• Cut of the Sail
• Attaching the Sail
• Loose Footed Sail
• Mast Hoops
• Distance Line
• Bottom

The sail itself is best proportioned with the following ratios:  luff 1.0, head 0.833, leech 1.73 and foot 1.02, according to John Leather's The Gaff Rig Handbook.  This "best proportion" is not always followed, of course, but in Leather's ideal gaff main sail, the angle of the gaff to the mast should be at 30 degrees, and the boom should rake upwards about 6 degrees (allowances must be made here for the height of the gooseneck, deckhouses, etc.)  It seems to me that the luff is a good starting point, as you know how high your throat halyard will raise the sail.  Multiplying the factors he gives by the luff length to find the dimensions of the head and the foot seem reasonable, and the length of the leech then sets the angle of the top of the sail.

The Weekender I built specifies a main sail with a luff of 118".  The corresponding head of the sail should be 98" according to Leather, but it is 68" on my plans.  The foot on my sail plan is 127", while Leather's formula would put it smaller at 120" (the luff of 118" x the factor of 1.02 equals 120".)  Fair enough, so far:  the designers of the Weekender have a slightly longer foot, and a head that is just 2/3 of the size Leather recommends.  I would expect that the dimension of the leech in my plan would then be longer ... it starts 7" farther out on the boom, and angles in at the head another 30".  But the leech length on my plan is 170", while Leather's formula would put it at 204".  That tells me the planned angle of the top of the sail, with the peak halyard made fast, is at an angle less than Leather suggests.  And the sail on my boat is smaller than the "ideal proportions" would suggest.  I will build the sail to the designer's proportions first, but experiment with the "ideal" sail later on.  That will require another gaff, as the gaff specified is a mere 74" long on my plans.

Leather uses these proportions for those gaffers that will not be flying a topsail.  With a topsail, he recommends easing the gaff to an angle of 42 degrees to the mast, with corresponding allowances made to the leech to accommodate this.

Designer Michael Kasten, of Kasten Marine Designs uses a unique sail plan that eliminates one halyard, so the sailor has but one halyard to raise and position the gaff.  Michael was generous enough to provide me with some of his drawings.  These are wonderful designs, with tall gaff mainsails that are much different from Leather's "ideal" sail.  Redpath, a wonderful gaff schooner reproduced below, has a luff of 29'.  Using Leather's dimensions, we would expect a head just over 24' long, a leech angling down for a length of just over 50', and a foot 29' 6".  But Kasten's successful design, again allowing a single sailor to raise this large a sail, has a narrower head of just 8' 2".  The gaff in the illustration below is set much less than the 30 degrees Leather provides, and the leech is just slightly longer than the luff at 30' 9".  Appropriate for his schooners, the foot is a mere 13' 6" instead of the 29' 6" the traditional dimensions would predict.

"One detail which may be of interest to you and your readers is that many of the gaff rigs that I've specified make use of a single halyard for the gaff.  It is made possible by the relatively short gaffs that I prefer, arranged much like the gaff rigs on the Baltimore Pilot Vessels of the last century."

"As I have discovered on my own 34 foot gaff schooner EMERALD, with short gaffs there is no need for a peak halyard.  Luff tension is adjusted at the gooseneck.  The benefit is to simplify the rig, to always keep the gaff in the same attitude while raising and lowering, to increase luff length for better windward sailing, to reduce weight aloft, and to eliminate those pesky tops'ls."

"On a schooner I do like to use a fisherman tops'l, as it provides enough area to be of excellent use.  The gaff tops'ls however are more trouble than they are worth (IMHO)."

Michael Kasten, November 20, 2000

(The fisherman's topsail is rigged between the fore and aft mast on a schooner, so those of us with a sloop, with its single mast, are out of luck here.  You can see the fisherman's topsail in the full illustration of Redpath above.)

A poor scan of Michael Kasten's leech rigging on Lucille, a 50' schooner.
 

