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renewontime dot com wrote:
Hi Roger, I'm guessing your asking why one ship might be more prone to causing seasickness than another? There are alot of determining factors, to name a few (I'm sure there are others, these are the ones that come to mind): Seas - The most obvious reason. The seas off the Washington / Oregon coast during the winter is about as bad as it gets. Gales hit every three days (like clockwork) and the seas are big and steep. I've been in bigger seas, but these seemed more uncomfortable. Seas and how a particular ship/boat handles them, vary as to what feels good or bad, depending on size, load condition, swell period, etc. Vessel Motion - A vessel's size, obviously, has a big effect on it's motion at sea. Additionally, a more stable vessel will roll faster, thus making the motion more uncomfortable. snip Couple all this with where are you working/quartered on the vessel. Surprisingly, I've noted that "accommodation" forward, tends to affect more people, than "accom" aft. BTW, Bilge Keels are great additions .... funny part is, that their best reduction in rolling ( note I said "rolling" ) is a mere 10%. As for blowing out windows/portholes.... heading is immaterial, vessel size is immaterial.... the right sea at the right moment, now, THAT'S important. otn |
BTW, Bilge Keels are great additions .... funny part is, that their best
reduction in rolling ( note I said "rolling" ) is a mere 10%. The way I understand it, bilge keels -increase- the rolling period (the time from heeling on one side to the other), and I'd guess that 10% is about right. I've never worked (or sailed for that matter) on a cruise ship (well... not entirely true... I was a cadet aboard a retired US Lines ship), but I understand their "active stabilizers" do a better job at keeping the vessel flat. Incidently (and we're way off topic), the most comfortable riding ship I ever worked on was the RV Kilo Moana, a SWATH (Submerged Waterplane Attached Twin Hull). You could literally leave your cup of coffee on a table in 20 foot seas and it wouldn't budge. SWATH's are actually -more- comfortable with seas on the beam, we frequently lied abeam to do scientific work. As for blowing out windows/portholes.... heading is immaterial, vessel size is immaterial.... the right sea at the right moment, now, THAT'S important. Good point. Mother Nature is rarely nice enough to give us seas from only -one- direction. Depending on your vessel's heading, your wake can reflect or refract off the side of your hull, interact with a sea and send it in nearly any direction at all. On the ships I've served on, all portholes up to the main deck had "deadlights", heavy, solid metal covers for when the weather gets nasty. When it got nasty, we just dogged them down. Never had one fail (not to say it isn't possible though). But things are probably different on the modern cruise ships. I've berthed near a number of cruise ships, and one I remember in particular had "sliding glass doors" to cabins above the main deck! You wonder what the designer was thinking... All the best, -- Paul =-----------------------------------= renewontime dot com FREE email reminder service for licensed mariners http://www.renewontime.com =-----------------------------------= |
renewontime dot com wrote:
a SWATH (Submerged Waterplane Attached Twin Hull). SWATH: SMALL Waterplane AREA Twin Hull Rick |
renewontime dot com wrote:
BTW, Bilge Keels are great additions .... funny part is, that their best reduction in rolling ( note I said "rolling" ) is a mere 10%. The way I understand it, bilge keels -increase- the rolling period (the time from heeling on one side to the other), and I'd guess that 10% is about right. I've never worked (or sailed for that matter) on a cruise ship (well... not entirely true... I was a cadet aboard a retired US Lines ship), but I understand their "active stabilizers" do a better job at keeping the vessel flat. Bilge keels have no effect on roll period, only rolling. Roll period is determined by GM. The higher the GM, the shorter the roll period. Active (fin) and passive (Flume) have a far greater ability to reduce rolling. G probably the best system includes all three. Incidently (and we're way off topic), the most comfortable riding ship I ever worked on was the RV Kilo Moana, a SWATH (Submerged Waterplane Attached Twin Hull). You could literally leave your cup of coffee on a table in 20 foot seas and it wouldn't budge. SWATH's are actually -more- comfortable with seas on the beam, we frequently lied abeam to do scientific work. For most conditions, these ARE considered about the most comfortable surface types, though reports I've heard say the can be pretty wet in beam seas and quite noisy in head seas. As for blowing out windows/portholes.... heading is immaterial, vessel size is immaterial.... the right sea at the right moment, now, THAT'S important. Good point. Mother Nature is rarely nice enough to give us seas from only -one- direction. Depending on your vessel's heading, your wake can reflect or refract off the side of your hull, interact with a sea and send it in nearly any direction at all. On the ships I've served on, all portholes up to the main deck had "deadlights", heavy, solid metal covers for when the weather gets nasty. When it got nasty, we just dogged them down. Never had one fail (not to say it isn't possible though). On the widely viewed picture of that Sea River (x-ATTRANSCO) tanker in rough seas, the porthole which was taken out, was on the Boat Deck. Having taken that ship through similar conditions, it was either bad luck or age, G which caused that blow out. I always tell people to look at the foremast on the foc'sle and the deck lights at the top of that mast. On at least one of those ships (class) you'll find the brackets which hold those lights, bent up, from seas coming aboard the bow. But things are probably different on the modern cruise ships. I've berthed near a number of cruise ships, and one I remember in particular had "sliding glass doors" to cabins above the main deck! You wonder what the designer was thinking... G Aside from the fact of the type of glass used and construction/location above the water, they probably considered that a cruise ship will normally do everything it can to stay clear of most serious weather. otn |
You fella's are both quite right in your corrections. My appologies.
