Why would a longer ship have less draft??

[Tampa Girl]

I have been considering taking the Oosterdam on the S.A./Antarctica cruise in 2010, but its length bothers me. I found something interesting when I pulled up one of the "compare ships" websites. The Amsterdam, at 780 ft. length,has a 26.6 ft. draft and a 106 ft. beam. The Oosterdam, which is considerably longer - 951 ft., has a 22 ft. draft and a 106 beam. Why would a longer ship have a shorter draft? This is of particular concern, given the Antactica waters. Also interesting: The Star Princess, which has been plying those waters, is also 951 ft. in length. However, its beam is 118 ft. and its draft is 27.2.
Finally, particularly for those of you have cruised in those waters: Which is more likely to affect whether a ship can get into smaller bays, or for that matter, its stability in rough waters: the draft, the length, or the beam?
Sorry for being so technical. Someone, please, enlighten me!

[Druke I]

Certainly not meant to be totally responsive to your question, but regarding the beam of 106' on two of the ships is of significant import - they can fit into the locks of the Panama Canal.

Star Princess is too wide to get into the locks!

Shallower draft does allow Oosterdam entry into some ports/harbors/waters that would exclude the deeper draft vessels.

Marine architects sometimes talk about fineness of hull, which is a ratio of length versus beam. Less beam may equate into smoother ride in certain sea conditions, while a longer hull may allow the ship to ride over the crests of an oncoming sea, reducing pitch.

There are so many variables regarding hull shape/draft/ride; one rule does not fit all.

[AWED23]

You may get many differing answers to your question. In fact, I'll bet on it. The beam generally relates to Panama capable measurement. the length too is limited by that. the Prinsendam is the smallest ship in HAL's fleet and yet was deemed the most seaworthy by the Captains at a recent conference.....Go figure.........:)

[NapTown Jim]

Its all mathmatical and is all because of Archemedes (sp?) Principle which is that if an object of a given mass can displace a given amount of water or other fluid of the same mass will float. Much as I hate to reference Wikipedia here's a full explanation of it...

http://en.wikipedia.org/wiki/Buoyancy

Thus a ship with the same beam, but longer length can displace more water and therefore will require less draft to float. What it really boils down to is Oosterdam is less 'dense' per area of hull than the Amsterdam and thus displaces less water.

[leoandhugh]

Also a lot depends on what type of service a ship is designed for. In the case of Rotterdam and Amsterdam, they were designed not only for cruising but also for Grand World Cruises where they spend many more days at sea and are exposed to rough weather more frequently. I doubt you will ever find a Vista ship doing a world cruise; about the only time they cross long expanses of ocean is when they do transAtlantic repositionings. A deeper draft tends to be more stable in rough seas and gales; there is more hull below the waterline compared to the amount of superstructure above.
The length of a ship has little to do with the bays they can enter, since with today's azipods in the stern and bow thrusters, they can virtually turn "on a dime"

[Tampa Girl]

Also a lot depends on what type of service a ship is designed for. In the case of Rotterdam and Amsterdam, they were designed not only for cruising but also for Grand World Cruises where they spend many more days at sea and are exposed to rough weather more frequently. I doubt you will ever find a Vista ship doing a world cruise; about the only time they cross long expanses of ocean is when they do transAtlantic repositionings. A deeper draft tends to be more stable in rough seas and gales; there is more hull below the waterline compared to the amount of superstructure above.
The length of a ship has little to do with the bays they can enter, since with today's azipods in the stern and bow thrusters, they can virtually
turn "on a dime"


Thanks, all of you! Appreciate the explanations. I feel better, in one sense, about taking the Oosterdam down to Antarctica, since it appears that she will be able to go where the Amsterdam has been cruising. But . . we may not be as comfortable in rough weather, if I understand you correctly. Which might argue for a cabin lower in the ship, say on the Upper Verandah deck, as opposed to the navigation deck? And, say, one mid-ship or toward the rear?

[cf_chuck]

Duplicate - sheesh

[cf_chuck]

Thanks, all of you! Appreciate the explanations. I feel better, in one sense, about taking the Oosterdam down to Antarctica, since it appears that she will be able to go where the Amsterdam has been cruising. But . . we may not be as comfortable in rough weather, if I understand you correctly. Which might argue for a cabin lower in the ship, say on the Upper Verandah deck, as opposed to the navigation deck? And, say, one mid-ship or toward the rear?

Under any set of conditions, the lower you are to the waterline and the closer to mid-ships, the smoother the ride. However, I suggest that you do not ignore that today's vessels can take on ballast (sea water) in order to increase the effective weight of the vessel, thereby increasing the draft when sea or wind conditions get rough (both can have an effect particularly since the wind profile of the ships is fairly large given a cross wind). Those vessels that were designed specifically for rough conditions have an advantage over those that were designed more for tranquil conditions, but both have the ability to make adjustments as conditions warrant.

[pilotdane]

As said earlier, for the smoothest ride get a cabin low and in the center of the ship. Ships generally moves about their center. Think of a see-saw. The center does not move much but the ends where you sit go up and down a lot. Stabilizers do very little to contol pitching (the bow going up & down) so cabins in the bow and stern can go up & down quite a bit while a cabin in the center will hardley move.

ships draught:
Harbors and docks are dredged to a certain depth. If your ship has a shallow draught it can get into more harbors & docks so, if your ship has a shallower draught you can tie-up at more docks and do less tendering. Cruise lines want to get into as many ports as possible so many modern ships have shallower draughts.

