Topsail schooner sail plans and rigging

[georgeband]

Phil,

I have checked through my notes and downloads and I have three other near-contemporary sources about mast making. I wonder why Fincham is referred to so often - is it because his work is in some way more correct, or have people followed a trend set early on by someone like Chapelle?

'A treatise on mast making' by John Cock, 1840. Pages 19-22, 26-27 and tables on pages 46, 47. These are rules to calculate by proportions from hull dimensions. 

'A treatise on marine architecture' by Peter Hedderwick', 1830. Pages 361-363. No tables but rules with proportions. 

'A rudimentary treatise on masting...' by Robert Kipping, 1864. I did not find proportional rules but he does give tables with examples for schooners of different weights and sizes.

Treatise_on_masting Cock.pdf

Hedderwick marine architecture 1830.pdf

Treatise_on_ masting Kipping.pdf

They also talk about hounds and cheeks...

 

George

Hedderwick marine architecture 1830.pdf

[Dr PR]

George,

 

Thanks for those references. I guess! Now I'll have to work through all this again - but that's not a problem.

 

I have attached my Excel 2010 spreadsheet for mast and spar calculations (I think). At the top are two green cells that contain the beam and line of flotation values in feet. Be cautious about converting to metric because I did a lot of feet to inches calculations for diameters throughout the page. It could be reworked to use multipliers in each calculation to convert from feet to meters and inches to centimeters - and vice versa.

 

Apparently Fincham was an influential ship designer for the Royal Navy and one of the first to try to standardize ships rigging. There weren't that many people to reference.

 

Professor William John Macquorn Rankine FRSE FRS was quite an influential mathematician who liked to generate mathematical formulae for everything. He reworked Fincham's rules verifying his work with actual ship dimensions. Look him up. He had a very wide range of interests, and was quite influential in many fields.

 

NOTE: THE ORIGINAL SPREADSHEET HAS BEEN UPDATED AND IS AVAILABLE IN A LATER POST.

 

Edited February 5, 2021 by Dr PR

[Dr PR]

George,

 

I found Cock's formulae gave results similar to Fincham and Rankine. Not exactly the same of course, but in the same ballpark. But his language to describe the rules is about as obtuse as any I have seen. Like many authors he assumes you already know what he means. Fortunately he doesn't just give his rules but he gives numerical values based upon a beam of 20.5 feet. To figure out what he is trying to say you will have to do a lot of calculations to test the many ways in which his instructions can be deciphered relative to the beam width.

 

Hedderwick's rules for schooners (page 361) also approximate Fincham and Rankine. He bases his calculations upon beam, load waterline length, and distance between the deck and keel (housing), compensating for the many different length, width and depth variations in hull designs. His descriptions are very clear despite more complex calculations than the other writers.

 

Both are useful texts for mid 1800s ship design. Thanks again.

Edited February 5, 2021 by Dr PR

[Dr PR]

George,

 

I have added Cock's and Hedderwick's calculations to the spreadsheet. There are now five values you must add (in the green cells).

Mast and spar calculations V2.xlsx

 

I have also added a PDF version of the spreadsheet:

Mast and spar dimensions.pdf

 

Edited February 7, 2021 by Dr PR

[georgeband]

Phil,

 

Thanks for expanding your spreadsheet which I will use in detail when I have finished the hull of Whiting. You are doing a great service for us all. 

 

I remember Rankine from studies on thermodynamics in my university days and his credentials as an engineer are impeccable. I have not found anything about John Cock apart from a couple of documents at the National Archives (UK) but these are dated 1742 and 1743 so there is something strange here. Unfortunately they have not been digitised and in the current Covid situation I am unable to get there to look at the originals. Sometimes researching is more fun than model making... 

 

George

[Dr PR]

George,

 

As long as I am doing this for me I think I should share it with others. After all, others are sharing a wealth of knowledge on this Forum for me to use and enjoy.

 

About Rankine - you just have to appreciate someone who helped develop the Laws of Thermodynamics!

 

James Burke told a story about the development of thermodynamics. The Brits were trying to figure out how to make steam engines work. The Scots were trying to figure out how much heat they needed to distill a gallon of Scotch Whiskey. Does this say something about priorities?

 

And you are right about the research being as interesting as the actual model building. I really enjoy it. I always wanted to understand how all that rigging worked on sailing ships.

 

When I was "building" the CAD model of the USS Oklahoma City CLG-5 I got so sidetracked with the research that it took 14 years to complete. In the meantime I investigated how just about everything on the ship worked and created a web site for the ship! One of these years I will use all of that information to build a real model of the ship.

