surveyors measure the gloss of boat coatings and surfaces with an optical instrument called a gloss meter. The gloss meter is a useful instrument for objectively measuring the gloss of a surface. Our gloss meter is capable of taking measurements in three different angles (20°, 60°, and 85°) which covers the entire coating applications. It provides quantifiable gloss measurements, expressed as gloss units (GU).

Some examples subject to our gloss meter measurements are as follows:

  • Gloss of coatings during the build process and pre-delivery at the shipyard
  • Gloss of coatings during pre-purchase inspections
  • Gloss of newly applied paint after a topcoat work
  • Gloss of repairs
  • Gloss of interiors such as varnishes

NDT – Galvanic Corrosion Inspections

Galvanic Corrosion
Galvanic Corrosion Aluminium Saildrive Strut

Our surveyors perform galvanic corrosion potential surveys to assess, diagnose and troubleshoot galvanic and stray current problems on a boat, yacht or dock.

Please contact us today for a for a free quotation, or please ask for a sample report.

(See also our post about dezincification.)

With a electric potential inspection, we are able to assess the following:

  • Measuring a boat’s hull potential

The hull potential for a vessel is a function of its hull material and its underwater metals. Whether it is an aluminum, steel, fiberglass or a wooden vessel, the hull potential shows if the vessel’s underwater metals are protected against corrosion or not.

  • Verifying the boat’s bonding system

Sacrificial anodes such as zinc anodes attached to the hull of the vessel’s hull provide corrosion protection to underwater metals including but not limited to propeller shafts, metal struts, rudder posts, through-hull fittings, seacocks, stern tubes etc. via the bonding system. We are able to verify each component’s good connection to the vessel’s bonding system.

  • Checking the boat’s galvanic isolation

When a boat’s AC shore cable is connected to a dock’s power pedestal, it is possible for the vessel to galvanically couple to other boats and further underwater metals in the vicinity. We are able to determine the galvanic currents to and from the boat and comment on the possible measures.

  • Locating stray currents on the boat

The most insidious form of marine corrosion is electrical leakage that causes electrolytic corrosion, also known as stray current corrosion. It is able to quickly consume vessel’s sacrificial anodes and critical underwater metal appurtenaces. We are able to detect its existence and pinpoint its cause. It is good practice to have the stray current property of a boat inspected regularly – before the hull starts “to boil” or the submerged fittings start to get pitted or dezincified.

Infrared Thermography

Temperature distribution in the stuffing box
Infrared Image of  the Temperature Distribution in the Stuffing Box

Infrared thermography is a technique to measure and spatially evaluate temperature patterns due to temperature differences. In recent times, Infrared (IR) thermography has become a powerful tool in various fields such as industrial investigations, environmental and military monitoring. It is used for law enforcement , and last not least, in the boating industry.

Contact us here to get a free quote for a thermal inspection.

The boating community benefits from this technology in two main fields of application:

  • Vessel hulls can be scanned in a quick and efficient manner in order to gain overview about invisible lurking problems. For that, the hull must be monitored in a state of “thermal imbalance”. If, after a thermography session,  the surveyors suspects damages in the hull, then they may resort to detailed, but slow NDT investigation, like ultrasound investigation.
  • The machinery, electrical installations and electronic systems of vessels are getting more complex over the years, and plumbing as well as heating/cooling equipment is nowadays the rule than the exception. Thermography is a fast and highly reliable method to establish where there is high temperature where it should not be, like with power cables with overload or cable connectors of high transition resistance and also where there is no temperature where expected.
High temperature of two loaded circuit breakers
High temperature of two loaded circuit breakers

With our FLIR  thermal camera we can perform thermographic inspections on various equipment and on hulls.

Some inspections we regularly carry out, often in the context of pre-purchase surveys are the following:

  • Water and moisture intrusions on hull and other areas,
  • Structural defects,
  • Engines, generators, gearboxes and their components,
  • Potential electrical overloads,
  • Joints and sections of electric lines such as circuit breakers, busses, etc.
  • Heating and air conditioning units,
  • Insulations,
  • Bearings, shafts, pulleys, etc.
  • Leaks and blockings in plumbing.

