The Offshore Voyaging Reference Site

Q&A Hydraulic In-Boom Roller Furling in Antartica


Very experienced member Matthieu Chauvel asked:

Does anyone have experience with hydraulic in-boom furling systems in below-freezing conditions (and/or proper heavy seas, 50 kts+)? Asking for owners of a yacht heading down to Antarctica that has what they (and the builder of course) say is quite a beefy, reliable custom system, but it hasn’t been tested in polar conditions yet.

Even night temperatures should remain well above the hydraulic fluid freezing point (call it -20 C with a little error margin) during the summer season, but maybe viscosity becomes a problem above that level? General ice build-up solutions and difficulty of sending crew forward while getting hosed down, at night, in towering waves already mentioned to them, but it would be nice to hear from people who have managed in that environment without problems, if any. 


Sorry, I don’t have much useful experience with hydraulic in-boom in extreme conditions. I was in the Arctic with one of those systems, but it did not get that cold.

The one thought I do have is that fisherfolk out of Atlantic Canada regularly work the waters of Hudson Strait in early winter, and so do Norwegian fisherfolk up as far as Svalbard, with hydraulics so it must be a solvable problem.

But, more importantly, if I were taking a boat into the high latitudes I would not have a complex system like that, particularly since the builder admits it has not been tested in those conditions.

I’m assuming this is a big boat, but even so I would go with slab reefing and then if worried about sending someone forward to the mast, bring the lines aft, although that would not be my choice. Instead, I would do good mast pulpits and a proper centreline jackline system.

I might also consider a Park Avenue boom, but that could also catch snow and ice, so maybe not.

If worried about loads on the reefing lines because of the boat size, I would install cross connected winches with coffee grinder pedestals. Two people can easily move a lot of line with a setup like that.

One could also add a hydraulic drive to the winches, but that adds risk and I would want to know the boat could be operated safely if the hydraulics failed.

Skip Novak has managed big boats fine in extreme conditions this way for decades and Phyllis and I had no trouble with slab on a 56-foot boat, including reefing and striking in 50-knot winds on one memorable occasion.

I would also say to your friend, if the boat is too big to handle with these simple systems, then add crew, probably professional.

We only have to look at what happened on Escape to see the dangers of a boat that is too big for the crew, and has complex systems, and that was not in the Drake Passage where conditions are likely to be far worse.

And I can’t tell you how scared I was of the automated rig on a big boat I went to Greenland on. If we had encountered 50 knots and big seas things would have almost certainly ended badly.

I do differ from Skip in one regard. I would add a storm trysail on its own track with its own halyard, so when expecting extreme conditions the main would come down and the trysail set. This, together with a storm jib set on an inner stay, is a rig that can take us to hell and back in safety.

If your friend decides to stick with in-boom, then I would strongly recommend this change. In fact, they could just motorsail to and from Antartica with this rig up, and be safe.

Matt, given your experience, I’m guessing I’m preaching to the choir, and I get that your friend won’t want to make all, or maybe any, of my recommended changes for one voyage, but maybe that just means he or she has the wrong boat for going to Antartica.

Anyway, thinking and writing about this was interesting.

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Arne Mogstad

I am not experienced enough to comment too much on this, but I sail in Northern Norway in winter, and when I bought my boat, my two last options, was one with in-boom, and the other slab reef (the one I bought). So just a couple comments:

The hydraulics should not be a big issue, but since it is not really designed for (extreme?) cold climate, I would probably replace the hydraulic fluid to keep the temperature tolerance as good as possible, preferably with a fluid designed for the expected temperatures.

Another point, though probably not so relevant, is that a lot of people here have in-mast furling, but I have not seen a single boat with in-boom furling. And indeed one of the main reasons I did not want it on my boat, is the fact that any snow and water will collect down on the roll and into the boom. Imagine going from mild to freezing temperatures, with water or sleet running down the sail and then freezing in the rolling mechanism. I would be extremely diligent about covering up the boom when the sail is down, having proper drainage holes for any water and wet snow to drain out, and places to inspect and preferably be able to reach and clear any buildup of snow and ice.

I have had problems with a furling headsail (the drum was iced down due to freezing seaspray), and I can vividly imagine a lot of ways a furling main, especially in-boom, can get in trouble due to freezing conditions. Especially repeated changes in temperatures going above-below freezing.

