Here at AAC we have long warned of the drawbacks of swept-back spreaders for cruising boats, the most notable being that the boom can’t be let out as far as it should be for correct trim on a broad reach or run, and that in turn makes:
- The boat hard to steer and generally squirrelly.
- The angle for a boom preventer is unfavourable so that the loads are higher and the slightest stretch will render it ineffective if caught aback.
Add the two together and the dangers while running off are significantly higher than on a straight-spreader boat.
But recently this trend has got a lot more extreme, as can be seen in the opening photo of a Beneteau Oceanis 37.1 where the mainsail is being stressed in crazy ways.
I would estimate that this problem will start if the boom is let out past about 30°…at best!
No, 30° is not an exaggeration. Here’s a shot taken on our J/109 of the boom vanged hard and let out as far as it can be without the main chafing on the spreaders, which is about 45° (the iPhone camera wide-angle distortion makes it look like less).
Hi John,
This looks to me like a “B&R” set-up enjoying the benefits of a fractional rig (jib & large roached mainsail), without the need for running backstays. Precisely engineered, these rigs can be manufactured to have a lighter section, especially up top and deck stepped for accommodation benefits.
Years ago we had a half-share in a Hunter that popularised the B&R rig on cruising yachts; several of the larger models circumnavigated. We had no issues coastal sailing as long as we reefed down early. It was rewarding to sail (especially upwind) vs the then typical large over-lapping masthead rigs or fractional rigs with runners.
I always thought the rig would benefit greatly from hi-modulus sails to replace the old baggy Dacron sails we had. And that the rig engineering was very exact, needing expert rigging – especially setting the pre-bend. Each rig component needs to be exactly tensioned.
And what struck me immediately when I saw the photo on the mooring was almost zero pre-bend – that seems wrong for a B&R set-up.
The top photo is plain ugly -> the mainsail not the photograph which captures things perfectly. I suspect with the correct pre-bend, the battens should form a nice S curve (bird’s eye view) with substantial wear patches to ameliorate the chafe issue at each batten and reef position.
Googling B&R rig provides a number of articles covering the pro’s and cons.
Hi Rob,
Sure I remember the B&R well, but then it died out…
I agree, the straight mast without pre-bend is a bit weird too, but I’m guessing that’s because the set up puts a lot of compression on the section.
Yes you could put on patches and that might work inshore day sailing but that won’t last long in any sort of wave train offshore, and added to that the bit I know about aerodynamics indicates that S curves are not that useful.
So, while I guess the issues could be ameliorated, I still just can’t see the benefit here (or of the B&R) other than the one I mention.
Hi Again Rob,
You also make a good point that this kind of rig takes expert tuning to be even half way safe, although, as I remember, the B&R was even more complex and the tune probably even more critical.
Anyway, the basic point for me is that cruising is a lot about reaching and running well and neither of these rigs do that well.
And up wind a standard two spreader fractional like on my j/109 would be, I’m fairly sure, way more flexible in different winds strengths, the great benefit of that rig, but to get said benefit we need a backstay to bend it and vary tension on the headstay: https://www.morganscloud.com/jhhtips/a-fractional-rig-is-like-a-gearbox/
And if we want a fat head to go up wind, then runners are the way to go since they bend the rig, and tension the headstay. The SunFast 33 (cool boat) is a fine example of this idea.
You are actually not supposed to sail these boats down down wind. I have sailed on similar boats, and we basically never went further down than 125 AWA. We would first gain some speed, and then indeed try to keep the AWA angle from getting to large. That mean indeed gibing downwind. But it was fast and comfortable.
Hi Krist,
I get that, and that’s exactly the way my J/109 works, but look at the comparison photos, at least as far as I can see, the Bennie’s mainsail would be on the spreaders at even 80 AWA, meaning no deeper that about 110 TWA, so it’s going to take a hell of a long time to get anywhere downwind like that, and this is supposed to be a cruising boat.
On the J/109 deepest wind angle with the A sail is about 150-160 TWA but to really get somewhere downwind that means setting the A-sail which cruisers won’t always want to do, particularly when the breeze is up—she is primarily a racing boat.
