Glide Rig: A Hybrid Rig for Rowing Sailboats

 

MUSTELID gliding along
Full Foresail - Roll Reefed Main - Driver

All I wanted was a tall ship

And a star to sail her by

  Through the night.

  Through the night!

-- Motherlode?

Glide Rig: A Hybrid Rig for Row/Sailboats

Why name a rig? Any technical description is a mouthful, and few people appreciate mansplaining. A good name is evocative, calling to mind traditional associations. Or suggestive, offering a clear clue to the nature of its subject.

Gaff Rig, for example, suggests the spar itself and the sail's quadrilateral shape follows. It evokes robust working sail standing against the gale. The more initiated might recall its ability to scandalize—dumping half its area in a sudden gust. They might recall peak and main halyards, running backstays, and the tack-to-peak creases that indicate a correct set.

So, here is a rig in search of a name...

But first, the mandatory get-in-the-door question from The Commitments: “'Oo are your influences??”

Phil Bolger (of course) observed that most of us aren't out to win a race or even do much sailing to windward if we have any choice in the matter. Outboards and engines mostly handle the windward hemi-circle, so why expend design effort, gear and $$$ on maximal windward ability? He accordingly started to offer simpler, cheaper rigs.

That got us thinking. For a rowing, mostly downwind sailboat, we want a long, slim hull. These  are easily driven but offer relatively low form stability. Ultra-shoal draft limits ballast stability. A snug, low-center-of-effort sail plan that is easily handled and reefed pairs perfectly.

On a row/sail craft, we primarily want the sailing rig to pull us down- or across the wind. Positioned well forward as a foresail—clear of a forward rowing cockpit—it should provide powerful lee helm and steady, balanced traction. For sailing upwind, however, the balance picture changes. We want the total CE moved aft to for weather-helm and good tacking.

Quadrilateral and spinnaker-like sails work, but don't transition easily between the two modes.

Enter Frederick Ljungström, inventor of Ljungström Rig a boomless, double Leg o' Mutton (LOM) triangular sail attached along a shared luff to a  rotating mast. Off-wind, it sets and handles much like roller-furling twin staysails, and like them, provides considerable upward lift.

Sailing into the wind, the sails are doubled, overlapping on the lee side and sheeted as one. This constitutes a half-reef, and a large aftward jump of its CE.

To reef, the mast rotates (we prefer righty-tighty, lefty-loosey), furling the sail snugly around the standing spar. No halyards, tack or clew downhauls, bunts, or nettles. Just roll it up and carry on! As a bonus, simple flat-cut LOMs furl tightly with minimal windage, forming conic sections similar to a Crab-Claw rig.

Since a slim hull cannot spread wide sheeting angles, we re-introduced booms along a loose foot. The result is a doubled variation of the Holopuni Quick-Rig (a great name!) which is similar to a setup offered on the SeaPearl 21.

Finally, three-masted junk schooners (e.g., CHINA CLOUD) inspired us with their fine control of their relatively low total CE, bow and stern maneuvers, and reduced area on each mast. Even on a smaller vessel (within reason), the advantages of multiple masts are striking.

Why Balance Matters When Rowing: Multiple sails give fine control over the balance of the helm. Especially when "motorsailing" (row AND sail), good balance leaves our hands free for the oars and reduces steering by stroke with ensuing fatigue. Even over a short haul, that makes a big difference! A driver - often set while rowing when the others are stowed - helps hold the bow up toward the wind. Where the bow want's to 'blow off' this is an asset.

A Problem on the Side—and a Solution

There is a catch with standard booms. They are fixed at the mast and sheeted toward their outboard end. As the sail is reefed, the clew moves inboard of the sheets, pulling laterally on the mid-boom, bending it toward the CE. Heavy spars and compromise arrangements are the usual fix.

Our solution? The Gliding Grommet.

We use a rope grommet that glides along a lightweight boom, with both the clew and sheets attached directly to it. A light clew/sheet outhaul is led through a turning block at boom's end, spreading the sail as desired.

When reefing, ease the outhaul, roller furl the sail as needed and make the outhaul fast. The grommet, clew and sheets are move inboard along the spar. The active, loaded portion of the boom automatically shortens, increasing relative strength. It absorbs the load purely in compression, avoiding mid-span bending stress. Cheap, DIY, and it works like a charm.

