marineSOLUTIONS

Your Marine Surveyors in the Eastern Mediterranean…


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Osmosis

Moisture Content Evaluation (Osmosis)

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 moulding techniques, the laminate will inevitably contain small voids, air pockets and minute gaps.

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 way 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 – compromising the integrity of the structural laminate.

Visible laminate blisters are the known, visible evidence of progressed osmosis. Invisible evidence such as 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 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 recorded.

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

  • Tramex Skipper
  • Tramex Skipper Plus
  • Sovereign Quantum Marine

The most important value we can add is the experience of our company and of our surveyors.

UT 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.

Hull Inspections with Ultrasonic Testing

Hull Inspections

Corrosion Measurement of Hull Plates with Ultrasonic Testing (UT):

Hull Inspections are often overlooked by boat owners. Just about anything that is made of common structural metals is subject to corrosion – more so in the marine environment than elsewhere and hull plates of boats are no exception.
Usually, boats are lifted ashore regularly, thus ensuring a superficial inspection of hull plates from the exterior. The particularly important problem on boats is the measurement of remaining wall thickness of hull plates which may be corroded on the inside surface. Such 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 are subject to corrosion be inspected on a regular basis.
To make things more complex, boat hull exteriors are coated with fillers often applied thickly for fairing, antifouling paints and various other types of coatings. Measurement with simple thickness gauges can be less effective at detecting pitting and measuring the true minimum thickness. An Ultrasonic Flaw Detector is by far superior to thickness gauges as it displays ultrasonic waveforms. From waveform, attenuation and phase shifts, an experienced NDT surveyor can infer remarkable information about the structure under inspection. The surveyor can also directly distinguish between true and false echoes. Furthermore, we are able to determine the exact wall thickness of hull plates without removing the fillers, paints or any coatings and without any harm to them.
We use Olympus Epoch 650 Ultrasonic Flaw Detector, a state of the art digital flaw detector and Olympus Panametrics transducers for inspections. The instrument configuration is accepted and used in aerospace industry. We keep the instrument calibration up to date.

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.

The Shackle Revisited

During our yacht surveys we rarely see shackles that have been moused. We remark that regularly in our reports, but I am not sure whether our clients all appreciate the importance of this.

Mousing is a simple and good practice to secure the bolt of a shackle to prevent it from getting unscrewed intentionally. I was reminded of this in a marina in Croatia where the pontoons had been shackled to the quay and all shackles had been moused.

Galvanized shackles tend to unscrew when they are under a pulsating load. Even if you tighten them carefully they eventually get unscrewed because the micro-stalactites of the zinc coating eventually get faired under the strain. Stainless steel shackles are also prone to unscrewing as the bolt’s thread usually is seated and rather slippery in comparison to galvanized hardware.

Using rope or galvanized wire is good for mousing, monel wire is even better, but even a cable tie will do as long as it is inspected regularly.

And by the way, the safe working load of shackles is determined by the diameter of the thread root, which is often smaller than the diameter of the shackle body.

Inspect your hardware, in particular the shackles, regularly. This way you can avoid losing your ground tackle. Losing ground tackle happens – usually at a time when it is least expected and most inconvenient, thus maximizing damages.

Surveys Related to Incidents

Incident and Damage Surveys

Collision, fire, machinery damage, material or design faults, burglary, embezzlement….Establishing the cause of damages, ensuring that the damages are repaired to acceptable standards and to fair repair costs is one of our core businesses.

We act swiftly and proactively. We go beyond recording and simply reporting the physical damage and we provide continuous guidance to our instructors throughout the damage assessment process. We produce detailed specifications of damage repairs on both hull and machinery major casualties.

We carry out investigations into the “root cause” of major failures in order to prevent re-occurrence. If applicable, we advise routes of recourse.

We regularly carry out interviews and collect the statements of parties involved in damage investigations.

We arrange and then oversee salvage operations, sometimes on board the casualty and throughout the operation, closely collaborating with the salvage master for ensuring safe and successful results.

We assist in the tendering and repair process, being involved with negotiations and settlement of the repair costs, having gained deep knowledge of shipyards’ practices and costing in the regions we operate throughout the Eastern Mediterranean.

Providing loss assessments for pleasure craft and yachts following accidents of all kinds is our daily business. We specialise in surveying marine damages and losses.

We are able to draw on the assistance of experts in all areas, both within the company and externally, to ensure the appropriate and individual treatment of every damage incident.

Courts rely on our expertise to establish the facts of incidents.

Collisions

Imagine a collision involving two (or more!) vessels of two different flags and the collision happening under the jurisdiction of yet another, further, state. Such incidents require swift and knowledgeable action and to convince authorities that the vessel, which is represented, will not defect over the border. We have handled a significant number of such incidents, small and large, and are always ready to act upon a call.

Other Incident Surveys We Cover Are:

  • Groundings
  • Flooding, Sinking
  • Fire and Explosions
  • Mast and Rig Failure
  • Sail and Canvas Damage
  • Heavy Weather Damages
  • Machinery Failures
  • Theft, Loss, Embezzlement

Sample Report

shotblasting

Shot Blasting

I dedicate this article to Erdem and Doğan…

For decades I have carried out shot blasting of many yachts with garnet, sand and other projectiles. In this article, I would like to summarize some of my experiences.

Sand blasting and shot blasting is the technique of cleaning and abrading surfaces of metals, glass and glasslike materials, wood and plastics. Compared to a grinding wheel, needle gun, power brush, solvent cleaning and other methods, it requires a complex organization, but it gives very successful results unreachable by any other method.

In particular when it comes to surface preparation of metals there is no other method that will come close to it.