Gaff connection to mast

[Roger Morrison]

I've just altered my sails (Grampian 23) to match my shortened mast which allows me to go under bridges of the Trent Canal's 22 ft clearance.

Seems i have it about 95% correct...that is all but having the 'gaff' ride in the mast track properly.

I can't have the conventional "yoke" because of mast protrusions. The sail maker who did the sail work seems stuck in convention and talked me out of my idea to attach the gaff to the sail's brass head with a pin through both the gaff--sloted to receive the head--and the sail-head; with additional lugs. I think that will work.

But my question is, should the gaff be constructed as light as possible? Aluminum tubing, etc how relevant is the weight to its working?

ALL help will be greatly appreciated! Roger

[Dave R1]

Roger, is the sail laced to the gaff or does the gaff have a track for sliding lugs? I'm assuming you're talking about the throat of the gaff and attaching the sail there? It seems to me that whatever you do to attach the throat cringle to to the gaff, you need to make sure it maintains alignment with the head of the sail. The same would apply at the peak.

I've never seen a fitting for a gaff that slides in a track although the idea is interesting to me if it works. Any chance you could post some pictures to show what you're working with?

[umop_apisdn]

Ok, I am having a hard time visualizing what you are trying to do. If you attach the gaff to the mast via a track, how does it swing off to the side? you would need some kind of gooseneck attaching the gaff to the track, wouldn't you?

Noel

[Craig]

Light gaffs are good as long as they don't bend under the weight of the sail and the tension of the peak halyard. If I understand what you are proposing, the head of the sail is all the holds the gaff near the mast, ie no gaff jaws riding on the mast to keep it centered over the sail head. If this is the case the stress will all be on the last lug in the sail track. This will impose shear loads on the sail at that lug, big ones. What do you mean by "mast protrusions"? The gaff needs to be attached to the main such that as the gaff is raised it brings the main sail up with it. It also needs to be restrained so the inner end of the gaff is centered on the mast at any angle. This can be accomplished using jaws, a saddle, a hoop, or, if you have sufficient track length and the track cars will take the strain, a track car set to pivot on the end of the gaff. The large brass eyelet at the head of the sail should be your lifting point and attached to the bottom of the gaff structure. Have a look at Franks Gaff Rig Pages on this site for examples. As the guys said, pictures would really help solve this one.

[PAR]

A gaff should be as light and strong as you can make it. Weight, particularly this high up, should be reduced as much as possible. This is also true of blocks, attachment points, lines and any other hardware up in the rig. All rigs will benefit from weight reductions aloft. The best gaffs I've seen are aluminum, or if the budget permits, carbon composite.

Gaffs running in a track have been tried, though I've yet to see one that didn't pull the track off the mast. I hope you'll have better luck. If the track was especially large for the boat, then you have a good chance of success. The gaff gooseneck also needs to be a good one, capable of twisting as well as up/down and side to side.

I do remember a "Meadow Lark" (gaff ketch by L. F. Herreshoff) that had it's gaffs on tracks, but the goosenecks (sliding) were custom bronze castings and the track the nice heavy forged pieces (also bronze) that are hard to find any more, without salvaging it from an old boat. These seemed to work very well, although the owner reported screws being added to the track at the top, because the track twisted and pulled the upper ones loose.

You can attach the gaff solely to the sail without attaching it to the mast. Your performance will suffer, as the top of the sail will twist off much more so then it does with a jaw or gooseneck. The sail will wear out much faster too, without additional reinforcement sewn into the head.

I dislike the idea of the head cringle fitting into a slot then using a pin to hold it. This sounds like a great way to split a wooden gaff. Lacing is about the simplest method of attaching the sail. A bolt rope groove or slug track is also handy, but much heavier then lacing, for very little more security. In reality, the gaff stays with the sail and there isn't much reason to remove it, other then repairs. Also a sock could be used, which would make removal much easier. The sock type of attachment (just like a luff sock on a mast) is the most aerodynamic configuration, but you can't see a pretty varnished gaff inside it.