Infrared thermography has the ability to identify problems before they grow and turn into serious issues. Regular IR thermography is common good practice for complex machinery like junction boxes and is a simple and effective prevention of fire damage.

Highly loaded circuit breaker in the AC Circuitry
Highly loaded circuit breaker in the AC Circuitry

Osmosis Evaluation

Moisture Content Evaluation (Osmosis)

We utilize several  state of the art moisture meters to assist in tracing osmosis and its pre-stages. The most important value we can add, though, is the experience of our company and of our surveyors.
We utilize several  state of the art moisture meters to assist in tracing osmosis and its pre-stages. The most important value we can add, though, is the experience of our company and of our surveyors.

A composite boat hull is a mixture of plastic matrix reinforced with fibers, created in layers which form the so called laminate. Due to the nature of conventional molding techniques, the laminate will inevitably contain small voids, air pockets and minute gaps. These form seeds of osmosis.

Contact us to arrange for a moisture content evaluation.

Moisture evaluation is a core step of our pre-purchase survey for fibre reinforced hulls.

Despite general assumption to the contrary, composite boat hulls are not totally waterproof. Water diffuses into and passes through the gel coat and the laminate, sometimes not in bulk but just as individual water molecules. Over time this water collect and coalesce within the voids inside the laminate. However, there are various water soluble components within the laminate like solvents and products of semi-completed reaction products emanating back from the manufacturing process. Eventually these products dissolve in and react with the condensed water inside the voids. This process is sometimes called “hydrolysis” or more commonly “osmosis”. In time, as a result of internal pressure buildup, the size of the voids increases. At some advanced stage the pressure in the voids becomes too high for the surrounding material to support and blisters are formed – starting to compromise the integrity of the structural laminate.

Visible laminate blisters are the known, visible evidence of progressed osmosis. Invisible evidence such as elevated moisture content of a boat hull laminate can be measured and preventive measures, slowing down or even stopping the process can be taken before it is too late.

A moisture meter can determine how much moisture has been absorbed by a composite boat hull non-invasively and without causing any damage. Good moisture meters can differentiate between moisture in various depths of the laminate.

Experienced surveyors can also differentiate between structural blisters leading to delamination of the hull and ancillary blisters in paint layers or similar. Also, not every reading of elevated moisture is an indication of osmosis and the surveyor must take great care to corroborate any finding by alternative methods. In other words, there is no simple and direct correlation between moisture meter readings and laminate condition – in the absence of other corroborating information operators must never be tempted to use moisture meter readings to make a diagnosis.

Still, it is a good practice that moisture readings of composite boat hulls are carried out regularly and are recorded.

We utilize several  state of the art moisture meters, all based on radio frequency absorption but all with  different properties, complementing each other.

  • Sovereign Quantum Marine
  • Tramex Skipper
  • Tramex Skipper Plus

The most important value we add, though, is the attitude and experience of our company and of our surveyors.

Ultrasound Testing of Welds

Ultrasonic Testing (UT) of Welds

Welding is the common process of joining materials through melting and fusion, and inspection of structural welds in metals is the single most common application for Ultrasonic Testing (UT). Welding can be done by means of several methods including electric arcs, gas flames, and lasers. For ultrasonic testing, the welding method is not a primary concern.

The most commonly encountered flaw types in welds are cracking, lack of fusion, incomplete penetration, porosity, and slag inclusions. All of these are potentially detectable through ultrasonic testing.

While straight beam techniques can be highly effective at finding laminar flaws, they are not effective when testing many common welds, where discontinuities are typically not parallel to the surface. The combination of weld geometry, the orientation of flaws, and the presence of the weld crown or bead require inspection from the side of the weld using a beam generated at an angle.

Shear wave testing, also known as angle beam inspection, is an ultrasonic testing technique used primarily for weld inspections. Weld inspection is accomplished by introducing shear waves into a plate at a selected angle and manipulating the transducer so as to scan the entire weld.

In typical inspections the sound beam will travel at the generated angle down to the bottom of the test piece and then reflect upward at the same angle. Moving the probe back and forth causes the sound beam to sweep across the full height of a weld. This scanning motion enables inspection of the entire weld volume and detection of discontinuities both at the fusion lines and within the weld body.