John, I think you’re right about the real reason for these.
Modern design trends call for two voluminous aft cabins, a wide low swim step, and often a dinghy garage. This is not, inherently, a stiff geometry. It’s floppy and bendy. It’s hard to brace it adequately to resist backstay loads.
Modern construction trends call for a moulded grid liner around the keel root and mast step. Much of the stiffness needed to resist rigging loads comes from this grid.
If you eliminate the backstay, you don’t have to build the entire aft half of the boat to resist a multi-ton upward bending force. You can make it wide open (good for living and selling) and lightly built (good for cost and performance). The loads are, instead, carried through shrouds and chain plates that bring those forces right back to the central structural grid liner. That simplifies manufacturing, further reducing cost. The engineering isn’t terribly difficult.
Look at the interior of a race boat. See how much visible structure is oriented directly along the load paths between mast step, keel root, headstay, backstay, and shrouds. Recreational boat buyers usually want all that structure to be hidden, or missing entirely. This type of rig is one way of achieving that. And it’s perfectly fine upwind; remember, boats that cruise or race from one port and are out for a few hours or days at a time spend 2/3 to 3/4 of each trip close-hauled or reaching. The fact that it’s problematic as a downwind rig for cruising? That doesn’t really factor into the design decision.
Hi Matt,
That makes sense and is very much in line with my thinking.
I guess I could see a case if it were not quite so radical (more like my 109), but as it is, as far as I’m concerned, this rig is simply not fit for task when we balance everything out, even for coastal cruising. I hear you on the percentage reaching and going to windward in theory, but in practice these days most coastal cruisers tend to motor a lot, so that skews the numbers back against the rig. And I’m pretty sure that the max apparent wind angle for proper trim will be 90 degrees or less, which means ~120 degree true, maybe less, so a lot of desirable wind angles are out. And then there is the ease in a puff problem which makes it even worse.
To me, this is a case, like the saildrive, where most all the advantages accrue to the builder and most all the disadvantages to the owner.
These swept back spreader rigs are another trend in dumbing down the boats. It’s a feature not meant to improve performance, it’s as you say to simplify and cheapen the build; also to make the boat feel less imposing at the boat show for the lady. If there’s no big wire at the back of the bus (the backstay), then the fat-ass stern seems more commodius while sitting at the show.
These boats are not meant to sail. Maybe I’m an old curmudgeon, but if the boat can’t safely perform when the going gets rough, it ain’t worth anything. Not being able to ease the main is DANGEROUS.
Im a member of the same club . I agree with your conclusions . These boats are targeted to the weekend warrior . Hmmm that’s seems to be 90% of the boaters out there .
Hi John,
I’m pretty much a weekend warrior myself these days, and even so I still don’t see any utility with this rig.
Hi Robert,
I would find it tough to argue with anything you wrote, particularly the last sentence, although I probably would not lay so much on the shoulders of women.
Hi John and all,
I have been working on some thoughts whose basic premise is that “labor savings” gear and those entities aimed at “comfort” often (always??) have a demand on the skipper/crew for greater vigilance and attention for problems to be averted: in other words, decreased labor is offset by greater mental effort (and a moments in-attention can be disastrous). The powered winch is paradigmatic in this regard: casual in-attentive use or use by the in-experienced crew can easily lead to injury.
It sounds like the flogging of the benefits of swept-back spreaders for the B&R rig that I remember from back-when may be in the same ball-park: the selling of gear where the benefit is not with the owner and where the down-sides are down-played or not addressed at all.
My best, Dick Stevenson, s/v Alchemy
Yes it is a bit harsh on the fairer sex, but reasonably accurate nonetheless, whilst not really their fault. Very typically it is the bloke who wants to sail and the wife needs ‘encouraging’ shall we say 😎. The problem is more that we are lying to women, or if not women specifically, then to less experienced sailors by leading them to think there are not consequences for their choices, which if also explained, would perhaps lead them to make better choices.
Very few novice sailors (male or female) really like tacking downwind any more than they like it upwind, although they do generally come to accept the latter and if the necessity of tacking downwind were explained I’m sure they’d make different (better) choices. Same thing with the higher risks of unintentional gybes. Or the consequences of the absence of effective hip holds on cavernous interiors. etc etc etc.