[Tampa Girl]

Thank you all. You have been most helpful. And to show you how much I treasured your advice, we have made reservations for the 01/30/2010 Oosterdam cruise - midship on the Upper Verandah deck. Decided that the Navigation Deck was higher than I wanted to be if the seas got really rough. I am so excited - this is a great itinerary!

[ginger and professor]

must be something with the Dutch ships. Here in the US there is no draft......

[DFD1]

Ships with a deeper draft are generally more stable in heavy sea conditions.

Last year Prinsendam took two 60 foot waves just minutes apart and, while everything inside was turned upside down including some passengers, the ship did okay.

I wonder how Oosterdam, or any of the Vistas, would take such heavy sea conditions.

[pilotdane]

There were some famous pictures taken when the QE2 and Queen Victoria (basically a Vista Class) crossed the Atlantic together. The pictures were taken from each ship looking at the other. One picture shows QV with the bow burried up to the superstructure. Apparently QE2 was able to maintain her speed through the rough seas but QV had to slow down. There is something to be said for the old liners versus modern cruise ships.

[cruzincurt]

On the SS Norway, formerly the SS France, they explained that the ship length was longer on purpose to span three average wave tops in the North Atlantic. I also suspect that a narrow, deeper draft is more stable much like the center board on a sailboat.

[Pam in CA]

Last year Prinsendam took two 60 foot waves just minutes apart and, while everything inside was turned upside down including some passengers, the ship did okay.I was on the Golden Princess Buenos Aires to Santiago cruise in February 07. We were having dinner the night before embarkation and a couple at the table next to us were from the Prinsendam; they told us that they had experienced over 70' waves. I don't think I'd want to be on the Golden or any other large ship in waves like that. IMHO, the Golden Princess, with about 2,800 passengers, was way too big for this itinerary; there were several ports where the number of passengers overwhelmed the local resources which meant that a lot of passengers were disappointed that more buses or tours couldn't be pulled out of thin air to accommodate them. I would say that fewer than 1/4 of the passengers were able to see or do anything in Stanley and the wait to get on the tender back to the ship in Puerto Montt was over an hour and a half long. Of course, that hasn't stopped Princess from using the Star Princess instead of the Golden. :(

Anyway, my friend wanted to do Antarctica so we booked the Amsterdam rather than the Star because we both felt that the Amsterdam was the more appropriate ship for this itinerary. Plus, it was a better itinerary. :)

[MightyQuinn]

My friend wanted to do Antarctica so we booked the Amsterdam rather than the Star because we both felt that the Amsterdam was the more appropriate ship for this itinerary. Plus, it was a better itinerary. :)
Hi Pam – We’re right behind you on the Amsterdam and agree with your choice! We’re doing a 38-nite “Collector’s Voyage” from Rio to Valparaiso around Cape Horn and then continuing onwards to Seattle next March/April. We decided against a sailing that included Antarctica only because we’ve already ventured to the 7th Continent aboard Society Expeditions World Discoverer & had the experience of a lifetime! Size really DOES matter in the Antarctic!;);)

[fcorey]

I hope you have a wonderful trip. My company recently assigned me South America as part of my territory nad I frequently travel to Brazil, and Argentina. There are many beautiful sights down there, I am green with envy I am sure it will be a wonderful trip.
As for the Oosterdam, she is actually the only HAL ship we have sailed on, and I've been on here in rougher weather, we had 18 foot plus seas from Yakutat bay down to Sitka. She is very sea worthy. However some of these ships today are so huge and look so top heavy I'd be wary too. The draft has more to do with the displacement (tonnage) of the ship as its distributed over length and beam. Oosterdam is called a panamax ship as she is just about as large a vessel as can navigate the current lockes. I think the max sizeis 106 foot beam but 960 feet long or there abouts.

[Tampa Girl]

Hi Pam – We’re right behind you on the Amsterdam and agree with your choice! We’re doing a 38-nite “Collector’s Voyage” from Rio to Valparaiso around Cape Horn and then continuing onwards to Seattle next March/April. We decided against a sailing that included Antarctica only because we’ve already ventured to the 7th Continent aboard Society Expeditions World Discoverer & had the experience of a lifetime! Size really DOES matter in the Antarctic!;);)

Have you also been on a larger ship in the Antarctica? If not, what is your basis for saying that "size really does matter in the Antarctic"? BTW, how large was the ship that just sank last winter in the Antarctica?

As for the Golden/Star Princess, I can see where dropping 2800 passengers into the Falklands might create a problem. Fortunately, the Oosterdam doesn't carry anywhere near that many. The Star is also wider in beam and deeper in draft, thereby possibly limiting itself in some channels. I have to believe that if HAL didn't firmly believe that the Oosterdam couldn't handle the Antarctic seas, it would not risk the lives of its staff, passengers, and reputation.

The comment about the QE2 and the QV was interesting. The superstructure of the QV, however, is not like the HAL Vista ships. It appears, at least from the pictures, to be very "boxy", which probably contributed to the QV's not handling the rough water as easily. The Vista class ships are sleek looking, sort of like comparing (for you cat lovers), a modern Siamese with our cobby little Persians:). In any event, DH and I cannot go this January on the Amsterdam, so we will sail on the "O" a year later and will have a great time. As someone mentioned, the itinerary for these trips is a major attraction.