This is a descriptive route/corridor speed-norms comparison only, it does not resolve, support, or undermine the causal question of whether StationKeeper messaging reduces speed (that question was tested separately with matched comparisons and a difference-in-differences analysis, which found no measurable added slowing from the message; see the main investigation report). This asks a different question: what speed do the same shipping corridors, in the same direction of travel, naturally see when the NARW seasonal speed rule isn't even in effect, and how does that compare to ordinary in-season ambient traffic and to the vessels that actually got messaged?
40,550Out-of-season transits
37,241In-season ambient transits
9.3 ktMedian out-of-season
8.7 ktMedian in-season ambient
+0.6 ktPooled median difference
What it shows
Out-of-season traffic runs modestly faster than in-season ambient traffic in 7 of 9 corridors (+0.1 to
+2.1 kt at the median), Block Island Sound and Off Race Point are the exceptions, both at very low absolute speeds
(median 2-8 kt), consistent with those boxes capturing slow near-port/anchorage traffic rather than open-corridor
transit. Where the gap is real, it's modest, mostly under 2 kt, and the pooled in-season-ambient median (8.7 kt)
already sits comfortably under the 10 kt NARW limit, meaning ordinary traffic isn't typically hugging the line
regardless of the rule. Critically, the messaged incidents' own pre-trigger speeds (11-14 kt in most corridors) sit
well above both seasonal baselines in 8 of 9 SMAs, these vessels are running faster than typical traffic on
the same routes, not just experiencing an ordinary cruising speed that happened to become illegal. A secondary,
modest signal: the same vessels show more speed variability out-of-season than in-season in 7 of 9 corridors
(e.g. Chesapeake: within-vessel SOG std 1.98 out-of-season vs 0.92 in-season), suggesting the season/rule environment
may narrow the speed distribution somewhat, though this reverses in one SMA and shouldn't be read as a clean verdict.
Comparison chart
Per-SMA detail
| SMA | n in-season | n out-season | Median in (kt) | Median out (kt) | Δ median | Pre-trigger median (kt) | Within-vessel std, in | Within-vessel std, out |
|---|---|---|---|---|---|---|---|---|
| Delaware SMA | 4224 | 4409 | 9.0 | 10.6 | +1.6 | 11.15 | 1.05 | 2.55 |
| Great South Channel | 556 | 467 | 9.0 | 10.4 | +1.4 | 12.3 | 0.49 | 1.1 |
| Block Island Sound | 4764 | 6257 | 3.1 | 2.0 | -1.1 | 12.25 | 1.08 | 1.62 |
| Chesapeake | 8899 | 7188 | 9.1 | 10.0 | +0.9 | 12.35 | 0.92 | 1.98 |
| NY/NJ | 8039 | 6846 | 8.9 | 9.5 | +0.6 | 13.1 | 1.63 | 2.11 |
| Mid-Atlantic (South) | 5422 | 6420 | 9.0 | 11.1 | +2.1 | 13.05 | 2.72 | 1.84 |
| Cape Cod Bay | 1085 | 2853 | 8.1 | 9.2 | +1.1 | 9.28 | 1.7 | 2.5 |
| Off Race Point | 383 | 1622 | 8.0 | 7.8 | -0.2 | 13.8 | 0.57 | 1.59 |
| Southeast/Calving Grounds | 3869 | 4488 | 8.9 | 9.0 | +0.1 | 12.6 | 1.68 | 2.26 |
Example Out-of-Season Vessel Movements
108 example transits (12 per SMA, sampled across the low/mid/high speed terciles to show variety, not just the median case), actual vessel paths through each corridor with no NARW speed rule in effect. Track colored green ≤10kt / yellow 10-12.1kt / red ≥12.1kt; ■ marks the transit's starting position; SMA boundary in magenta. Some corridors (Cape Cod Bay, Off Race Point) show tight crossing/looping patterns rather than clean transit lines , likely fishing or loitering traffic rather than through-traffic, worth keeping in mind when reading their speed stats.
