SEICHES, CLIPPERS, BOMBS, ICE TSUNAMI, AND WITCHES - 31 DECEMBER, 2022
Working the Mesabi or doing ice-breaking on the Lakes, the weather is not noticed, you simply fight it and win, where even simple tasks like shopping, or getting to work create agony and hardship it hones your resolve to survive, I have winter worked the Buffalo and Hwy 19 corridor through Hamburg/East Aurora, and even been snow-stranded overnight in the garden of Eden, N.Y. believe me, the natives there are fine, the newbies not so much.
The Great Lakes create a significant volume of shipping from foreign ocean-going vessels, the entry locks between the St. Lawrence River Seaway and Great Lakes have a maximum size limit for vessels wishing to transit the Seaway of (222.5 m) 730 feet in length, (23.2 m) 76 foot beam, and a (8.1 m) 25..5 foot draft, creating a special design class-size of vessels called “Seawaymax” which are specific to Lakes/ocean use.
Locks separate several of the Lakes from themselves. heading west from Lake Ontario where the vessels must transit the Welland Canal, allows vessels to bypass the Niagara Falls between Lake Ontario and Lake Erie, this eight lock system of successive locks raises or lowers vessels 325.5 feet, once into Lake Erie, a vessel can pass on to Lake Huron and Lake Michigan without encountering any locks.
However, further North, the famous Soo Locks, separates Lake Huron from Lake Superior, and produce a 21-foot elevation change of water level, the Soo Locks have two locks, the old MacArthur Lock (for smaller vessels) and the new Poe Lock (for large vessels), all the Lakes locks now have air-balloon pads that extend from the pier and hold the vessel in place, as the water level changes.
Sea going vessels are out of their element here on the Great Lakes, those November “witches” I write about so much about lead to “Ice”, lake-effect snow, water spouts, and the many “Clippers” and “bombs” that move across the North Coast Lakes, making navigation far different than seagoing operations, Weather conditions can change quickly, seemingly without warning, and the shape of the Lakes themselves can produce unpredictable winds. Unlike the ocean, swells are steep and very close together, which could make a 20-foot Lake sea very hazardous for large unfamiliar ocean vessels accustomed to “time spaced” swells.
A big problem arrives at docking…. weather conditions and wave actions are significant concerns on the Lakes, but the Lakes also experience “Seiches”, which are typically caused when strong winds and rapid changes in atmospheric pressure pile up water on one end of the lake. Seiches can affect drafts in already shallow areas and pose threats to vessels trying to tie alongside a dock.
Arriving sea goers are accustomed to port-supplied landing crews for their arrival-departure tie-downs, and longshoremen to load/unload their cargo, Lake boat crews typically perform their own line operations and their boats all have self-unloading capabilities, when pulling alongside a pier, the Lake boat will lower several crew members via a boomed-down bosun’s chair onto the pier to do line handling and tie-down, ocean vessels usually have to cleat tie a bosun’s chair, and lower on a hand line, making an equipment failure or unfamiliarity a leading cause of injury during docking.
Lakers are self-unloading vessels, Hullett's used to do this work (see my earlier articles), nowadays, on board bucket conveyors scoop cargo from the hold, feeding it onto a conveyor, that takes it to an elevator, where the cargo is then lifted and moved to the pier, ocean arriving vessels usually need to hire unloader crews and arrive at a crane dock to unload.
The Coast Guard ice breakers and the harbor tugs work the lakes to keep shipping alive, and the lakes are more friendly when iced over than they are before and after the ice. Seiches are best described as currents, they are unseen hard-to-understand phenomena that have to be experienced, they are all over the lakes, and we have them here in my riverine harbor aplenty.
Sometimes they feel like earthquakes… clear, quiet, flat water (mirror pond) days suddenly a 6-8 inch wave or a set of waves arise, and move across the water, add in a wind, and these errant swells can be 12” high… they act like a riptide sometimes, when trying to dock skippers blame the “current” or the tidal action for their awkward multiple tries, but, it is the seiche. On the lakes, Seiches are very common, and local mariners have given them a spirit-level “monster” identity, like the witches, and Bessie, lake sharks, ghost ship tales, or the Lake Michigan “triangle”.
ALSO SEE: 21 JANUARY, 2022 18 FEBRUARY, 2020 1 APRIL, 2019 5 MARCH, 2019 27 FEBRUARY, 2019
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