The 1970s saw further rapid advances in boat design, with new boats becoming quickly outclassed. It also coincided with a new rule for rating race boats, the International Offshore Rule (IOR).

This had an enormous effect on yacht design – many cruising yachts also sported the narrow, pinched sterns of the era.

IOR severely penalised righting moment, so the bulb keels that had started to gain in popularity in the late 1960s disappeared. Instead, lightly ballasted keels, with their centre of gravity well above the mid point, became the norm.

In my view this set yacht design back by almost two decades. It also had important safety implications in terms of ultimate stability that helped contribute to the Fastnet race disaster at the end of the decade.

Nevertheless yachts became faster and were generally more robust, more reliable and more fun to sail.

For instance, the Macwester 27 of 1972 – a development of the earlier 26 – was one of the first yachts to benefit from tank testing to improve its hydrodynamic efficiency.

The result was significantly deeper bilge keels that were set at more efficient angles and a more effective rudder. This transformed speed and handling and, combined with a new interior, created a desirable yacht.

This was also the heyday of home boatbuilding.

Participation in boating continued to grow at a staggering rate, so the demand for craft far outstripped what the second-hand market could supply.

By contrast, today’s boat buyers reap the benefits of the huge number of boats that were built in the 1970s and now often change hands at very modest prices.

It’s often thought that sensible cruising yachts of this era were built exceptionally strongly.

Incidents today tend to be shared rapidly via social media, but 40 years ago it was easier to keep embarrassing events quiet.

Yet, there were numerous examples of problems, including a near new Westerly Pageant that sank on its tidal mooring in Chichester harbour when one of the keels parted company with the hull.

Similarly, all but a few Westerly GK29s, Fulmars and Konsorts had to have the reinforcement that spreads the keel loads in the bilge replaced with top-hat stringers in place of the original glass-over-plywood frames.

As with 1970s cars, the scale of some problems at this time should not be underestimated – large numbers of near-new boats had to be modified and Westerly was by no means the only manufacturer that suffered.

Fortunately for today’s buyers the appropriate repair procedures were well understood and have usually withstood the test of time well.

Designer profile: Olin Stephens

America’s Cup hero and yacht designer Olin Stephens

With a career that started in the 1920s, Olin Stephens was one of the most successful and prolific designers of the 20th century.

In the early and mid-1970s he was still producing craft that excelled at every level in offshore racing and prestigious events including the Rolex Fastnet, Sydney Hobart and Whitbread Round the World races.

His designs also dominated the America’s Cup from its post-war revival in 1958 until 1980.

Stephens’ S&S 34 of 1969 had proved hugely successful, to the extent that former British Prime Minister Sir Edward Heath owned one in which he won the Sydney Hobart Race.

The design was to continue to prove successful for many years, including winning a heavy weather Round Britain and Ireland Race in the 1990s, and successfully completing several non-stop circumnavigations via the Southern Ocean. It remains a sought after and very capable classic.

This was also the era of Nautor’s early Swan designs, all of which came from the Sparkman & Stephens office until after Olin’s retirement at the age of 70. The best known by far was the Swan 65, thanks to Sayula II taking overall victory in the first Whitbread and second, third and fifth places four years later. Newer S&S designs won the next two races.

The early part of the 1970s was still an era in which successful offshore racing yachts would also make first-class cruisers and many of these boats still ply the world’s oceans.

Tomahawk 25 – 1970

Marcon grew to become a huge boatbuilder in the 1970s, having been founded with the launch of the Trident 24 in 1960. Other models, including the Cutlass 27 (1967) and Sabre 27 (1968) followed, heralding a period of rapid growth that at one stage saw the company moulding some 15 designs, including the entire Rival range.

As well as laminating bare hull and deck mouldings for other boatbuilders, Marcon also supplied a large number of boats for home completion. While some of these suffered from a clearly DIY level of fit out, a few were completed to an extremely high standard that would have been unaffordable on a commercial basis.

The Tomahawk is an Alan Hill design that was offered in bilge and fin keel formats, both with a skeg hung rudder. This was a spacious design for a boat of its size in this era, both on deck and below.

