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Mast Lengths and their above deck heights for HMB Endeavour


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David Steel: The Elements & Practice of Rigging and Seamanship 1794

 

1) HEIGHT OF MASTS IN THE ROYAL NAVY

Mastmaking – Page 39:

Rule:       Length of Lower Deck + extreme breadth : 2 → Height of Main mast

 

- Mast:

For ENDEAVOUR

- Main mast:

58ʹ 5"

- Fore mast: 8/9 of Main mast

51ʹ 117/64"

- Mizen mast: 6/7 of Main mast

50ʹ 055/64"

- Main topmast: 3/5 of Main mast

35ʹ 019/32"

- Fore topmast: 8/9 of Main topmast

31ʹ 155/64"

- Mizen topmast: ¾ of Main topmast

26ʹ 37/16"

- Topgallant mast: ½ of Topmast

13ʹ 123/32"

- Bowsprits of 80 gun ships and upwards: 7/11 of Main mast

---

- Bowsprits of 74 gun ships and under: ⅗ of their Main masts

35ʹ 019/32"

 

 

2) DIAMETERS IN PROPORTION TO THEIR LENGTH

Main- and Fore mast:

 

- of ships of 28 guns and under

⅞ of an inch to every yard in length

Mizen masts:

 

- of ships of 50 guns and under

⅔ of the diameter of the Main mast

Main- and Fore Topmasts:

 

One inch to every yard in the length of the Fore topmast

Mizen topmast:

7/10 of the diameter of the Main topmast

Topgallant masts:

One inch to every yard in their lengths

Bowsprits:

 

- in 50 gun ships and under

The same diameter as the Main mast

 

 

3) PROPORTIONAL LENGTH IN YARDS, IN THE ROYAL NAVY

Main yard:

8/9 of the Main mast

Fore yard:

7/8 of the Main yard

Mizen yard:

6/7 of the Main yard

Main-topsail yard:

5/7 of the Main yard

Fore-topsail yard:

7/8 of the Main-topsail yard

Mizen-topsail yard:

2/3 of the Main-topsail yard

Topgallant yards:

 

- Seventy-four gun ships and under

3/5 of their topsail yards

Crossjack yard:

The same as the Fore-topsail yard

Spritsail yard:

The same as the Fore-topsail yard

Spritsail-topsail yard:

The same as the Fore-topgallant yard

Studdingsail yards:

4/7 of their booms

Driver yard:

The same as the Fore-topgallant yard

 

 

4) PROPORTIONAL DIAMETERS OF YARDS

Main- and Fore yard, at the slings:

7/10 of an inch for every yard in length

Mizzen yard:

2/3 of the diameter of the Main yard

Topsail yard:

5/8 of an inch to every yard in length

Topgallant yard:

6/10 of an inch to every yard in length

Spritsail yard:

The same diameter as the Fore-topsail yard

Spritsail-topsail yard:

The same diameter as the Fore-topgallant yard

Studdingsail yards:

One inch in diameter to every 5 feet in the length

Crossjack yard:

The same diameter sa the Fore-topsail yard

Driver yard:

The same diameter as the Fore-topgallant yard

 

 

5) PROPORTIONAL LENGTH OF BOOMS

Lower Studdingsail booms:

5/9 of the Main yard

Top Studdingsail booms:

½ the length of the yards they go on

Flying Jib boom:

5/7 of the Bowsprit

 

 

6) PROPORTIONAL DIAMETER OF BOOMS

Studdingsail booms:

One inch to every 5 feet in the length

Flying Jibb booms:

7/8 of an inch to every yard in the length

 

 

7) PROPORTIONAL LENGTH OF GAFFS

Length of the gaffs:

5/8 of their respective booms

Diameter of the gaffs:

The same as their booms

 

 

PROPORTIONAL LENGTH OF STAFFS

Length of the Ensign staff:

⅓ of the Main mast, above the Taffarel

Length of the Jack staff:

½ the length of the Ensign staff, above the Taffarel

Diameter of the Ensign staff:

Half an inch to every yard in the length

Diameter of the Jack staff:

¾ on an inch to every yard in the length

 

 

9) Masts and Yards &c. for Boats

Long boats, sloop fashion, but with Lug-sails

 

Length

 

 

 

 

 

 

 

Main mast:

Twice and half the breadth of the boat

Main yard:

5/8 of the Main mast

Fore mast:

7/8 of the Main mast

Fore yard:

5/8 of the Fore mast

Bowsprit:

½ of the Main mast

 

 

 

 

Diameters in frictional parts of an inch to every foot in length

 

 

Main mast:

¼

Fore mast:

¼

Main yard:

¼

Fore yard:

¼

Bowsprit:

5/8

 

Pinnaces with Latteen-sails

Lengths of the Masts:

Twice the breadth of the boat and 8 inches added

Length of the Topmasts:

The length of the mast and 1/9 more

Scarf of the Lower mast:

¼ its length

 

 

 

 

Diameter of the masts:

5/16 of an inch to every foot in length

Diameter of the Topmasts:

2/10 of an inch to every foot in length

 

 

Pinnaces and yawls with Sprit-sails

Lengths of the Main- and Fore masts:

Twice and ¼ the breadth of the boat

Length of the Sprits:

⅛ more than the mast

Diameter of the masts:

¼ of an inch to every foot in length

Diameter of the Sprits:

⅛ of an inch to every foot in length

archnav - January 2021

 

 

Edited by archnav

All the best,

Tom

 

(sapere aude)

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  • 2 weeks later...

As an retired engineer, I found this topic very interesting, especially the Age of Sail Ships available on Age of Sail Books at the Historic Naval Ships Association.

 

 

I also noticed with great interest Plate 5 of Chapter 1, which shows top masts and yards, as it definitely shows a practice I always felt was correct, but often not modeled, in the shape of the spars. I think typically, on models, spars are tapered linearly, that is having a constant taper beginning at the normally straight/parallel/octagonal center section, and tapering to a smaller diameter at the end. Thus, the proliferation of articles on tapering spars on a lathe, using two straight pieces of wood with sand paper on them, using a plane with guides or even using a chopstick-maker, all of which result in a straight and linear taper. But, from an engineering standpoint, a spar with a linear taper is weaker toward the center than ideal and/or thicker to the end, resulting in an inefficient use of wood and weight, especially so high up on a sailing ship.

 

I always felt that spars should be closer in shape to a really flat ellipse, tapering not at all near the center, and tapering much more toward the end. As the strength (section modulus) of any round component is proportional to the CUBE of the diameter rather than the diameter, so even if the bending moment were half the maximum the halfway out the spar, the required diameter would be closer to 80%, not 50%

 

Anyhow (sorry for being so wordy), the diagram quoted, from the above source, CLEARLY shows the taper in spars is NOT linear, but much more rounded, giving more strength toward the center than a linear taper would give it:

 

mastplate5.jpg

This is probably clearest on the largest Main or Lower Yard, by comparing its shape with the Studdingsail Boom above it on the left side. Also, the dimension of the diameter in fractions of the full diameter is given in many cases, and examining those values will show the varying taper along the length. (I used a spreadsheet, of course -- engineer!)

 

While I'm sure many modelers do make the spars "rounded" correctly this way, rather than with a linear taper, as I said above, with so many articles geared around producing a straight taper, it definitely gives the impression spars should have the linear taper, when in fact that is not correct (at least for many ships). 

 

It's good to know that my "lazy" way of tapering spars, by using a belt sander and tapering by eye, resulting in a non-linear taper, in fact gives the more correct result! 🙂

 

 

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