The Offshore Voyaging Reference Site

Parallel Or Swept-Back Spreaders?

The boat we chartered had one rig design feature that has become almost ubiquitous these days—swept back spreaders. Heavily swept spreaders in fact, with massive cap shrouds to keep the central panel of the rig from pumping, as there were no forward lowers or even a babystay to do that job. The backstays were far smaller diameter, and in effect, simply controIled the top of the rig. And this was on masthead rigged boat—in fact, it was almost a Begstrom rig, where there are no backstays at all (and it won’t be long before…).

Swept spreaders have been around for years, but they really only took off on this side of the Atlantic in the late seventies when they started appearing on cruiser-racers (like Sigma’s, for example) where they enabled a simple fractional rig to be used without recourse to running backstays and multiple spreaders. It was only after a while that many owners found that they were still better off with runners, but that’s by the by.

But What About For Cruising?

Now what’s OK for charging around the cans is one thing; few fractional boats run in races, preferring to gybe downwind whenever possible, and their sails don’t tend to last long enough for chafe to be a big issue. But we who tend to be short handed and stick to white sails (except in light airs) will happily run before favourable winds, wing and wing. And to do that in safety, you need to be able to square the main away as much as possible, to avoid an accidental gybe—I know a preventer is essential, but first you have to get the main as much as is practically possible at right angles to the centreline of the boat with the wind dead over the stern. Otherwise, you’ve got to sort out some form of twin jib arrangement, and dispense with the main—at more cost and complexity.

But it seemed to me that with the rig we had chafe would be a problem over anything but short distances. I know you can pad the spreaders, put reinforcing patches on the main, strap the vang down tight to stop the boom from rising and falling constantly, but for a long downwind passage in the trade winds (say), chafe must take its toll. We found that the main was already on the spreaders when the wind over the stern was at 150º, limiting us to broad reaching, realistically.

And that makes reefing downwind a real pain, too. The boat we sailed had a nicely made fully battened main, and the normal routine of trimming the main in a little before reefing to get the sail off the spreaders simply wasn’t enough, because as soon as the halyard was eased the main sagged onto the spreaders again, and the battens caught. I’m sure that with practice improvements could be made, but I doubt they could assist short handed cruising crews, where one person tends to put in a reef on their own. Maybe they’re most suited to be used with roller furling mainsails, themselves a subject for much debate.

So Why Are They Becoming The Norm?

Some say they can make for closer sheeting angles for headsails, but there are other ways of achieving that such as sheeting inside shrouds. OK, without forward lowers or a babystay there’s less windage and weight aloft. And in some cases it may be possible to use a smaller section mast, I’ve heard it claimed.

But the over-riding factor seems to me to be cost. It must be far less expensive for a yard to install one oversized set of chainplates taking all of the rigging loads into a suitably reinforced matrix in the hull than the traditional way of installing several chainplates, plus their attachments below deck, reinforcing the hull over a larger area and then concealing them with joinery. The latter is far more  labour intensive, and labour costs money—lots of it. And as you can also do away with the cost of the lowers, mast attachments, bottlescrews and the like, it may be understandable why that would be an attractive option for builders, especially in the current climate. Boatbuilidng has always been a financially precarious business, and cost cutting exercises that don’t on the face of it harm the ‘product’ (i.e. the rig still stays up), but help the bottom line, must be hard to ignore.

Some of the earlier boats that have one big ‘cluster’ chainplate are now a good few years old, and there have been reports of failures of these units, usually on GRP boats where the stainless chainplate has suffered from unseen crevice corrosion below deck level. These units are, in effect, massive single points of failure, and should (at least) be checked regularly for any signs of corrosion—although that’s often easier said than done as they tend to be built in, and hard to get at. Because if the chainplate fails, there’s little or no chance that you can save the rig, unlike a traditional fore and aft lower set up, where one stay failing might not be catastrophic.

But Are They What We Need?

The move away from traditional cruising rigs with their multi-point support at the lower level has been going on for some time now, although there are still yards building dedicated cruising boats that will not compromise on what has been battle-tested. There may be adherents for swept spreaders, and in some circumstances (such as racing), maybe they make sense. And on a boat designed for charter where keeping build cost down is critical, and durability and ease of handling might be considered less important, then the wholesale change towards them is understandable. But as to whether they belong on a dedicated cruising boat, I’d have my doubts. And if, as I suspect, the move towards them in the area of cruising boat design is largely a cost saving exercise, then surely it could be argued that it’s a classic case of ‘spoiling the ship for a ha’porth of tar’. But I could be wrong, so if anyone can come up with any reason why swept back spreaders offer a real benefit for an offshore cruising boat—I’d love to hear of it.

