Writing a Dive Report an Engineer Will Actually Accept
By Cheryl Ansel, DOT bridge program engineer, NHI-qualified team leader. Reviewed by Amanda McCallister, editor.
Underwater Inspection | Cathodic Protection & Anodes January 12, 2019. Tombigbee River, Alabama. Bottom temperature 39 degrees, current about 3 knots, and I was hanging a hammerhead off the pier while a diver surfaced from a two-hour bottom time. He handed me a report: 'Steel looks good, some rust, minor erosion.' My bridge engineer read it, stared at me, and asked why we'd spent $3,000 for a dive report that could have been written from the bank with a pair of binoculars. I've signed off on roughly 400 underwater inspections as a state DOT bridge program engineer and NHI-qualified team leader. That diver isn't alone. Most reports I reject fail for the same reasons: too vague, no measurements, no photographs, no connection to the inspection spec. The good news is that a perfect report is mostly structure and discipline. Here's how to write one an engineer will actually accept.
Lead with the answer
Engineers skim. We don't read a dive report like a novel. We look for the NBI condition rating, the critical findings, and the recommendation on the first page. If you bury a 'pile 14 has a 3-foot section missing' in paragraph four, I'm going to miss it, and the report goes back. Start with a summary block: bridge ID, element numbers, condition state, and one sentence on the worst thing you saw. Then provide the detail you based it on.
Quantify or don't write it
'Mild corrosion' means nothing. 'Minor deterioration' means nothing. 'Worn' means nothing. What I need is a number: section loss measured with ultrasonic testing, crack width measured with a crack gauge, coating breakdown percentage from a standard tape. If you can't measure it, write 'not measured' and tell me why. A report full of adjectives gets kicked back. A report full of numbers gets signed.
Show me what you saw
I've seen reports with two photos: one of the murky water and one of a rusty pile from a foot away with no scale. Useless. Take photographs with a scale and a direction marker. Draw a simple sketch of the element and mark the defect locations. Photograph the crack with a ruler across it, the section loss with a tape measure held against the pile, the coating failure with a grid. Mark the station and orientation on each image. If I can't tell what I'm looking at, I can't use it.
Separate fact from interpretation
Observation: 'Exposed rebar at pile 12, 12-inch-long section, rust staining below.' Interpretation: 'Moderate deterioration, condition state 2.' Those are two different things. When you write 'dangerous,' you're making a judgment call that may not be in your wheelhouse. Report the facts, then give your assessment as a separate item. The engineer's job is to translate facts into a rating. Your job is to make sure the facts are measurable and undeniable.
Follow the spec, not your habit
Every state DOT has a bridge inspection manual, and virtually all follow the FHWA structure inspection framework. Use the exact language from the condition state definitions. If you're not sure whether something is a 'sound' or 'deficient' condition, quote the manual. I'd rather see 'condition state 2 per language in Table 5.3' than your rewritten version. And when in doubt, email the engineer and ask what format they want before you start. Ten minutes of asking saves two days of rewriting.
Frequently Asked Questions
What if I'm a commercial diver, not an engineer? Do I need to know all this? You need to know the terminology and the format. The engineer interprets the findings; you report the observations. Learning the NBI condition states and how to take measurements makes your report infinitely more useful. How detailed should the photos be? If you're photographing a crack, put a ruler across it. If you're documenting section loss, put a scale alongside. Always include a direction reference and a marker that identifies the station. A photo without scale is a photo of nothing. What's the biggest mistake divers make in reports? Writing 'worn' when they mean 'corroded' and 'rust' when they mean 'section loss.' Be specific about what you saw, where you saw it, and how big it was. Vague language costs everyone time and money.