To answer the question in the first post, the Risley hull plating in the bow is 36.5mm thick, with a 50mm plate attached to the stem bar. Close up photos of the hull (near where Paul Beesley has noted the black hull paint) will show the transition from the upper hull to the ice belt of thicker plate. This plating reduces gradually to 28mm plate around the midship area, then gets thicker again to 32mm around the stern.
As Paul B. mentions, grade of steel is very important, and Lloyd's Grade E is used for the hull.
As Paul also noted, the ability to break ice is influenced by many factors, but I have been aboard the Risley inside Thunder Bay harbour with perfectly flat ice and at a constant speed broken 4 foot thick ice. We know this because as we manoeuvred at higher speed in the harbour, chunks of ice would be kicked over the stern roller onto the after deck, allowing us to run out with a tape measure to confirm the thickness.
Samuel Risley capabilties
Re: Samuel Risley capabilties
Last year during the early spring Great Lakes shipping ice crisis I started to educate myself on the range of icebreakers that exist in the world. I was curious where the Mackinaw (2), Risley, Griffon, etc ranked amongst the other ships around the globe. Somebody here referred me to this fascinating chart from 2013. It seems to categorize these boats by engine horsepower:
http://www.uscg.mil/hq/cg5/cg552/docs/2 ... 0Chart.pdf
So as I understand it the most capable of the icebeakers that are permanently on the Lakes are all considered "light" icebreakers. Even the retired mighty Mackinaw (1) would not have made the above chart as it just misses the 10K HP cutoff. Last year during the worst of the spring ice one of the CCG "medium" duty ships came to help in the upper Lakes. As I understand it the most capable of the icebreakers are too wide to make it into the upper lakes.
Also I have been following the story around Antarctica of the fishing vessel trapped in ice that was freed & towed out by the "heavy" icebreaker USCG Polar Star:
http://www.gsnmagazine.com/node/43895?c ... t_security
http://www.uscg.mil/hq/cg5/cg552/docs/2 ... 0Chart.pdf
So as I understand it the most capable of the icebeakers that are permanently on the Lakes are all considered "light" icebreakers. Even the retired mighty Mackinaw (1) would not have made the above chart as it just misses the 10K HP cutoff. Last year during the worst of the spring ice one of the CCG "medium" duty ships came to help in the upper Lakes. As I understand it the most capable of the icebreakers are too wide to make it into the upper lakes.
Also I have been following the story around Antarctica of the fishing vessel trapped in ice that was freed & towed out by the "heavy" icebreaker USCG Polar Star:
http://www.gsnmagazine.com/node/43895?c ... t_security
Re: Samuel Risley capabilties
Paul, thank you so much for your reply. I had a chance to see the Risley at work last week when it brought the Algomarine into Owen Sound. It is the first time I have seen an icebreaker working and it was a treat to watch!
Enjoy PEI!
Enjoy PEI!
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Guest
Re: Samuel Risley capabilties
Paul, thanks very much for the enlightening and humorous response !
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Paul Beesley
Re: Samuel Risley capabilties
Thickness of the hull steel is only one important consideration for an icebreaker. Steel quality is most important as it must be able to withstand not only heavy pounding but also extremes of temperature.
The Titanic was vulnerable because of the steel used in her hull construction. "A metallurgical analysis of steel taken from the hull of the Titanic's wreckage reveals that it had a high ductile-brittle transition temperature, making it unsuitable for service at low temperatures; at the time of the collision, the temperature of the sea water was -2°C. The analysis also shows, however, that the steel used was probably the best plain carbon ship plate available at the time of the ship's construction."
Steel making and metallurgy have advanced greatly since the early 1900s.
The framing that holds the hull plates also is required to be robust and to be closer spaced than on ordinary ships. One of the frames in the Risley's bow area is shown in this photograph, with my thumb as reference. http://www.boatnerd.com/pictures/specia ... 1-1-01.jpg
Another important, and often overlooked feature, is the hull coating. Icebreakers generally have a purpose-made hull coating that allows them to slip through the ice with less friction than ordinary painted, or rusted, hulls. As this coating breaks down with use and age the icebreaker has more difficulty moving through the ice. More power is used to overcome friction than to continue moving. In this photo the black coating below the ice moustache is "Inerta", and it is applied to reduce friction. http://www.boatnerd.com/pictures/specia ... 1-3-01.jpg
How much ice a breaker can move through at continuous speed is somewhat like miles-per-gallon calculations. Very much ideal and mostly imaginary with no reflection of reality.
