Mast Lengths and their above deck heights for HMB Endeavour

[archnav]

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 March 27, 2021 by archnav

[druxey]

Very nice, except I'm sure lengths were not taken down to  64th of an inch. The nearest inch would be fine!

[rraisley]

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:

 

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! 🙂

 

 

[Lieste]

Boudriot clearly indicates a 'round' taper for the French practice in the 74 Gun Ship. I see no reason to use a linear taper for the reasons given above.