A Primer for Steel Boat Inspection

For those surveyors out there who wish to inspect steel vessels, here is some advice that may be of assistance in expanding your practice.

Our first objective in the inspection process of metal hulls is to understand acceptable construction and welding techniques used in steel construction. Unfortunately, there are no rules for building recreational vessels that aren’t classed under registry regulations. A good set of rules for building and classing steel vessels under 61 meters (200 feet) as set forth by the American Bureau of Shipping, can be a great help, but most vessels you will view will come no where near these standards. Another good help is the U.S.C.G. Circular # 7 – 68, Notes on Inspection and Repair of Steel Hulls. This serves as a guide to a Coast Guard Inspector for inspected vessels, and is limited in scope, but a great aid. This publication is especially helpful to a surveyor preparing to launch forth in expanding his/her practice to include steel vessels.

My personal experience started in a boatyard cutting the deteriorated bottom off a steel Chris Craft Roamer, re-framing and re-plating. The sum of this experience can be stated as hot, noisy, and burn-producing. This particular vessel was donated by Chris Craft to Inco Nickel Co. for coating testing. Some coatings worked well and others did not as evidenced by plating that appeared like a vegetable colander in some sections. There are lots of different coatings, coal, tar, zinc-enriched epoxy, and epoxy barrier coats. You also see flame zinc or flame aluminum coatings, but not too frequently. A steel vessel inspector needs a working knowledge of sandblasting techniques and pitfalls along with an understanding of coatings, application and identifying coating failures. My most memorable failure came in a shipyard in Cumana, Venezuela. My wife and I had built a mild steel Colvin designed Gazelle lug-rigged schooner and had decided to do a sandblast because of the favorable exchange rate. Much to our dismay, our little home was floating on about 16-20 mills of coal tar epoxy. I call that the mercy factor. Our little lash up had rusted through along the T-bar longitudinals on the underbody. The wastage had occurred from improper internal coating coupled with a partial flooding on our first shake down voyage. The worst thing about building your own boat is that when something goes wrong, the finger always points to the builder. Proper preparation and coating are paramount for reasonable service life. This boat was only seven years old at the time. Thank God the yard where we were was offshore and the exchange rate was 27 to our 1 or our cruising budget would have been holed. The life of a well-constructed steel vessel is highly dependent on four things; good design, good material, good welding, and good coating.

Most plate and frame material you inspect on steel yachts will be low carbon mild steel and occasionally you will see core-ten steel. Mild steel scales and core-ten pancake scales. The welding techniques differ as mild steel cannot be welded hot and fast and core-ten cannot be continually welded as it can distort. So you will see more starts and stops and this type is much more difficult to weld. I use a welder’s chipping hammer often in my inspections to explore corrosion. Don’t be surprised if you happen to go through on older vessels, and be sure to have written permission from owners before and after to prevent some costly embarrassment.

A metal hull inspector needs to know where to look and what to look for. You need to know how to identify three basic problems: deterioration, defects and damage. Deterioration is the largest single defect you will have to identify. This inherent problem is due more often than not to age. The older the vessel is, the more likely you are going to see this type of deterioration, be it rust or pitting. The next largest problem is lack of proper maintenance. The largest inherent problem with steel yacht construction, be they auxiliary sail or power, is the fact that most are not constructed with maintenance in mind. Cabin soles, ceilings, and insulation cover so much of a vessel’s structure and totally restrict internal inspections in many areas. Many steel yachts have integrated tanks–water, fuel or waste–and most do not have inspection plates to allow entry and most of your inspections will not involve entry. Hull defects are often easier to identify because they may be more readily evident. Plate deformation is reflective in nature. If you have plating deformation, you should suspect and look for reflective internal framing defects. Severe point loading from impact or hard grounding can cause cracking or tearing of the plate, frames or welds. A strong light and a keen eye are your best weapons here.

The inspector needs to have sufficient knowledge to determine if deterioration or damage have had significant impact on the vessel’s integrity to affect safety or sea keeping ability. He also needs to have sufficient knowledge to recommend proper repairs or replacements if deemed necessary. Circular #7 – 68 also gives guidance on acceptable repair methods.

Once, years ago, I was doing a joint survey on an offshore fuel barge in St. Eustacia. My portion of this inspection involved audio gauging all the deck plating and potting their values for a registry inspection. I noted the readings were diminishing in the half breadth mid section. For grins, I looked down the side plating port and starboard and saw a slight plating deformation. I conveyed my findings to the ABS Inspector that was doing an internal inspection. He looked over the side and promptly informed me that this large offshore fuel barge evidenced pre-catastrophic mid-section bending signs and it was immediately removed from service for extensive repairs.

