Sigma 33: one of the most successful one designs ever launched

One of the most successful offshore one-designs ever launched, the Sigma 33 is also becoming widely recognised as a capable and versatile cruising yacht

The Sigma 33's hull is a strongly built one-piece GRP structure, hand-laid using chopped-strand mat and woven rovings. Credit: David Harding Credit: David Harding

The Sigma 33 is known for many things. She's the boat that was to have been called the Skua 33 until an existing Skua class complained and her name was changed.

She's the boat that missed out on selection as one of the three ‘official’ one designs following the Royal Ocean Racing Club's one-design conference in 1978, but which went on to outsell all those that were chosen.

She's the boat that was known as the ‘six-knots upwind and six-knots downwind’ boat – rather unkindly, perhaps.

The deck-stepped fractional rig has a single set of well-swept spreaders. Credit: David Harding

But above all she's known as one of the most outstandingly successful one-design racing yachts the world has ever known, fielding fleets of 70+ boats at Cowes Week in the early 1980s.

Of a total of 364 Sigma 33s built between 1978 and 1991, that's a remarkably high percentage making the start line.

It proved how precisely she hit the spot. Her designer, David Thomas, had done it again.

He said to me on a number of occasions that the trick wasn't just to design a boat that people wanted to sail; you also had to design a boat that people wanted to buy.

He was very good at that.

As a racing boat, then, the Sigma 33 was an unqualified success.

She wasn't the trendiest boat of her size, and today, 45 years on, she's widely seen as perhaps a little staid and pedestrian in racing circles.

Thomas wanted a boat that was modern yet not extreme; that looked reasonably racy and was easy to sail close to its potential.

The deck layout of the Sigma 33 is conventional for a performance cruiser of the time. Non-skid strips forward of the mast and on the foredeck are helpful for the mastman and bowman. Credit: David Harding

This wasn't a boat in which the hot-shots would disappear over the horizon while the club sailors were spat out of the back of the fleet.

She's forgiving and easy to get going; qualities that make her popular in short-handed races to this day.

A lot of race boats are hard to keep on the boil, demanding full concentration all the time.

The Sigma 33 isn't like that, but getting the last 5% out of her is hard. That's what made the racing close and made it difficult to win.

David Thomas himself won the nationals more than once in his own Sigma 33, Circe.

Despite her one- design origins, the Sigma 33 makes an excellent fast cruiser. Over 360 were built. Credit: David Harding

It wasn't just as a one-design that the Sigma excelled, however. Designed towards the end of the International Offshore Rule era, she also proved to be competitive under IOR.

What's more, though conceived as a race boat, she wasn't so flighty that leisurely sailing was out of the question, or that sailing from the Solent to Cork Week with a small delivery crew would be a major challenge.

In fact the cruising potential was recognised when, in 1981, Marine Projects started building a cruising version, the 33C, with a shorter masthead rig and longer, shallower keel.

Even this de-tuned Sigma was no slouch.

After a double Atlantic crossing, a 33C won the two-handed class in the breezy 2011 Fastnet.

A Sigma 36 finished second and a 38 came fourth.

Looking at the Sigma 33 now, it's not hard to date her as a design.

The raked stem, the relatively low hounds, the narrow stern (by modern standards) and the IOR-shaped keel (longer in the chord at the root than at the tip) all give you a pretty good idea of when she was launched.

A classically proportioned fractional rig and balanced hull lines combine to create an attractive boat. Credit: David Harding

David Thomas later said that she would have been faster if she hadn't had ‘an upside-down keel’.

That was the shape of the day, because the IOR penalised stability: a low centre of gravity didn't get you a favourable rating.

Despite all this, and largely because she was (and is) a conservative design in many ways, the Sigma has had a long life both as a racer and as a cruiser.

She proved her offshore capabilities early on, when two boats survived the 1979 Fastnet Race.

One was sailed by David Thomas, with a crew that included Bill Dixon and Sigma surveyor supreme, David ‘Hoppy’ Hopkins.

A full-depth cockpit locker to starboard swallows plenty of warps and fenders. Credit: David Harding

Sigma 33s are still winning today at national level under IRC, one topping its class in Cowes Week in 2021.

They’re also becoming increasingly accepted as good cruising boats.

Some owners, on giving up racing to go cruising, have decided to make a few changes to their Sigma rather than to change boats.