As permanent liveaboard cruiser’s we share anchorages constantly with people in modern boats who are now often feeling seriously fragile about their cruising dream. They have been seriously frightened in 25-30 knots of wind that was extremely unpleasant in their (not fit for purpose) boat. None of the flash electric gizmos work reliably and they’re spending a fortune on repairs and marinas.
I sometimes feel like a counsellor, gently talking these people down and rebuilding their dream. I was delighted several months ago when a couple we’d had such a conversation with over LOTS of drinks the night before rowed across the next day (their electric outboard wasn’t working) and asked if they could look at our boat and what had led to us buying it rather than one like theirs. I’ve now had several such conversations and just this week, out of the blue, that first couple rang to say they’d sold their 1 year old $500k+ 40 footer and made an offer of less than half on a 25 year old Hylas 47 and were having the electrics and plumbing completely redone, the very simple Perkins motor rebuilt, new electronics and thru-hulls, new steering, rigging and sails, leaving them with over $100k left over in their pockets for freedom chips. They told me their cruising dream was now back intact and they hoped to join us in the South Pacific next year on their fit for purpose boat. I thought, what a lovely story. Never in a million years would I have thought they’d have done that.
Hi Paul,
That is indeed a loverly story and the Hylas 47 is, I think, the Stevens 47 under a different name, if so, it’s a great choice. One thing you might suggest, if you talk with them again and it’s not too late, is to replace not rebuild the engine. Small engine rebuilds, while theoretically doable have a very bad record in actuality to the point that over 50% of the ones I have tracked (a bunch) have ended with a new engine in a year or so, on top of the rebuild. It would be so sad if an unreliable engine derailed their dreams again.
The other thing is that I’m still uncomfortable with the implied assumption that women are more fearful or don’t want to go sailing. I have learned from Phyllis over the years how upsetting and demeaning these kinds of generalizations can be. I, and I suspect you, would not dream (I hope) of saying or even implying for example “all men are…” but somehow it seems to be OK to imply “all women are…”. It’s not.
I also think that much of the reason that it may appear that way is that women are more willing to express their doubts and ask difficult questions than we men who are constrained by the fear of being seen as a wimp by our fellow men. Bottom line women often don’t fake it the way we do when they are uncomfortable and we can learn from that. Authenticity is a good thing to be admired, not the opposite.
And then of course there are the many women who are fantastic, and indomitable, offshore sailors, who we should never forget.
Thanks John. Great point about the engine rebuild. They were prepared to rebuild or replace but it turns out it has the same Perkins motor we have (4-236) with 3,500 hours and their mechanic looked at it and said all it needed were the injectors serviced and new gaskets and o-rings in the injector pump, lift pump diaphragm, heat exchanger serviced and new belts and hoses. We know of these motors still going strong with upwards of 15,000 hours in boats. Good luck getting that out of a modern marine diesel!
Also totally agree about the mischaracterisation of women. It’s not women per se, but less experienced sailors who are being misled by the marine industry into making poor choices.
Hi Paul,
I too am a fan of the Perkins engines and that sounds like a good course of action and pretty much exactly what I had done to the Yanmar in our J/109 when we bought her.
Hi John,
Regarding spreader angle to the horizontal, if the rigging is discontinuous, then the designer gets much more flexibility as a triangle with fixed lengths is fully defined and also has fixed angles. We have a new mooring neighbor this year with a Beneteau similar to the one that you pictured and it has discontinuous rigging but I don’t know if it is discontinuous at the top spreader. I don’t like discontinuous rigging for a cruising boat but it does solve the spreader angle issue.