The sister-ship of the Risley, CCGS Earl Grey, works in the Atlantic and Gulf of St Lawrence. In order to deal with the ocean weather conditions she is ballasted far more deeply than the Risley with the result that her performance in ice may be significantly different.
Ice conditions determine much of the capability of the breakers. Fast ice, that is water that has frozen from shore to shore and is perfectly flat, is fairly easy to break through. At a certain point in the ice growth, as it gets thicker and harder, the breaker's bow will actually ride up onto the ice and the weight and inertia will break through the ice.
If you put a little snow on the ice much of the breaker's power now goes into trying to push through the snow and progress is minimised, especially if the snow is wet or the hull coating is compromised.
Ridging or Windrows make passage through the ice much more difficult. In the case of Port Colborne the prevailing winds over the winter usually build a large pressure ridge outside the canal entrance and this will get deeper and wider and more frozen as winter progresses. It may even reach the bottom of the lake. Not only is this difficult to break through, usually you chip away at it by backing and filling, you must be concerned about the bow riding up which drives the stern down and risks damaging the props and rudders should they come into contact with the lake bottom.
In the 90s when I was Mate on the Earl Grey we were escorting the Diamond Star (Now the Dara Desgagnes) into the Miramichi River in New Brunswick. The Grey got stuck in a very heavy ridge. We could not avoid it as the navigable channel was quite narrow. Despite the best efforts of the Star's Captain the ship hit the stern of the Grey with a tremendous blow, and pushed us through the ridge. It also put a rather large dent in the stern roller, which is very heavy steel and probably absorbed most of the force thereby preventing even more damage. It threw me out of my chair and onto the deck! Once everyone had made their various checks for damage and changed their underwear we noticed that the impact had launched the Star's free-fall lifeboat and it was merrily floating around in the only bit of open water within a hundred miles.
Another consideration is where the ice is. In the St Mary's and Detroit/ St Clair rivers once the ice is broken is has nowhere to go. Further downstream is more ice and that prevents broken ice from moving along. As more and more ships pass through this ice it gets more and more chewed up until it has the consistency of very cold porridge, and also has become much deeper in the channel. No amount of icebreaking will make conditions better and escorting ships through, as shown in the St Clair Cut this winter, becomes nearly impossible.
Did I mention wind and current and tides? These greatly affect ice conditions and subsequent ice navigation.
As I write this I am holed up in a B & B in Summerside, Prince Edward Island watching a blizzard wreak havoc outside my window. Not too far from here is the Canadian Icebreaker Henry Larsen and Irving's tanker Acadian. The Larsen is a class 1200 icebreaker with 15,783 hp. It spends every summer in the Arctic. She was sent to assist the Acadian because the ice conditions in Northumberland Strait are getting worse, or better depending on your point of view, each day. This storm, with its 100+ kph (60 MPH) winds will greatly change the ice conditions and will adversely affect the escort when it resumes. Then the tide will go up and down every 6 hours or so and will, at times, make the ice cover so tight that even the Larsen will not be able to move through it.
So, to answer your question, how thick is the hull on the Risley? I forget!
Enjoy the ice.
Paul
The Titanic was vulnerable because of the steel used in her hull construction. "A metallurgical analysis of steel taken from the hull of the Titanic's wreckage reveals that it had a high ductile-brittle transition temperature, making it unsuitable for service at low temperatures; at the time of the collision, the temperature of the sea water was -2°C. The analysis also shows, however, that the steel used was probably the best plain carbon ship plate available at the time of the ship's construction."
Steel making and metallurgy have advanced greatly since the early 1900s.
The framing that holds the hull plates also is required to be robust and to be closer spaced than on ordinary ships. One of the frames in the Risley's bow area is shown in this photograph, with my thumb as reference. http://www.boatnerd.com/pictures/specia ... 1-1-01.jpg
Another important, and often overlooked feature, is the hull coating. Icebreakers generally have a purpose-made hull coating that allows them to slip through the ice with less friction than ordinary painted, or rusted, hulls. As this coating breaks down with use and age the icebreaker has more difficulty moving through the ice. More power is used to overcome friction than to continue moving. In this photo the black coating below the ice moustache is "Inerta", and it is applied to reduce friction. http://www.boatnerd.com/pictures/specia ... 1-3-01.jpg
How much ice a breaker can move through at continuous speed is somewhat like miles-per-gallon calculations. Very much ideal and mostly imaginary with no reflection of reality.