One with whom I sailed 10 years ago had bought a 33 with the intention of racing it. He had raced dinghies and smaller cruisers, but enjoyed the cruising so much that he never actually raced the Sigma.

He frequently sailed past 40-footers, and returned from Cherbourg to Poole on one occasion in 6.5 hours. Of course speed is relative.

A lever backstay tensioner worked well on Sigmas, though some owners added yet more power. Credit: David Harding

Would a Sigma 33 ever get the better of today's 33ft pace-setters, such as the Sun Fast 3300, J/99 or JPK 1010?

Highly unlikely, even if it was upwind all the way, but the Sigma is still capable of springing surprises on the race course.

In any event, she's a quick boat for a 33ft cruiser.

One Sigma owner who knows this is Mark Heseltine, who has co-owned Trufflehunter since 1985.

And that's not the full extent of his involvement in Sigmas, because he had a share in one of the very first boats to leave the factory some years earlier.

Stowage for a liferaft is beneath a lift-out moulding at the forward end of the cockpit. Credit: David Harding

That one had been a move up from a GK 24, both the GK and the first Sigma being named Proven Sharpe after CID detective Chief Superintendent Proven Sharpe, who was based nearby in Devon at the time.

CS Sharpe graciously consented to the use of his name and even popped along to the GK's launching party.

Before moving into cruisers, Mark had spent many years racing dinghies and had also been involved in an Olympic campaign in the Soling with his brother, Richard, competing against the likes of John Oakeley.

Having joined the offshore world – while continuing to sail dinghies too – Mark did a substantial amount of offshore sailing, including the 1982 Round Britain Race in the first Sigma.

Towing genoa cars are well worth having whether you’re cruising or racing. Credit: David Harding

Entrants on that occasion included Robin Knox-Johnston, Chay Blyth, John Oakeley (again), Rob and Naomi James and Bob Fisher.

Along with Chay Blyth (during his British Steel days) and the late great Mike Birch, Rob and Naomi James were among the big names of the day to spend time in Dartmouth in the 1970s.

Both Mark and I were based on the Dart and doing a lot of sailing – often in different boats, sometimes in the same one – so we were fortunate to findourselves rubbing shoulders with some of the world's greatest sailors.

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At various times Mark had the GK 24, a J/24 and the Sigma 33s, all of which I raced with him from Dartmouth and sometimes elsewhere.

We sailed in a distinctly blustery J/24 nationals in Poole in 1984, which preceded the worlds and where the entry list was a veritable Who's Who of theyacht-racing world.

Another national championship was with the Sigma in Cowes in 1989 – a year when a certain Mr Thomas won – so when we met for a sail last summer it had been over 30 years since I had sailed on Trufflehunter and too long since I had sailed from Dittisham, where I was brought up and where Mark's family has kept boats since the 1950s.

A nicely finished saloon for a sporty boat, with no interior mouldings, bulkheads bondeddirectly to hull and deck, and vinyl panels overhead. Credit: David Harding

We chose a stunning day for our sail, with just enough wind after an hour or two to get Trufflehunter powered up nicely and remind me that the Sigma 33 is a thoroughly enjoyable and responsive boat to sail.

At the helm you have a comfortable perch on the coamings abaft the mainsheet traveller.

For fully crewed racing or short-handed cruising, the layout and hardware work well, though if single-handing without an autopilot you need to hop over the traveller to reach the headsail winches on their plinths either side of the companionway.

Mark treated Trufflehunter to a Harken windward-sheeting car while he was still racing (winning the European Championship in 1990 and the nationals in 1995).

Otherwise, most of the hardware is original.

Hanging space with zip-up doors opposite the heads between the saloon and forecabin. Credit: David Harding

As for the ‘software’, cruising sails in Dacron have replaced the racing laminates.

The mainsail has luff sliders rather than a bolt-rope, and the headsail is on a reefing system.

Despite having made these changes for ease of handling, Mark acknowledges that: ‘Sigma 33s are still jolly good cruising boats even with the original sails, because they sail fantastically well with the working jib in any sort of breeze. We had a cracking sail once along the south coast of Brittany, slicing through the 40-footers that were struggling with their roller-reefing headsails. We overtook them with no trouble’.

As we sailed across Start Bay, Mark refreshed my memory on some of the details when he and two other crew were lifted by helicopter from a liferaft after abandoning a 39-footer west of Bermuda.

They had been on a delivery from the UK to Annapolis when the keel started wobbling rather alarmingly and showed every sign of being about to drop off.

