Finding 1, from the archive

Does inspection history predict casualties?

A vessel’s inspection history does not predict whether it will be in a casualty. A previous casualty does — at more than twice the rate.

If you price, underwrite, finance or survey barges and towing vessels, the deficiency record is not telling you what it is commonly taken to tell you.

Deficiencies recorded before the year, against casualties in it

Prior deficiencies	Vessel-years	With a casualty	Rate	Lift
None	62,625	17,457	27.9%	1.00
1	16,010	4,508	28.2%	1.01
2-3	11,715	3,183	27.2%	0.98
4-9	8,496	2,306	27.1%	0.98
10 or more	3,216	887	27.6%	0.99

Lift is the band's rate divided by the rate across all 102,062 vessel-years (27.8%); 1.00 means the band is indistinguishable from the population. The spread across every band, from no recorded deficiencies to ten or more, is 0.04. There is no trend to read.

The same method, on a signal that is there

Prior casualties	Vessel-years	With a casualty	Rate	Lift
None	72,475	15,048	20.8%	0.75
One or more	29,587	13,293	44.9%	1.62

A factor of 2.16 on the same data. The method can separate groups. It does not separate them by deficiency history.

Citing this

Maury (Thalor Technologies Inc). “Does inspection history predict casualties?” 102,062 vessel-years, 2004–2021. Computed from USCG PSIX and IIR records retrieved 18 September 2026. https://mauryrecords.com/signal.html

The full method — every limit, how to check it, and what it does not say

Measured on barges and towing vessels, 2004–2021 — the classes for which casualty records were retrieved when this finding was computed. Every other class Maury now holds is outside it, and no figure on this page includes one.

The biggest caveat

The cohort is casualty-enriched. 8,617 of 17,678 hulls (49%) have at least one recorded casualty, so the 27.8% base rate is a rate within this cohort and is not a casualty rate for the US barge fleet. The comparison between bands is unaffected. Both sides are what the Coast Guard wrote down, and this is a correlation over a window, not a causal claim. It says nothing about any individual vessel: Maury does not score, rate, or grade vessels.

Cohort definition. One row per vessel-year; prior deficiencies counts deficiencies recorded against the hull before that year began, and casualty means the hull appears in a Coast Guard incident investigation for that year. Across 102,062 vessel-years, 2004–2021: a barge’s recorded deficiencies before a year say nothing measurable about whether it appears in a casualty record in that year.

Elsewhere

Finding 2: hulls that changed filed operator two or more times show a casualty rate 1.51× those that never did; which way it runs, the record does not say.
Populations: cohorts by type, build decade and length · operators of record

The population, not the hull

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