Glide Rig Specification

Mulling all this together, pulling out the main points and generalizing, we arrive at...

The "glide" emphasis is on downwind sailing and a strong balance shift for upwind sailing, supported by the working rig (I.e., without sail changes):

• Foresail in 'cat' position (well forward) and,
• Sets large area for off-wind sailing
• Reduces area and moves CE aft for upwind sailing
  
  
• Main near amidships and/or,
• Backs up the foresail for downwind sailing
• Becomes the driving upwind sail
  
  
• Driver well aft
• A smaller sail for balance and riding

"Glide" can be used adjectivally in the usual manner... where we would say "That's a junk schooner, ketch or yawl", we can say "That's a glide schooner, ketch or yawl" or combine them, "That's a glide junk schooner, ketch or yawl." 

Generally speaking, we wouldn't apply the glide adjective to schooners, ketches and yawls that don't pass drive from the foresail to main when switching from down to upwind sailing, and vice versa. Ditto cutters, sloops and catboats.

But any schooner, ketch or yawl is arguably a glide rig. It's a threshold, as is often the case. Boundaries are fuzzy and often the subject of over-heated tavern debate. Personally, I find it a simple matter of personal perspective... we each get one and to each their own.

With this in mind:

• Two- or three-masted schooner, ketch, and yawl variants may qualify.

• Main and driver with other planforms and rigging may qualify.

• Rig particulars—such as specific sail planforms, unstayed masts, roller furling, the Gliding Grommet solution, and such—are handy but optional.

NOTE: We call the stern sail a driver... it seemed the better option among mizzen (confusing), jigger (???), dandy (too high-brow?) and spanker (let's not go there).

MUSTELID's Glide Rig

I would now call MUSTELID's a three-masted glide LOM ketch rig. Fore and main sails are of equal height. LUTRA's main will be slightly taller (also quadrilateral with a sprit in the mix), so I'd call her a three masted glide hybrid schooner rig.

We tested Glide Rig extensively in MUSTELID over a wide range of conditions, as documented in the video series, MUSTELID Venture.

MUSTELID's foresail is a Ljungström sail (double LOM) rigged and positioned as described above.

Her midships main is a single LOM boomed as described and set aft of the forward cockpit. In this position, it becomes the heart of any windward sailing we might do, with the foresail reefed (moving the combined CE aft) and doubled over to sheet as an LOM. We offset this one to clear the BIRDWATCHER cabin's mid-line companionway.

We set a small LOM driver dead aft for offwind sailing, to 'crank in' weather helm, hold the bow up when drifting and serve as a riding sail. It is a big help when rowing in headwinds, especially when we must row at an angle to the wind. This sail was offset opposite the Main to clear the rudder and tiller. In this position, it can be squared across the transom for a mid-line, downwind push.

It is sprit-boomed in pretty much the standard manner. The boom is longer than usual, extending forward of the mast. A U-sheet leading forward attaches one leg to the inboard end of the boom and one to the outboard. This gives us leverage to trim and make fast. The sail is fixed to the mast (no halyard)... to stow, we release the snotter and raise the outboard end of the boom alongside the mast. A light line fixed to the masthead is used to wrap and secure the boom and vertical, hand-rolled bunt of the sail.

Roll yer own and glide on, Friends!

Rigged for Success: LOM/Ljungstrom + Quick-Rig Booms

 

MUSTELID's LOM Main and Ljungstrom Foresail

Live life as if everything is rigged in your favor.

-- Rumi

Rigged for Success: 
    LOM/Ljungstrom + Quick-Rig Booms

I'd like to share a suite of ideas toward a family of lesser known rigs for smaller vessels that I think show a great deal of promise. Part historical, part convergent evolution, part innovation, the result is a simple but versatile, robust rig that can be DIYed at low cost.

Leg o' Mutton (LOM) Sails

This tasty moniker simply means a triangular sail. They're commonly used for headsails (jibs, staysails, etc.), mains (often called Bermudan sails) and drivers (small sails set far aft).

Ljungstrom Rig (2 x LOM)

Ljungstrom Rig uses a pair of LOMs, joined along their luffs and set on a free-standing, rotating mast. No booms were used to avoid troublesome impacts with crew.

This configuration works similar to twin head sails off the wind. From a beam reach on up, the sails are doubled over to one side and sheeted as one.