Edited February 7, 2021 by Dr PR

[Dart]

Question. Why did you make such a bend of the boom?

[allanyed]

Phil,

As to thermodynamics and priorities   I sailed on many ships with steam turbines and up and downers and I drank Scotch.  I  still drink Scotch but I don't know of any ships using steam these days.

 

Dart,  I love the photos of the Mary G. Powers that you posted.  I have no idea why the boom is arced but maybe if the rigging is removed it would be straighter.   I for one would like to know more on this one.

 

Allan

 

 

[Bob Cleek]

11 minutes ago, allanyed said:

Dart,  I love the photos of the Mary G. Powers that you posted.  I have no idea why the boom is arced but maybe if the rigging is removed it would be straighter.   I for one would like to know more on this one.

My guess is that there's a fair amount of flexion in a boom of that length, particularly because it's a solid round spar, rather than a glued up box girder. Comparing the two photos, it appears to have much less arc when under sail, as the sail holds the boom up along the foot. You can see when she's under sail that the arc is the result of the tension on the mid-boom mainsail sheeting tackle. In the photo of her alongside, you see more arc because the boom is only held up by the topping lift and the gaff boom appears to be laying on top of the main boom to boot. 

[Dart]

I see. As a version.

One more question.

I drew a drawing of a Russian military clipper ship. But I don't understand how the topsail tack changes?

 

Edited February 7, 2021 by Dart

[Dr PR]

I think Bob makes a good point. In some cases the topping lift attaches to the aft end of the boom and runs through tackle attached to the mast top and down to the deck. However, in some cases the topping lift is attached to the mast top and runs through a sheave near the aft end of the boom and back to tackle near the mast. In either case the lift pulls up on the boom end.

 

The boom sheets are usually attached to the boom about 2/3 of the boom length (give or take a little) from the mast, and these pull down/in on the boom.

 

With the topping lift supporting (pulling up) the end of the boom and the sheets pulling down closer to the middle of the boom the forces would tend to bend the boom down.

 

Another reason for the curvature would be gravity and time. With the boom supported only at the ends gravity would eventually cause the middle to sag.

 

Schooners typically have lighter mast and spars than larger square riggers, and the main boom on schooners is much longer that typical for the spankers on square riggers. So schooners have long booms of relatively small diameter, and this would allow them to flex more.

[Dr PR]

Dart,

 

That is a "European style" spar gaff topsail. I described the rigging in an earlier post #16 in this thread for the Main Gaff Topsail. The halliard raises the spar. The tack pulls down to stretch the sail vertically. The sheet spreads the sail horizontally to the end of the gaff.

 

The "American style" typically had the spar oriented almost vertically,  but the rigging was the same. It depended upon the cut of the sail.

 

Does this answer your question?

[Dart]

 

13 minutes ago, Dr PR said:

Another reason for the curvature would be gravity and time. With the boom supported only at the ends gravity would eventually cause the middle to sag.

 

No. Time has nothing to do with it. There are photos of completely new schooners, with the same boom.

This is an American fishing schooner built in 1884. Photo from 1886. The boom is also curved.

Edited February 7, 2021 by Dart

[Dart]

7 minutes ago, Dr PR said:

Does this answer your question?

Thanks. I see. I thought the topsail was lowered at every tack.

[Dr PR]

Dart,

 

Sorry, I didn't understand your question. "Tack" is the name of the lower fore corner of the sail, and the gear that is attached to handle the sail.

 

It also means changing course.

 

I have photos of ships with the lower corner of the sail (tack) on the windward or leeward sides of the gaff, so they didn't try to raise the sail tack over the peak halliard for the gaff. Either way the sail caught the wind.

 

However, on some schooners with flying topsails (the luff is not attached to the topmast) there is a brail attached to the sail tack and run through a block at the sail peak and back down to the deck. This brail allows the sail tack to be raised over the gaff peak halliard. But for this to work there must be port and starboard tack lines to haul the sail tack down on either side of the gaff and gaff sail. This would be purely a matter of preference for the vessel's captain or owner, and they might change their minds occasionally and try something different.

 

With the American style gaff yard topsail there was no interference between the vertical yard and the mast when tacking. For the European style gaff yard topsail (with the yard more horizontal) they may have lowered the yard when tacking and then raised it again on the lee side. The main idea behind this type of sail was that it could be rigged on deck and then hoisted aloft quickly, and then dropped to the deck again to "furl" the sail. No one had to go aloft.

