When it comes to series-building large cruisers, Oyster Yachts is the undisputed world leader. The yard’s evergreen popularity lies with its bluewater cruisers up to 60ft (Boat test: Oyster 475 and 545) and, more recently, its unrivalled success with 80-footers. But two new launches, the 675 and the 745, herald a new modern look and era for Oyster: the hull shapes, drawn by Humphreys Yacht Design, are more powerful than their predecessors, beamier with greater form stability; they both sport twin rudders, flush foredecks and blade jibs and have more power in their rigs and keels. These two yachts (69ft and 75ft LOA respectively) are still bluewater cruisers but they have been given a very purposeful new image: the stretched coachroof window line marks the style of this new range; the signature wraparound window remains, but with a lower profile than we have seen on past models.

However, what really sets the 675 and 745 apart is the range of options available. This 675 is the first Oyster to offer a forward master cabin as a standard option and there is a wide variety of internal layouts available. Below the waterline, twin rudders reduce draught sufficiently to enable Oyster to offer a ‘super shoal’ centreboard version, while on deck a cutter rig can be specified in place of the single blade jib.

All models bigger than the 675 are now offered with conventional sloping transoms or extended vertical transoms as standard, while smaller models have been fitted with the extension on request. Other than create a very different look, the extended version doubles the size of the lazarette stowage and creates the option for a tender garage – another first for Oyster.

It is rare for an owner to know exactly what they want in a yacht of this size, so having all these options designed in is a way of helping the owner and the yard to create a personalised yacht. “We can’t change the main structural bulkheads but there is enough latitude within the design by Rob [Humphreys] to offer a variety of layouts,” Oyster’s CEO David Tydeman explained. “We can’t take it to extremes but we’re a hell of a lot more flexible than we used to be.”

Other than her sportier shape and style, first impressions of the 675 might not be that dissimilar to the 625 (as. Indeed it has a very similar four-cabin layout, albeit without needing the walk-through galley of the 625. But the 675 is £500,000 more expensive than the 625, which sounds like a lot for an extra 3ft of length. But you only need small gains in length to create significant extra volume.

In comparison to the 625 and the 655, the 675 has more volume in all three dimensions, with higher topsides, more beam and more volume in the bow. This creates sufficient space for a forward master cabin with en-suite heads, or a large guest cabin in the bow. Depending on the choices made forward, the aft cabin space can remain intact or be divided into two.

Oyster considers this new 675 to be about the limit in size an owner can still operate a yacht without crew, yet concedes that a temporary paid hand may still be advisable to keep the yacht suitably maintained. But the simultaneous launch of another new design, the 745, is for those who will sail with crew.

“Most of our big boat success has been through loyalty,” says Tydeman, referring to the 72ft-88ft bracket. It is interesting therefore that two thirds of Oyster owners in the 62ft-72ft bracket are new to the brand. The owners of the test boat Babiana are very capable ex-Swan 45 sailors, for example, who want to sail themselves and use an occasional paid hand – exactly the sort of use for which the boat is designed.

Smooth running

Something happens when you leave port on a quality-built superyacht: you don’t really hear anything. If you are below decks you may not even notice you are moving. I had a similar experience on the 675. There was no big fanfare and no propulsion vibration.

Where we tested: The Solent

Wind: 5-13 knots over calm sea.

Model: hull no 1, Babiana, with conventional transom and owner’s cabin aft

Insulation, together with the peace it can bring, is especially important for a centre-cockpit boat, on which owners tend to live aboard for long periods. Observing the yachts in build helps you appreciate how Oyster achieves this effect. The plywood for example includes an insulation sandwich within the layers of ply, and every joint is sealed with glassfibre to make it airtight and boost sound insulation. The result is remarkably relaxing.

It’s perhaps customary to see modern large Oysters sporting carbon rigs and fully battened sails, so it was slightly surprising to find a more cruising-friendly Spectra mainsail unfurl from Babiana’s alloy mast. But I was told that 90 per cent of 655s were fitted with an in-mast solution – a choice that is indicative of a hands-on owner who wants to cruise short-handed.

The test boat was only three-quarters commissioned, the rig stepped just in time for the yacht to make its world debut at Southampton Boat Show in September. Our trial was more of a snapshot on the day after the show closed. The boat then left directly for Ipswich, where the rig was due to be removed before she is transported this winter to the Düsseldorf Boat Show.

So she wasn’t exactly ‘tuned’, but during our initial fetch that turned into a beat down Southampton Water in 10 knots of breeze, I quickly learnt that she is more than capable of creating a good first impression. In 7 to 9 knots true we matched the breeze with sails slightly freed, and when the wind speed hit double figures I could feel more power as the boat heeled. “We’ve gone wider aft with more form stability than before,” Rob Humphreys commented, while also sailing her for the first time.

We tacked out through the main channel around the Brambles Bank, the blade jib making the 38-tonne yacht nimble enough to be thrown quickly through the tacks. The use of a blade rather than Oyster’s conventional overlapping headsail helps her point and also keeps the clew forward and well away from the guest cockpit. The jib is tacked to an electric Reckmann furler and there is a hydraulically tensioned removable inner stormstay fitted as standard.

The 675 felt nicely balanced. The twin spade rudders, bonded to composite rudder stocks, ensure a light feel on the wheel without losing that telltale nudge when they load up. However, once the breeze dropped back below 7 knots, or when we were sailing at a deeper angle, the helm became neutral.

When the wind does disappear, the 180hp Volvo engine driving a Bruntons four-blade folding prop proved efficient (7 knots at 1,500rpm) and there are vast fuel tanks (1,900lt) for long-distance cruising.

The helm position is a little high and inboard for my liking. To leeward, for instance, I found myself straining out to see the telltales and there is no comfortable position to perch out or stand over the high coaming. But there is a good, clear view forward over that lower-profile coachroof and the double helm seats each side provide a luxurious place from which to command a watch.

The jib sheet lead is cleverly designed to run aft along the base of the long coachroof windows and up through a moulded scoop in the coamings directly to the primaries each side. The boom ends relatively far aft with a single point mainsheet led straight to an aft winch, negating the need for a traveller. The primary and runner/spinnaker winches are mounted aft of the helms, to keep the cockpit clear for guest use.

The cockpit forward of the twin binnacles is suitably resplendent – ideal for guests wishing to remain clear of the sailing systems. The beamy aft deck extends even further if a counter stern is chosen and the excellent quarter benches are large enough to seat three each side.