The cockpit extends almost to the transom, while below decks early boats had a linear galley to port, with a dinette that converted to a double berth opposite. Later models had a more traditional arrangement with two settee berths and a small galley aft. A full-width heads compartment separates the forecabin from the saloon.

LOA: 7.70m (25ft 4in)
LWL: 6.10m (20ft 0in)
Beam: 2.60m (8ft 6in)
Draught (fin keel): 1.40m (4ft 8in)
Draught (twin keel): 0.90m (3ft 0in)
Displacement: 2,300kg (5,066lb)
Ballast: 1,000kg (2,200lb)
Price now: £2,500-£7,000
tomahawk25.co.uk

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Laser – 1970

Canadian Bruce Kirby visualised an entirely new type of boat when he first sketched the Laser, a design that was reputedly created on the back of an envelope. It was conceived as a simple car-toppable boat that would be fun to sail, rewarding to race and made use of recent advances in materials.

In some senses this is the ultimate minimal boat – a slender hull with low freeboard, single sail and vestigial cockpit. A key benefit is that, unlike other dinghies of its time, the boat doesn’t need tedious bailing after a capsize. It proved an outstanding success, fleets quickly sprang up around the world and more than 215,000 have now been sold.

For best performance in the standard format the boat needs a big sailor – someone over six feet tall and weighing at least 80kg. Smaller rigs, dubbed Radial and 4.7, were therefore developed for smaller and younger sailors. This further boosted the Laser’s popularity, even though the smaller sails are underpowered relative to the hull weight.

Seven years later the Topper was born of a similar concept, but is a smaller boat of a perfect size for teenagers. It was made of almost indestructible polypropylene and at one time was the biggest injection moulding in the world.

LOA: 4.20m (13ft 9in)
LWL: 3.81m (12ft 6in)
Beam: 1.39m (4ft 7in)
Hull weight: 59kg (130lb)
Standard sail area: 7.06m2 (76ft2)
Price today: £600-£4,000
laser.org

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Contessa 32 – 1971

This was the second design from David Sadler to be built by Lymington boat builder Jeremy Rogers, following the long keel Contessa 26 of 1966. At the time it represented the state of the art, with a separate skeg-hung rudder, high-aspect mainsail and large overlapping genoas.

Low freeboard and narrow beam helped keep total weight in check and contribute to ultimate stability, at the expense of the boat being wet in a seaway and reduced internal volume. The keel-stepped masthead rig is typical of early IOR inspired sail plans, with small mainsails and large overlapping genoas.

Nevertheless the hull shape is excellent for thrashing to windward in a blow and the high angle of vanishing stability – an astonishing 156° – makes for a supremely seaworthy vessel. A Contessa 32 was the smallest boat to finish the 1979 Fastnet race and examples have been sailed all over the globe.

Other designs of the same era have similar shapes, from the Nicholson 55 and Swan 65 to the 22ft Pandora and even the 19ft Squib racing keelboat that evolved into the Hunter 19 and Europa mini cruisers.

LOA: 9.75m (32ft 0in)
LWL: 7.31m (24ft 0in)
Beam: 3.00m (9ft 10in)
Draught: 1.65m (5ft 6in)
Displacement: 4,300kg (9,480lb)
Ballast: 2,045kg (4,508lb)
Sail area: 52.2m2 (562ft2)
Price today: £14,000-£40,000
co32.org

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Moody 33 – 1973

This this was the first model in a range of Angus Primrose-designed yachts that marked the famous yard’s move from low-volume semi-custom boat building to becoming one of Europe’s most successful new boat sales operations.

Although the original accommodation layout was quite conventional for a centre cockpit boat of the era, it represented a giant step forward in cruising yacht design on this side of the Atlantic.

In particular the wide-beamed hull design was unusual at this time and is even not narrow by today’s standards. The later 333 models adopted a walk through to the aft cabin, albeit with limited headroom, while the 33S had an aft cockpit arrangement with a double quarter cabin.

The boat’s sailing qualities also surprised many at the time of her launch, with her then long waterline length enabling faster passage times than many ostensibly more performance oriented designs of the same length. However, a moderate draught and that wide hull limit progress in light airs and when close-hauled.