Pros:

• Boomstrike is eliminated (the rig's original focus).
• Light, inexpensive spares and gear.
• Quick set/reef, roller un/furling via the mast.
• Sailing off-wind, one side can be jibed for 'instant' 50% reef.
• Sail area aloft catches higher, upper wind-flows.
• Low Center of Effort (CE).
• Twin sails tend to center down the wind.
• Potential for hands-free operation.
• Sail steering is straightforward (haul to the side you wish to sail).
• UV resistant fabric along luff and foot eliminate sail covers.
• At least in smaller vessels, the furled rig is easy to set and strike, and compact for storage.
  
  

Cons:

• Lack of a boom makes spreading sail difficult (especially on narrow hulls).
• No clew outhaul or vang options.
• In contrast to twin stays'ls (unless the mast is canted) it generates no bow lift.
  
  

Adding a Boom

The addition of a boom set under a loose-footed LOM allows spreading, a clew out-haul and vang, addressing the main cons.

Interestingly, this approach was taken by both the Sea Pearl 21 (adventurously sailed by Stephen and Ginny Ladd, among others), and is marketed as Holopuni Quick-Rig (by Holopuni Canoes). Convergent evolution?

Both of these designs lead their clew outhauls via track along the top of the boom and sheets to the end of the boom. When the sail is reefed, the upward pull of the clew at mid-boom is resisted by the end positioned on the mast and the downward pull of the sheets at boom's end. 

As a sail's belly is blown full, pulling the clew strongly toward the tack, the boom resists in compression. If it is deflected from straight by the perpendicular pull of the clew between mast and sheet lands, that strength plummets. Usual solution? A heavy boom or one made with expensive, exotic materials.

Hmm.

What if we oppose sheet and clew tensions by having them meet at the same point? They cancel out, unloading the mid-boom! The clew outhaul - led to boom's end, then turned back toward the mast to the clew completes the picture. A rope grommet - travelling along the boom - is the perfect attachment point... simple, cheap and DIY.

Principle parts of the rigging...
This platform and 'collar' are primitive but functional

How We Go About It

Rotating Mast and Gear

In our small-ish boats, we went with a thumb-sized dowel protruding from the rounded bottom of the mast. This is inserted into a hole in its step - a fixed plate of thick HMD (cutting board plastic). This secures the foot but it allows it to rotate with very little friction. The upper partners are simply a loose-fit, fixed square around the mast. The distance between step and partners should be between 10% (minimum) and 15+% (healthy) of the mast's overall length for adequate cantilever.

A gate can swivel open to free one face for raising/lowering or close and lock to contain it. 'Box' sides at the step hold the foot in place for lowering. A pin led through one side and into a corresponding hole in the lower mast prevents rotation against high winds or rock and roll.

Each boom requires an arrangement that fixes their height above the partners, yet allows the mast to rotate independently. 

Our solution is a platform affixed to the mast with a collar from boom's mast end, around the mast, set above the platform... the collar is not so loose as to slip below the platform, but not so tight as to grip the mast.

Booms

Booms can be quite light as compression span decreases as the sail is reefed, and diameter per unit of span increases - functionally speaking, reefing makes them stronger. Further, they are subject to no significant side forces along that span. Sea trials help settle in on a light boom with comfortable margins of safety.

Each boom has a rope grommet loosely fit around it (sized so it doesn't bind when pulled at a flat angle). 

We fix a pinch cleat for the clew outhaul at the boom's mast end, pinch horn down (10deg) toward the distal end. This allows the line to ride over the non-pinch horn (up and toward the mast), under control hands-free as it pays out while furling.

A ring seized to the distal end of the boom turns the outhaul back toward the grommet.

The outhaul leads from its cleat, through the grommet (helps control a slack outhaul) to the turning ring, and back to the grommet. We fix it to the grommet's upper side, allowing a tail which is tied to the clew. We prefer little play between clew and grommet.

The sheet is fixed to the grommet's lower side and led to deck level. A turning device (multiple or travelling for an improved lead?) leads it toward a clear, handy to the crew. We prefer enough friction on the cleat to hold in steady wind but ease in heavy gusts... no lock hitch.

Sails

We used light nylon fabric to build flat-cut sails. These are responsive, and furl neatly around the slightly tapered masts. They are stretchy enough to take on some belly (camber) when full of wind.

Downside is that camber can't be flattened easily in high winds. But reefing is so easy, we can reduce power that way.