I was thinking about this tip yesterday as we sailed up a narrow channel with one of these boats. Since the visibility was poor and I wanted to focus on navigation, we lazily sailed up the side of the channel mostly wing and wing. Had there been much more breeze, we would have dropped the jib. The boat with significant spreader sweep was tacking downwind and had to jibe 15+ times. They also presented a very tricky target to plot and unless they had ARPA, they could not track any other targets themselves as an EBL requires constant heading and speed. Our VMG was much better and we were able to pass them easily due to a bit of plotting on our end. In this case, I believe that their options to safely sail that channel were to put the main on the spreaders and sail deep (would the helm have been acceptable? would a crash jibe be acceptable? how about wear and tear?), take down the main and sail jib only, or just motor with the sails down. This is definitely not representative of the majority of sailing but it still made me laugh as I had just read your tip.
There is 1 benefit of this that I haven’t seen mentioned here and that is that you can run a slightly bigger jib that sheets inside the shrouds. However, I would much prefer a rig like that on most J boats than this.
Eric
Hi Eric,
Thanks for the good point on spreader angle. I had to think about it a bit, but after a while I got it that the compression on the spreader will be on-axes even though it’s not bisecting the angle the shroud makes at the spreader end, and that the real issue with spreaders that don’t bisect is the danger of them slipping on the shroud. Do I have that right? If so, it’s a bit of a revelation for me since I had always assumed, without really thinking about it, that not having dihedral resulted in off axes loads on the spreaders, and I have also heard that said many times.
Anyway, your story about the boat sailing up the channel really highlights the drawback in the real world.
And good point that swept back spreaders allow a bigger jib at tighter sheeting angles, which illustrates that pretty much anything, no matter how strange looking, can have a benefit if we look hard enough, but conversely it’s the package of benefits against the package of drawbacks that must be evaluated and by that measure I think we can rate radically swept back spreaders as a giant fail.
The load on the spreader is purely axial compression. They aren’t supposed to take any significant bending load, and the way they’re pinned at the mast prevents them from supporting any significant bending load.
If your shroud is continuous over the spreader tip and is not fixed to the spreader tip, then you need the spreader to bisect the angle made by the shroud. Otherwise, the spreader will slip.
This is not a concern if the shroud is securely clamped to the spreader tip, or is made in two separate pieces that both terminate at the tip. It is very common in industrial rigging, utility poles, etc. to have a spreader that makes a 90° angle to the shroud below and a 45° angle to the shroud above. It works just fine.
Boatbuilders usually prefer continuous shrouds – they’re cheaper and easier.
Whether the spreaders are horizontal or dihedral, and whether the shrouds are continuous or are affixed at the spreader tip, has little or nothing to do with whether the spreaders are swept back.
Swept-back spreaders without a fixed backstay are used either to simplify and cheapen the rigging and the aft structure of the hull, or to allow a high-roach mainsail for better performance. Taken to an extreme, they are definitely problematic downwind. They are generally not so problematic upwind, and may have a few advantages in a boat that spends much of its time close-hauled (more mainsail roach; tendency of headstay tension to increase with heeling moment). Personally, I don’t think those marginal advantages outweigh the significant downsides of a no-backstay, radically-swept-spreader rig.
The arguments haven’t really changed since AAC’s 2011 analysis of them ( https://www.morganscloud.com/2011/09/02/parallel-swept-back-spreaders/ ).
Hi Matt,
Thanks for the fill on that. I have got to the point where I really appreciate and even enjoy when ideas I, and many others took to be fact without really ever thinking about it, get corrected and cleaned up—it’s always good to learn new things. It was also a really good exercise to figure out the why of it after Eric’s comment, and even better to have you confirm the new thinking.
Downside is I have to go fix one of my tuning articles!
Matt has it covered. The only thing that I will add is that the end conditions matter a lot in beams. If you are worried about buckling, you have much more buckling resistance is the beam is fixed to the structure it attaches to rather than on a pin joint. However, this requires that you get the alignment right. If someone mis-adjusts the rig with discontinuous rigging and you have a fixed constraint, you can suddenly put a lot of bending into that beam (spreader) and that can really exacerbate buckling. For a top end race team, they might be able to handle the fixed constraint. For a cruising boat that will have many sets of standing rigging over its lifetime, it is much safer if there is a pin/hinge so that you don’t accidentally misalign things.
