The Offshore Voyaging Reference Site

Q&A—Sizing a Staysail Roller Furler


Having a good look at some of the pictures where I can see the furling gear you used on MC it appears to me that it is about 1 size smaller then your head furler. Is this correct? And if so, were you ever concerned about its size in heavy weather?

Member, Pepijn


Interesting question. Definitely got me thinking. Let’s start by looking at the forces involved:

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Dick Stevenson

Hi Pepijn and John,
As an example of what has worked for us.
We sail a Valiant 42 which is a true cutter (mast almost amidships) and have done so for over a couple of decades, visiting ~~70 countries and a couple of North Atlantic crossings.
The jib topsail (~~110%) is on a Schaefer 3100 and the staysail (working size) is on a Schaefer 2100: this was how the boat was built. We bought Alchemy used 20+ years ago and I was concerned about Schaefer gear and its sizing when I purchased the boat, but some due diligence led me to feel they were quality units sized correctly. Our experience has borne out that assessment.
I am also in the loop for many other Valiant 42s, many of which have wandered widely in unfriendly waters and most equipped like Alchemy and I have heard no reports of problems.
Not sure what the wire size is on the staysail, the jib topsail is on rod.
We have sailed in heavy weather with the staysail and various levels of reefs in the main. I do not remember getting rail down, but I am sure I have been.
My best, Dick Stevenson, s/v Alchemy
Ps. There are boats are out there calling themselves cutters which are better described as double headsail sloops. It is my observation that many of their staysail rigging choices/design look under-spec’ed.

Eric Klem

Hi John,

The guideline to be 1 size smaller seems reasonable although it is always going to be boat specific. One thing to keep in mind is that as we switch from a jib to a staysail, the center of effort moves down so to get the same heeling moment, you need more force from the sail. Fighting this is the increased healing moment from windage as the wind speed increases. For a really low windage boat, the forces might actually be greater on the staysail furling gear than the jib whereas most boats with a decent amount of windage I would expect it to go the other way. I don’t have any numbers on this but I am sure someone does.

It would be interesting to know what the limiting factor on the furling systems is from a load standpoint. I would assume that the whole thing is designed together but it is possible that some parts are deflection limited while others are stress limited. For example, if the foil were deflection limited to keep the foil from twisting up too much, it may be “oversized” if kept short such as on a staysail. On the other hand, if that component is only designed around torsional stress, I doubt the length of it matters.


Dick Stevenson

Hi John,
I am not sure why you say that the advice that roller furling manufacturers give to not use a winch on a furling line is completely impractical. With a fair number of miles on Alchemy, I can only think of once where I resorted to a winch. Perhaps it is a boat/sail size issue: Alchemy is 40 feet.
I do think that boats are often initially poorly set up to pull in the headsails by hand: leads are poor, turning blocks could be slipperier, etc. And a one direction friction device often needs to be introduced to enable the crew pulling in the jib to advance hand-holds on the pennant and, perhaps, rest a second between pulls and too often there is no intervening friction producing device to allow that rest. Often also the design positions the crew in an awkward, sometimes unsafe, position to do the pulling and make likely that a flogging sail will jerk the pennant out of one’s hand letting the sail un-roll dramatically.
Controlling the pennant is crucial. I have seen some use a ratcheting block at the end.  I put a snubber winch on the rail athwart the cockpit which is used exclusively as a turning post and, with a wrap or 2, to prevent the pennant being snatched out of my hand. The pennant is then led right to center cockpit behind the dodger where one is most safe and I can get a good stance for the pulling.
I suspect it may be some better for the sail to be brought in by hand as I can do it quite quickly when I fall off to a broad reach and the sail is largely blanketed and loads are still significant, but easily handle-able.  
My best, Dick Stevenson, s/v Alchemy

Dick Stevenson

No John, no.
Not a matter of strength.
Much more likely a naivete from a sailing/cruising career where I am almost completely self-taught and where I have almost never sailed with other skippers or on other boats. It never occurred to me to use a winch on the smaller boats before Alchemy and I just kept up the habit and it never came up what others did.
That and I saw the down side of a boat when in a squall he furled the main and because it was so tightly wrapped he ran out of furling line and winched the pennant right out of the furling drum. The sail flew out and things got ugly quickly.
And, yes, in my initial post I said that boat size was likely the most relevant difference. And, perhaps, my Valiant is approaching the upper limit of doing furling by hand. it is fun to re-think these things as there are definitely times when I do not want to work to get in the sail.
I do appreciate the thought that I can resort to using a winch when it makes sense.
My best, Dick