A contractor comes up to you and confidently proclaims, “I can guarantee the stability of your ship just by looking at your hull.” Do you trust this person? Of course not! In the same line, you cannot judge the stability of a ship just by riding around in the bay. The real test of stability comes from rare, extreme events. Conjure up an image of the worst storm combined with loss of power. Those are the days when you really need stability. At those times, your ship’s stability becomes a safety tool to protect you from danger. When thinking about maintenance for the future, we need to remember extreme stability.
Take an example of extreme stability requirements: the IMO severe wind and roll criteria. This is a typical stability regulation that applies to all ships on an international voyage. Some may complain that this regulation seems unreasonably harsh. After all, it calls for a situation where the ship rolls all the way from port to starboard, driven by a perfectly timed gust of wind. That gust rolls the ship all the way to 50 deg of heel. Seems unrealistic? Instead, imagine how such requirements give you good odds of survival when the worst happens.
Imagine you are caught in a bad storm. The waves are just as tall as you hull. The helm struggles to keep the ship’s bow into the waves. And then . . . the worst happens. You lose main power, the auxiliaries go out, and the emergency generator won’t start. The ship drifts and starts to take huge waves on the beam. It gets slammed and rolls 50 deg to starboard. The deck slips out from under your feet and you cling to the console. You struggle to stay upright as pencils and coffee cups fly past your head and crash against the bulkhead. You have no chance of controlling the ship; you can barely hold onto the console. The ship hovers at the end of its 50 deg roll. It hovers there a moment. You fear it may keep rolling and capsize.
And then . . . the ship levels back out. The regulations protected you from this event. We know that bad situations happen often enough, and the ship needs to protect you as best as possible. We must consider more than your daily operations. Remember this when planning for stability maintenance. The stability of your ship is more than ride comfort and paperwork. In those extreme events, it becomes a safety mechanism designed to protect you.
Want to learn a little more? The video below goes into more detail about extreme stability and why we should appreciate it.
[QUOTE=AHTS Master;194594]I am obviously missing something here.[/QUOTE]
Sorry if the post missed the mark. I have encountered some crew on smaller boats that really don’t appreciate what ship stability protects them from. One operator actually gauged their stability just by driving the boat around the boat (small boat). So, I made this video to try and emphasize that we need to consider the extreme situations when evaluating a ship’s stability.
Do you have any suggestions on how I could improve the message?
. Stability varies and the requirement for stability varies depending on the application. Hard chine boat is hard to turn over, lots of initial stability, once it reaches a point it will capsize quickly giving little warning. Motor lifeboat like the CG 44 footers have low initial stability but will come back from deep rolls. If they go over they are designed to keep rolling and come back upright. So the most stable boat is the least “seaworthy”
Cargo ship different with variable capacity. Too stiff can cause real problems. Years ago we responded to a container ship that lost power and a considerable part of the deck load overboard. Rolled beam to for several days before a commercial tug picked her up. Damage to cargo in containers remaining and more noticeable inside the deck house was extensive, from rolling too fast. She might not have capsized still major damage.
[QUOTE=nickninevah;194611]Sorry if the post missed the mark. I have encountered some crew on smaller boats that really don’t appreciate what ship stability protects them from. [B]One operator actually gauged their stability just by driving the boat around the boat (small boat). [/B]So, I made this video to try and emphasize that we need to consider the extreme situations when evaluating a ship’s stability.
Do you have any suggestions on how I could improve the message?[/QUOTE]
[QUOTE=Island_Sailor;194670]What???
I have no idea how this would work.[/QUOTE]
I know. My point exactly. I do a fair amount of work with smaller boats. That means less experienced captains and lower tonnage license. So I hear some pretty interesting misconceptions. I work as a consultant naval architect. Usually by the time clients come to me, it is because something went wrong. Some accident under investigation, a new boat fails to make design speed, or a ship failed inspection when renewing their COI. Unfortunately, I have very few engineering options to fix things after the fact. And no one goes to the consultant beforehand. So, I’m hoping these videos will offer some general advice and help people avoid the common mistakes in the future.
I’m still fine tuning my delivery. I know this stuff gets boring, so I try to add a little drama and keep it on the light side. I’d love any feedback. Was the video boring? Or would you prefer less drama and more fact-based?
I mean I really don’t know - not even the first clue what they would be doing.
Making a wake with one boat and timing the roll period on the other boat?
Sending the junior guy out in bad weather in one boat and waiting on the other boat to see if he survives?
Tying a line onto a mast/crane/superstructure/etc. and trying to pull one boat over with the other boat?
[QUOTE=nickninevah;194675]I know. My point exactly. I do a fair amount of work with smaller boats. That means less experienced captains and lower tonnage license. So I hear some pretty interesting misconceptions. I work as a consultant naval architect. Usually by the time clients come to me, it is because something went wrong. Some accident under investigation, a new boat fails to make design speed, or a ship failed inspection when renewing their COI. Unfortunately, I have very few engineering options to fix things after the fact. And no one goes to the consultant beforehand. So, I’m hoping these videos will offer some general advice and help people avoid the common mistakes in the future.
I’m still fine tuning my delivery. I know this stuff gets boring, so I try to add a little drama and keep it on the light side. I’d love any feedback. Was the video boring? Or would you prefer less drama and more fact-based?