Ice brackers

[Mirko]

I'm think to develop my thesis about ice breackers, can somebody suggest me where I can find material, books or sites? Thanks

[David Robb]

Originally Posted by Mirko

I'm think to develop my thesis about ice breackers, can somebody suggest me where I can find material, books or sites? Thanks

I spent three years on an ice breaker in the Great Lakes and I don't know of any books on the subject. Even the Coast Guard teaches it by passing the skill from Captain to Captain. There ae a couple things that I can tell you that are essentail to their design:
1. They must be built very heavy. On the 110' tug I was on, the hull was 5/8" armor plates steel where 3/8" mild steel would normally be sufficient.
2. Big engines and iron props - no variable pitch propellors. The ice will shear their gears.
3. In the forefoot, cut a notch that starts at the face of the stem at the waterline and angle aft 60 degrees from vertical then drop vertical last 6 - 9'" or thickness (molding) of keel. Put TONS of concrete and boiler punchings in this area to add weight.
How it works: the ship hits the ice, rides up ontop of the shelf, the weight of the bow presses down on the ice and breaks it apart. Once it is broken, you can get through it unless it's Spring and the wind is blowing.
Knowing how to design an ice breaker takes an enormous amount of knowledge about the dynamics of ice which is different in the dead of winter than it is in Spring. In the winter, it's a problem of force. In the Spring, it's all about pressure. I could talk for hours about this but if you live in the area of a CG station with an ice breaker, go talk to the skipper and ask to talk to the guy who breaks the most ice on board.
Write if you need more.

[Raykenn]

Mirko,

You might try going to the Kavener Mas / Helsinki shipyard web page. They have some basic information there. They are building an ice breaker there right now, and you might be able to find someone from the yard to recommend some reference texts. Also, the university in Helsinki has an extensive naval archetecture program with a department that specializes in ice breakers.

Good hunting

R. Kennedy

[Mirko]

Hi David Robb, thanks for your reply. I have a question, would you explain me why you can't pass through the broken ice if it's Spring and the wind is blowing?

Thanks

Mirko

[David Robb]

Spring ice is soft and becomes slush. Because ice forms in large fields, it is pushed by the wind like waves. When a field touches shore, the wind continues to press the field towards the shore and increase the pressure insode the field. When you try to run a ship through it, the ship creates pressure. Who ever has the most pressure, wins! Often, we used two ships to break spring ice like skis. We would clear a path as far as we could go until we built up so much ice and pressure under our bow we had to pull back and let it loosen up. The ship alongside of us would push forward and push their ice into our path thereby relieving the pressure in their path and so on.
We were once caught solid in a 16 knot wind. The next day, the wind was calm and the ice simple drifted away. There are many devices ship use to make breaking easier but I don't have time to go into it here. Look up the thread on the ship yards. The Russians have he largest ice breakers in the worls. Every year at New Years, they take tourists to the exact North Pole and do a televised Ice Festival in the ice then casually drive home like it was nothing.
Write if you need more.

Originally Posted by Mirko

Hi David Robb, thanks for your reply. I have a question, would you explain me why you can't pass through the broken ice if it's Spring and the wind is blowing?

Thanks

Mirko