You’re right about the Gulf of Alaska, but the Bering Sea has little fetch and short wave periods. I think it’s mostly a vessel size issue though. The vessels I’ve worked of the same size range roll rough. It’s unpleasant at best.
About the GOM and OSVs, that is my main experience. I have never experienced a better ride by letting it just find it’s own heading. I would assume that is due to the shorter period as well as shorter rolling period.
Interestingly enough, I have worked on a 280’ that was what I thought was a fairly stiff vessel under most circumstances but now I am on a 312’ that rides much stiffer. So much more stiff in fact that the company decided to add a set of anti-roll tanks on the 02 deck. It had no qualms about throwing you about in a snappy manner.
The different hull styles rode different in a stern sea as well. The 280’ had more of a flat hull and seemed to take a stern sea very well. The 312’ has more of a tumblehome design on the stern and rolls with the passing of each sea.
Even though I know it would be ok… Turning around in 40 ft seas would make me nervous. I do not like doing it in 20 ft…
A stiff vessel is going to want to follow the slope of the wave, an example of a extremely stiff craft is raft.
1 Like
Correct, that is what I was commenting to. Both vessels reacted very quickly to wave action but the larger vessel surprised me by being a bit snappier.
Correct me if I’m wrong because it’s been a few years, but the 312’s are a fair bit wider than the 3rd gen 280’s and once they built them one less deck hi not that much taller.
Also they have counter to their sterns, not tumblehome.
2 Likes
You are correct, they are wider than the 280’ and the first 312’s had an additional deck.
My mistake on the counter tumblehome. Now I have research to do.
Yeah being wider and not much taller they are going to have a stiffer ride, that’s just the physics of it. Especially since their mid bodies are still a box. The 240’ I was on for a few years was a decent riding boat, but not great. Not enough volume under the house to keep them from pitching hard.
1 Like
Fetch has a point of diminishing returns. Beyond a certain point, it does not matter how much bigger a body of water is. Weather systems are only just so big. A large body of water will have many different, and often contradictory, weather systems at any point in time.
While there is a huge diffrence between 10 miles of fetch and 100 miles of fetch, I’m not sure there is much difference between 100 miles and 1000 miles of fetch.
The Gulf of Alaska and the Bering Sea are both bigger than the Gulf of Mexico. Compare the distance from Tampa to Brownsville against the distance from Cape Flattery to Dutch Harbor, or Naknek to Petropavlosk. Also, the Aleutian Islands do not do much to interrupt fetch from the Pacific into the Bering Sea. Winds and currents are much stronger close to the Aleutians, and seas bigger, than further offshore.
Although “northers” in the GOM can be very rough, the GOM is mill pond compared to Alaska.
Yeah, I figured the shorter ones would be pretty snappy. The one i’m on is a good bit higher but only about 5 or 6 feet wider also a much larger house, I assumed a more tender ride. It just caught me slightly by surprise.
To my knowledge most OSV’s are going to be operating with a much larger GM than a RORO or Container ship. Very rarely are they tender vessels.
2 Likes
I can’t see why beam seas would be categorically (good word) dangerous.
Call the the wind, sea/swell direction 000 degrees. (in a relative sense)
Some general rules:
We say that a heading of 000 (heading into it) ( +/- twenty degrees) is time tested with limitations.
Also we can say 180 maybe (+/- 20) is ok, also with limitations,
One advantage of these two heading (head to and on the stern) is the encounter period can be adjusted to some extent by changing speed.
It’s reasonable to assume that 045 / 315 (+/-) are bad headings for head seas. Also 135 / 225 are bad headings for down wind.
But what about 090 /270? If the ship is in synchronous rolling it’s a bad heading. So it depends upon (unlike the other headings) the rolling period of the ship and the wave period.
The 090/270 is also +/- 20 degrees as the encounter period can be adjusted somewhat by changing heading rather then by speed.
The question is if 000 and 180 are both minimums as far as motion is 090/270 the max as many assume or are the 045/135 heading the worse? The answer is, it depends.
Freighterman1
When seas are 30-feet or less, experienced captains will often turn the vessel about at mid-day and put the weather on the stern for an hour, to give the mate and crew an opportunity to check the deck for dangers, and check cargo lashings.
No deck inspection and deck inspection.
We all had to sprint in bad weather between waves from the midships to aft for the first table setting but the captain ordered the mates to turn the ship for his easy walk to the second table, three times a day. Captain’s privilege…
2 Likes
When oil was first discovered in the North Sea it was all with American boats, rigs and construction barges and the idea that; “The North Sea is no bigger than the GoM, so WTF”?
They quickly learnt that it isn’t size that matters.
I cannot say for large ships because
I have no experience with them.
Lying-a-hull under bare poles with the hatches secured and everyone in the bunk may be the best strategy while waiting for a storm to pass in a 40’ sailboat.
Lying-a-Hull in a storm will generally be a bad idea in tugboat. It’s about like being inside a paint shaker.
That said, there are times when you can make good speed Towing in the trough of a big sea on your intended track, or on an acceptable alternative track. Especially, with a light barge (not many lashings to worry about and enough freeboard to prevent boarding seas).
1 Like
The North Sea can be a mean regular hell hole. The Americans in the beginning of the oil exploration, complete with Texas drawl, were shocked by the fury of the North Sea. There supply boats were not built for those powerful short waves. They thought they had seen it all in the GOM…
The picture shows the famous historic 18 meter freak wave at the Norwegian Draupner oil rig in the North Sea. Out of nowhere…
1 Like
One of my Newfie friends has some interesting video he shot on big PSV while backloading from a jack up rig in the North Sea. From the huge change in the air gap, I’d estimate the long swell at about 40 feet. There wasn’t a lot of wind. He said DP wouldn’t hold her. He had to do it manually.
22.5 m. wave was recorded by the waverider buoy at Statfjord B in Nov. 1981.
I worked on and attended the sea trials of the Smit-Lloyd 8, 9, 10, 11, 12 and 14. In good seaman’s tradition number 13, which could bring disaster to the ship, was skipped.Those sea trials on a rough North Sea were often not exactly for the faint hearted. Scores of landlubbers from the yard and others became very sea sick. The smell of vomit throughout the accommodation was horrible.
3 Likes
Yes and no. The practically unlimited fetch is one reason why the Southern Ocean has such historically bad seas.
My point is that to get 20 ft waves in a small body of water actually takes more wind to stack them that high and when you do get them they are steeper and closer together than 20 ft waves in a large ocean.
Looks like the inside of a washing machine. 
I hope you weren’t the fella standing on the port bridge wing in the video.