Scantlings of Gratings

[Steve20]

This post is a continuation of a post in the Nautical/Naval History section of these forums:
https://modelshipworld.com/topic/34553-hms-victory-renovation-outer-planking-removed/

 

A visit to HMS Victory at Portsmouth added to my uncertainty in the making of gratings.  This led me to investigate the subject and I’m now posting my findings on MSW in case there’s something that someone else can take from them. As The Naval history forum is not the right place for this; I post it here where I think it probably belongs.

 

The Elements and Practice of Naval Architecture, 1812 Edition, David Steel.

COAMINGS. The raised borders of oak about the edge of the hatches and scuttles, which prevent water from flowing down from the deck. The inside upper edge has a rabbet to receive the gratings.

 

GRATINGS. The lattice coverings of the hatchways, which are made with openings to admit air, or light, by cross battens and ledges. The openings should never be so large as to admit the heel of a man’s shoe, as they may otherwise endanger those who pass over them.

 

BATTENS. ….. Battens for gratings are narrow thin laths of Oak.

 

LEDGES. Oak or fir scantlings used in framing the decks, which are let into the carlings athwartships. The ledges for gratings are similar, but arch or round up agreeable to the head ledges.

 

HEAD-LEDGES.  The ‘thwartship pieces which frame the hatchways and ladders.

 

 

The Arming and Fitting of English Ships of War 1600-1815, Brian Lavery.
‘Essentially a grating was made up of strips of timber running fore and aft, and others running athwartships across them. The thwartships timbers, known as ledges, were the deepest. In the early nineteenth century they were cut approximately 3in square in cross-section. Recesses were cut at suitable intervals, to take the battens which ran fore and aft. The battens were as broad as the ledges, but they were only about 3/4in deep, except for the outermost ones, which were deeper, for they gave strength to the structure, and fitted into the recess into the coaming. The grating curved upwards towards the centre line of the ship, as did the head ledge to which it was fitted. The spaces between the battens and ledges were roughly equal to their widths, but this was open to slight adjustment to allow the grating to fit into a specific space. Gratings were nearly always rectangular, except for the few oval ones fitted on the hatches above the steerage on some large ships of the late seventeenth century.’

Brian Lavery also shows photos of the main hatch of an NMM model of a 70-gun ship, c1730, which conforms with this description.

 

To summarise the above, deck grating battens run fore and aft, ledges athwartships, and the battens are cut into recesses on the ledges.

However, there does appear to be occasion where the grating location calls for battens to run athwartships, as in the Victory beakhead shown in the photos, below.

 

 

The Elements and Practice of Naval Architecture, 1812 Edition, David Steel.

Table of Each Dimension or Scantling for the Upper Deck Gratings:

 

Summary of upper deck grating scantlings given in the table:

• Ledges of ships 24-guns and up are 3in broad and 3 1/2in deep, and battens are 3in broad and 3/4in thick.
• For ships less than 24-guns ledges are 2 1/2in broad and 3in deep, and battens are 2 1/2in broad and 3/4in thick.
• For Denmark yachts ledges are 2in broad and 2 1/2in deep, and battens are 2in broad and 3/4in thick.
• For East India ships 818 tons to 1257 tons, West India ships 330 tons to 544 tons, and Packets of 201 tons, ledges are 2 1/2in broad and 3in deep, and battens are 2 1/2in broad and 3/4in thick.
• For Schooners of 133 tons, ledges are 2in broad and 3in deep, and battens are 2in broad and 5/8in thick.
• For brigs and sloops ledges are 2 1/2in broad and 3in deep, and battens are 1 1/4in broad and 1 1/4in thick.

 

For other decks, grating scantlings will often differ.

 

 

Upper Deck Grating with Battens running fore and aft:

 

Middle Deck Grating with Battens running fore and aft:

 

Beakhead Grating with Battens running athwartship:

 

 

Edited May 14, 2023 by Steve20

[Gregory]

Thanks a lot for this!   I bookmarked it for future reference..

 

It's unfortunate that a lot of kits provide gratings that scale to 6" openings or bigger, and a beginning kit builder may not have the tools to make their own, or be inclined to spend a lot on aftermarket stuff..

 

Here is a little grate work I'm doing for my Rattlesnake.  This is version  1.

Made up from scratch cherry coamings, and the grating is made from a Syren boxwood grating kit.

I'm thinking of trying to make the grating from pear to get a little more contrast.

 

Edited June 7, 2023 by Gregory

[allanyed]

On 5/14/2023 at 12:04 PM, Steve20 said:

The Elements and Practice of Naval Architecture, 1812 Edition, David Steel.

Further to this information, Steel gives scantlings for the head ledges and coamings for each deck. Examples:

Folios XXXIV and XXXV

Upper deck of a 16 gun

Coamings stood 1' 1"  above the deck and were 4 1/2" thick at the underside and 4" at the upper side.  The head ledges were 3 1/2" thick and rounded 1"

 

By contrast for the upper deck on a 44 gun, 

Coamings stood 1' 3" inches above the deck and were 6" at the underside and 5" at the upper side.  The head ledges were 5" and rounded 1 1/2"

 

NB   I THINK there MAY be an error in the Sim Comfort version of the scantlings that I just spotted.  For the dimensions for 50 gun to 110 gun, the height above the deck on the upper deck is from 3 1/2" to 4"  I THINK it should be 1' 3 1/2" to 1' 4" to remain consistent with the others.   

 

They did vary with time, but a 1795 Navy Board order stipulated that coamings were to be built well clear of the deck, approximately 15 in to 18in above deck level.  

 

For the gun deck, the opposite large difference exists with the larger ships having a height above the deck of well over 1 foot but for smaller ships, only 3 or 4 inches.  I have no idea if these scantlings are correct in all cases or not.  If they are correct, I do wonder why the massive variation, especially going from the 50 gun to the 44 gun ships.  

 

Allan

[druxey]

Yes, there are a few typographical errors in Steel's tables. I'm amazed that, in so many pages, there are so few! As with the above example, it's usually easy to figure out the correct values from the neighboring tables of scantlings.

[allanyed]

Unfortunately I have propagated the problem Druxey as I used the same exact figures in the Scantlings of the Royal Navy when compiling the various sources of scantlings for the book and at this point I am not sure how to provide the corrections.   

 

Allan

. 

Edited June 7, 2023 by allanyed