They didn't wait for that to happen. The boat was never seen again.

A good-sized chart table with stowage and instrument space – something rarely found on modern 33-footers. Credit: David Harding

Mark's account of the incident was published in Yachting Monthly in 1986.

Having not arrived in the USA quite as he had hoped on that occasion, Mark made it more comfortably a few years later as commodore of the Royal Western Yacht Club, to greet the finishers in the 2000 OSTAR (singlehanded trans-Atlantic race) that had been started in Plymouth by the RWYC.

One of the prizes he presented was to Ellen MacArthur, the surprise winner of the Open 60s.

MacArthur returned the favour two years later, presenting Mark with the trophy for winning the Squib class in Cowes Week.

On the subject of comfortable arrivals, let's take a quick look below decks on the Sigma.

To starboard of the companionway, the galley is basic but perfectly functional. Credit: David Harding

It's the traditional British layout: forecabin, heads and hanging locker, saloon, galley, chart table and quarter berth.

With no internal mouldings except in the heads, stowage and access to the hull is generally good, though the space under the saloon berths is used for water tankage to centralise the weight.

You can stand up (headroom is 6ft 1in/1.85m), lie down and cook, both in harbour and under way.

For a boat that was conceived as a one-design, it's pretty civilised.

Between his sailing bases in Plymouth and on the Dart, Mark's smaller boats in recent decades have included a Devon Yawl, a Squib and a J/80.

But it's the Sigma that has proved to have the staying power, and it's easy to see why.

Whatever sailors of modern, sportier boats might have to say, the Sigma 33 is not a ‘six knots upwind and six knots downwind’ boat.

Six knots is not a bad upwind speed for a 33-footer anyway – as long as the boat points, which the Sigma does – and, while she might not surf downwind asreadily as some, she will get up and go.

I remember a lively spinnaker reach back across the English Channel in the pitch black of the early hours during the offshore race of the 1989 nationals, when we were all trimming hard to use every surfable wave.

Although designed as a racing boat, the Sigma 33 has a cockpit that works equally well for leisurely sailing. Credit: David Harding

We managed a lot more than six knots then, and Mark's maximum to date has been 14.4 knots.

The Sigma 33 has mellowed with age. She's no longer the boat of the argy-bargy racer, of ‘he who shouts loudest at the leeward mark’.

She did have that reputation for a time.

And while it's true that some 33s that have been raced hard might look a little worn, on the whole they’re pretty tough boats.

Cosmetics aside, these boats have stood up well when not sailed by crews who went mad with ultra-powerful backstay tensioners.

Mark put Trufflehunter through an extensive refurbishment over the winter of 2021-2022 and she looks remarkably fresh for a 35-year-old boat.

As another Sigma 33 owner put it recently, ‘This is a boat that looks good, looks after you and is fun to be with. Those are three vital elements in any relationship.’

Ben Sutcliffe-Davies, Marine Surveyor and full member of the Yacht Brokers Designers & Surveyors Association (YDSA) www.bensutcliffemarine.co.uk

The longevity of the Sigma 33 is a testament to David Thomas's design and the build quality of Marine Projects.

When considering a Sigma 33, be mindful of the boat's background, particularly the kind of sailing she has done.

Several of them have been raced hard, so background checks on racing campaigns and incidents is extremely prudent.

I have surveyed several Sigma 33s as part of damage claims or pre-purchase surveys.

Accommodation plan for a Sigma 33. Credit: Maxine Heath

The common issues are usually the softening of decks, when they are balsa core, and the cracking of areas around deck combining arrangements.

Pay close attention to the hull-to-deck joints; any issues are likely to be caused from previous contact or collisions with other boats, where these joints have been compromised.

One of the classic clues is the condition of her alloy toe rail for impacts; examine the bedding down of the toe rail too for signs of contact.

Look internally for any signs of water damage as a result of impacts.

Sail plan for a Sigma 33. Credit: Maxine Heath

Watch out for any cracks or failing of the main bulkhead; I am aware of many owners who overload the rig when tuning it.

Make sure you take the boat out of the water and carry out a keel tip test; it is important to see the hull with the keel in suspension.

Load the base of the keel to make sure the keel and, in particular the hull, doesn't deflect.

Then set the craft down and ensure the hull doesn't sag over the keel which could indicate laminate softening developing around keel root areas.