Had the gaff received the evolutional development the Bermudian rig did in the 20th century, I suspect both the boom and gaff would commonly employ bolt rope grooves along with the mast. The same could be said about tracks, but of suitable dimension to withstand the heavy loads the gaff will impose. Possibly the track could be reinforced at the top and at the reef points, maybe with a bordering piece of material to absorb some of the side loads. Of course the ultimate setup would have full battens on adjustable cars, but who's got the money for something like that. The price on one track car will be more then some spend on the whole of their rig.

[Roger Morrison]

WOW!!! So much response so soon! Thanks loads!!! I'll try to clarify a bit??

Pictures would help but don't have a digital camera.

MAST TRACK, is a slot in the aluminum mast, probably better called the sail track. Conventional 'lugs' attached to the sail, slide up and down... It is in this "track" that i hope to have the 'gaff' slide...

The mast is 17 feet, very sturdy and the slot also of course, contending with all forces etc. The sail is aprox 85 square feet and the gaff about 5 feet.

I thought about one of the "adjustable sail/batten cars" but $$$ However i think that is the principle that i want to adapt??? Using an aluminum gaff sloted and pinned to an extended--customized-- sail head that is raised from a hole just above the pinned gaff, seems to be workable IF there are sufficient lugs appropriately spaced--close enough/not too close--attached to the over-sized sail head...

The gaff could then swing as need-be with the sail, using the same attachment mechanism: lugs in the mast/sail track...

Why not use the conventional, varnished piece of craftmanship? The "protrusions"--this is a mast that once had spreaders--cockpit light, side stays, etc This presented a challenge to design an alternative that seemed more fitting and do-able with modern materials and techno-stuff...

Are most/all gaff-rigs on Cat-Boats??? Maybe that should have been my first thought, eh?

Thanks to each! Your suggestions and questions have been most helpful! Keep 'em comin'! Roger

[ChrisObee]

MAST TRACK' date=' is a slot in the aluminum mast, probably better called the sail track. Conventional 'lugs' attached to the sail, slide up and down... It is in this "track" that i hope to have the 'gaff' slide...

[/quote']

Much of the concern of previous posts seems to be related to a sail track that is attached to the outside of a mast rather than a part of the mast. In many aluminum mast profiles there is a bolt rope groove that is internal to the mast. I have never seen a gaff with gooseneck riding in the bold rope grove but I don't see why it couldn't be done.

[PAR]

Chris is correct, this is a bolt rope groove, used almost exclusively on aluminum extruded masts. A double articulated gooseneck fitting (none are currently commercially available, you'll have to make one) for the gaff could solve the binding issues, inherent in this type of mast purchase.

Sail slugs (plastic or metal) will bind pretty quickly at angles of incidence greater then 10 degrees or so. This isn't an issue with a sail, as it's quite flexible. The gaff isn't and will place heavy side loads on the bolt rope groove, likely crushing the sides of the groove, widening it until the slugs fall loose. If a universal joint type of connection (double jointed) was made between the slug and the gaff, then the loads wouldn't be placed on the groove, but on the slug and gaff, where they belong and can be tolerated.

The only other issue you need to address will be binding as the "car" goes up and down. With the weight of the gaff alone, it would bind a normal sized slug in the groove. The manufactures solve this with "self lubricating" materials or bearings, that run in the groove. They also make the slide part much longer, so it has more bearing area to accept the loads. A longer slug (maybe 4 times longer then a stock slug) will be less likely to bind, because it can't rotate as far off the centerline of the groove. If you take a close look at the manufactured batten cars (which will be loaded less then a gaff car) you'll have much of the engineering issues solved. Adopt the principles and apply them to your project. You don't need fancy bearings and adjusters, but the layout and construction should give you an idea of the loads you're going to need to resist.

Maybe a home made headboard with a HDPE slide about 6" long attached (lashed maybe) to it. The HDPE (StarBoard) will slide nice, is self lubricating and is about the easiest stuff to work with files, drills and other tools. The headboard can be aluminum plate (both sides of the sail) and pop riveted over the sail. Holes in both the HDPE slide and headboard can receive the lashings, which would permit the articulation needed to prevent most of the binding issues from side to side.