Eric
Hi Eric,
That’s a really good point about the importance of getting discontinues rigging exactly right when the spreader roots are fixed, which it increasingly the case these days as more and more mast builders go over to solid spreader bars. Hall Spars got our’s dead nuts when they built us a new rig for the McCurdy and Rhodes, but I had a knock down drag out fight with the rigging company that made the rod for our J/109 (the first time) over just that point because the elbows (used to retain the spreaders on continues rod rigging) were not quite right on the caps, that and half the cold heads were misshapen…and half the terminals not locked properly—we have to watch every detail.
Wow, what a trend! The comments are just as interesting as the article. I can’t begin to imagine sailing with that constraint. For sure that a mix of saving money for the builder and the demands of the consumers for roomier layouts are leading to this.
Well, well, I’ll go sip my tea in the cockpit looking at all the spreaders of the monohulls, maybe even use the binoculars to that end.
Thanks for keeping me curious!!
And, maybe I’m being a bit of a romantic ( which if been called ), they don’t look good, like sailboats should.
Ralph
Hi Ralph,
I feel that way too, but kept it out of the Tip so as to be more objective. That said, I think some modern designs can be loverly to look at, the new Dragonfly 40 trimaran comes to mind, but this one just does not work aesthetically for me either.
It’s yet another incredibly dumb design feature being foisted on unsuspecting buyers by designers who have never been cruising and spend way too much time schmoozing the bean counters of boat builders and sailmakers. Anyone buying one of these is going to have to buy a new main every year.
The main sail flow profile is trashed. I can’t imagine the shape being efficient, especially in combination with any forward sail.
Hi John,
Thanks for the always interesting commentary. I need to respond to the discussion about heavily-swept spreaders to point out that while they have significant downsides for offshore cruising, (which I recognize is the primary thrust of your site), for the great majority of sailors this solution is well worth considering.
When sailing upwind or close-reaching, a square-head mainsail is dramatically better-performing than a pintop mainsail. The lift/drag profile is greatly improved: read– lift is driving force, drag is heeling force, so more push forward, less push sideways. We have quantified this in our design work– the reduced heeling force for the same driving force amounts to something like 7-8 percent– so you can reduce designed sail area and still sail fast, or alternatively, you can keep the sail area and sail faster for the same heel. In addition, there’s extra sail area up high, where there’s more wind; the large head provides leverage to automatically de-power the mainsail when a puff hits; and for a given sail area, the mast can be shorter, with all those attendant benefits.
While ocean cruisers go to lengths not to sail upwind, many other sailors are constrained by terrain, schedules, and family conditions to cruise coastally, where performance in all directions is an important element. For sailors who have these constraints, and who want to sail light, fun, fast boats, a rig with shrouds heavily-swept and located at the rail, with no running backstays (or runners that can be deployed only when things are “sporty” as you say), and with a large jib sheeted forward and inboard of the shrouds and a powerful square-top mainsail can be a great solution.
Best-suited for this rig are boats whose displacement/length ratios are low enough to sail fast downwind, pulling apparent wind forward– boats that are enough faster sailing hotter angles than squaring off and sailing dead down wing-and-wing. For folks who are not going to spend days running, sailing hotter angles and periodically jibing is a safer solution as well, as an accidental jibe is much less likely than when wing-and-wing, and if legs are too short to warrant setting up a preventer, avoiding accidental jibes is very important. But, if necessary, a boat rigged like this can certainly sail nearly dead downwind– just keep the mainsail trimmed to limit pressure on the spreaders, and accept the slightly lower boat speed. wing-and-wing is possible, too– in fact the trimmed-in main directs breeze to the jib more effectively than a squared-off pintop main.I’ve done it on my own boat, I know it works.
For long-distance offshore sailing I would always recommend for my clients a more conventional rig for all the good reasons you have described over the years– sturdiness, ease of running, redundancy, ease of shortening sail. But for many other sailing missions, the square-top without the need for runners can be a fun, fast and safe way to sail. I’d say try it before you knock it–you might be amazed at how much nicer your J-109 might perform with a similar rig.
Hi Robert,
I agree with all of that, in fact I stipulate it in my tip (fat head main etc). That said it’s good to have some of that quantified, thank you.