Example Vessel List
| Vessel | AIS type | MMSI | SMA | Date | Min (kt) | Max (kt) | Avg (kt) | Distance (nm) |
|---|---|---|---|---|---|---|---|---|
| BRANDY STATION | Other type | 368803000 | Delaware SMA | 2026-09-01 | 0.0 | 9.5 | 1.0 | 13.2 |
| CALUSA COAST | Tug | 367029960 | Delaware SMA | 2026-06-14 | 4.1 | 7.2 | 5.1 | 18.6 |
| ETERNITY | Passenger | 367099280 | Delaware SMA | 2026-05-01 | 6.5 | 8.3 | 7.1 | 3.9 |
| DEFENDER | Tug | 368138460 | Delaware SMA | 2026-07-13 | 5.6 | 9.4 | 7.9 | 162.6 |
| LA CONDAMINE | Tanker | 228433700 | Delaware SMA | 2026-07-27 | 6.7 | 10.8 | 8.4 | 17.2 |
| AS FELICIA | Cargo | 255806103 | Delaware SMA | 2026-05-15 | 4.1 | 14.6 | 10.7 | 29.9 |
| WICKY SPIRIT | Tanker | 316041032 | Delaware SMA | 2026-07-24 | 8.1 | 11.2 | 11.0 | 19.8 |
| MANTA NILGUN | Cargo | 538009477 | Delaware SMA | 2026-08-21 | 7.6 | 12.9 | 12.2 | 19.2 |
| MSC STAR R | Cargo | 636015031 | Delaware SMA | 2026-06-22 | 8.3 | 13.9 | 12.6 | 18.8 |
| NYMFAION LADY | Tanker | 563164700 | Delaware SMA | 2026-07-20 | 9.8 | 15.1 | 13.4 | 19.1 |
| R/V JOANNE DAIBER | Not available | 338169577 | Delaware SMA | 2026-08-18 | 13.8 | 19.6 | 16.9 | 39.0 |
| CG45665 | Search and rescue vessel | 369493665 | Delaware SMA | 2026-05-09 | 33.9 | 33.9 | 33.9 | 0.0 |
| AVENGER | Fishing | 367379150 | Great South Channel | 2026-03-10 | 0.0 | 6.1 | 2.6 | 25.4 |
| MSC SINDY | Cargo | 372736000 | Great South Channel | 2026-02-08 | 4.0 | 8.5 | 6.0 | 29.7 |
| BBC FELIX | Cargo | 255916062 | Great South Channel | 2026-01-17 | 7.9 | 11.5 | 9.3 | 25.5 |
| MSC BERANGERE | Cargo | 636021665 | Great South Channel | 2026-01-01 | 9.1 | 10.2 | 9.4 | 15.1 |
| BULK ATACAMA | Cargo | 636022964 | Great South Channel | 2026-03-11 | 9.2 | 9.5 | 9.4 | 13.5 |
| INDEPENDENCE OTS | Passenger | 309374000 | Great South Channel | 2026-09-04 | 9.8 | 9.9 | 9.9 | 1.1 |
| ZIM EMERALD | Cargo | 563291900 | Great South Channel | 2026-01-22 | 10.7 | 11.9 | 11.2 | 27.7 |
| HAFNIA TIGER | Tanker | 564230000 | Great South Channel | 2026-01-22 | 11.4 | 12.6 | 12.2 | 19.9 |
| LUNITA | Cargo | 257427000 | Great South Channel | 2026-01-04 | 12.1 | 12.5 | 12.4 | 10.7 |
| HAFNIA DAISY | Tanker | 249347000 | Great South Channel | 2026-01-25 | 13.2 | 13.9 | 13.5 | 14.1 |
| ZIM CORAL | Cargo | 563291700 | Great South Channel | 2026-03-31 | 9.3 | 16.1 | 15.2 | 18.9 |
| CG45678 | Search and rescue vessel | 369493678 | Great South Channel | 2026-08-20 | 0.9 | 37.3 | 22.9 | 10.4 |
| WIND SCYLLA | Cargo | 356068000 | Block Island Sound | 2026-08-26 | 0.0 | 0.1 | 0.0 | 0.0 |
| NANUQ | Wing in ground | 338361000 | Block Island Sound | 2026-08-14 | 0.0 | 9.6 | 0.8 | 7.0 |
