Fishing Vesels stability

[Guillermo]

I'm opening this trhead to gather all possible information on fishing vessels' stability, specially for the smaller units, and promote its discussion and study.

To begin with, I attach a very interesting 2006 paper on the stability of small, wide-beamed, high sided FV. From there:

"In the UK the imposition of rules to control fishing effort to protect fish stocks has had an unwanted effect on the design and mission of fishing vessels in what had been a traditional and evolutionary industry. New designs are being developed with small length to breadth ratios and some are optimised for ‘rulebeating’ instead of safe operation on the very diverse waters of the UK coastline [2]. Deep beamy vessels are now appearing with high-sided shelter decks; many of these vessels go against the conventional wisdom of the Naval Architect. The adoption of the rulebeater design has been a fast one and offers (under the current system), lucrative benefits to the fishermen for extracting more resource usually at a reduced operating cost. The deviation from traditional designs has made wide working platforms with low L/B ratios and typically stiff motions with high accelerations. Little account has been made to investigate if the stability of these vessels once compromised leads to a more onerous case in terms of capsize, due to flooding or lifting weights high on derricks."

Cheers

[murdomack]

I was amazed to find that the "Rulebeater" seemed to beat the conventional longer style in most of the tests.
A fisherman I knew from my schooldays stepped down from a very successfull, conventional 70ft siene trawler to a "rulebeating", probably 12M, about twenty years ago. Everyone thought he was crazy, but he was able to sell her on and retire ten years later. She was always the top grossing prawn vessel at her local port.
She was a Cygnus GRP hull ballasted with glassed in steel punchings. Seen from the quayside she looked like a pocket battleship with a large power block at the stern.
Used sensibly with regard to weather and fishing location a vessel like the one shown can be a very viable proposition.
I'm not an expert on the fishing tragedy statistics, but my recollections seem to be of larger vessels in the 70ft+ range operating, or dodging, in quite severe weather in open seas.
Fishing vessels nowadays are also being modified on a regular basis as gear and fishing trends change. It must be hard for the crews to understand all of the changes to the vessels sea-keeping that these modifications and additions can bring about.
Back around 1875 my great grandfather drift-netted for herring with a crew of five in a 33ft open, clinker built boat, ballasted with rocks and powered by oars and lug sail. Most years they followed the herring from the Minch around the north of Scotland as far as Peterhead. They weren't rich but they earned a living. There were no weather forecasts then but most of the vessels made it back home at the end of each season. They must have had a greater respect for the sea than today's fishermen.

http://www.ansulaire.com/Index.htm

Murdo

[eponodyne]

My grandfather did that kind of fishing off Norway's Lofoten Islands and Ulvangsoye with probably much the same sort of gear. He later made his way to the Puget Sound area and had three vessels built, the Hoover, the Roosevelt and the Coolidge. Hoover was lost off Sitka in the late '80s, as far as I know, after losing power and being washed onshore in surf. Roosevelt was still afloat and fishing productively as of winter '97. Coolidge I know nothing about.

All three were in the 70' range, with the typical Pacific Northwest trawler lines; deep, narrow, heavy boats with fantail sterns and high plumb ("dory") prows; carrying a mast and boom for hoisting duty and wearing a leg-o-mutton sail to steady and maybe help a little if the wind was right. Power provided by big, BIG, slow-turning Diesels and construction was correspondingly stout, of old-growth Douglas fir and oak frames with OGDF planks running to 8/4 thick.

My mother spent quite a bit of time aboard of Hoover when she was a girl, and reports that she had quite a nice motion, never lurching or rolling too deep-- but she also wasn't aboard for any of the *really* heavy stuff up North in the Bering.

Wish I knew more about these vessels. If anybody in the Puget Sound area has any info, please feel free to let me know.

[TollyWally]

We would call those old time Norski boats halibut schooners, not trawlers. Updated with aluminum shelterdecks there are a dozen or more still fishing the northern halibut grounds they pioneered. Wonderful boats.

[eponodyne]

I know for a fact that at various times Hoover was rigged as a trawler, a troller, a longliner, and a seiner, depending on what fisheries were most productive. I know she did some fishing for nurse sharks in the early days of WWII (when she was overflown off the California coast by a Japanese scout plane) and am pretty sure she did some two-and three-man jockey fishing for tuna out of Southern California and the Baja.

Relevance to this thread being, that this sort of vessel with that sort of lines seems to be a kind of do-anything vessel. The times changed and the boats weren't as productive, relatively, as newer vessels building with a narrower focus; but the boats themselves, and their type, are just fine sea-boats.

[Guillermo]

Hi all! Thanks for your posts.
I've just found this interesting web page named "Technician-history analysis of ship seakeeping" and want to share it: http://www.science.sakhalin.ru/Ship/Vlad_E1.html
Vasily N. Khramushin offers there an interesting "draft of universal vessel" (not totally new, because such kind of hull lines were used in some 19th century warships), probably quite expensive to build because of the all curved surfaces. I'm trying to remember something I've read about the stability and seakeeping of this kind of hulls, but I don't remember now....

Here an Ian McLeod's design of an extreme 'under 12 m rulebeater': http://www.ikmacleod-navalarchitect....shing-boat.htm

I attach a couple of images of other present 'rulebeater' FVs, as well as the first privately owned trawler in SA.
Any more images any of you may share?

Cheers.

[Guillermo]

La Redoutable, one of the ironclad ships of the century, had lines resembling those proposed by Khramushin.
http://en.wikipedia.org/wiki/French_...ble_%281876%29
(I have to find out more about this....)
Cheers.

[Guillermo]

I had already posted a previous edition of this 'Best Practice Guide to Vessel Stability' somewhere else, but this one includes some interesting pages on solving flooding problems aboard, and I think it's interesting to gather in this thread again all FV stability related documents.
I'll greatly appreciate all contributions to this end.
Cheers.

[TollyWally]

Not trying to hijack this thread, here's a covershot of a pair of boats like Eponodyne's grandfathers.

[Guillermo]

Already posted, but also an interesting video for this thread's purposes:
http://es.youtube.com/watch?v=swdyn7...eature=related

[Guillermo]

For those interested, there's going to take a place a technical session on fishing vessels' safety, the 21st of May at the Navalia Shipbuilding Exhibition, Vigo. I will give a dissertation on the safety of small FV from the point of view of stability.

Cheers.

[mflapan]

Dear Guillermo

You might be interested in a paper that I prepared on fishing vessel safety. It contains some statistics on OH&S and fire safety that you might find of interest. The paper challenges the view that fishermen should be treated as second-class citizens for safety.

http://www.nmsc.gov.au/documents/Aus...%20Vessels.pdf

Regards
Mori

[Guillermo]

Thanks a lot, Mori!

All the best.

[Guillermo]

I would like to ask european designers of small commercial fishing vessels what do they think about the necessity of designing to a certain amount of GT, as well as the difficulties experienced in doing so.

In my experience the EU regulations, which use the GT as a measurement of the fishing effort, are a nonsense from a naval architecture point of view and are forcing dangerous designs.

What's your experience?

Cheers.

[peter radclyffe]

the main problem the world over appears to be harbours & fishing grounds ? with restricted draft, it is too expensive to fasten say a 30 ton ballast keel to counteract 20 tons of top hamper on a beamer say, & impractical to increase her draft by a third, but if you did I thi nk a lot of the stability problems would be overcome