hatches and deck camber

[hamilton]

This question has probably been posed and answered elsewhere, but after a few searches I came up dry, so I'll ask here - would hatches & gratings have been rounded down to match the camber of the relevant decks? Thanks in advance for any guidance here!

hamilton

[druxey]

The round up (not camber*) of hatches varied. At certain eras and nationalities, the round up could be considerably more than that of the deck. Do you have a specific time and nationality in mind?

 

* The word camber, very often seen in reference to the round up of decks or deck beams is actually incorrect! In marine dictionaries the word refers to a downward curve of a deck as seen from the side. Normally decks curve up towards the end of a ship, but in some cases the forward end of a deck curves down to allow the cables to come in above the deck when the hawse holes are low. This condition is camber!

[hamilton]

Thanks for the clarification Druxey - these distinctions are good to know! I'm thinking of English vessels of the early 18th century (1719-1745). Thanks again

hamilton

[SJSoane]

Hi Hamilton,

 

Just to make life more interesting, the HMS Bellona 1760 has serpentine shaped hatches and gratings, as seen here in the contemporary model.

 

Mark

 

 

[popeye2sea]

8 hours ago, druxey said:

The round up (not camber*) of hatches varied. At certain eras and nationalities, the round up could be considerably more than that of the deck. Do you have a specific time and nationality in mind?

 

* The word camber, very often seen in reference to the round up of decks or deck beams is actually incorrect! In marine dictionaries the word refers to a downward curve of a deck as seen from the side. Normally decks curve up towards the end of a ship, but in some cases the forward end of a deck curves down to allow the cables to come in above the deck when the hawse holes are low. This condition is camber!

Incorrect.  The camber of a deck is its athwartships arching.  The pitch or sheer of a deck is its slope fore and aft.

The Mirriam Webster definition of camber is:

To curve upward in the middle.

To arch slightly.

A slight convexity, arching, or curvature (as of a beam ,deck, or road)

 

 

The main point in common with all the references I have seen is that camber is a description of arching upwards in the middle of something.

Comes from the old French chambre and Latin camur meaning bent, crooked, or arched.

Regards,

 

[Mark P]

Good Morning Gentlemen;

 

One thing to keep in mind is that nautical terms often shifted meaning over the years. Sir Henry Manwayring's Seaman's Dictionary, written ca 1630, lists and defines quite a few words which later came to mean something different to his description.

 

The curve in the decks, as seen from the side, was also sometimes referred to as the 'Hanging of the deck'. 

 

With reference to Hamilton's question, as Druxey says above, the curvature of the hatches (referred to as the 'round up') varied. In the absence of any verifiable information, though, the best approach is probably to give them a curvature somewhat greater than the deck, as this seems to have been the most usual.

 

All the best,

 

Mark P 

[G. Delacroix]

Hello,

If it helps, in France in the first half of the 18th century, they used to give an extra (French) inch and a half (40 mm) of curvature in the middle to the gratings for better resistance.

GD

 

 

[allanyed]

Hi Henry

Miriam's dictionary is not a nautical dictionary so probably not really applicable.   Rounding or round up is the correct term for the curvature of the beams athwartships (when looking fore and aft.)  Look at the scantlings in the Establishments, Steel and the Shipbuilder's Repository and you will see that each deck for each size ship is described to "round up" or have a "rounding" a specific number of inches.  In addition, if you look at contemporary contracts, where this curvature is specified, it is referred to as rounding.  Camber is not a term used anywhere in these contemporary sources even though the definition does seem to fit.  

Allan

[druxey]

'Camber' is the term used frequently and inaccurately today, which is due to etymological shifting. There are many other examples of this. We see the word 'careen' used in the news, when actually the correct term is 'career'. Careen, which most ship modellers know is the term to turn a beached vessel over on one side to clean the bottom, is often used to describe rapid, uncontrolled movement of a motor vehicle or train as in "The runaway bus careened down the street." Well, I suppose it might have ended up on its side!

[wefalck]

Oops, I honestly believed that this is the camber of the beams, analogous to the camber of a road profile with actually a similar purpose, namely shedding water more easily. Druxey is right, just checked in Paasch's 'From Keel to Truck', and there the transversal curve of the deck beams indeed it the rounding, while the curve in longitudinal profile of a keel is the camber, and that of the deck is the sheer ... good by to what I thought was a good piece of nautical knowledge.

[Jaager]

9 hours ago, Mark P said:

he curve in the decks, as seen from the side, was also sometimes referred to as the 'Hanging of the deck'. 

Looking at a hammock from the side, I can see where that phrase would come to mind as a generally understood description.  They were a lot more familiar with hammocks.

[Jim Lad]

But if you look at a modern book of ship construction, you'll find camber as the transverse curvature of the beams as per below from HJ Pursey's "Merchant Ship Construction":

 

Camber: is the curvature given to weather decks to help them to shed water.  Tween decks are not usually cambered.  The standard camber 1/50; that is, a rise of approximately 1/4 inch for each foot of the length of the beam.

 

John

[druxey]

Jim: As I mentioned, there are shifts of meanings of words. Camber is just one example. Just look up the dictionary definition of 'fulsome'. It used to mean the very opposite of the present intended usage!

[Dr PR]

In 20th century US Navy ship design:

 

"Camber" is the transverse (port to starboard) curvature of large weather decks, highest along the centerline and lower at deck edges.

 

"Sheer" is the lengthwise curvature of the large weather decks, typically highest at bow and stern.

 

Not all weather decks had camber or sheer. Some had camber but no sheer and smaller decks typically had neither.

 

I'm sure the terminology has changed with time and coountry, and even different locations within a country.

 

****

 

As far as the hatch gratings go, I suspect it was the larger, fancier ships that had the curved gratings. Smaller and less expensive vessels probably had flat gratings, especially merchant vessels. Flat gratings would be easier and cheaper to build.

[allanyed]

Phil, your comment on smaller vessels made me curious.  I looked at photos of the contemporary model of the royal yacht Henrietta (1670) and the gratings seem to be flat or possibly conform to the rounding of the beams.  This may also have to do with the era.   I believe the coamings and head ledges rose above the flat of the deck much higher as time went on.  The following are the Henrietta,  a fourth rate of 1705 and the Prince Royal 1773

Allan