Go for it and call a friend that has a digital camera.

[Dave R1]

I'm wondering if there's any way you could manage with a gaff saddle instead of the slug/car in the track or jaws. The saddle wouldn't reach around the mast as far as jaws and you wouldn't have to engineer a fitting to the gaff. Here's an example from the Port Townsend foundry but I'm sure others could be found as well and if you can do the fabrication or know some one, it wouldn't be that tough to make either.

[Dave R1]

Here's a couple of pictures of gaff saddles from Classic Marine

[Ken_Potts]

I like the headboard idea. I must emphasize that my endorsement is that of a person who has never, ever sailed on a gaffer so please don't expend time, money or effort on my say-so (yes, sadly, my name's Ken and I'm gaff challenged).

Wouldn't the gaff saddle still need a loop going around the mast to secure it, or am I misunderstanding the forces at work? Does the saddle stay in place against the mast just through the tension of the throat/peak halyards?

[Barry Pyeatt]

I ran across a 27' gaffer in Grenada with a similar situation and still had the issues with spreader nubs causing interference with any gaff jaws or potential use of a saddle.

The owner had modified his rig to accept the Glen-l Goosneck to work with his aluminum mast. He used the following part with a wooden gaff.

http://boatdesigns.com/prodinfo.asp?number=13%2D031

He said it works out just fine and gives him movement in both vertical and horizontal planes on the gaff. He tied the slide together with the top slide on the mainsail cringle so that there was plenty of "beef" to make it work.

Saw it under sail a couple days later and it looked to be working just fine in moderately heavy wind conditions. He seemed to be able to maintain a good sail shape and certainly didn't have any problems tacking or running down wind either.

[Dave R1]

Ken, the gaff saddle wouldn't need anything around the front of the mast. Neither do jaws. Jaws commonly get a parrel but I think that is more for keeping halyards out of the jaws. Certainly when the sail is raised the forces on the gaff from the halyards work to keep the jaws/saddle on the mast. On my boat the jaws do move away from the mast when the sail is down but my sail is laced to the mast and the lacing loosens considerably when the sail is down. The sail in question would use lugs in a track so the luff would stay close to the mast in any position.

[Roger Morrison]

More THANKS!! Dave the pics were great and i linked to England and their pics...most helpful.

Par: Maybe a home made headboard with a HDPE slide about 6" long attached (lashed maybe) to it. The HDPE (StarBoard) will slide nice, is self lubricating and is about the easiest stuff to work with files, drills and other tools. The headboard can be aluminum plate (both sides of the sail) and pop riveted over the sail. Holes in both the HDPE slide and headboard can receive the lashings, which would permit the articulation needed to prevent most of the binding issues from side to side.

Sounds like where i'm heading. I just bought some LEXAN to sandwich the sail and beef up between the the 2 pieces that extend above the sail. This will give aprox 3/8 inch thickness to which the gaff will be pinned. Also found aluminum tubing 1-1/2 inch dia. I'll fill the ends, about a foot, with wood to add strength and bearing...

Questions: what is HDPE? IF i visualize your suggestion of a 6" slide: Proper plastic material formed as a long-lug...small holes drilled through which "lashing" (maybe stainless picture wire?) attaches it to the 'rope-bolt' of the sail...at the headboard...to which the gaff is attached???

Today i'll check out the 'cars' on the full-battens of the sail that was tailored last year with a stiffened, rounded top. Which works well, but having my original sail...why not a gaff?? So here i is....What's life without a, "messing-about" project, eh? Ever yearning, ever learning!! Roger

[PAR]

Ever seen a white plastic cutting board? That's HDPE (High Density PolyEthylene) sold as StarBoard and other brand names. I use it to make sheaves in home made blocks, bearings, slice it up for washers in kick-up rudders to ease movement, ditto for centerboards, in fact it makes a great material for rudder and centerboard blades. It's very easy to work, with wood cutting tools or a sharp knife. It's not a structural material and has limitations, but it also has many good uses. Those plastic sail slugs are likely made from it.