| JO-ANN V | Fishing | 368294050 | Block Island Sound | 2026-07-19 | 0.0 | 8.8 | 1.4 | 20.2 |
| SEA WIND | Fishing | 368364250 | Block Island Sound | 2026-07-30 | 0.7 | 4.0 | 2.7 | 33.3 |
| ECO EDISON | Other type | 368359690 | Block Island Sound | 2026-08-07 | 0.0 | 10.1 | 3.3 | 55.7 |
| SOVEREIGN | Tug | 205644000 | Block Island Sound | 2026-05-28 | 0.0 | 9.2 | 3.4 | 30.8 |
| GENERATER | High speed craft | 368379370 | Block Island Sound | 2026-06-08 | 0.0 | 9.9 | 5.3 | 66.5 |
| ERICA KNIGHT | Fishing | 338402566 | Block Island Sound | 2026-07-03 | 0.0 | 9.6 | 5.4 | 25.2 |
| ATLANTIC PIONEER | High speed craft (HSC) | 367722360 | Block Island Sound | 2026-05-27 | 0.0 | 24.4 | 6.1 | 18.1 |
| NACC PROVIDENCE | Cargo | 352001173 | Block Island Sound | 2026-07-24 | 5.9 | 6.7 | 6.4 | 33.4 |
| ARGO B | Cargo | 538003906 | Block Island Sound | 2026-05-28 | 10.2 | 11.2 | 10.9 | 34.1 |
| Unknown | Sailing | 338650608 | Block Island Sound | 2026-05-09 | 52.7 | 52.7 | 52.7 | 0.0 |
| LIVING STONE | Other type | 244010952 | Chesapeake | 2026-08-23 | 0.0 | 0.2 | 0.0 | 1.4 |
| NEPTUN FURY | Tug | 244514000 | Chesapeake | 2026-05-04 | 0.0 | 9.7 | 3.3 | 11.6 |
| WARSHIP 95 | Military ops | 369962000 | Chesapeake | 2026-06-30 | 0.0 | 12.0 | 5.5 | 28.8 |
| CHARYBDIS | Other type | 338146000 | Chesapeake | 2026-09-05 | 3.0 | 10.0 | 6.8 | 23.2 |
| HOS ROSEBUD | Cargo | 368269610 | Chesapeake | 2026-07-17 | 9.2 | 10.4 | 10.0 | 18.5 |
| GIA GLORY | Cargo | 538009917 | Chesapeake | 2026-08-16 | 9.7 | 10.7 | 10.3 | 19.7 |
| SMUGGLERS POINT | Fishing | 367163370 | Chesapeake | 2026-08-14 | 11.1 | 12.7 | 12.1 | 11.2 |
| HAMPTON ROADS | Pilot vessel | 368042970 | Chesapeake | 2026-06-15 | 6.0 | 24.6 | 12.7 | 4.6 |
| SANDERLING ACE | Cargo | 538007573 | Chesapeake | 2026-06-18 | 10.1 | 16.8 | 12.7 | 19.2 |
| GRANDE LAGOS | Cargo | 247341100 | Chesapeake | 2026-08-28 | 8.5 | 14.7 | 12.9 | 19.9 |
| SANTA LORETTA | Cargo | 218643000 | Chesapeake | 2026-08-23 | 9.6 | 18.0 | 16.8 | 19.6 |
| VBFD FIRE BOAT 12 | Search and rescue vessel | 338560912 | Chesapeake | 2026-08-28 | 4.5 | 39.6 | 34.7 | 3.6 |
| ARCTIC STAR | Tanker | 241952000 | NY/NJ | 2026-07-30 | 0.0 | 0.5 | 0.0 | 1.3 |
| CAPTAIN DAVE III | Passenger | 367610930 | NY/NJ | 2026-08-10 | 0.0 | 8.8 | 1.1 | 5.4 |
| PRIDE OF BALTIMORE 2 | Sailing | 303615000 | NY/NJ | 2026-07-03 | 4.0 | 4.2 | 4.2 | 0.1 |
| Unknown | Sailing | 228796000 | NY/NJ | 2026-07-07 | 2.9 | 9.0 | 7.1 | 9.3 |
| ONE AQUILA | Cargo | 374858000 | NY/NJ | 2026-08-08 | 6.0 | 12.3 | 8.0 | 22.4 |
| CHOPTANK | Towing | 367147860 | NY/NJ | 2026-06-05 | 7.0 | 9.3 | 8.3 | 22.3 |
| STI WESTMINSTER | Tanker | 538005539 | NY/NJ | 2026-06-11 | 0.0 | 13.8 | 8.4 | 16.8 |
