Patent Log


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Joshua Gulch

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On page 41 of David Brown's "Last Log," he mentions Californian damaging her patent log in the ice field. What exactly was this, and how was it used?
Am I to understand that it was like a little odometer towed behind the vessel? Does anyone have a diagram of one?

Thanks in advance.

Josh.
 
May 8, 2001
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double post.
 
May 8, 2001
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Hey Joshua. That is not fair. I am not to page 41 yet... Good to see you here again my time traveling friend.
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Colleen
 

Dave Gittins

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A patent log of 1912 consisted of a small brass device that was shaped like a bomb with twisted fins to make it spin when dragged through the sea. It was a foot or so long, depending on the model. It was attached to a long length of a specially plaited rope that was intended to resist twisting. Titanic would have needed a good 100 metres of rope. The actual length needed a bit of fiddling with to get it right for a particular ship.

The other end of the rope was attached to a meter, rather like a water or electricity meter. It showed the distance run since the log was last streamed. The spinning rope turned the mechanism in the meter, which showed the distance run. A wheel-governor or flywheel between the end of the rope and the meter helped to keep the action smooth. Titanic used Walker’s Neptune log, which was the model designed for speeds of more than 18 knots, not the Cherub model mentioned by some sources.

Once set up properly, these logs were quite accurate, and they continue to be used in the era of GPS by some cruising yachties. The log was occasionally taken by sharks and if you reversed engines you had to get the log in smartly or it might be drawn into the propeller. Californian may have done this, though the ice got the blame.
 

Joshua Gulch

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Colleen,
Hey hey! Good to see you, too! I'm finding more time between classes to be able to dig into my books, though online play time later is trickier. I'm trying, though!

Dave,
Thanks for the information!

If I understand it right, the line would be attached to the log's nose, which would allow the greater spin on the x-axis thanks to the twisted fins causing the spin as it's dragged. The log's turning of the rope then registers on the meter aboard ship. Did I get that right?

Where would Titanic's have been deployed from? Presumably the fantail I'd assume, but I've never seen any indication of the meter on Titanic. Where'd they store the thing?

I'm just curious.

Josh.
 

Dave Gittins

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The meter was mounted on the port end of the aft docking bridge, which overhung the line of the hull sufficiently to keep the log line clear. I suppose they stored it in a handy locker when it was not being used. It was only used after dropping the pilot and getting clear of the shallows. It was quite a small gadget apart from the log line. The meter was maybe 4" in diameter.

My source for the location BTW is Quartermaster George Rowe.
 
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