A hull campaign means thousands of readings taken through the paint, on grids defined in advance and repeated at every survey. Three things count: measuring without blasting, not losing the link between reading and point, and standing up to the yard.
- ✓ Measurement through the paint with Echo-Echo mode
- ✓ Grid file for strakes, frames and structures
- ✓ Scan mode for the minimum of the square
- ✓ B-Scan where the plate is irregularly corroded
- ✓ IP65 protection for dry dock and staging
- ✓ Report generated with DakMaster™
A ship’s plating loses thickness from both sides: electrochemical corrosion works on the outside, while inside it is the cargo, the ballast and the humidity of the tanks. Neither process shows until it is advanced, and the paint that protects the plate is also what prevents its condition being judged by eye.
The periodical surveys required by the classification societies are therefore based on extensive thickness measurements, on point grids laid down by the inspection plan. The practical constraint is that those measurements have to be taken without removing the protection: blasting every point would destroy the coating and mean restoring it. Echo-Echo ThruPaint™ mode settles the matter by measuring between two echoes inside the metal.
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The second problem is the sheer volume of data. On a vessel of ordinary size several thousand readings are easily reached, each one tied to a strake, a frame and a position. If that link is lost, the report becomes a list of numbers of no value for the next survey.
How the survey is organised
- The inspection plan defines which structures to measure and at what density
- On the instrument the grid file that mirrors that coding is prepared
- On each square scan mode is used: what matters is the minimum, not an average
- Where the corrosion is patchy, the B-Scan shows the profile along the path
- At the end of the day the data is downloaded and consolidated in DakMaster™
A valid instrument calibration is part of the file that accompanies the survey.
Recommended instruments
| Instrument | Why in this application |
|---|---|
| Dakota MX1-DL | 999 × 52 grid file and over 225,000 readings: a whole hull in one file |
| Dakota MX2-DL | A-Scan, B-Scan and waveform storage for the critical areas |
| Dakota ZX6-DL | Echo-Echo ThruPaint, IP65 and data logger: the dry-dock instrument |
| Dakota CMX2-DL | 110 dB gain range for heavily corroded plate |
Frequently asked questions
Not with an instrument that has Echo-Echo mode, which measures between two echoes inside the metal and leaves the coating out. In Pulse-Echo mode alone the paint would instead be counted as thickness, and on a grid of thousands of points the error would spread across the whole survey.
Because safety depends on the weakest point, not on the average of the area. Scan mode holds the lowest value met while the probe travels across the square: it is the way not to miss a localised hollow between one grid point and the next.
It depends on the inspection plan and the size of the vessel, but several thousand readings are easily reached. That is why in this application the capacity of the data logger and the size of the grid file are real selection criteria: the MX1-DL and MX2-DL have 4 GB and grid files up to 999 × 52.
Back to Marine and Offshore. For a campaign on a vessel, write to us giving the type of vessel, the condition of the coating and the grid density required.
Further information and contacts
Systems division and sensor integration partner : www.roder.it
More information about RODER SRL : about us
Contact for general information : info@roder.it
Contact for information about these products : info@roder.it
The information contained on this web page is provided for information purposes only. Although it has been compiled with the utmost care, it does not constitute a contractual offer or a binding commitment to supply. It may contain transcription, translation or typographical errors. For precise and up-to-date information, please contact our company directly.
Some images on this website have been intentionally generated using Artificial Intelligence (AI). This is because, for many applications and projects, it is not possible to disclose photographs of the installation or of the actual system due to confidentiality agreements, confidentiality clauses and non-disclosure agreements (NDAs).