Further Reading

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Matt Marsh

For offshore cruising? Nope, Colin, I’m hard-pressed to think of a good reason to choose the swept spreader, no backstay option there. The arguments you raise are all valid ones.

I can see the appeal of such a rig for a club racer or day-sail boat. The builder’s cost is one factor; having fewer strings to tweak could be another. (Although, considering the number of lines coming off modern masts, that’s probably just a minor concern.) And it looks “racy”, which counts for an awful lot these days; that’s probably the main reason, considering that these things are still pretty pricey compared to more traditional, less fancy workboat rigs that perform just as well.

I have to ask, though: Since we’re talking about cruising boats, why are we still locked into old racing rules that require the mast to be fixed in all six degrees of freedom? A properly engineered rotating mast is no more vulnerable than a properly engineered conventional one, and it could allow the mainsail to be set at any angle with no chafing. This is even more true of cruising multihulls, with their wide staying base. I’m not saying it’s the right solution for everyone (it’s not). But we do need to stop thinking like racers and not base cruising designs on arbitrary racing rules.

Colin Speedie

Hi Matt

I’ve only sailed on one boat (a cat) with a rotating mast, and granted it was a fast ex ocean racer, it was surprisingly easy to work with. I’d imagine that the lack of adoption of such rigs is partly cost, and partly complexity.

It would be interesting to hear from any designer with experience of such rigs to hear what they think.

Best wishes

Colin

David Nutt

Given that Danza was designed in the late sixties by Robert Clark (she is a sister ship to Chay Blythe’s ‘British Steel’) she has the runners and the good old fashioned staying systems. We still have the chafe issue of the main on the spreaders and have addressed it by laminating nylon webbing onto the sail at critical points. We also have a pvc hose split and attached to the aft side of the spreaders. These two measures have paid off in spades by minimizing chafe.

Colin Speedie

Hi David

Robert Clark was one of the titans of design of his era – I sailed one of his 72ft designs for several years, and she was a phenomenal boat, balanced and very powerful.

We have webbing strapping running along each of the full battens, and it takes all of the punishment, but we haven’t tried the PVC tubing idea yet – sounds good though, and as we prepare for the Atlantic we’ll give it a try.

Best wishes

Colin

Jean-François Eeman

Dear Colin,

You are not wrong ! For a (blue water) cruising boat made to last, there are, according to me, no valuable reasons to have swept back spreaders. Stories saying it enables you to have additional trimming possibilities does not make any sense on the kind of boats we are talking about. (Again according to me, the same thing is true for 7/8 or 9/10 rigging on our kind of boats.)

And Yes, it is all about the cost… We have calculated the difference and the amount is quite amazing… Offering it as an option would be a solution for the clients. But I’m afraid most yards will not want to complicate their production process with such an option…

I’m like you: I would like to be convinced there is a benefit to swept back spreaders. Maybe somebody will come up…

Jean-François

Colin Speedie

Hi Jean-Francois

I’m with you in that I like a simple, well stayed masthead rig, and I’d sacrifice 10% of additional performance for a dependable stay-up rig. There may be advantages in fractional rigs performance wise, but I’ve found that they demand more trimming to get the best out of them, which is fine if you’re prepared to do that – but I’m not for cruising.

And it’s intriguing that you’ve looked at the potential cost saving by opting for a swept spreader rig – and your conclusions confirm what I have always suspected…

Best wishes

Colin

Victor Raymond

Steve Dashew chose swept spreaders on his high performance cruising yachts both alloy and fiberglass. I think the reason was less or no reliance on the back stays. Of course most of his boats were of ketch rigging so that may be part of his reasoning. High performance may be another.
Personally I would prefer no stays or spreaders at all but that is another rig altogether ala Eric Sponberg.

Colin Speedie

Hi Victor

I’ve always liked the idea of unstayed masts, having sailed a Laser in my youth, and loved the way that the mast would bend and spill the gusts.

And I’d suspect that it was as much ‘traditionalist’ thinking that undermined the original Freedom range of yachts, with their unstayed wishbone rigs. They had their faults – the early ones with the sleeved sails were pigs to reef – but as they developed and adopted fully battened sails those failings diminished.

I thought they made good cruising boats – others may disagree!

Best wishes

Colin

Matt Marsh

If unstayed masts are going to come into the picture, we surely must mention the Nonsuch with its single free-standing catboat/wishbone setup. There are something like 975 of them out there. Almost everyone who’s sailed on one loves it and finds them very easy to handle.