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Use of lead sheathing on the knee of the head


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It seems that there are various references to lead being used to sheath the leading edge of the knee of the head extending above the waterline and "down to the gripe" (AOTS Diana).  The Minerva model in the US Naval Academy collection 'appears' to show a single piece of lead as described but this does not seem to be a common feature on other other period models.  I say 'appears' because there is no way to differentiate the colour of this to the copper plates

 

This raises some questions that I hope that those more studied than I can answer:

 

  • What purpose did the lead sheathing serve?  - protection seems the obvious answer
  • What time period would this haven been used in, and is it unique to British ships?  Haven't seem this referenced much at all
  • Probably a given that there would need to be some sort of material between the copper and the lead due to galvanic corrosion risk (?)

Insight anyone?

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I suspect tarred felt may have been used as 'insulator' between copper and lead. I believe it was an 18th century feature, Jason. The draught marks were usually of lead also. Before copper sheathing, the draught marks appear to have been incised into stem and stern posts. The marks were often filled with red paint, judging by contemporary models that show this feature.

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Draft marks for Dartmouth, 1655, wrecked in 1690, were cut of sheet lead, nailed if I recall correctly to stem and stern.  They were Roman numerals, the line about 1 inch wide.  Height 6 to 6.5 inches.  There was a line across top and bottom, probably to hold things together.  Actually I should use present tense since some have been collected.

 

This is a similar shape, what the metals might be I don't know.  Photo is from Parks Canada, HMS Investigator, sent out to try to rescue the Franklin expedition, so first half of 19th century.

 

post-17589-0-42469200-1447717668.jpg

Edited by jbshan
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  • 1 month later...

Hi Jason;

 

The gripe and the cutwater were leaded.  The principal reason was to protect against chafing from the anchor cable as the ship swung in tides or currents.

 

The paragraph below is from a contract for building the Bellerophon,  signed in January 1785.  She was launched the following year.  However,  the contract is a standard printed form,  and was used for other vessels around the same time,  and also in hand-written versions,  where the wording is very similar.

 

This is under the heading 'GRIPE' on the contract.

 

'To lead the Gripe with thick Lead of 12lb to the Foot Square,  to lap each side 6" and buried in a rabbit,  fastened with proper Nails,  their Heads dipt in Lead,  and to run up from 8' abaft the Ends of the Keel,  so high as the lower Cheek,  the ends to be let into the Wood and well fastened,  to have Horshoes to the Gripe properly fastened.'

 

I am not sure how this practice continued after coppering became standard,  but as that was in the early 1780s,  it must have been usual at the time of this contract,  so maybe it was still done under the copper,  or maybe its continued mention was just another example of bureaucratic inertia. 

 

All the best,

 

Mark P

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Druxey I believe the roman numerals were made of copper at a later date when the hulls were coppered, the numerals on the HMS Sirius wreck in Mauritius have been found by the archaeologist's on the site

I have pictures of them for my model of the Sirius but I am not allowed to reproduce them at the moment, although I have asked for permission to show some of them on this site as I think they would be extremely useful to us model builders

Edited by paulsutcliffe
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