Studdingsail Boom Length

[BANYAN]

Hi folks, back with another question for the more knowledgeable on these matters.

 

I have read and searched far and wide to try and find guidance on the lengths of studdingsail booms.  I have found guidance on the diameters (1" in every 5 feet of length) but except for one 'tid bit' provided by Jans Sajt (following) whom suggests they were about half of the length of the 'entire' yard I have not been able to find any guidance.  These were not given in the ship's specifications either so I am hoping someone can point me in the correct direction.  I have checked Lees, Lever, Harland, Underhill and Kipping.

 

http://www.jans-sajt.se/contents/Navigation/Modelling/Patterns_Rigg_Stunsails.htm

"The studding sail boom was half as long as the entire yard. When set, the yard would be extended to 1.5 of its own length. "

 

I am not sure if the auther intended to use the word "entire' in this respect as that would make the boom as long as one side of the yard itself.  This does not make sense to me - does he actually mean half of one side of the yard?

 

Would appreciate any suggestions or pointers; many thanks

 

Pat 

 

 

[Bob Cleek]

I think that he meant 1.5 times the length of the entire yard when both booms were run out, or 1.5 times half the length of the yard when only one boom was run out. In other words, the length of a stuns'l boom was approximately half the length of the boom and they were run out to extend half of their length with the inboard half of the stuns'l boom doubling the yard. I've never seen any that were otherwise.

 

Since the purpose of the stuns'l booms was to expand the sail area, it makes sense that they would be made as large as possible, which would be half the length of the boom to which they were attached. I think the simplicity of the measurement practice was such that it's failure to be addressed in the contemporary literature is unremarkable.  

[Dr PR]

Lees gives examples of sunsail boom lengths on page 194 for ships of 1716 and on page 204 for 1838.

 

Stunsail boom length

                                          1716 100 gun     1716 70 gun    1838 1st class   1838 3rd class    1838 frigate

main yard length x                0.56                     0.56                     0.57                     0.58                  0.57

topsail yard length x             0.64                     0.63                     0.71                     0.70                  0.71

topgallant yard length x         -                           -                         0.80                     0.78                  0.79

 

The numbers are pretty consistent regardless of ship size. Maybe a bit smaller in the early 1700s than in the 1800s.

 

Stunsail yard lengths

 

Lees does say the sunsail yards were about 1/3 the length of the yard up to 1745 and then about half the length.

 

However tables in the back of Lees (page 200) give actual dimensions. For a 110 gun ship of 1815 the stunsail yard lengths on the main mast were 0.37 (main yard), 0.4 (topsail yard) and 0.44 (topgallant yard) times the length of the yards. There are some variations in the numbers for different sized ships, but they are still in the range of 0.35 to 0.45 of the yard length. The tables on pages 194 and 204 also give stunsail yard dimensions for several ship sizes.

 

Lees gives data for English ships. Some American ships of the 1812 period carried excessively large tophampers, so the spar lengths may have been longer.

 

I wouldn't get too hung up on precise boom/yard lengths. These things varied with different ship builders and different periods. Close is good enough unless you have an accurate spar dimension table for the ship you are building.

Edited March 21, 2021 by Dr PR

[BANYAN]

Thanks for the info Bob and Dr. Per.  It just goes to show that no matter how often I checked, somehow I still missed that info in Lees.  Can't figure how I did that, but do appreciate the pointer. 

 

Dr. Per, I am assuming the decimal values you provide are you calculations of the values provided in the tables (Lees)?  As suggested, I am not too hung up on the exact length just need a 'rule' or indicated length to work with to get an idea of the diameters (for the ID of the irons).

 

Many thanks 

 

Pat

Edited March 23, 2021 by BANYAN

[Dr PR]

Pat,

 

Yes, the relative lengths are my calculations. I was surprised to see that they came out very consistent over a large range of ship sizes.

 

I understand your problem finding information in Lees. I sometimes have trouble with it too.

 

On my topsail schooner project I could find very few "rules" for masting and rigging, and they all were for English ships. One of the interesting things about the American topsail schooners of the early 1800s is that they invariably put aloft longer masts and spars and larger sails than the British. This made them faster but trickier to handle. I determined my own rules by examining drawings and working from published data for a bunch of American schooners.

 

So lacking any other option I looked through the tables in the back of Lees. As it happens I was just coming to the same question about stunsail booms and yards as you did.

[Lieste]

Taking one measurement off Boudriot 74 Gun. Fore yard & Lower Studding boom half width:
1:72
95.5mm OA, 36mm Extension of Studding Boom beyond yard end , 59mm Length of Studding boom.
So the boom is roughly the same as the yard's semi-length, and when fitted but stowed, the butt end is seen 'at' the sling for the yard.

(Note both the Yard Arm and the Arm of the Studding boom are extended beyond where the canvas is flown, and the Studding sail is carried in all the way to the edge of the course, but falls short by a similar amount from it's own boom end).

Edited March 24, 2021 by Lieste
Correction 'Sling' for 'lift'

[BANYAN]

Thanks again for the info Dr. Per and Lieste; much appreciated.

 

Dr. Per - appreciate that clarification which allowed me to move on using the Lees  tabular data.  For my project I found the 1st Class Brig data aligned quite closely with the screw-sloop I am researching and building. I applied the same formula to determine the appropriate ratio/proportion and applied it to my needs; as follows (the measured is as taken from the profile photograph of the ship I have - and conforms with the calculated proportions)

Yard/Boom	Lees	Boom Length (Proportion of the Yard)	Victoria Boom Length	Victoria Given Diameter
Lower Yard	55’		56’ (Specified)
Lower Boom	36’	0.55	32’ 6” (Measured)	6½” (Measured)
Topsail Yard	41’’		43’ (Specified)
Topsail Boom	27’ 6”	0.67	28’ 10” (Calculated)	5¾” (Calculated)
Topgallant Yard	27”		25’ 6” (Specified)
Topgallant Boom	20’ 6”	0.76	19’ 4” (Calculated)	⩳4” (Calculated)

 

I must admit, due to the peculiarities of the spars in this vessel (similar as to what you appear to be finding with your project also) I have not looked closely at tabular data, especially in Kipping and Fincham.  I may have to revise my thoughts on that; but, I am happy to say I have almost concluded my research in this aspect (spars) and well down the track with the rigging now.   Thanks again for your info and pointer.

 

cheers

 

Pat