This brings me to a short discussion about audio gauging. First, let me say that although I have done registry work on double skin tankers and large barges, I am not NDT (non-destructive testing) certified. My training came through hours and hours crawling through ships at the San Juan dock in Puerto Rico and other Caribbean countries. In those days, in order to take an audio gauge reading you first had to take a side grinder and grind off the coating to bare metal to get your reading. It was hot nasty work with cantankerous equipment, often with poor results. The audio gauge I now own is a Cygnus 2 and will read right through most coatings. The newer equipment works on an improved pulse echo method. The probe vibrates in a short pulse creating an ultrasound, which enters the metal. The probe then waits for the return echo acting as a receiver and converts the echoes into electrical signals, which are converted into timings in digital form. Basically, it’s a glorified depth sounder that works through metal and not water. If you want to own this equipment, be prepared to spend two to three thousand dollars on the equipment itself and several hundred per year to have it calibrated and certified. If you are really interested contact Cygnus Instruments, Inc. Annapolis MD (410-276-9771) as one source for good quality equipment.

Like a moisture meter, an audio gauge is just another tool that has limited capability; your findings will be open to interpretation and are limited directly to your experience. Audio gauges will only read fairly parallel metal surfaces; they won’t read scale or pitting. The U.S.C.G. Guide to Inspecting Steel Vessels gives parameters on acceptable wastage up to the necessity of replating. This 25% rule can be applied to any vessel you will be inspecting. You do not need an audio gauge to inspect steel boats. A strong light, pit gauge and a chipping hammer are all you need to get started, coupled with knowledge. Most steel vessels waste from the inside out. There are many areas that you can’t inspect, but if you look and listen well, all boats will talk to you, and over time you will be like a good tracker and learn to read signs. Many times I have had the unpleasant chore of telling a prospective buyer that due to poor construction, lack of maintenance, improper coating and general deterioration, he should walk away from a seemingly attractive and presently functional steel boat. You had better tell him now, before he gets his first yard bill, or his attorney may come a-calling. I know of one steel vessel that was valued and never hauled. It turned out that the bottom was severely wasted and required replacement. Needless to say a long court battle occurred. Don’t ever get talked into a limited inspection. Short money is just that, short.

Many yachts you may be asked to inspect have their freeboard or decks faired with polyester or epoxy putties and audio gauging on the faired side is of no value. On a lot of older vessels, the fairing is losing its adherence to the plate, and simple soft sounding should tell the tale here. Only a trained eye coupled with construction information and knowledge of how these vessels and their coatings normally deteriorate and where, will tell the tale of present condition. Shaft logs, rudder-tubes, propeller apertures, bilges, chines and longitudinal frames, all have different deterioration problems if not properly constructed and installed. Only lots of time crawling through and observing well-constructed metal boats gives the inspector the edge. A strong word of caution to those who want to expand into barge construction: It takes Oxygen to support rust and lots of people are killed each year entering sealed spaces–tank voids and barges that won’t support life—because the Oxygen has been depleted by rust. The old time miners would lower a Canary into the shaft and if the bird came back dead they knew not to go there. Gas and Oxygen meters are available, but, like audio gauge equipment, they are expensive. Often we use 24-hour ventilation with hatch or manhole covers off, and without forced air assistance; If its very still, this may be of little or no help. A space that has no Oxygen will give the inspector no warning prior to dealing you a fatal blow, and also the man that attempts a rescue. Most large dry dock facilities have a Chemist available to inspect and certify a space safe for entry. If you don’t know, don’t go, is my advice.

A final word of advice: Steel vessels are more difficult to inspect and offer the inspector an entirely different set of challenges compared to the bread and butter of glass reinforced plastic construction that most surveyors are familiar with. There are several good books on steel yacht construction you may want to add to your library such as Small Steel Craft, Design, Construction and Maintenance by Ian Nicholson, and The Complete Guide to Metal Boat Building, Maintenance and Repair by Bruce Roberts Goodson. Also there are several good books on corrosion; Metal Corrosion in Boats by Nigel Warren, 2nd edition and Boat Owners Guide to Corrosion by Everett Collier. The local U.S.C.G. Marine Safety Office should be happy to make you a copy of # 7-68.

I approach every vessel I inspect like it was a poisonous snake coiled to bite me. Approach it cautiously and equipped with humility and a strong desire to keep learning and improve your reporting. Locate a mentor to bring you along and up to speed on how to approach and survey a steel vessel before you represent yourself as a competent surveyor of steel hulls.

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