LOA: 10.06m (33ft 0in)
LWL: 8.69m (28ft 5in)
Beam: 3.51m (11ft 5in)
Draught: 1.35m (4ft 5in)
Displacement: 4,773kg (10,500lb)
Ballast: 1,730kg (3,815lb)
Sail area: 42.0m2 (452sq ft)
Price today: £14,000-£22,000
moodyowners.org

Continues below…

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Jeanneau Melody – 1974

As well as new hull shapes, builders were also experimenting with new accommodation arrangements. In 1970 Jeanneau had already set new standards in interior space with the 29ft 6in Folie Douce, partly thanks to the boat’s wide beam. Six years later this was updated with an extended coachroof and renamed the Brin de Folie.

However, it was the 34ft Melody that introduced the interior layout that within 10 years would be adopted by almost every other new yacht of this size right up to the present day – the double quarter cabin.

On the Melody this is a little cramped, as the stern sections are narrower than on later designs, but this trend-setting arrangement was immediately copied and improved upon.

Early designs with a quarter cabin were often seen to be lightweight and flighty, but the Melody is a very solid sea boat.

A hefty ballast ratio and deep draught combine to make this a very capable vessel, even in heavy weather, while a powerful rig ensures good progress even in light airs. Around 600 were built.

LOA: 10.25m (33ft 7in)
LWL: 8.70m (28ft 6in)
Beam: 3.38m (11ft 1in)
Draught: 1.90m (6ft 3in)
Displacement: 6,000kg (13,228lb)
Ballast: 2,900kg (6,400kg)
Sail area: 55.3m2 (596ft2)
Price today: £12,000-£20,000
jeanneau-owners.com

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Quarter Tonners – (1967-1996)

As the decade wore on the rise of the IOR rating rule for racing yachts had an enormous effect on yacht design. The smaller Quarter Ton level rating class gave designers great opportunities to experiment, which resulted in some weird and wonderful shapes including bumps and hollows intended to exploit loopholes in the rule. This test bed also produced some important advances in yacht design.

The rule changed regularly in an attempt to keep up with designers’ creativity, so boats quickly became outclassed. As a result a thriving industry sprang up to build new designs. The class also established the reputations of a slew of designers that are still well known today, including Ron Holland, Ed Dubois, Bruce Farr and Doug Peterson.

These boats were at the forefront of innovation, which was often driven by small companies working in less than ideal conditions. It’s a long time since anything on a similar scale has existed in the UK, although there are hints of it in Poland, which has a long maritime heritage and inexpensive industrial premises.

In the early 1970s Quarter Tonners still had narrow sterns and were short waterline displacement boats, but as the decade progressed transoms broadened, opening the way to surfing, or even planing performance downwind.

Until the mid-1970s designs like Westerly’s GK24, Ron Holland’s Eygthene 24 and the David Thomas-designed Bolero (pictured) also offered tenable accommodation and were often marketed as cruiser racers. However, by the end of the decade freeboard and coachroofs had both diminished in size, with stripped out interiors having minimal volume becoming the norm. After this point high-end racing yachts and performance cruisers continued to diverge.

LOA: 7.80m (25ft 7in)
LWL:6.80m (22ft 4in)
Beam: 2.50m (8ft 4in)
Draught: 1.40m (4ft 8in)
Displacement: 1,272kg (4,170lb)
Price today: £3,000-£25,000
quartertonclass.org

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The Drascombe story

Those who preferred more leisurely sailing in smaller boats were also well catered for. Although the Drascombe Lugger pre-dates the 1970s, this was the decade in which the popularity of the designs took off and some 4,500 from 14-22ft have now been built across more than a dozen different models.

The original 18ft Lugger, built in wood by designer John Watkinson in 1965, was an undecked open daysailer with an easily handled loose footed yawl rig.

Watkinson took his first wooden production model to the 1968 London boat show, where it proved unexpectedly popular – he took an order within half an hour of the show opening, plus a further ten before the show ended.

That led to him licensing Honnor Marine to build the boats in fibreglass. When they exhibited the first boat in 1969 sales took off.

Large families loved the big cockpit that meant children could bring their friends sailing and there was heaps of space for picnics. The outboard engine is mounted well aft to keep noise as far away from the crew as possible.

