This morning at 6 am., we left North West Providence Channel in the Bahamian chain of islands and entered the North Atlantic on our way to Punta Delgada in the Azores. We are supposed to arrive there on 7 May, so we have six beautiful sea days ahead of us. The weather is cooperating with partly cloudy skies and a gentle breeze and the North Atlantic is letting its presence known with only a very low swell. It just makes the Prinsendam move a little bit. Just enough to let everybody know that they are on a ship but not so much that it is really noticeable when you go around.
When you cross the ocean you have the option to do that in various ways and that has to do with the fact that the earth is a sphere. Normally it is a given that a straight line gives the shortest distance between two points. However as the earth is curved, it is not the case when the distance becomes longer and longer. Due to the curvature of the earth, a straight line is not the shortest route; it is a curved line or arc that follows the path of the smallest curvature of the earth; we call this a Great Circle line. A straight line is called a Rhumb line. The difference between the two lines is that the Great circle line closely follows the curvature of the globe and is therefore the shorter route, but it takes the ship on a higher latitude. A Rhumb line is longer but stays more to the south.
As a captain I have the option to choose which route I will take. The shorter Great Circle, which will save time and fuel or the Rhumb line, which is longer and costs more time and fuel, but as it stays further south it might bring better weather. Therefore it is important to scrutinize the weather charts in the northern parts of the North Atlantic with great intent, as that is where most of the bad weather is coming from. Not only wind and rain but also wave fields left behind by storms, storms long gone, but which can still make for an unpleasant ship movement.
An example of the difference between Rhumb line and Great Circle in distance
This time all looked well on the weather charts and thus I decided on the Great Circle route. This route is about 35 miles shorter than the Rhumb line and so I save nearly two hours in steaming time. As we have a set arrival time, I can now sail a little bit slower and save some fuel. If the weather would suddenly change then there is always the option to change from Great Circle to Rhumb line and from that moment follow a more southerly route again. However the weather looks good, so I think we will be ok.
One thing that I always find a pity is that we cannot look under the water when we enter the North Atlantic. The Bahamian chain of islands is nothing else than the tops of mountain ranges at the edge of the North American shelf. So when we sail away from them, these mountains slope down to what we call the bottom of the ocean. Within 12 hours of entering the North Atlantic that bottom is over 15000 feet away. Then the ocean floor becomes flat. Well relatively flat in comparison with the height of those “mountains”. This flat area is called the Hatteras Abyssal plain. There are still height differences here of around 1500 feet, but compared with the 15000 feet average depth that is relatively flat. I always find it a pity, that we cannot see that, because just looking at a sea chart with the depth contours, does not give you a good idea about the immensity of it all. 15000 feet is a very long way down if you have to swim it.
Yesterday; was the 30th. of April which is the official birthday of the Dutch Queen. Her Majesty Queen Beatrix of the Netherlands. Normally we throw a nice party on the ship in her honor but due to the change over day in Fort Lauderdale we could not do that. As you will have read in the news, the festivities in the Netherlands were cut short as a lunatic driving a car plowed through the spectators who were watching the Queen in the royal coach going around the town. As far as I know 5 spectators were killed and numerous severely injured. The lunatic himself also died from his injuries so we will never know why he did it. Our thoughts here on board are with the bereaved family’s, and in a way I am glad we did not have the chance to throw a party as it would not have been right to do so. Most of the festivities in the Netherlands were completely cancelled and the country is currently in mourning.
Tomorrow will be our second day at sea and the weather is still holding well.
May 2, 2009 at 12:27 pm
Thank you for naming the 2 lines a vessel can travel, Captain. My instructors for in-house update courses never bothered.
I phoned home to find out what on earth happened during the parade for the celebrations of the Queen’s birthday. Apparently, 7 have died and over 10 were injured. What is this world coming too, right?
On 9 May Prince Maurits and his wife are officially opening an exhibition of Dutch Masters, which lasts for several months. In case we have anti-royalists in my town I need to consider where I will be standing to see them!