Icebreakers--the ships, not conversation tips

Noah Body

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Folks,

Going from ancient memory, icebreakers go after "white ice" and not "blue ice", or ice that's extremely thick. If I remember correctly, this is to prevent the ship from riding up on the floe it can't break through and become trapped. If this happens, then pieces of the floe it's already broken through (called "bergy bits"!) can get sucked under the stern and shatter the props. Is this in fact correct?

Also, would these ships be displacement vessels, or semi-displacement vessels? And what speed would they be traveling at--six knots? Slower? Faster?

I'll be paying my good friend Mr. Google a visit in a bit, but in the meantime, if someone has some info...please share!

Thanks.
 

RJK

Sheriff Bullwinkle the Poet says:
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I rode a freshwater Coast Guard icebreaker in Lake Erie in July. Their main job was to rescue ships caught in early ice in early Winter, and to keep the Huron - Mackinaw channel open in early Spring.
My knowledge is limited to what the crew told me.
The ship fills itself with fuel at the beginning of the season to gain as much weight as possible.
The bow is spoon shaped so that it will ride up on the ice. they had a thruster in the bow, that would suck the water out from under the ice, leaving nothing but air, making it easier for the weight of the ship to break it.
When I asked about ice getting into the screws, they said Ice floats, by the time it got back that far, it would be at the surface.
5 or 6 knots is about the right speed.
I was most impressed with the thickness of the hull 1 5/8 inch thick plating.
hope this helps
 

Tsu Dho Nimh

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The props are shielded to minimize the risk from the "bergy bits".

My ex was briefly on a breaker and he said it was the worst experience of his sea-going career: the design is optimized for breaking ice, not stability. It rolled side-to-side like a pig in mud in open water and when they were breaking ice, it lunged and crashed constantly like a bucking horse.