A rudder that turns through almost 180° makes the Fulmar very manoeuvrable. Credit: Colin Work

Surprising though it might seem in some ways, the Fulmar has much in common with the Sigma 33.

The boats were aimed at different markets when they were launched in the late 1970s, but both came from well-known British builders and designers, some of their vital statistics are not dissimilar, both have fractional rigs, their layouts below decks are fundamentally the same and they both sail very nicely indeed.

The Fulmar is a heavier boat with a higher ballast ratio and shallower draught, and was conceived with more of an emphasis on cruising.

Nonetheless, she quickly established a reputation for being fast, responsive and enjoyable to sail, and is widely regarded as one of the best Westerlys ever built.

After the Westerly Griffon, she was the second design by Ed Dubois, who was commissioned to give Westerly a sportier and more modern image.

Whereas the Griffon replaced the Centaur (eventually, because demand meant the Centaur had to remain in production for a while), the Fulmar replaced the Laurent Giles-designed 31s – Longbow, Renown, Pentland and Berwick.

The Fulmar was offered with a choice of fin or twin keels. Credit: David Harding

In Westerly tradition she was offered with a choice of fin or twin keels, and a few were also built with lifting keels that swung up under the hull.

In fin-keel form she was used for the Royal Lymington Cup for a number of years.

This match-racing series attracted many of the world's top sailors of the day and did the Fulmar's reputation no harm at all.

Despite being perhaps a little more cruisey than some of them were used to, she was recognised as a swift boat with few vices and remarkable manoeuvrability, which made her ideally suited to the role.

Few changes were made during the 12-year production run, though a small number of boats were built with aft cabins in place of the quarter berth.

Then in 1992 she was given a sugar-scoop and stretched to become the Fulmar 33.

Only a handful of 33s were built before production finally ended in 1997. Well over 400 Fulmars left the factory in total.

The OOD 34 was later modified to become the Contessa 34. Credit: David Harding

Another design from the same era, the OOD 34 was the largest of the three boats selected by the Royal Ocean Racing Club's 1978 one-design conference, together with the Impala 28 and the Aphrodite 101.

She came from the board of Doug Peterson, whose Contessa 28 had been launched the year before, in 1977.

Despite her ‘official one-design’ status, the OOD 34 was never destined to sell in large numbers.

While some survived the 1979 Fastnet relatively unscathed, two found themselves in the wrong place at the wrong time.

One was abandoned after capsizing, and the other sank following multiple knockdowns.

The design – built, like the Contessa 32, by Jeremy Rogers – was subsequently held up as an example of how relatively light-displacement boats with high-volume hulls were inherently less stable than the likes of the Contessa.

In her defence, many felt that the OOD had been both unlucky and unfairly singled out.

OOD 34s have subsequently been cruised and raced widely, though their masthead rig and large foretriangle can make them physically demanding in racing mode.

The class hasn't raced as a one-design for some years and the 80-odd boats built (by injection-moulding, of which Rogers was an early adopter) are now widely scattered, with most being in the UK and Holland.

After production of the OOD ended, about 20 more were built as the Contessa 34, with a shorter rig, heavier keel and a different deck and interior.

Fast and well finished, the Albin Nova 33 sold in large numbers in Scandinavia. Credit: David Harding

Designed by Peter Norlin and built in Sweden by Albin Marine, the Nova 33 proved extremely popular in Scandinavia.

Around 500 were built during a production run of 16 years – more than the Sigma 33 or even the Fulmar – though they’re less well known in the UK.

In traditional Scandinavian style, they’re slippery boats with a generous fractional rig.

Even so, they’re generally regarded as well mannered and easy to sail.

The iron fin keel is relatively long and a skeg runs aft to the semi-balanced rudder.

Like most boats of this era, they will struggle to keep up with newer designs downwind in any breeze but are known as exceptional performers to windward.

A keel-stepped rig keeps the mast section reasonably slim.

Unlike many Scandinavian designs the Nova has a keel cast in iron rather than lead.

Below decks the layout is very much of its time and similar to the Sigma and Fulmar, only with the chart table and quarter berth to starboard instead ofto port.

It's a wide berth; sometimes considered a cosy double for two slim people on intimate terms. Interior fit-out is to a high standard.

Well-finished woodwork abounds, and stowage – including plentiful drawers– makes good use of the space.

This feature, together with the pillar handholds by galley and chart table and the coaming locker in the cockpit, set her apart from most modern equivalents.