 

****

 

I took another look at the drawing of the Russian clipper. It has gaff sails on all three masts! Does this make it a three mast fore and main topsail schooner? It is another good example of the ambiguity in assigning names to individual ship rigs.

 

****

 

I didn't mean to say that gravity and time alone were responsible for the curvature of the boom, and your 1886 photo of the 1884 schooner shows the curved boom on a relatively new schooner. But gravity would add to the curvature of the long narrow boom, and I would suspect that with time the boom would continue to sag more from the constant influence of gravity. But it looks to me that the primary cause might be the opposing forces of the lift and sheets.

 

One other thing I am trying to understand is the cut of the gaff sail. Why doesn't the sail hold up the center of the boom? Some references say some sails were made with a curvature ("gore") to the foot to increase sail area. From your photo of the Mary G. Powers it looks like the foot of the sail is curved to match the curvature of the boom. So there is no attempt to cut the sail to provide extra lift to the center of the boom.

Edited February 8, 2021 by Dr PR

[Dr PR]

Here is a spreadsheet for calculating rigging diameters. I have included an Excel 2010 file and a PDF printout.

 

Enter a value for the mast diameter in the green cell and all rigging sizes will be calculated. I label the mast diameter as "Model mast diameter" but you can also enter the real ship mast diameter. Use English (inches) or metric (millimeters) and the resulting calculations will be in the same units. The mast diameter 0.320 inches is for the 1:48 scale topsail schooner model I am working on.

 

CAUTION: The last three calculations for gun carriage rigging are based upon actual cannon bores in inches, and calculated for a 1:48 scale model. You will need to recalculate these for a different scale or if you want to use metric units.

 

All of these values are based upon Lees' formulae. They will work for ships or schooners. Everything is based upon the mast diameter.

 

Rigging calculations.xlsx

 

Rigging calculations.pdf

[Bob Cleek]

13 hours ago, Dr PR said:

In some cases the topping lift attaches to the aft end of the boom and runs through tackle attached to the mast top and down to the deck. However, in some cases the topping lift is attached to the mast top and runs through a sheave near the aft end of the boom and back to tackle near the mast. In either case the lift pulls up on the boom end.

While he latter rigging arrangement requires less line, the former is by far the more mechanically efficient. The boom being rigid, in the latter arrangement, half or more of your energy is simply pushing the boom against the mast, as with a bowstring and an arrow. I can't imagine why anybody would rig a topping lift in that manner.

 

There may be some confusion in interpreting some drawings, as "a sheave near the aft end of the boom and back to tackle near the mast" is very common, but the line through the sheave is actually the outhaul for the sail on that boom, not the topping lift.

 

I also noted in passing that you describe "foot ropes" (plural) on the end of the main boom and a notation on the drawing as "footropes P&S." Why would one ever need two foot ropes, one on the port side of the boom and the other on the starboard side of the boom? Both would hang beneath the boom. What would be the purpose of that? Boom foot ropes are not used all that much, compared to yard foot ropes. On the boom, they may on occasion be used when bending the mainsail or to pass a gasket around the loose canvas at the clew of a reefed main, but that's about it. 

Edited February 8, 2021 by Bob Cleek

[Dr PR]

Bob,

 

I have seen rigging diagrams and photos of both ways to rig the topping lift. In the drawings the mainsail outhaul ran through a small block attached near the end of the boom and the lift ran through the sheave in the boom. I agree with you that the way with the lift passing through tackle at the mast top makes more sense to me.

 

I have also read at least one account saying the the foot ropes were duplicated port and starboard, and I have seen this arrangement on the Lady Washington replica. They are called "boom horses" on the Lady Washington sail plan. The rope had an eye spliced in the aft end and the two parts ran parallel up to a point inboard of the taffrail where the lines looped over the boom and were spliced. Wooden cleats on the boom held the foot ropes in place. Maybe they are doubled for safety? Maybe it was just easier this way? Here is a photo.

 

 

 

To me this is just another example of how there is no one "right way" to rig a ship. Also notice that they used two sheets instead of one riding on a metal horse behind the rudder as on some vessels. And notice the clever way they locked the tiller to the rope- and could easily unlatch it when they wanted the tiller to swing free.

 

The ship was underway and motoring out of harbor against the wind and tide, so this is the operating configuration.