For 2xLOMs we screwed the webbed luffs to the mast, but are now considering a pocket for easier installation and removal. Others have found that a simple lanyard from tack to mast is sufficient for furling.

Handling the Ljungstrom

We set the Ljungstrom sail well forward, where it can pull us bow down the wind. 

We don't typically vang our sails to flatten them. Instead, we vary the sheet leads and/or reef a little more than we might. This avoids extra gear, handling and the heavier booms required. Personal call, however. 

Furled Set Up

When furled, the sail is snugly wrapped around the mast. The boom(s), if any, are vertical. Sheets are left slack and hanging. One clew outhaul is marline-hitched once or twice along the mast, securing all the bits, then made fast at its pinch cleat (low).


Setting Sail

Unhitch the outhaul, then refasten to its cleat. Uncoil sheets and lead aft to their cleats. Both outhaul and sheets will go slack as the sail is unrolled. Unpin mast if locked.

Depending on wind, you might wish to round up. For downwind departures, you may have to work in stages, trimming sheets as you go.

Unroll the sail by rotating the mast (we prefer 'righty-tighty; lefty-loosey' as standard... we do this by hand, but various rope windings are possible).

Once unfurled as far as desired, haul the outhaul(s) for the curve you wish, then make fast. Trim sheets and fall off to heading. Backing sail is easy and effective. If you wish to open the sails, do so.

On the Wind

Here the sails are overlapped and are sheeted as one (outer one generally the focus of our attention). They handle pretty much as any boomed LOM.

Off the Wind

Sailing off the wind, the sail is typically balanced like a delta kite. All things being equal, it want s to hold the bow centered downwind. More belly is often a good trade-off against more area.

To steer using sail, haul the sheet on the side toward which you wish to turn (easy, now!). This shortens its force vector and directs it to that side. The opposite sail, now relatively stronger and with a longer lever-arm, works to rotate the hull that-away. Like the reins of a horse!

In a heavy gust, you have a 50% reef at hand. You can jibe one sail (lapping one over the other) or let it fly (this can be harder to retrieve... get a wide angle). But if this comes up, consider roller reefing ASAP. Consider that, in high winds, you don't have to set them wing and wing... they sail well as one.

Odd Situations

If a sudden squall has invited letting both sails fly (they're trailing down the wind from the bow), calmly roller reef until you can bring them in and under control.

If such a situation has reversed their usual sides, don't panic... just hand the sheets around the mast, or refasten them for a fair lead and carry on. The sails won't care.

The whole mast, sails and all, can be furled, hitched up and let over as a sea-anchor.

All in All

We found these LOM/Ljungstrom + Quick-Rig Booms to be simple, cheap, versatile and powerful. Each piece is DIY-able from scavenged materials. Nothing about them couldn't be made in the field, at a pinch.

The lightness of the spars is a BIG advantage, especially as we age. The masts should be manageable for as long as we're likely to be able to row.

In researching the history of the rig, the few who have used it are soberly impressed by its virtues. It is not the fastest rig out there, but its no slouch, and pays its way with easy handling and quick reefing.

I'm hoping to see more of these on the water in the coming years!

Full Ljungstrom / Reefed LOM
Sprit-Boomed LOM Aft

References

Sea Pearl 21 Review by Josh Colvin

About Holopuni Canoes by Nick Beck

Rigging MUSTELID and MUSTELID Voyage by Anke and Dave

MUSTELID Venture (Video Series)

MUSTELID
Photo courtesy of David Reece

MUSTELID Venture (Video Series)

Anke and I are proud (and a little nervous) to announce that Small Boats Nation (online, and affiliated with WoodenBoat) is releasing a 15 part video series, produced by ourselves and featuring our MUSTELID Venture.

Episodes are collected in this Playlist and this Collection at SBN as they are released. This is outside their paywall, so no subscription is required to view the series.  

Episode 1 introduces us, how we live, the need and proposal for our vessel.

Episodes 1 - 6 focus on MUSTELID's goals, concepts, construction, outfit, rig and life aboard.

Episodes 7 - 14  follow our trip in MUSTELID around Chichagof Island (plus a detour).

Episode 15 takes a look back on what we learned (I'll link this once released).

Plans for MUSTELID and other designs are available at triloboats.com.

*****

Small Boats Nation has a wealth of useful information... please consider subscribing. I've written this article for them about this trip which appears in their July 2023 issue.