Last weekend we took a lovely 3 day cruise: out of Salem Sound, around Cape Ann, into Plum Island Sound, out to the Isles of Shoals, and back home through the Annisquam Canal.
The boat handled beautifully with the exception of our downwind leg heading north around Cape Ann. The southerly wind at 15-20kts stirred up 3ft following seas at maybe a 4s period, and Spray rolled in a way that was uncomfortable for the crew (and a little unnerving for the captain). I’ve successfully limited downwind roll on much larger following waves (5ft at 12s period) by countersteering, but if this is possible
My intuitions about downwind stability from sailing Lasers as a kid, with guesses about how they should or shouldn’t apply to a Nonsuch, are:
A big roll can carry enough momentum to turtle the Laser [does not apply to Nonsuch because of the keel]
If the clew of the sail dips into the water, the resistance can abruptly decelerate and turn the boat. [Does not apply (as much?) because of the greater relative weight of the hull]
roll-induced steering can cause a dangerous gybe [does apply]
I would be grateful if folks could weigh in with their intuitions about downwind stability on the Nonsuch, things to avoid, and strategies for managing or mitigating roll. Thanks, and looking forward to the discussion!
I ran into a similar issue with my Nonsuch 36 on the North Sea. Conditions were a bit different from what you describe — less than 10kts of breeze but an old swell of 1–1.5m running. With just enough wind to keep moving, the boat was rolling heavily, the rig taking a beating, mast swaying uncomfortably. For a while I considered what many other sailboats around me were already doing: dropping sail and motoring.
Instead, I tried something else: I sheeted the sail in to about 40–45 degrees.
What happened surprised me:
When the boat rolled on the swell, the motion was noticeably damped by the mainsail.
Because the sail was no longer fully aligned with the rolling motion, but more “crosswise” to it, it acted like a stabilizer.
The mast stopped its violent swaying, because it was actually being put to work rather than left free to whip.
And the boat even picked up speed, since some of the rolling energy was effectively converted into drive.
Result: far less rolling, steadier rig, better motion, and more speed.
Of course, this may not work in every situation or on every point of sail — but it’s a trick that worked well for me that day, and might be worth experimenting with before reaching for the ignition key.
I have a 26 and it tends to roll more than the 30. In 17-20 knots of breeze putting a reef in helps reduce the roll. I also agree with Mark that sheeting in also helps. I do not sheet in as far as 45 degrees because of concerns of an accidental gybe. Bringing the boom in helps dampen roll but also shortens/narrows the beam so the boom is less likely to take a dip during a roll.
@mark_h and @RMP – thank you both for your suggestions. I had a chance to experiment under similar conditions last weekend. In 20-25kts we double reefed the main and sheeted in to about 60º. This reduced the rolling (and narrowed the beam as @RMP points out) to the point where we felt comfortable – although it was still important for the helmsman to steer properly through each wave.
Through experimenting I found that the roll was least when we took the waves almost square on the stern, which surprised me.