My problem with this is one of degree. As I say in the tip, swept back spreaders can work, but my thinking is that when swept back so far that the main can’t be trimmed properly past a close reach, the trend has gone too far. We see this over and over in boat design, a good idea gets pushed and pushed until it becomes a bad idea.
Sure you can sail further down wind while overtimed but I’m sure you will agree that doing so is undesirable since an over trimmed main is inefficient and has a negative effect on helm balance. The first thing any new sailor learns on a reach close or broad is “when in doubt, let it out”. And then what about a hard puff? Easing the main and/or vang is how we avoid a wipe out.
Also, the other thing is that the loss of the back stay means that the biggest benefit of a fractional rig is also lost: the ability to bend the mast at will, and also tighten the headstay as the breeze comes up.
So sure, fat head mains are great, and fractional rigs are great, but my thinking is that little or nothing was gained in this implementation, except cost savings for the builder, and a lot lost for the sailor.
I think my concern is supported well because, at least as far as I know, there are no racing boats rigged this way and I would be pretty sure that if it were fast and functional it would be used by racers. Rather, boats like say the SunFast 33 use moderate swept back spreaders and runners to the top of the rig so they can bend the mast and tighten the head stay.
So would my 109 be faster up wind with a fat head main? Undoubtably, but it would not look like this boat, but rather like a SunFast 33. And the drawback would be runners to tend.
Hi Robert,
I took a look at your Signature 24 and I think you and I are closer in our thinking than it might first appear given that as far as I can see the aft sweep back angle on your boat is considerably less than on the Beneteau, so, as I say in my first answer, this is a difference in degree issue. My guess is that Beneteau went as far as they did because that would result in lower loads on the shroud chain plates, which, in turn, would require less expensive structure. Also the usage case for the two boats are very different.
So that leaves the trade off of losing the adjustment capabilities of a permanent back stay in exchange for a fat head mainsail, assuming one is not willing to go with mast head runners like the SunFast, which is the best of both worlds, but clearly wrong for your Signature 24 and for my single handed usage in confined waters on Mahone Bay.
That said, I’m guessing that you could, and maybe do, have the ability to bend the mast on the Signature with a combo of mainsheet and vang tension, as we used to in the 505 class, although that does require adjustable mast blocking (often a magic box on a 505) to get the max benefit.
As a point of reference, many offshore performance multihulls have rotating masts so that when sailing deeper angles downwind, the leeward spreader(s) if so equipped rotate away from the mainsail thus the issue of the spreader making contact with the mainsail is avoided. However you could have the leeward mast shroud contacting the back of the mainsail. While not a point loading issue it can lead to chafe primarily on full length batten pockets.
With the exception of the Dragonfly 25, Dragonfly trimarans have non-rotating masts. The masts have a system of diamond and jumper stays that provide structural support and pre-bend for the mast. The system has a moderate setback similar to the J/109. The mast stays up via the forestay and two adjustable shrouds that are attached further back on the floats (when the boat is unfolded and sailing) such that they function kind of in a hybrid fashion as a combination shroud/backstay. The adjustment on each shroud is via a 4:1 purchase (one for each shroud). You do not adjust the shrouds with this purchase system while sailing. You set up the proper tension on each shroud after the boat is fully unfolded. The only time I will consider changing the tension is when deep broad reaching down to around 140-160 TWA. I’ll ease off the leeward shroud to minimize the contact of the shroud against the back of the mainsail (but I have to remember to put it back on before jibing). Note that if the purchase system failed in any way or was inadvertently released, the shroud will still function and keep the rig standing. It will just be very eased leading the rig sagging to leeward. It would be very apparent!
I agree with all here that the more severely swept rigs referenced here are a bad trend and I believe many less experienced sailors buying these boats are not aware of the issue until after they purchase the boats. It must be a conspiracy between the builders (more room, more stuff, more sellable) and the sailmakers (frequent mainsail repairs and/or replacements)!
Hi Bob,
Thanks for the fill on that. It’s also worth noting for others that the Dragonfly cats are a good deal faster on a reach that the boat in question, so the apparent wind is further forward for a given true wind angle thereby further reducing the problem.