I'd make a 6" long cylinder to fit the luff groove, but it would also have two "eyes" carved into the aft face or through bolted with machine bolts. One of the draw backs to HDPE is it doesn't take screws well and must be through bolted to attach it to stuff. It can be welded to itself, but this requires a special heat gun and plastic welding rods. I've also found no glue that works very well with the stuff, certainly no structural adhesive. The top eye would be tied to the gaff, the second the sail. This joint needs be very flexible.

You can see on the sliding gooseneck from Glen-L, that the tack has a swivel and the boom has a "U" joint. This permits the sail to adopt the angle of incidence it wants, without twisting or other wise yanking on the boom. Now in your application you'd have it mounted upside down. The gaff would attach to the pre-drilled flat bar stock (lousy drilled pattern, because the holes line up, which will split a wooden boom or gaff) and the head would attach to the halyard swivel. The downhaul loop, would be used for the throat halyard which could have it's own swivel if desired.

In other words, skip the "hard" headboard idea (I thought about it, and changed my mind). The gaff will need to be "peaked" and scandalized from time to time and a hard headboard will prevent this. On a jib headed sail, the headboard can be hard, but a gaff needs to be soft. Typically on a gaff sail, there are several layers of additional cloth sewn into the area, to offer this extra strength, but remain reasonably flexible. Other then the head being attached to the gaff, the next closest attachment on the mast is usually a fair distance away (farther down the mast). This permits the head and gaff some movement, without binding up the lower attachment.

The Glen-L piece isn't very expensive and should be strongly considered. The engineering is already done for you, it's corrosion resistant and has all the little attachment points, just where you need them.

[Barry Pyeatt]

One other type of material that works well is UHMW.

This is the higher density polyurethane material that is used for fixtures on power tools and lots of other applications where high strength and slippery characteristics along with workability using standard woodworking tools. It is available in sheets or rods as well as other structural shapes in a wide variety of thickness and dimensions. Lee Valley has sheet goods that are used for power tools at reasonable prices.

It is denser and substantially harder than the white polyethelene cutting board type of materail. It is used a lot for rub strips on the keels of boats as well as for sheeves and slugs. Also available in colors. You can do a Google scan and find a number of dealers that have it available in most any size of shape you might find useful. Can also be tapped to hold standard machine screws.

The Glen-L gooseneck has also been used with aluminum tube to fabricate booms. Could conceivably be fabricated with a section of standard luff groove mast (smaller cross section) to form the gaff and the entire edge of the main set with slugs for a more efficient air flow overall. Not sure about any significant weight savings however.

[Roger Morrison]

PAR, a friend uses HDPE in his business, so easy to get.

BARRY, i've thought about a light mast piece as a gaff and think it'd work well... combining ideas as they are coming together, and working with what i have started, i think i will:

* Use the mahogany gaff i have, and fasten two lugs to it.

* Run a strap, already made by the sail maker, above the gaff to attach the halyard.

This will leave the sail-head "soft", and allow more flexible permanence--as i understand its need--at this critical point of sail, mast and gaff union. IF i have undestood things correctly???

IF this works, i'll switch to an aluminum gaff, with the same throat connection, for a lighter weight ease of operation???

Edited PS: "Bridle"-- How best to connect the halyard to the gaff-bridle (if i have the term right?)? As it appears in pics, i've seen 2 ways with a single halyard: >>> The halyard is led through a "ring" that slides on the bridle (should the B be taut or slack?) then to the sail-head???

>>>The halyard is attached directly to the bridle, hauling all up from the gaff??? This seems to be when using a short gaff??

>>> It also appears, with the former, that the pull from the gaff bridle seems to be about 1/3 from the throat end, and angling up 10 to 20 degrees??

>>> Should the bridle be attached at the very top-end/peak of the gaff or some placer lower??

>>> My halyards run through blocks in the mast-head. My last questions???

I would REALLY like to make this work! However, if it doesn't, i now know more about "yokes, jaws and saddles" sooooo...... thoughts? Thanks again to everyone!!! Roger