Author Topic: Eighteenth-century book with knots  (Read 9353 times)

DerekSmith

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Re: Eighteenth-century book with knots
« Reply #15 on: August 19, 2011, 11:57:03 AM »

Aren't we talking about the image contained in your post,
in which two teams apparently are pulling on two blocks,
with rather short multi-line spans to some obscure, cage-like
contraption fixed on a hawswer?  There is no detail there,
nor good sense, IMO.

--dl*
====

The image is the one linked in reply number 2.  If you click on the page, you are taken to an enlargement with magnification facility, and there is plenty of detail to be had, including the detail that Barry picked up re the apparent frailty of the windlass assemblies, the detail of the major load seemingly to be in the line from wharf to windlass to 'basket thing' to vessel, and the fact that the hauling team are hauling on a pulley anchor with a 1:3 mechanical (dis)advantage.

Another thing I just noticed - there are FOUR ends in the assembly - one on the vessel, one on the wharf, one at the pulley block and one after the hauling team.  This begs the question of 'What on earth is going on inside the 'basket' object?'

@Barry, I think for recovery, the barrels will be empty and employed as buoyancy tanks in case the lifting vessels take water to prevent them from sinking along with the just recovered wreck...

Derek

struktor

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Re: Eighteenth-century book with knots
« Reply #16 on: August 19, 2011, 02:56:41 PM »
The image is the one linked in reply number 2.  If you click on the page, you are taken to an enlargement with magnification facility, and there is plenty of detail to be had, including the detail that Barry picked up re the apparent frailty of the windlass assemblies, the detail of the major load seemingly to be in the line from wharf to windlass to 'basket thing' to vessel, and the fact that the hauling team are hauling on a pulley anchor with a 1:3 mechanical (dis)advantage.

Another thing I just noticed - there are FOUR ends in the assembly - one on the vessel, one on the wharf, one at the pulley block and one after the hauling team.  This begs the question of 'What on earth is going on inside the 'basket' object?'

@Barry, I think for recovery, the barrels will be empty and employed as buoyancy tanks in case the lifting vessels take water to prevent them from sinking along with the just recovered wreck...


''Marine salvage: a guide for boaters and divers'' ; George H. Reid
http://books.google.com/books?id=yrzSh2aG4WMC&pg=PA52&hl=pl&source=gbs_selected_pages&cad=3#v=onepage&q&f=false
http://books.google.pl/books?id=yrzSh2aG4WMC&source=gbs_book_similarbooks
pp : 26;28;46;52

Struktor



struktor

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Re: Eighteenth-century book with knots
« Reply #17 on: August 29, 2011, 12:45:44 PM »
Could they be acting as some sort of intelligent pulley anchor?  Giving out rope if the swell takes the craft away from the dock?

Figure 1. Rope-making in ancient egypt. Tomb of Akhethotep and Ptahhotep, about 2300 BC.
The round tool hanging from the rope close to the person to the left is perhaps
a stone helping the ropemakers to gauge that sufficient tensile stress is present.
Drawing by K. Olsen.

Source:
http://iopscience.iop.org/0295-5075/93/6/60004/fulltext


Additionally:
http://etacar.put.poznan.pl/piotr.pieranski//EPJE.pdf
http://www.youtube.com/user/pieranski#p/u/3/rzdRrs8OFjU

Dan_Lehman

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Re: Eighteenth-century book with knots
« Reply #18 on: September 03, 2011, 05:20:26 AM »

Aren't we talking about the image contained in your post,
in which two teams apparently are pulling on two blocks,
with rather short multi-line spans to some obscure, cage-like
contraption fixed on a hawswer?  There is no detail there,
nor good sense, IMO.

--dl*
====

The image is the one linked in reply number 2.
If you click on the page, you are taken to an enlargement with magnification facility,
and there is plenty of detail to be had, including the detail that Barry picked up re the
apparent frailty of the windlass assemblies, ...

The answer then is "yes"; I stand by my prior opinion
--that the artist had no clue, and possibly was trying to
show various methods all at once.  I.p., there is no good
illustration of the semi-apparent block-&-tackle --no haul
line distinct from the attached-to-near-block line the men
are hauling upon; no hint of the inside-a-*cage* whatever
at the away end, attached to the boat-pulling hawser.


--dl*
====