The sister-ship of the Risley, CCGS Earl Grey, works in the Atlantic and Gulf of St Lawrence. In order to deal with the ocean weather conditions she is ballasted far more deeply than the Risley with the result that her performance in ice may be significantly different.
Ice conditions determine much of the capability of the breakers. Fast ice, that is water that has frozen from shore to shore and is perfectly flat, is fairly easy to break through. At a certain point in the ice growth, as it gets thicker and harder, the breaker's bow will actually ride up onto the ice and the weight and inertia will break through the ice.
If you put a little snow on the ice much of the breaker's power now goes into trying to push through the snow and progress is minimised, especially if the snow is wet or the hull coating is compromised.
Ridging or Windrows make passage through the ice much more difficult. In the case of Port Colborne the prevailing winds over the winter usually build a large pressure ridge outside the canal entrance and this will get deeper and wider and more frozen as winter progresses. It may even reach the bottom of the lake. Not only is this difficult to break through, usually you chip away at it by backing and filling, you must be concerned about the bow riding up which drives the stern down and risks damaging the props and rudders should they come into contact with the lake bottom.
In the 90s when I was Mate on the Earl Grey we were escorting the Diamond Star (Now the Dara Desgagnes) into the Miramichi River in New Brunswick. The Grey got stuck in a very heavy ridge. We could not avoid it as the navigable channel was quite narrow. Despite the best efforts of the Star's Captain the ship hit the stern of the Grey with a tremendous blow, and pushed us through the ridge. It also put a rather large dent in the stern roller, which is very heavy steel and probably absorbed most of the force thereby preventing even more damage. It threw me out of my chair and onto the deck! Once everyone had made their various checks for damage and changed their underwear we noticed that the impact had launched the Star's free-fall lifeboat and it was merrily floating around in the only bit of open water within a hundred miles.
Another consideration is where the ice is. In the St Mary's and Detroit/ St Clair rivers once the ice is broken is has nowhere to go. Further downstream is more ice and that prevents broken ice from moving along. As more and more ships pass through this ice it gets more and more chewed up until it has the consistency of very cold porridge, and also has become much deeper in the channel. No amount of icebreaking will make conditions better and escorting ships through, as shown in the St Clair Cut this winter, becomes nearly impossible.
Did I mention wind and current and tides? These greatly affect ice conditions and subsequent ice navigation.
As I write this I am holed up in a B & B in Summerside, Prince Edward Island watching a blizzard wreak havoc outside my window. Not too far from here is the Canadian Icebreaker Henry Larsen and Irving's tanker Acadian. The Larsen is a class 1200 icebreaker with 15,783 hp. It spends every summer in the Arctic. She was sent to assist the Acadian because the ice conditions in Northumberland Strait are getting worse, or better depending on your point of view, each day. This storm, with its 100+ kph (60 MPH) winds will greatly change the ice conditions and will adversely affect the escort when it resumes. Then the tide will go up and down every 6 hours or so and will, at times, make the ice cover so tight that even the Larsen will not be able to move through it.
So, to answer your question, how thick is the hull on the Risley? I forget!
Enjoy the ice.
Paul
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Guest
Re: Samuel Risley capabilties
Need to get Paul Beasley to weigh in on this as he captained the Risley for a few years.
Re: Samuel Risley capabilties
Years ago I toured the Risley while it was docked in Grand Haven for the Coast Guard Festival. The handout they provided says:
"The Risley can move steadily through ice up to 84 cm thick."
That's 33 inches without backing and ramming. And of course not all ice is created equal, so it could be much more or less depending on actual conditions.
"The Risley can move steadily through ice up to 84 cm thick."
That's 33 inches without backing and ramming. And of course not all ice is created equal, so it could be much more or less depending on actual conditions.
Samuel Risley capabilties
I was wondering if anyone could tell me what the ice breaking capabilities of the Samuel Risley are? I have read in a couple of places that it can break 24 inches of ice, and in other places 33 inches. How much ice can it proceed through while underway and what is the maximum amount it can break?
Also, how thick is the steel in the hull (in the ice breaking part as well as the rest?
I have read that the US Bay Class breakers can proceed through 20 inches and break 36 inches by ramming. It would seem that the Risley, being much larger, could handle more than them.
Any info would be appreciated.
Also, how thick is the steel in the hull (in the ice breaking part as well as the rest?
I have read that the US Bay Class breakers can proceed through 20 inches and break 36 inches by ramming. It would seem that the Risley, being much larger, could handle more than them.
Any info would be appreciated.