"Loose-footed" or "laced to the boom" is given some attention by Leather.  He declares a loose footed mainsail must be a vertically cut, or at least diagonally (introducing that cut for the first time in his book.)  Attached at the luff side at the clew (lowest corner of the luff) and at the leech side at the tack (the corresponding lowest corner of the leech.)  Leather further explains that the tack is attached to the deck by a lanyard, although I am not at all clear here what he means, unless a block or fairlead on the end of the boom receives the lanyard attached to the tack, and then it is rove to the deck fitting.  Michael Kasten, whose designs favor the loose-footed mainsail,  includes this set up on his drawing for Lucille, a 50' schooner.  A poor scan is provided in the left column.

Marlin style lacing.  One method of attaching the sail to the boom.

The "horse" is the rod just below "E" that allows the clew to be pulled towards the end of the boom by the line that is shown running from the clew at "E", through the boom (you can see the faint "inside" block in the boom in the illustration) and under the boom near "B" and finally to "D", where the clew outhaul tackle is.  We can see that it is made fast to the boom itself, with the bitter end rove to a cleat near the boom jaws.  On many small boats, the horse is dispensed with, and the clew is hauled aft with a lanyard secured to an eye or cleat on the boom.

Lacing the Sail to the Boom
Lacing the sail to the boom can be accomplished on nearly any size craft by using a marlin-style lace as shown in the left column.  Although a number of other methods have their fans, including spiral lacing and "robands" -- tieing each grommet in the sail to the boom with an individual loop.  I changed to "robands" after seeing that marlin-style lacing didn't allow the foot of the sail to rest nicely along the top of the boom, but rather smashed it along the side.  Lacing to the boom is not unique to the gaff rig, and most books such as Rigger's Apprentice and Knowing the Ropes have numerous examples.  Leather includes some diagrams of even more alternates, including attaching the foot to a batten affixed on the boom.  

John Leather's version of "Forth and Back" lacing, as found in the Gaff Rig Handbook.
 
 
 
 
 
 

Even though I did err in identifying the rig at first, I've decided to leave it here to show an excellent method of spiral lacing of the sail to the mast.  For small craft, lacing the sail as shown here works well, and avoids the cost of rigging mast hoops.

Roger identifies this as "forth and back" lacing, where on page 87 of his book he says "... go around the mast and through the lowest grommet in the luff of the sail, and then reverse direction and come back round the mast the opposite way" as shown above.  By reversing direction each time you go through a grommet, you lace the sail to the mast with less friction, and it works much more smoothly.   

John Leather shows another method with reduced friction, shown at left.  Below that, are two more examples of lacing methods, the standard spiral lacing and a "more secure" variation shown below it.  

Mast hoops are often used to attach the gaff sail to the mast, tied to the sail with "small stuff" (light line) as shown on the left.  This is instead of lacing the sail to the mast.  Two methods to secure mast hoops to the main sail are shown in the left column.

Traditionally, mast hoops are made of steamed, bent and riveted white oak, but common on small craft and among the cheapies (like me), ABS couplers for DWV pipe, sold by your local building supply store, are cut into 1/2 to 3/4" wide hoops by sawing with a hacksaw (or better yet, a band saw.)  You can also buy plastic mast hoops already cut, although they are more expensive.  

The formula for figuring how large to have the hoops is to size them about 25% larger than the largest diameter of the mast.  For most small craft, 3" or 4" diameters are usually fine, and provide a readily available and inexpensive source for mast hoops.  

Sail Rite sells 3 and 4" mast hoops out of steamed and bent white oak for under $20 each.  For larger craft, check the Classifieds section of Wooden Boat Magazine for several small woodworking companies that make traditional mast hoops.  (The Gaff Rig Page generally only links to companies or sources we have personal experience with.  If you know of a boatbuilder you would like to recommend to our readers, please let me know.

Note the line along the left side of this illustration.  This is the "distance line," intended to keep the mast hoops an equal distance from each other, and prevent them from hanging up as the sail is raised and lowered.  It is tied off to the top mast hoop and the bottom mast hoop, and this is one line you don't have to do anything with while sailing.  While I've been told it is rarely neccessary on small craft, I did receive an email from Daniel Boucher, a reader of these pages, stating that the addition of the distance line helped on his small schooner, a 26 ft LOA and 22.5 ft LOD boat you can see on his web page by clicking here..