Captain’s Blog: Icebreaking
by Guest Blogger
July 23, 2009
Pete Willcox has been sailing on Greenpeace ships for 28 years. He’s currently our skipper on the Arctic Sunrise off the coast of Greenland. This is the second in a series of Captain’s Blogs that we’ll be publishing throughout the three-month expedition to bear witness to the Arctic Meltdown caused by global warming.
The bow of the Arctic Sunrise, barely visible on the left of this image, works its way through the sea ice © Greenpeace/Nick Cobbing
The helicopter gets off the deck at 0800. The ship’s main engine starts 20 minutes later. We are headed south at 0900, and the engine needs a while to warm up. The helicopter gets delayed, but at 0901, Eric has cast off our line, and we are underway.
The Arctic Ocean pack ice has invaded Nares Strait. It is old (called multi-year) sea ice, and averages six meters thick. This is way thicker than anything we can break with Arctic Sunrise. So before it can trap us in Hall Basin, we escape south. The crew all walks around telling each other that this is good, as we are all bored with Petermann.
This is, of course, a big joke. All of us feel incredibly fortunate to have spent the last two and a half weeks here. It has felt like being on a high mountaintop I imagine. You spend weeks climbing, and minutes on the top. We have been able to spend weeks here, and it’s been a real treat.
The sea ice is chasing us into the bay of large icebergs. The east side of Kane Basin is the Humboldt Glacier. Being a grounded glacier, the pieces that break off are huge. As a result, Kane Basin is littered with icebergs. There are maybe 70 that we can see from here. It’s a real contrast to Petermann, where the glacier is floating. From a distance the glacier ice breaking off from Petermann does not seem very different from the sea ice that forms over the winter. But these icebergs from Humboldt are ten to twenty meters high.
The helicopter gets delayed a couple times on its mission. We don’t need to wait, as they are… quite a bit faster than we are. Ten times faster. When they land, Jason comes up to the bridge to show us pictures of the pod of narwhals they flew over on he way back. Narwhals are attributed to starting the unicorn legend. The males (mostly, not exclusively) have a long tusk coming out of their forehead. Nobody is sure why. Maybe it’s just to look cool.
We are trying to get to the far northeast corner of Kane Basin. The further northeast we can go, the closer we will be to Petermann. Every five days or so for the next two to three weeks, we will have to service our cameras at Petermann. The closer we can get, the easier the flight.
On the way in we pass our first group of walrus. As I am looking up the ice for a lead, I notice a large brown mass. Too large and brown to be seals. When one lifts up his head, and I see to tusks sticking out the front of his face, I know it is walrus. Melanie says walrus have tusks to hold their heads off the ice so that they do not drown in their own shit, which they lay around in. I think she is being tough on walrus, but then she has seen about a thousand more than I have.
For the first time in this trip we do some real icebreaking. The ice is mostly first-year sea ice, sprinkled with pieces of glacier ice, which is much harder. It does not look very thick, and seem to be 50% melt pools, some of which go right through. At first, it is pretty easy going. With 90% power on, we are just able to break through the 50cm ice. Then we have to stop, back up one ship length, and charge at it again. And again. And again. As we cut alongside a large ‘berg, I understand Arne’s explanation of ice under pressure. Here is ebb tide is pushing the floating sea ice against the grounded berg. The ice stops cracking ahead of us. We have to back up every boat length, and ram it again.
This explains Arne’s first rule of icebreaking. Avoid it. Always look for a lead or a way to get around it. Icebreaking is time consuming and sucks down tons of fuel.
"Hey Arne, look out for the rock", I say. Normally this would not be necessary, and would refer to a rock on the chart below the water. In this case a pretty large boulder has rolled down the nearby cliff, and during the winter, rolled a quarter mile out onto the ice. And in this case, the warning is a joke, which we all laugh over. Our passage sends the rock down to the bottom.
After an hour we get through, and follow a lead up along the shore under the cliffs. A few minutes later we anchor in 75 meters of water. Our guys in Amsterdam added three more shots (one shot is 27.5m) to our starboard chain, giving us nine shots. Use the European formula for anchoring, the number of shots of chain needed is equal to the square root of the depth in meters, we put 8 shots on deck and call it a night.
Note to my friends from Castine. This anchoring formula is intelligent. I first learned it in Arne’s (are you getting a picture yet?) bridge manual from 15 years ago on the MV Greenpeace. Notice that when you anchor in 64 meters of water, it gives you a scope of 3.4 to 1. When you anchor in 16 meters of water, it gives you 6.8 to 1. This is much smarter than just using a scope of 7 to 1 for all depths.
The other thing I did that you sailors might be interested in is use the Bowditch " Distance by Vertical Angle" tables to help figure out the height of the nearby cliff. I have very rarely used those tables, and never to determine elevation. But the surveys are so inaccurate up here that I think we got some useful data. According to Nobletec (our electronic chart), we anchored on top of the 500 metre hill top last night.