Sometimes the connection between what my brain is thinking and what my hands are typing is something less than 100% at 0230 in the morning. Nice to know we have such a knowledgeable group here to keep things straight... ;-) As for how a SWATH handles seas on the beam, bow and quarter: the only SWATH I've sailed on was the KM, so my opinions are based on her. I'm guessing she was designed for seas up to about 20 - 25 feet, as that's about how high the bottom of the main superstructure is above the WL. One might expect beam seas to be a problem, but in reality in that range they weren't a problem, and when they were on the bow there was some pitching, but no much. The only time I could feel any real motion (still nothing compared to a conventional mono hulled ship) was underway with the seas on a quarter, which gave the motion a wierd "cork screw" kind of feeling too it. Still nothing compared to any other ship I've been on... When the seas got bigger than that, it was a bit spooky, as the seas would pound the unprotected superstructure (in our case, the mess area), and continue pounding under the superstructure until they passed underneath. Overall though, SWATH's make an ideal research platform as they are very stable and maneuverable while lying a hull or station keeping. They do have their weaknesses (most troublesome was her extreme sensitivity to any shift or change in our carried load) but otherwise a very nice ride. -- Paul =-----------------------------------= renewontime dot com FREE email reminder service for licensed mariners http://www.renewontime.com =-----------------------------------= |
Dave wrote:
On Sat, 05 Feb 2005 01:59:36 GMT, otnmbrd said: Couple all this with where are you working/quartered on the vessel. Surprisingly, I've noted that "accommodation" forward, tends to affect more people, than "accom" aft. Hmm. Interesting. On the ship I was on, the wardroom and officers' quarters were forward. The goat locker and crew's quarters were amid ship. Ship must have been designed by a CPO. G If you're talking Navy (Destroyer or cruiser) I wouldn't call those accoms fwd. Fwd of midships, but not fwd. No, I'm talking about accoms that leave just enough room for the anchor windlass, fwd of them..... damned uncomfortable. |
I presume he was asking precisely what he said, not inviting your
dissertation. My appologies, again. I read the post too quickly and assumed (wrongly) that "Cayuse" was the word "cause" but misspelled, not a vessels name. It wasn't until he replied that I realized my error. -- Paul =-----------------------------------= renewontime dot com FREE email reminder service for licensed mariners http://www.renewontime.com =-----------------------------------= |
Hmm. Interesting. On the ship I was on, the wardroom and officers'
quarters were forward. The goat locker and crew's quarters were amid ship. Ship must have been designed by a CPO. G If you're talking Navy (Destroyer or cruiser) I wouldn't call those accoms fwd. Fwd of midships, but not fwd. No, I'm talking about accoms that leave just enough room for the anchor windlass, fwd of them..... damned uncomfortable. While on the NOAA ship McArthur I berthed in the forward crew's quarters, which was just aft of the Bos'n's and chain lockers and while in the Navy and aboard USS Morton (a Forest Sherman class destroyer), I berthed in forward officer's country, which was just forward of the Wardroom and aft of the forward gun mount (or just forward of the CG). I can vouch that there was a -huge- difference between the two "forward" berthing areas. -- Paul =-----------------------------------= renewontime dot com FREE email reminder service for licensed mariners http://www.renewontime.com =-----------------------------------= |
Subject: Can a 45' sailboat survive a 50' wave ? From: (JAXAshby) Date: 2/5/2005 5:06 A.M. Pacific Standard Time Message-id: over the knee, did you REALLY intend to say that waves on the bow of a ship can blow out the windows on the stern? If that is not what you intended, just why did you say it? I see you're still making stupid interpretations of what you think people said. Just for fun, because you won't understand it and never will experience it, and although otn didn't say it, .... yes.,..... seas coming over the bow can break windows on the stern. Shen |
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