We use Olympus Epoch 650 Ultrasonic Flaw Detector, a state of the art digital flaw detector, and Olympus Panametrics angle beam (shear wave) transducers for inspection of welds. With ultrasonic inspection, we are able to detect the following defects in welds:

  • Cracks in the weld zone.
  • Discontinuities and incomplete penetration of weld joints.
  • Lack of fusion in welded joints.
  • Porosity in welded joints.
  • Slag inclusions in the welded joints.
  • Areas with distortion.
  • Stratification of weld metal.

marineSOLUTIONS has invested extensively in the training of personnel and assortment of equipment. We come equipped not only with an understanding of shear wave testing, but also with a comprehensive skill-set of conventional and advanced non-destructive testing techniques and provide the highest level of service.

Percussion Testing

Percussion Testing

The traditional coin-tap testing is one of the oldest methods of non-destructive testing and it is regularly used for testing laminated structures. Percussion testing requires the marine surveyor to tap each point of the structure to be inspected with a coin and listen to the resulting sound radiated by the structure.

Unfortunately, the coin tapping method is dependent upon the inspector’s hearing and interpretation, the results are subject to interference from workplace noise, and this technique is unable to provide quantitative data.

Surveyor Cem Baykent carrying out Percussion Test
Percussion Test

Composites are widely used in aerospace industry. One of the biggest players in that industry; Boeing; has developed an Electronic Digital Tap Hammer that provides a quantitative measure of the hammer/composite impulse time that can be correlated to flaws such as delaminations in the structure. The instrumented tap hammer supplements the tonal discrimination of the operator with a numeric readout that is related to local part quality. The effects of background noise and operator differences on the inspection results are eliminated. This hammer is relatively insensitive to the magnitude or forcefulness of the hammer hit, but very sensitive to the local stiffness of the structure. This method provides objectivity in the test, increases the sensitivity of the test and enables the inspector to collect quantitative results of the actual impact response.

This method and device is used by both Boeing Commercial Airplane Group as well as Boeing Defense & Space Group on the composite commercial and military aircraft.

marineSOLUTIONS has invested in this Electronic Digital Tap Hammer which can be applied to many composite requirements on boats.

Metal Hull Inspections and Corrosion Measurement

Metal Hull Inspections

Overlooking metal hull inspections are surprisingly common. Be it plain neglect, be it burying the head in sand – compromised hull integrity is invitation to the worst.

(Please contact us here for a free Hull Inspection Quote.)

Just about anything that is made of metals is subject to corrosion – more so in the marine environment than elsewhere and metal hull plates of boats are no exception.
Usually, boats are lifted ashore regularly, thus enabling a superficial inspection of hull plates from the exterior. However, corrosion also progresses from the interior and only after most material is wasted interior damages can be detected from outside with conventional means. To make it worse, interior corrosion progresses mainly in areas impossible or almost impossible to see by bilge inspections. Interior corrosion is often not detectable by visual inspection as the access to bilges is limited due to various components and structures such as tanks and machinery.
If undetected over a period of time, corrosion will weaken hull plates and possibly lead to dangerous structural failures. Both safety and economic considerations require that hull plates that may be subject to corrosion be inspected on a regular basis.
To make things more complex, yacht hull exteriors are coated with fillers often applied thickly for fairing, antifouling paints and various other types of coatings.

Corrosion Measurement of Hull Plates with Ultrasonic Testing (UT)

Metal hull plate thickness assessment with ultrasound and without removing  fillers, paint layers or any coatings. To left: Olympus Epoch 650 Ultrasonic Flaw Detector spectrum on a progressively pitted aluminium hull plate.
Metal hull plate thickness assessment with ultrasound and without removing  fillers, paint layers or any coatings. To left: Olympus Epoch 650 Ultrasonic Flaw Detector spectrum on a progressively pitted aluminium hull plate. The distinct double hump (with summit to left) of this severe case would dissolve at less severe pitting into a single hump with “softened up left shoulder”. The hull plate section, as seen to right, will not reveal the pitting, for once, as the surface has been faired and coated and furthermore, as the interior is masked by tanks and other internal structures.