| SFL MAUI | Cargo | 636021013 | NY/NJ | 2026-05-25 | 6.4 | 11.2 | 8.9 | 20.5 |
| MSC NOA | Cargo | 636018659 | NY/NJ | 2026-06-25 | 8.0 | 10.1 | 9.1 | 22.6 |
| PORT EVERGLADES EXPR | Cargo | 563281200 | NY/NJ | 2026-07-04 | 5.0 | 17.6 | 13.3 | 22.2 |
| ATLANTIC SEA | Cargo | 215800000 | NY/NJ | 2026-06-26 | 8.3 | 14.7 | 13.4 | 23.6 |
| FDNY M8A | Search and rescue vessel | 368111610 | NY/NJ | 2026-07-31 | 0.1 | 36.0 | 25.7 | 17.1 |
| MAERSK HARTFORD | Cargo | 338403000 | Mid-Atlantic (South) | 2026-08-30 | 0.0 | 0.4 | 0.0 | 1.9 |
| SPIEKEROOG | Cargo | 305997000 | Mid-Atlantic (South) | 2026-04-30 | 0.0 | 0.5 | 0.2 | 0.8 |
| BIG M CASINO | Passenger | 366992110 | Mid-Atlantic (South) | 2026-06-14 | 2.8 | 13.8 | 8.2 | 53.1 |
| Unknown | Unknown | 241552170 | Mid-Atlantic (South) | 2026-07-30 | 8.3 | 8.3 | 8.3 | 0.0 |
| TWIN COVE | Pleasure craft | 368069720 | Mid-Atlantic (South) | 2026-05-19 | 6.7 | 10.4 | 9.0 | 54.1 |
| NABELLA | Pleasure craft | 338427981 | Mid-Atlantic (South) | 2026-04-28 | 4.4 | 16.0 | 10.0 | 9.9 |
| SPRING ODYSSEY | Cargo | 352006552 | Mid-Atlantic (South) | 2026-06-29 | 11.2 | 12.2 | 11.9 | 3.4 |
| ALTAMIRA EXPRESS | Cargo | 563277100 | Mid-Atlantic (South) | 2026-09-03 | 7.3 | 16.3 | 13.3 | 20.2 |
| OOCL KAPOK | Cargo | 477156100 | Mid-Atlantic (South) | 2026-05-18 | 10.8 | 16.7 | 13.8 | 18.9 |
| CMA CGM GANGES | Cargo | 256104000 | Mid-Atlantic (South) | 2026-08-28 | 0.0 | 17.6 | 14.1 | 86.6 |
| ALLIANCE FAIRFAX | Cargo | 366771000 | Mid-Atlantic (South) | 2026-07-07 | 10.0 | 15.4 | 14.3 | 1975.0 |
| MS-CF-1 | Law enforcement | 338556454 | Mid-Atlantic (South) | 2026-07-01 | 40.7 | 43.0 | 41.9 | 3.0 |
| CHECKMATE40 | Pleasure craft | 368460470 | Cape Cod Bay | 2026-06-25 | 0.0 | 0.0 | 0.0 | 4.8 |
| JOY | Passenger | 368086399 | Cape Cod Bay | 2026-08-21 | 0.0 | 10.1 | 1.9 | 24.3 |
| CGC MAURICE JESTER | Law enforcement | 338926452 | Cape Cod Bay | 2026-06-02 | 2.5 | 13.2 | 6.1 | 73.1 |
| ROBERT GRAY | High speed craft | 368158120 | Cape Cod Bay | 2026-07-16 | 7.1 | 10.1 | 8.3 | 185.5 |
| SEA HAWK | Spare | 366843420 | Cape Cod Bay | 2026-05-23 | 7.7 | 10.1 | 9.7 | 26.7 |
| RV DISCOVERY | Other type | 338522247 | Cape Cod Bay | 2026-06-25 | 0.2 | 16.8 | 10.6 | 71.6 |
| DOLPHIN X | Not available | 367487640 | Cape Cod Bay | 2026-05-22 | 0.0 | 23.9 | 10.8 | 37.0 |
| TAILS OF THE SEA | Passenger | 367450190 | Cape Cod Bay | 2026-06-13 | 0.0 | 25.4 | 12.7 | 216.1 |
| ANJILIS | Pleasure craft | 319072000 | Cape Cod Bay | 2026-08-10 | 10.7 | 13.5 | 13.0 | 26.5 |
| PATIENCE | Pleasure craft | 319844000 | Cape Cod Bay | 2026-07-18 | 10.0 | 13.8 | 13.0 | 45.3 |
| CG29136 | Search and rescue vessel | 369990136 | Cape Cod Bay | 2026-05-21 | 0.0 | 42.2 | 24.4 | 10.9 |
