Model Boat Mayhem
Mess Deck: General Section => Full Scale Ships => Topic started by: boatmadman on June 13, 2009, 06:28:58 am
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Think they overpumped the ballast tanks!
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You missed these two Ian
(http://i124.photobucket.com/albums/p8/DickyD_photos/disaster2006_mightyserv_4.gif)
(http://i124.photobucket.com/albums/p8/DickyD_photos/disaster2006_mightyserv_1.gif)
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Will yours do that ? {-)
daz
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Hope not Daz :o
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More Here http://cargolaw.com/2006nightmare_mightyserve3.html#the-feature
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They were very lucky that no one died during this event. I guess that the crew knew some thing was wrong and moved to locations to get off the boat quickly.
Duane
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They were very lucky that no one died during this event. I guess that the crew knew some thing was wrong and moved to locations to get off the boat quickly.
Duane
It Was Lucky For The MS3 Crew But Unforunate For Her Sister Ship MS1 Which Lost All Hands, I Wanted To Build The Blue Swan Thinking No-One Would Have Done That Before Little Was I To Know Someone On Here Done Her Lol, So i Now Have Another Project On The Boards....*Top Secret*
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Although the pics by themselves are "impressive", and on the assumption that somebody is now looking for another job, I have a question.
Is there a demarcation line (however finely drawn) as to when a surface vessel becomes a sub-surface vessel? U-Boats were designated as "boats" with a submersible ability.
The type of vessel (mega heavy lift and "semi" submersible) shown in the pics must share some of the stability and buoyancy problems encountered by "true" submarines. To attain neutral buoyancy the limits must be very fine and precise. Even a couple of tons (2 cubic yards) of extra weight could well spell "disaster". Just a thought. BY.
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Crash dive springs to mind (taken from silent hunter 3) :D
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Where did you say that water level line was
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Crash dive springs to mind (taken from silent hunter 3) :D
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Where did you say that water level line was
Oh dear, and here was simple little me thinking I might get a sensible answer.
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Hi Bryan,
Perhaps main ballast tanks to take her to limit and say maybe 3 or 4 small (ton?) ballast tanks amidships with high capacity constant inlet/ outlet capabilities???
I am uninitiated in the wonders of modern semi-subs but just the way I would go about it.
Greg
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Oh dear, and here was simple little me thinking I might get a sensible answer.
[/quote]
Sorry couldn't resist it :embarrassed:
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Bryan,
I have considerable experience of non-submersible offshore transport barges but the intent with those was always to keep them above water and to that effect ballast plans for the loaded condition were always checked and independently double-checked before approval.
First generation semi-sub cargo barges were non self-propelled and had fairly basic ballasting systems often using pumps for ballasting and pumps/compressed-air for deballasting but they did not submerge to quite the extent that the Super and Mighty Servant Class vessels do. The later vessels became bigger, self-propelled and able to submerge further but - as far as I am aware - ballasting systems remained fairly low-tech.
The big semi-sub, twin-hull, crane vessels used offshore with lift capacities ca. 20,000 ton have very sophisticated, high-capacity, ballasting systems which are computer controlled to provide rapid reaction to the application of big hook loads. I put this info in here because I wonder if something similar, although not as sophisticated, may be in use on the current generation of semi-sub barges.
As you would expect, the residual buoyancy in the semi-sub barges lies partly in the submerged stern of the barge, fine-tuned to stop it going right down (supplemented by the demountable tower tanks fitted aft when this does not interfere with the cargo) and the forward accommodation/machinery/bridge tower structure. A delicate balancing act that I'm glad I never had to cope with.
Some heavy-lift semi-sub jobs converted from tankers retain the aft superstructure and foc'sle and use side-loading, Thus I would expect these to retain far better stability and reserve buoyancy than the all-for'd types.
Does this help?
Cheers,
Barry M
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I think one of the biggest stability issues with these things is transverse stability.
In either design, the in built stability is at the bow and stern, transverse stability must be through use of various tankage.
I dont have any real life experience of these things, but having built a model of Blue Marlin, I very quickly came to understand the stability difficulties these things have. The first time the model went in the test tank it would capsize for fun, it was so sensitive.
Even with stabilizing foam added, its very tender and sensitive to wind and ripples (waves).
Ian
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Ian,
They are all heavily sub-divided with wing and centre tanks. However, it's worth bearing in mind that the 'model effect' comes into play when scaling down. The full size job is considerably less tender.
Cheers
Barry M
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To BarryM...thanks, a very interesting post.
During my sea-going "career" I was always more concerned with keeping water out rather than to voluntarily let it in. But I suppose "tankers" (and any other ship, come to think of it) have a degree of sinkage. But in my memory of "stability", the usual rules cease to apply once the deck edge is submerged. I guess "our" calculations were arranged around a rolling ship when only one deck edge was submerged. But I seem to recall that the calculations immediately went from "static" stability to "dynamic"...a different set of "rules" altogether.
Having said that, it's interesting that RFAs "Fort George" and "Victoria" have huge built-in buoyancy structures at the back end....above the main deck, a bit like the semi-submersible vessels we are discussing. But I think these ones are to hold the ship above the water on a temporary basis to allow more time for evacuation and possible salvage. Don't know what would happen to the pointy end though!. BY.