Saturday 19 May 1666

Up, and to the office all the morning. At noon took Mr. Deane (lately come to towne) home with me to dinner, and there after giving him some reprimands and good advice about his deportment in the place where by my interest he is at Harwich, and then declaring my resolution of being his friend still, we did then fall to discourse about his ship “Rupert,” built by him there, which succeeds so well as he hath got great honour by it, and I some by recommending him; the King, Duke, and every body saying it is the best ship that was ever built. And then he fell to explain to me his manner of casting the draught of water which a ship will draw before-hand: which is a secret the King and all admire in him; and he is the first that hath come to any certainty before-hand, of foretelling the draught of water of a ship before she be launched. I must confess I am much pleased in his successe in this business, and do admire at the confidence of Castle who did undervalue the draught Deane sent up to me, that I was ashamed to owne it or him, Castle asking of me upon the first sight of it whether he that laid it down had ever built a ship or no, which made me the more doubtfull of him. He being gone, I to the office, where much business and many persons to speake with me. Late home and to bed, glad to be at a little quiett.

12 Annotations

Terry Foreman   Link to this

Deane "is the first that hath come to any certainty before-hand, of foretelling the draught of water of a ship before she be launched."

http://en.wikipedia.org/wiki/Draft_(hull)

L&M note that such calculations were rare but that Deane had now made them for his Rupert http://en.wikipedia.org/wiki/HMS_Rupert_(1666) and Christopher Pett's Royal Katherine http://en.wikipedia.org/wiki/HMS_Royal_Katherine

Robert Gertz   Link to this

"...there after giving him some reprimands and good advice about his deportment in the place where by my interest he is at Harwich, and then declaring my resolution of being his friend still, we did then fall to discourse about his ship “Rupert,” built by him there, which succeeds so well as he hath got great honour by it..."

"So Pepys...Now your protege has done so well by Us..."

"Oh, Sire."

"We were wondering when We would get to see a ship designed and built by you."

"Oh...Sire...I..."

"Lets see Deane whom all the world knows by your own report was appointed by your decision took how long to build his? We shall make it a sporting challenge for you by giving you half the time to surpass him."

"Sire. I heartily endorse this effort." Penn, standing by, notes solemnly. "There is no one...No one...Who has such confidence in matters naval...Especially given his short experience in the field. I am certain that this is not mere talk on his part and that his confidence will be borne out by practical result."

Ruben   Link to this

The Rupert, a ship of the line, will be in service more than a hundred years!

A. Hamilton   Link to this

The whiz kids get together. Pepys was 28, Deane 24 when they met in 1662 and they each recognized the talent and ambition of the other. Now Deane at 28 is hailed as the new master of shipbuilding (first time in 2 generations the laurel has not gone to a Pett, I believe) and Sam has become the indispensable Navy quartermaster. (The birth date in the drop-down flag at Deane's name has his birth date as 1648; it should be 1638).

Tom Carr   Link to this

"...casting the draught of water..."

I just can't imagine how to do this without differential calculus and differential equations. Newton/Leibniz haven't invented it yet!

Newton didn't publish "Philosophiæ Naturalis Principia Mathematica" until 1687. Of course, Sam's name appears on the title page as he was president of the Royal Society at the time. Practical applications such as this didn't come about until the 19th century.

http://books.google.com/books?id=_lF1DZ1OPJQC&p...

djc   Link to this

"I just can’t imagine how to do this without differential calculus and differential equations"

squared paper, count the cubes.

JKM   Link to this

What did Pepys object to about Deane's "deportment" at Harwich, I wonder? Perhaps, like many talented engineer-types, he didn't bow & scrape enough to visiting bigwigs.

GrahamT   Link to this

“I just can’t imagine how to do this without differential calculus and differential equations”
Maybe he used a scale model, which we know shipbuilders made to show their clients, calculated the weight it was expected to be from the amount of timber used and standard hardware, scaled the weight to the model by adding lead, and then floated it in a tub and measured the draught. This could then be scaled up to life size.
Or, maybe he had an empirical formula for measuring the hull volume which was more accurate than other shipbuilders' formulae. If you know the displacement (volume of water equivalent to weight of ship) and the volume of the hull at different draughts, then the final draught can be calculated.
I don't think counting squares on 2D graph paper would work for a 3D problem, but maybe if you used a sheet for each cross-section through the hull it would work.

If you don't have Newton and Liebnitz, you use Euclid and Archimedes. We have computers and advanced mathmatics, so forget there are often simpler ways of doing complex sums.

However unless Deane left documentation, we will never know for sure how he did it, but it is fun to guess.

Michael Robinson   Link to this

unless Deane left documentation

L&M note "Pepys retained in his library an undated MS. entitled 'Mr Deane's Method of measuring the Body of a Shipp and precalculating her Draft of Water': PL 2501."

The Pepys Library also contains Deane's manuscript 'Doctrine of Naval Architecture,' PL 2190, written at Pepy's request in 1670 [pub. Brian Lavery (ed.), 'Deane's Doctrine of Naval Architecture, 1670,' London and Annapolis: 1981, 2nd. 1986] and an additional volume of Deane's MSS calculations and drawings, PL 2241.

cgs   Link to this

"so forget there are often simpler ways of doing complex sums."
Some call it "rule de thumb"

Harvey   Link to this

"... don’t think counting squares on 2D graph paper would work for a 3D problem..."

'Count the CUBES'.

Ivan   Link to this

Could someone who understands such matters perhaps consult Deane's manuscripts in Pepy's library in Cambridge and report back? Then the mystery of the method Deane used could be cleared up rather than argued about.

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