| PROVINCETOWN III | Passenger | 366954420 | Cape Cod Bay | 2026-07-10 | 0.0 | 30.6 | 28.2 | 282.9 |
| HURRICANE II | Other type | 366859760 | Off Race Point | 2026-05-08 | 0.0 | 20.0 | 1.3 | 1.2 |
| TAILS OF THE SEA | Passenger | 367450190 | Off Race Point | 2026-08-10 | 0.3 | 13.9 | 3.8 | 0.8 |
| CAPT JOHN & SON | Passenger | 367450150 | Off Race Point | 2026-07-12 | 0.2 | 17.7 | 4.2 | 5.8 |
| TAILS OF THE SEA | Passenger | 367450190 | Off Race Point | 2026-06-20 | 0.1 | 20.4 | 6.0 | 11.5 |
| CAPT JOHN & SON | Passenger | 367450150 | Off Race Point | 2026-06-13 | 0.0 | 18.2 | 7.9 | 41.5 |
| DENALI | Spare | 367452180 | Off Race Point | 2026-08-23 | 8.1 | 8.7 | 8.4 | 11.2 |
| CGC WILLIAM CHADWICK | Law enforcement | 338926450 | Off Race Point | 2026-07-10 | 8.6 | 11.1 | 9.9 | 45.5 |
| DAISY MAE | Not available | 367797720 | Off Race Point | 2026-05-27 | 9.9 | 10.8 | 10.3 | 18.3 |
| EVER FRANK | Cargo | 563163400 | Off Race Point | 2026-06-29 | 8.5 | 15.1 | 11.5 | 86.8 |
| PRIVATEER IV | Passenger | 367529770 | Off Race Point | 2026-06-05 | 0.0 | 19.1 | 13.3 | 46.7 |
| SANCTUARY | High speed craft | 367677670 | Off Race Point | 2026-06-09 | 0.1 | 29.8 | 15.2 | 114.4 |
| CG27102 | Search and rescue vessel | 338926622 | Off Race Point | 2026-06-05 | 30.1 | 37.3 | 34.4 | 1.2 |
| UBC TILBURY | Cargo | 212040000 | Southeast/Calving Grounds | 2026-07-05 | 0.0 | 0.9 | 0.2 | 1.1 |
| SMITH PRIVATEER | Not available | 367396520 | Southeast/Calving Grounds | 2026-07-12 | 0.0 | 8.0 | 2.2 | 45.3 |
| PACIFIC DAWN | Towing | 366847780 | Southeast/Calving Grounds | 2026-07-10 | 6.4 | 7.4 | 7.0 | 6.1 |
| SAGA MONAL | Cargo | 311001622 | Southeast/Calving Grounds | 2026-05-24 | 0.0 | 11.7 | 7.1 | 22.5 |
| CALCASIEU RIVER | Port tender | 367313850 | Southeast/Calving Grounds | 2026-08-10 | 0.0 | 22.7 | 8.0 | 61.4 |
| HOEGH SEOUL | Cargo | 257496000 | Southeast/Calving Grounds | 2026-05-01 | 4.7 | 11.6 | 8.6 | 27.8 |
| NORDMOSEL | Cargo | 255806294 | Southeast/Calving Grounds | 2026-08-01 | 4.3 | 12.9 | 10.4 | 27.2 |
| LIBRA LEADER | Cargo | 636022754 | Southeast/Calving Grounds | 2026-04-25 | 8.7 | 16.8 | 10.6 | 31.7 |
| TITANIA | Cargo | 248225000 | Southeast/Calving Grounds | 2026-04-21 | 5.1 | 14.1 | 11.4 | 28.2 |
| ATB LIBERTY | Towing | 369109000 | Southeast/Calving Grounds | 2026-08-15 | 10.1 | 12.8 | 11.7 | 36.0 |
| US GOVT VESSEL 19 | Military ops | 368926297 | Southeast/Calving Grounds | 2026-08-20 | 9.8 | 15.2 | 11.7 | 5.6 |
| USCG 33154 | Military ops | 369493454 | Southeast/Calving Grounds | 2026-08-14 | 38.1 | 41.6 | 39.7 | 24.6 |
Distance = total path length tracked that day within the SMA polygon, not straight-line displacement.