pr0wler
30.05.2021 14:51:23
yes, storm watch is generally 30 minutes on the helm as opposed to 4 hours, but when conditions get to that point heave to or lay a hull are the options. here
See full version: During the age of sail, what was the procedure for a reasonably sized ship to weather a hurricane
yes, storm watch is generally 30 minutes on the helm as opposed to 4 hours, but when conditions get to that point heave to or lay a hull are the options. here
Running before high winds is madness, it is incredibly difficult to maintain the helm whilst running and a gybe will destroy the rigging, I would never consider running before anything above a force 8. At force 12 the deck would be unmanned due to the inability to breath the air, it's full of sea foam by that time. here
The main thing I was thinking about is, with the helm being open to the elements, was some poor, unfortunate soul required to remain topside to steer? Or is there some mechanism to use below decks? But I'm also looking for more general procedure that they would follow in an effort to survive.
There is no controversy here; running before the wind under heavily reefed sails (with maybe a single fore-staysail) is exactly what you would do unless, of course, you found yourself on a lee shore, but even then, since visibility would suck and you wouldn't have much notion of your position, once you saw a lee shore, or heard the crash of surf, it'd probably be too late. more
Your options were usually either to run before the storm or head up into it. Running isn't a bad option but waves breaking over the stern and sudden changes could be problematic and dangerous. Heading up into the storm will be rougher but retain a larger degree of control over the ship and the helm. For both you would have a minimum of sails out, a jib or two and everything else reefed or brought in.
Steering-way means that the ship is moving forward with enough power to steer rather than just getting pushed around by waves and wind. The ship must keep its bow (the front end) pointing into the waves to plow through them safely, since a massive wave striking the ship's side could roll the vessel over and sink it. Wind and waves will try to turn the vessel, and pushing against them requires forward momentum.
The most dangerous ship in a hurricane is an empty one. That's because the weight of cargo helps stabilize the ship against the waves. Ballast provides a little stabilizing weight when ships sail empty, but not always enough.
To steer clear of hurricanes, mariners need good weather information. A century ago, weather updates at sea were limited to Morse code messages, but since the 1980s, weather updates have come to printers or fax machines right on the ship's bridge. U.S. cargo ships are required to carry a Navigational Telex (NAVTEX) machine, a radio receiver that picks up medium-frequency radio signals and converts them into a text printout. Another system called Weatherfax uses higher frequency radio waves to send black-and-white images to shipboard fax machines.
What if a ship must face a hurricane at sea? "You would try to steer for the area of the ocean that is going to see the shallowest waves and the lowest winds," Hardberger says. The "low side" or "clean side" of the storm is usually the side counterclockwise from its leading edge.
Storms are part of life at sea, however. "If a ship is in the ocean, you're going to have heavy weather," says Fred Pickhardt, chief meteorologist at Ocean Weather Services. Captains can't dodge every storm, because, as Pickhardt explained, "ships are typically on a very tight schedule. Just the fuel alone on ships can be tens of thousands of dollars a day, so a two or three day delay or deviation can cost big bucks, so they always want to minimize it."
Of course, the best plan is to get out of a hurricane's way. "At a modern ship speed of 14 knots, you should be able to outrun a hurricane," he says. But, Pickhardt says, "the later you leave, the less options you have. When you cut it too close, sometimes you get in trouble."
Two criticisms are often made against investments in rotor sails: [links]
It is noteworthy that the mean wind speed at most points exceeds 14 knots and is very close to the 17 knots threshold, which corresponds to the transition from the Beaufort 4 to the Beaufort 5 scale. The lower wind speeds near the equator (points 25-30) are as expected. At most other points, both in the South Atlantic (points 1-13) and in the Indian Ocean (points 14-24), the mean wind speeds are strong and able to provide very significant propulsion power to the rotor sails. This power is maximized by optimally adjusting the sails’ rotation speed as the wind speed fluctuates around its mean. [links]
Wind speeds 30 meters above sea level at the 30 fixed locations shown in Figure 1 for January 2015 – Decemeber 2017 (3 years). The values in the Table above illustrate the average wind speed and its Q1, Q2, Q3 quartiles, namely the wind speeds that are exceded by 75%, 50% and 25%, respectively, of the wind speed records at the fixed locations. For example, at location 12, located at Cape Town, the average wind speed during the selected 3-year period is 16.9 kn, the highest recorded wind speed is 52.1 kn, and 25% of the recorded wind speeds were higher than 21.6 kn. The wind speed data was obtained from the organization Copernicus. [links]
By: Paul D. Sclavounos, Professor of Mechanical Engineering and Naval Architecture, Massachusetts Institute of Technology
Nikos Mazarakis, Client Relation and General Office Manager, StormGeo Greece
and Dimitris Katsanos, Senior Research Scientist, National Observatory of Athens
Each criticism can be addressed as follows: [links]
Consider a 30,000 dwt bulk carrier consuming 25 tons of fuel per day fitted with four rotors for the duration of a voyage. Based on available data, the average fuel consumption savings is conservatively assumed to be 20%. With the cost of fuel at $500/ton, the resulting income is $2,500/day or $912,600/year. If the installation of four rotors is an isolated acquisition by the ship owner or charterer at a cost of $500,000/rotor ($2M total), the payback time is 2.2 years and the investment might not be undertaken. When the acquisition is a component of a portfolio investment in removable rotors mounted on a fleet of vessels, a NPV analysis suggests a potentially very profitable investment.
The reef-tackle cringles should be double instead of single, and connected by a stout span into which the reef-tackle hooks, Fig. 374, Plate 71. This distributes the heavy strain of the reef-tackle, and is much better than the present plan. more
French Reefs. The first and second reef bands of topsails in our service, and all reefs of square sails in the British and French navies, are now fitted with rope jack-stays instead of points, with reefing beckets, Fig. 367, secured on the yard. here
Head-Earings. Small manilla rope, one end spliced into the head-earing cringle. the other end whipped. It is cut long enough for two turns from the staple to the head-earing cringle, with end enough for several turns through the backer. here
The storm mizzen is a triangular sail set abaft the mizzen-mast on a vertical “stay,” hooked under the after trestle-tree, and set up on deck.