Sloping deck

[Don Case]

This is a picture of the Discovery1789. Notice the upper(?) deck right in the middle of the picture. It slopes off quite a bit. Is that for drainage for any water that come in the hawse holes? There would have to be a scupper there also wouldn't there

[druxey]

No, although it does help drain. The deck is sloped down (this is actually describing 'camber' as the word was used then) to the hawse holes. This allowed the cable to come up on the weather deck. If a deck lower, the hawse holes would be too close to the waterline. On this plan the hawse holes and scupper are not shown.

 

To clarify; 'camber' is the rounding down of a deck as seen longitudinally and 'round up' is the correct term for the transverse (athwartships) curve of the deck and beams.

[Don Case]

That fits. This is much more than normal camber. At least I thought camber was spread evenly over the full length of the deck. In the last 8' it droops about 1' . On the plan(as well as I can make out) the deck is straight and then drops off in the last 8'.

I noticed that you called this the weather deck. This is the deck under the forecastle. It's not really exposed to the weather but it does look like it's open to the weather at the aft end of the forecastle. (back by the stove)

[Dr PR]

Druxy,

 

Modern use of the term "camber" refers to the side to side (transverse) curvature of a deck, always highest at the centerline and lower at the deck edges. This prevents water standing on weather decks when in port.

 

The longitudinal (fore to aft) curvature is called "sheer." The weather deck at the bow is typically higher than at midships. The stern may also me higher than midships, depending upon the ship.

 

Any idea when "rounding down" became "sheer" and "rounding up" became "camber?"

[iMustBeCrazy]

Don, it seems to start at the mast, so about 16'. This might make it clearer.

 

 

[allanyed]

Hi Phil, 

"Rounding down"  is a  new term for me.   Regarding rounding up, I have never seen this term, but it surely is the same as the terms that I have seen used.   For the Brits (I can't speak for other nations), in studying the Establishments of 1719, 1745 and 1750, the Shipbuilders Repository, and  several contracts from the 17th, 18th, and 19th centuries I have only seen the term "to round".    The words up or down are not used at all.   In the case of the Establishments and the SR, the scantlings for how much the beams are  to round are given for each rate of ship as well as for each deck.    Later, in the early 19th century Steel used  "to round" in the main text of The Elements and Practice of Naval Architecture but in the scantlings portfolios, he used the term "to round up" for each deck and each rate.  Not trying to be picky here, just finding this very interesting, especially the term rounding down as I cannot find it used anywhere in either contemporary or modern sources.

 

As to the amount of sheer Steel does give the location of the various rails based on the location of the sheer rail which he detailed in relation to the upper edge of the rabbet of the keel "afore, midship, and abaft"  in folio fifty-five.  Appreciate if you could steer me to  where you found the information on sheer and rounding down scantlings.    

 

Thank you very much. 

 

[druxey]

Meanings and usage of words change over time. I do not know when 'camber' was adopted to replace 'round up' but suspect it was in the mid-nineteenth century. However, camber was the descriptive word used to describe the deck construction seen in the draught above.

 

Steel, Naval Architecture page 14,1805:

 

CAMBER. Hollow or arching upwards. the decks are said to be cambered when their height increase toward the middle, from stem and stern, in the direction of the ship's length.

[Dr PR]

Camber is also used today for the curvature of a road surface from side to side, higher in the middle. So i suppose it could apply to any surface that is curved to be higher in the center than at the edges.

 

Webster's unabridged says it means curved higher at the center. It id of French origin. I don't have the Oxford English Dictionary to see when it was first used in English and what the meaning was then.

 

I first heard the word with reference to the vertical tilt of automobile wheels (dad was a mechanic).

[georgeband]

I had a quick look in Falconer's universal dictionary of the marine (1784) and he said 

 

 

Falconer's definitions for 'rounding' have nothing to do with curvature so the term probably emerged in the late 1700's or early 1800's. 

 

JJ Moore had almost identical wording in his dictionary printed in 1801. Plagiarism was rife back then and still shows its ugly face now.  Both dictionaries can be found on the web as pdf files. 

 

George

[Don Case]

I was under the impression that cambered was referring to an even curve of the entire deck. Like both ends are a foot lower than the middle. This is not even. The deck has a bit of camber over it's length but then it drops off in the last 8-12" at the stem.