Here at AAC we have long warned of the drawbacks of swept backed spreaders for cruising boats, the most notable being 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 squirraly.
- The angle for a boom preventer 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 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.