Edited February 13, 2021 by Dr PR

[Dr PR]

Here is my latest spreadsheet for calculating just about everything for masting and rigging. I have modified it to allow you to enter your model's scale to calculate the final values. And then the spreadsheet can calculate the number of packages of Syren rope and blocks you need and total the final price!

 

(Prices as of 28 February 2021)

 

Mast spar and rigging calculations.xlsx

[EricWilliamMarshall]

@Dr PR, I’m astounded by your work here! This is a gold mine! Many thanks for sharing some of the fruits of your labors!

[Bob Cleek]

On 2/9/2021 at 11:37 PM, Dr PR said:

I have also read at least one account saying the the foot ropes were duplicated port and starboard, and I have seen this arrangement on the Lady Washington replica. They are called "boom horses" on the Lady Washington sail plan. The rope had an eye spliced in the aft end and the two parts ran parallel up to a point inboard of the taffrail where the lines looped over the boom and were spliced. Wooden cleats on the boom held the foot ropes in place. Maybe they are doubled for safety? Maybe it was just easier this way? Here is a photo.

 

That horse arrangement would permit crew to work either side of the boom on the horses simultaneously. (They're called horses on the yards, too, the pendents along the yards' lengths which support the horses are called stirrups, IIRC.) However, again, one would question what evolution would occasion the need to have two crew out on the boom at the same time.  Given their size, they'd provide a "leg up" from the taffrail, but that's about it.  The swivel guns mounted port and starboard are unusual as well, unless, of course, somebody is trying to board the vessel broadside to the stern. (Normally, they would be stowed below and only mounted for action and then on the side from whence an attack was anticipated.)   Lady Washington's designer, who consulted me on another of this traditional designs long ago, knows what he's doing and takes care to get it all historically correct. You won't go far wrong following his lead.

[Dr PR]

Bob,

 

Thanks.

 

The Lady Washington had swivel gun mounts at several points along the sides. I suspect the two guns were mounted on the stern for show while the ship was taking tourists for a ride. People weren't allowed aft of the binnacle while the ship was sailing to avoid the swing of the tiller and the boom rigging. No swivels were mounted forward where the passengers were milling around.

 

They were also doing "combat" excursions with the Hawaiian Chieftain at that time. They fired the guns on those excursions.

[georgeband]

Phil,

 

Thanks again for your work which is culminating in the spreadsheet of doom. There is a vast amount of information that you have compiled here and I for one will make use of it. 

I have one more request which loops back to comments of yours when you embarked on this voyage:  you said that most of the references did not define their terms such as 'length'. You did this earlier with some useful diagrams and it would be helpful to include these in the spreadsheet. When I open the spreadsheet again in several months it will save some time and puzzled head scratching if the pictures are there on one of the tabs. 

 

My thanks once more for saving me a job and doing it so well. 

 

Regards,

 

George

[Dr PR]

George,

 

Good idea. I didn't think of putting a picture in the spreadsheet.

[Dr PR]

Here is an updated version of the spreadsheet with the rigging definitions drawing embedded in the spreadsheet.

Mast spar and rigging calculations.xlsx

[flying_dutchman2]

WOW, One of the best and most detailed "read" I have ever experienced here on MSW. I have several books on rigging and they don't even come close to the details you give on various items on a ship.

 

Like some have said, "write a book about it" and I would be the first one to buy it. 

 

Marcus 

[Dr PR]

Marcus,

 

Thanks. But I am not an "expert!" I am a student and this is all a learning exercise. Keep that in mind. I'm sure others will find faults in what I have written and hopefully provide corrections. And as I have said many times, there was no one "correct" way to rig any vessel. There are a lot of exceptions to these rules!

 

The spreadsheets are mainly for schooners and do not include everything about full ship rigging mentioned in Lees and Mondfeld.

[georgeband]

Phil,

Simply outstanding. Thank you.

 

George

[EricWilliamMarshall]

Off topic question - what do you create your images and diagrams with?

I would also second the vote that you track down a copy of The Global Schooner by Marquardt. Lots of detail and useful images. It has become pricey used but with patience you will find a reasonable copy. 

Regarding being a 'student', this is the how students become masters. Plus the more you share this, the more vetting and details will accumulate.  So write an article for Nautical Research Journal. You will get feedback and possible validation. 

 

[Dr PR]

I use an inexpensive CAD program (DesignCAD 3D Max) to create the 2D and 3D drawings and produce image files. Sometimes I edit the images in a photo editing program (Photoshop) to add or remove details, text, etc., and to crop and resize images.