Further designs soon followed, with the 22ft Longboat unveiled in 1970. Unlike the Lugger, this was also offered with a small two-berth cabin, giving additional flexibility.

Yet the boat weighs only 480kg, so it can be towed by a relatively small car, while the simple rig with short masts makes for quick and easy launching and recovery. A clear measure of the success of the concept is the Drascombes are one of a handful of designs from their era that are still in build today.

LOA: 5.72m (18ft 9in)
Beam: 1.90m (6ft 3in)
Displacement: 340kg (748lb)
Sail area: 12.26m2 (132ft2)
Price today: £2,500-£6,500
drascombe-association.org.uk

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Sigma 33 – 1979

This David Thomas design was conceived as a fast one-design cruiser racer. It was an instant hit with the racing community and before long the class had a 70-strong fleet competing at Cowes Week.

Much had changed in design terms since the launch of the Contessa 32 eight years earlier. The Sigma has the feel of a larger yacht – a factor that’s also reflected in the accommodation volume. Thomas stayed with a traditional layout, but greater beam and higher freeboard dramatically increases the accommodation volume.

Under water the boat is a fundamentally different shape, with a shallower canoe body and broader transom, yet proportionately less wetted surface area.

The large balanced spade rudder improves control, especially in a quartering sea, while the increased form stability and broader aft sections markedly reduce rolling when sailing downwind.

Today, the Sigma 33 is seen as a moderate design by cruisers and heavy and sluggish among the racing community.

How did it score in the seaworthiness stakes?

The Sigma 33 doesn’t benefit from the Contessa 32’s high angle of vanishing stability (AVS), but it’s still well proven. The prototype lost a coachroof window in the 1979 Fastnet race storm, when the aperture widened as the structure distorted on a big wave. Nevertheless, it became one of the smallest boats to finish the race, albeit in very experienced hands. Subsequent boats have two separate windows, with structure between them, in place of the prototype’s long single window.

Even though the Sigma 33 was not intended as an IOR design key features were still influenced by the rule and Thomas later remarked that the keel would be more effective if it was bolted on upside down!

LOA: 9.90m (32ft 9in)
LWL: 8.00m (26ft 3in)
Beam: 3.20m (10ft 6in)
Draught: 1.70m (5ft 7in)
Displacement: 4,000kg (8,820lb)
Ballast: 1,680kg (3,704lb)
Price today: £15,000-£26,000
sigma33.co.uk

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1979 Fastnet disaster

The decade ended with one of the biggest disasters ever to hit the boating world.

Three days into the 600-mile race winds built unexpectedly to a sustained Force 10, with some competitors recording gusts above 70 knots.

In all 24 yachts were abandoned, five of which sank, 15 competitors lost their lives, and a further six people on non-racing yachts in the area also died. That toll was the UK’s largest ever peacetime rescue mission, involving some 4,000 people.

More than a third of the fleet experienced a knock-down to 90° and a quarter beyond that, including many boats that fully inverted or pitch poled.

Part of the problem was that the IOR rule penalised righting moment and encouraged low ballast ratios.

This effectively banned low centre of gravity keels, which made knockdowns and inversions more likely. The problem was further exacerbated by the trend towards wide hulls that are more stable in the inverted position.

Since many new cruising designs of the day were based on a successful IOR hull, there’s also a raft of cruising designs that have less than ideal ultimate stability.

For cruising sailors the legacy of IOR means many thousands of affordable boats built during one of the most active ever periods of boatbuilding lack the stability they could have.

The effects of this are two-fold. In moderate conditions reduced stability means a more tender boat that needs reefing earlier and more frequently, and one that will respond to gusts in a more dramatic manner.

In extremis, if caught in severe weather lack of stability makes it easier for wave action to capsize a boat. And if it rolls to 180°, a design with a low AVS will have less chance of being righted in a timely manner.

On a positive note, the subsequent inquiry led to important improvements in lifejacket, safety harness and liferaft design.

One other important point is rarely made in this context.

The accuracy of medium term weather forecasts has been improving at a rate of around one day per decade since the late 1970s. In other words the six-day forecast now has similar accuracy to the 48-hour forecast in 1979.