Metal plate thickness can be assessed with ultrasonic thickness gauges without removing  fillers, paint layers or any coatings and without any harm to them. However, these devices deduct minimum plate thicknesses by preset algorithms and may be misleading at times, in particular when attempting to assess pitted plates. An Ultrasonic Flaw Detector as we utilize in house, is by far superior to thickness gauges as it displays the ultrasonic echo spectrum. From waveform, attenuation and phase shifts, an experienced NDT surveyor can infer remarkable information about the plate and further structure under inspection. The experienced surveyor can also distinguish between true echoes and the many false reflections and diffractions and more.
We use the Olympus Epoch 650 Ultrasonic Flaw Detector, a state of the art digital flaw detector and Olympus Panametrics transducers for inspections. This state of the art instrument configuration is accepted and used in many disciplines, including the pipeline and aerospace industry. Our surveyors are trained regularly and both on job and theoretical and we keep our instruments calibrated and up to date. We have invested into numerous sound and flawed samples in order to have standards at hand for most of the issues we encounter.

(Please contact us here for a free Ultrasonic Inspection Quote.)

Link to Sandblasting (In Turkish)

Ultrasonic Testing (UT)

Ultrasonic Testing (UT) of Composite Boats and Spars:

Many modern boats are built from composites – a combination of fibers and plastic matrices. Fibers might be randomly arranged, then flattened

Non Destructive Testing NDT Survey
Non Destructive Testing (NDT)

into a sheet (called a chopped strand mat), or woven into a fabric. The fiber material is often glass, aramid or carbon where the plastic matrix is most often based on polymers such as polyester, vinylester or epoxy resins.
Moreover, the trend for carbon fiber spars for sailboats is on the rise. Nowadays, carbon fiber spars are not only seen on racers but are also placed on a range of vessels such as cruising yachts, mega yachts and even on classic yachts.
Due to the prevalence of fiber-reinforced composites (whether it is glass, aramid or carbon fibers) in boats, and due to lower safety coefficients, the need for damage-detection and characterization has increased.
Hidden internal flaws and defects within a composite structure are not uncommon. These hidden flaws and defects might be resulting from manufacturing anomalies, applied stresses or weaknesses, accidents or improper repairs. They can have a significant impact on the structural integrity of the boat and are normally not detectable by radiography or by NDT techniques other than Ultrasonic Testing (UT).

Ultrasonic Testing (UT) can be used to detect the following:

  • Uniformity of laminate thickness
  • Presence and type of delaminations
  • Presence of voids and/or porosity
  • Quality and bonding of laminate and integrity of repairs
  • Inclusions and alien material presence in laminate

Advantages of Ultrasonic Testing of Composite Boats and Spars:

  • One-sided access is sufficient
  • Highly portable equipment provides inspections at remote locations and – at a pinch – even working aloft
  • Minimal or no surface preparation is needed
  • Highly accurate in determining the exact point of a hidden anomaly and its main characteristics such as depth, size and shape
  • Provides instantaneous results and objective data

Ultrasonic testing with the correct equipment and standard samples and with well-trained operators is a powerful and non-invasive method of detecting flaws and defects in composite materials. marineSOLUTIONS has invested extensively in the training of personnel, assortment of equipment and standard samples. Equipment and standard samples can be applied to many composite requirements.
We use Olympus Epoch 650 Ultrasonic Flaw Detector, a state of the art digital flaw detector and Olympus Panametrics transducers some of which are specially designed and developed for inspection of composites. The instrument configuration is accepted and used in aerospace industry. The instrument calibration is kept up to date.

Non Destructive Testing

Non Destructive Testing (NDT) on Boats

Non-destructive testing (NDT) methods are powerful and non-invasive techniques to determine the integrity of a component or structure of a boat and to discover flaws without causing any damage. NDT methods do not harm, stress or destroy the material being inspected. Because of this, NDT is a highly valuable and state-of-the-art technique that saves both time and costs in inspection and evaluation of boat structures and components.

NDT inspections can be made during the building process of a vessel, pre-delivery, pre-purchase, routine surveys, damage inspection or as a part of post-repair inspections.

Some NDT services we carry out regularly are as follows: