Credit: Tom Van Oossanen

Do you know your captive winches from your two-skin mainsails?

22 March 2021· Marilyn Mower

Never fear – Marilyn Mower is on hand to explain the latest innovations in sailing tech...

Sailors like to figure things out. You might be the type who takes things apart mumbling, “So that’s how that works.” If you’ve ever prised the cover off a manual three-speed deck winch and marvelled at the gears, you know who you are. Some things are a bit harder to investigate, so the Virtual BOAT Show is going to help you look under the hood.

Submarine Anchors

The narrower the bow, the more difficult it is to deploy anchors. For cruising boats, a Manson ray-type anchor or two snugged up tight or a protruding bow roller with a plough anchor are typical kit. But performance boats don’t appreciate weight or obstacles forward. Hydraulically powered arms that catapult anchors from lockers aft of jib furlers are one solution. Another is underwater deployment or the submarine anchor. This moves the weight of anchor, chain and windlasses lower in the boat and several frames back from the bow plus keeps the deck clear for sail handling and dock lines.

First came the invention of a “bomb bay-style” underwater anchor compartment with port and starboard doors opening on centreline and an anchor dropping straight out of the bottom through a rubber tube to keep the chain from rubbing on the hull. Today’s submarine anchors are a bit more sophisticated.

“There are basically four ways to do this,” says Henry Hawkins, COO of Baltic Yachts. “The majority use one of two systems where the anchor forms part of the hull, although it depends on owner preference and choice of anchor.”

Credit: Baltic Yachts

The 2002 Visione has one plow-type anchor that slides out of the hull on a chute that looks like a typical bow roller attached to a rectangular section of the hull bottom. A hydraulic arm depresses the front of that section so that gravity makes the anchor slide down the roller and out of the boat. For retrieving, a vertical windlass back aft above the chain locker reels in the chain and when the anchor shaft reaches the lip of the roller, a guide snugs it into position, then the hydraulic arm lifts the door.

On 42-metre Pink Gin, the owner chose a Danforth-type anchor and the anchor’s custom bottom plate attaches to a section of hull a shade larger than the anchor. Chain released, it drops straight down from its watertight box. Raise the anchor and guides position its flukes when it enters the hull so that it aligns properly, rises to its top position and is locked in place. The section of hull bottom is snug against a flange and water is pumped from the box.

The recently launched 44.8-metre Canova uses two CQR-type anchors mounted one behind the other on centreline. When either anchor chain is released, its shaft pivots up in the anchor compartment and then drops clear of the hull, the chain exiting its own locker via rollers and a chain tube. Cutouts in the hull match the shape of the CQRs and a flange keeps it sealed.

In all cases the anchor and chain lockers are watertight from the rest of the hull and are vented above waterline preventing pressure build-up in the anchor compartment. Crew have access to the windlasses from the deck.


It’s been 14 years since Maltese Falcon appeared, and two and a half since Black Pearl was delivered. Their closest kin is a 19th-century square-rigged clipper ship with sails draped vertically from yardarms controlled by lines and sheets. During the mid-1970s oil embargo, a project soliciting ideas for sail-powered cargo ships inspired Wilhelm Prölss to propose an unstayed tripod-style version of a square rigger mast called the Dynarig. Experiments showed the concept was far more efficient than conventional square rigs.

But the idea remained unloved until Tom Perkins chose an updated version by Gerard Dykstra for Maltese Falcon, taking advantage of new technology for lightweight spars, hydraulic sail controls and roller furling.

Credit: Emirates Team New Zealand

Keys to the efficiency are the fact the sails sit in front of the mast – no turbulence, and the yards, unlike the clippers, have a 12 per cent camber to shape the sail into a proper airfoil.

The sails fill the space between the yards so that each rig becomes a single wing. To stow, sails roll up vertically in pairs inside the mast. Each course of sail has four little motors mounted on its yards to pull the sails out of the mast and tension them.

Once all the sails on the mast are set the mast, turned by motors at the base, is rotated to catch the breeze. Each mast is stayed only at the deck and at the keel, so no shrouds. It’s all done push button – no sheets to trim, no crew go aloft.

Credit: Dynarig

Refining the aspect ratio of rig height to yardarm length and experimenting with camber have been the latest achievements. “More camber generates higher driving forces, resulting in better downwind performance, while less camber reduces drag and will improve upwind performance,” says Damon Roberts, technical director for Magma Structures. “Twelve per cent seems appropriate for a large passage-making vessel. Progressively flattening the camber on the rigs as you move aft enables more efficient sail interaction, so the main and mizzen mast spars on Black Pearl have a 10 per cent camber. Future two-masted vessels will likely carry fuller sails on the front and flatter sails on the back.”

Sam Watson, CEO of Southern Spars, is tasked with applying the North Sails Design suite to the concept in partnership with Magma to see how the rigs can be sleeker. “Do you need three rigs? We are beginning to think two may be better,” he says, while Roberts notes the two-spar setup is aerodynamically more efficient upwind.

Two-Skin Mainsails

Credit: Emirates Team New Zealand

While most of the America’s Cup chatter has been about the foils, recent comments by sailors let slide there is something new about the mainsail and the mast. The phrase was “two-skin sail with pairwise battens”. What?

“I don’t know why they call it that,” says Burns Fallow, the genius behind America’s Cup sail development for North Sails and now permanently embedded with Emirates Team New Zealand. “It’s just two mainsails, each one with battens like a regular sail.” 

Yeah, well sort of.

The Class Rule says the mast can rotate. There’s also a mention that there can be two hoisting tracks on the mast. That last part isn’t addressed in the “Rule Highlights” and is easy to gloss over unless you ask why.

“The hard wings for the last three cups were incredibly efficient but heavy. The mast and main for these boats weigh 600kg less but they can’t generate as much lift at slower speeds,” says Fallow. “These masts are a bit short [26.5 metres from deck] in comparison to boat length, but you don’t need a big rig when you are foiling.”

Credit: Emirates Team New Zealand

But two skins?

The first thing Fallow points out is that the mast is not round or an ellipse, but D-shaped with the two mainsail tracks mounted on the flat side that is 400 millimetres wide. Both tracks hoist identical carbon-fibre 3Di mainsails with separate heads, tacks and clews. “The top four metres of sails can be controlled independently of the midsection [think high-horsepower zone],” he says.

Next, Fallow suggests we picture the perfect aeroplane wing and how it generates lift. If a sail comes out of a mast in the centre, there will be a dead zone of turbulence right behind it until the air reattaches to the sail to create lift. Put that sail closer to the edge of the D and rotate the mast a few degrees and, presto, much more like that perfect foil for upwind work. Tack and you get the same advantage on the other side. “But the battens can’t be spring tensioned to hold the shape; it all has to be managed by the trimmers whose power comes from the grinders,” he says.

How far apart are the tracks on the mast?

“I can’t tell you that.”

So no boom? “No.”

So how many strings do you need to control the top of the sail separately from the mid-section and the bottom? Is there a traveller? Where do they sheet?

“I can’t tell you that, either, but it is a lot simpler than it sounds.”


Credit: Eva-Stina Kjellman

In the early round-the-world racing days, a crude little fan on a pole could be clamped on to a stern rail and lowered into the water behind a speeding boat. The water turned the blades and a miniature alternator created electrical charge that was captured by the connected ship’s battery. It wasn’t pretty, but it kept the instruments working. Now hydrogenerators are fast becoming a mainstay in the renewable energy mix for cruising boats, after gaining real traction during the 2008 Vendée Globe race, when they were widely fitted to the IMOCA 60 fleet. For yachts sailing to or through marine preserves, they are essential.

Today the state-of-the-art is a steerable electric drive leg where a skeg that looks much like the lower part of an outboard engine is geared through a couple of 90-degree turns to an electric motor located above the unit and powered by the ship’s electrical supply instead of a direct-drive engine. A generator or a battery bank can be elsewhere. Drive legs pack a lot of torque into a small package.

Here’s where the beauty of sailing yachts shines like a beacon. When the boat is under sail, instead of feathering the prop, let it spin. Now as the gears turn, the electric motor becomes a generator sending current back to the switchboard either to be used for the mod cons or to charge the batteries for free with zero emissions.

Canting Lifting Keels

Canting keels certainly aren’t a new development in yachting. In fact, the first sailing yacht to sport such an advancement below the waterline was a 13.7 metre Jim Young design named Fiery Cross, launched in the 1950s. Unlike a traditional fin keel that sits perpendicular to the boat, a canting keel has the ability to swing from port to starboard, acting as a form of ballast to counteract the heeling force of the sail. Shifting the keel to windward allows the helmsman to sail closer to level which, in a regatta setting, can shave off precious seconds, and makes for smoother sailing with a roll dampening effect.

This can be seen in its most advanced form on the latest addition to the ClubSwan fleet from Finnish sailing shipyard Nautor’s Swan. The all-new ClubSwan 80 was designed as a technical racing machine, built from a lightweight carbon fibre hull accompanied by a side foil for additional lift. The 24 metre model is the first in the series to carry a keel that both cants and lifts for maximum performance on the race circuit and practical access to berthing in shallow marinas, reducing its draft from 6.3- to 4.5-metres

Nautor's Swan has its eyes set on the 2022 Maxi Rolex Cup, aiming and level the Maxi playing field with its new one design model. Currently under construction at Persico Marine, the ClubSwan 80 is available for immediate orders and first models are due to be delivered during 2021.

Captive Winches

Perini Navi is synonymous with captive winches. Over the years the team, under the direction of Fabio Perini, has refined the original concept of the simple drum, gear and motor that can be adjusted to varying loads and speeds. Now the latest generation is bringing AI into the mix to automate some of the function.

Typically, superyacht winches or furlers only function from a direct user command. Perini is making them intelligent, meaning they can react on their own in certain situations such as quickly taking up slack in a weather sheet via a mechanism that can sense small variations in the sheet load and software that manages the machine.

The winches have been pushed to improve performance – pulling 100 metres per minute so a jib can be deployed in just 16 seconds – while reducing power consumption.

The reduction in consumption is possible due to a multi-gearing system with two small electric motors. This supports the trend of hybrid power systems and needing to keep power demand in check to increase silent mode operations. This evolution of the Perini sailing system will showcase on new 42-metre and 47-metre models currently in construction.