That said, the high latitudes are getting warmer and warmer, so the cold may not be a problem. Last year a friend of mine that work in Antarctica could spend most of the time in t-shirts…

Matthieu Chauvel

Hi Arne, thanks v much for this. Absolutely, switching to special low-temp hydraulic fluid, heating solutions for said fluid (screwplug and blanket types), as well as spares for all key rubber components (seals, hoses etc don’t like cold and are probably a weaker link than the fluid viscosity itself) mentioned to them. But you’re right, the obvious main concern is the boom and all it contains turning into a perfect ice collecting hammock! Daytime temps will be fine definitely, but that could be problematic too because nighttime temps (despite nights being v short) still drop below freezing, so bits of snow/sleet, sea spray and liquidish fog solidify then. Mind you, taking the sail down is the potential worry, not being able to raise it for a couple hours is generally no big deal (assuming the engine works when you have to get moving quickly at night because bergs are bearing down on you — which will be a problem on a bigger boat with deeper draft, since you can’t anchor in very shallow depths where the bigger bits can’t drift, and this having to get away fast happens often), still…entirely agree!

Arne Mogstad

Absolutely, taking it down is the big scary issue. The amount that drifting snow can pack up can be hard to understand before it is experienced. In this regard, I am thinking a boom interior that is packed with drifting snow, ice, etc, and when trying to roll it up, there is simply not room inside the boom. Hence mentioning large openings to be able to clear out any buildup.

Again, I have no experience with this gear, only being outdoor in arctic conditions, and a little bit of sailing. If this is realistic problems, I don’t know. But I was surprised by how difficult the winter could make it for my boat, and she is very simple.

And as you say, daytime temps can be fine, but that is what I would be the most scared of. Frozen sea is rather soft and relatively easy to get rid of, while fresh water (snow and rain) that freeze up again can be like hardened epoxy.

Hope it all goes well! Kindly, Arne 🙂

Neil McCubbin

I can only agree with John.
The crews of boats we have met with in-boom furling systems all talk about procedures they had to develop to make the system work. Some would be VERY difficult to follow in seriously bad weather.
I can slab beef our 550 sq ft mainsail myself, with only manual winches.
One key is to have a positive attachment for the luff cringle, rather than the common hook. We use a large Wichard snap shackle into a ring on webbing through the cringle.
The builder says it is a “reliable custom” system. To me that is an oxymoron, unless it has been extensively tested in real life conditions.

Matthieu Chauvel

Hi Neil, thanks! Yup, once saw a superyacht get absolutely wrecked (well, not actually ‘wrecked’ in a nautical sense thankfully, but it was a lengthy sh*t show and people were very lucky not to get seriously injured) when their in-boom furling failed in as benign an environment as a stiff-breezed Antigua Week. Plenty of muscle on board, but they clearly hadn’t worked out their back-up method, unlike esteemed Morganscloud members of course!
+1 on the strong snap shackle cringle ring attachment point, I’ve added this to Obelix too.
I’m gonna give the custom super duper system the benefit of the doubt for now, it’s just a whole other level of gear from anything I’ve experienced (beefy for sure, complexity…different story as John seems to have experienced during his cruise on Vivid) and chances are I won’t ever get the chance, but the Southern Ocean is a much more competent judge…

Matthieu Chauvel

A huge thank you John for taking the time ponder and write out such a thoughtful answer, as well as making it nicely visible which I see has already attracted more collective Morganscloud wisdom!! This little choir says “Amen”. I have already diplomatically sent very similar advice, give or take a couple minor details, to the official prep advisor, who will undoubtedly even more diplomatically share it with the owner! 🙂 To the extent I learn anything useful re. their procedures both with the furlers (yes, plural) working fine and in case of failure/manual back-up as well as any feedback from their actual voyage, I will make sure to pass it on here. We’re talking about a big boat indeed, so there will be plenty of professional meat on board. Suspect sailing and or motorsailing under headsails only in case of any worries will be a big part of the answer. One good (?) thing about Antarctica cruises is that you have to get to Ushuaia/Puerto Williams first, which usually gives opportunities to iron out big wind procedures on the way down…still leaves the Drake which can take it up a notch again and icing issues though. To be continued hopefully…