Aloft Photo (28K)

Fair Leads

Back to Fairleads Index

Changing Spreaders

This month's Fair Leads is the result of a recent Puzzler, in which we asked the question, "When is it a good idea to change spreader design and/or dimensions?" Since one of the prizes was for the largest number of sensible answers, we got a lot of information from the entries, so much so that I just had to stop and elaborate on some of them for this column.
Nearly all of the reasons (in italics) come from entrants Mike Montgomery, Russ Lang, and Brent Trockman. Others had a lot of similar answers, and some very different ones as well, but these are representative of the scope and creativity we saw.

For Racing Skippers:
If you are not winning, blame the sailmaker, as the skipper is always correct. When that is no longer convincing, look aloft for things to change. Do not look underwater or inside your own head for improvements, as you cannot see anything there.
Excellent point here, actually, because sometimes changing the spreaders (or anything else in the rig) only seems like a good idea. Be sure to check on your motivations before making any rig "improvements." In particular, run rig load numbers, consult with your sailmaker, rigger, and /or sparbuilder before leaping into ill-considered novelties.

Change your whole rig, if possible. The budget-minded will just start with the spreaders.
Are they the best aerodynamic shape? A new shape will have a different width and profile to accommodate the different 'foil' shape.
There are boats out there with hopelessly inappropriate rigs, or at least with some inappropriate components. With spreaders, as we'll see below, this can be a matter of too much or too little length or strength, and these will be a problem for any boat. But sometimes the problems are subtle, like aerodynamic efficiency, and many boats just wouldn't notice the difference between a really aerodynamic spreader, and one that is fairly clunky, or at least not notice it enough to justify the bother and expense of new gear.
So if you have a really tweezy racing boat that somehow ended up with barely-radiused 2x6 spreaders, that boat is going see major improvements once you reduce drag – and maybe even add a little lift – with refined spreaders. But beware, aerodynamics is a fussy subject, as correspondent Brent Trockman reminds us when he justifies replacement when,
"The airfoil section of the old spreaders is a Selig 7030, which produces laminar flow up to about 35 miles per hour, but then induces too much turbulence at higher speeds resulting in a tea kettle like whistle all night when anchored at Cojo and trying to get some rest before rounding Point Conception and break- testing spreaders."
If you have a heavy old cruiser, maybe it might be appropriate just to reshape the drag generators you have up there, assuming, of course, that there are no other problems, like wrong length, strength, etc.

Are they too big? That damn sailmaker shaped the jib incorrectly and now we cannot sheet in as tightly• shorten the spreaders.
Whether or not the sailmaker was up to snuff, there's no advantage to having overlong spreaders, and several disadvantages:

  • The longer unsupported length means that the material has to be stiffer –and thus heavier – to resist buckling. So a shorter spreader can be a smaller section, for less windage, weight, and drag.
  • A shorter spreader receives less load altogether, because the shroud(s) form a shallower angle to it, which makes for less compression.
  • A shorter spreader is less liable to snag other items. Or as our correspondent Brent Trockman put it,
    "The old spreaders are too wide and get caught and ripped off the mast with a horrible wrenching noise because my neighbor, with the 70 foot Palmer Johnson, who is part owner of the marina, has the professional crew dock in such a way that the flukes of a 200 pound Bruce anchor hang off into the fairway, perilously close the the port uppers of Andante when trying to make the turn into my slip. Slightly shorter spreaders would have saved the cost of polishing the right fluke of the good attorney's Bruce anchor, not to mention saving me the cost of my insurance deductible and the embarrassment of performing this docking maneuver in front the entire law firm, who are enjoying their Christmas party."

    Maybe they were too big right from the factory. It could be they used the same extrusion for a number of boat sizes and rig configurations.
    Sadly, this happens all the time, with less-than-wonderful sparbuilders crippling a rig by just using whatever's on the shelf. Usually, they err on the heavy side, or we'd have more catastrophic failures, but the boat is still being held back, for no good reason.

    1. The old spreaders broke twice or more
    2. I made the mast a little taller or shorter following a splice, (see number one)
    There's a fair amount of uninformed, "yeah, it'll probably hold" engineering out there. But really, someone else has already done all the hard work in working out formulas and moments and such; all you have to do is learn how to run those numbers, to get a known quantity.

    The sockets are of the fixed type, and no matter what I can't get the angle of the shrouds equal, or close to it, on the top and bottom due to poor design from the factory.
    Yes, another factory flaw. Spreaders that angle up properly are under pure compression, so are more resistant to buckling, so can be lighter for the same load, and/or have a higher factor of safety. Properly-angled spreaders are also disinclined to slipping down and eventually collapsing, something that leads to a high proportion of all rig failures.

    The original design is such that I am worried the old spreaders are not strong enough for the increased compression due to the larger size Dyform rigging I installed before reading the Riggers Apprentice.
    Did I say that? It's true that Dyform (or rod) will be stronger than other wires of other constructions, but this will not change the load on the spreaders, unless you put the wrong size shrouds on. For instance, if you replace properly-sized 1x19 with Dyform, you should be able to reduce the diameter of the Dyform, and still end up with the same strength. Regardless of what is passing over those spreader tips, find out what the load is, and then find the right spreaders.

    The old spreaders are held in place by clevis pins, and the holes in the spreader are egg shaped.
    Ah, yes, a common problem with older spreaders of this type, and the reason why you don't see this type so much any more. But it is sometimes possible to ream and bush the old holes, which simultaneously cures the egg shape and provides more surface area, to prevent future distortions.

    The old spreaders are too long and result in too wide of a sheeting angle.
    The old spreaders are too short and result in less than 12 degrees at the angle of intersection of the uppers and the masthead.     It is often possible to shorten spreaders that are too long, in which case it is usually necessary also to shorten the wires that pass over them. It is much harder to lengthen spreaders, and sometimes getting new, longer spreaders can be a bad idea. (i.e., if you got that 12ƒ, but had spreaders that were wider than the boat). In that case, it might be worth considering moving the attachment point of the spreaders, or adding additional sets of spreaders.

    And finally,
    Your old spreaders are too wide, inhibiting bird crap from making it all the way to the deck. Um. Maybe. But one neat trick is to seize a piece of string to the upper shroud on each side, a couple of inches above the spreader. Tension, then seize the other end to a little strapeye on the mast, also a couple of inches above the spreader. A yarn tell-tale or two will assure that birds will see this string, but they won't want to land on the spreader.

    End