Sailing yachts are designed to sail and motorboats to motor, right? And never the twain shall interbreed – at least not successfully? This hasn’t stopped people trying.

Motor-sailers have always been around. More recently we have also seen the planing power-sailer, as epitomised by the phenomenally successful MacGregor 26.

Some might argue that power-sailers, like motor-sailers, have been compromises that neither motor nor sail particularly well.

But whatever your views, the fact is that now, nearly 25 years after the power-sailing version of the MacGregor (the MacGregor 26X) appeared, we have a British-built boat of similar size that will motor efficiently and comfortably at 15 knots without compromise to its sailing ability.

If you’re helming from the coaming, the engine box can be used as a foot brace. Credit: David Harding

So how has this been achieved, and what lessons have been learned from the attempts of earlier builders?

Well, all previous power-sailers that have sold in any number have had certain characteristics in common.

One is lacklustre sailing performance, even though I have met MacGregor owners who defend them to the hilt.

After MacGregor’s 26X came the 26M. It sailed slightly better but was still heavily compromised, as was the Polish-built Odin 26 (later reincarnated as the Imexus 27) and Legend’s Edge 27.

Video: Trailer sailing made easy

The best performer under sail was the Tide 28, which made the headlines when a 14-year-old Michael Perham sailed Cheeky Monkey across the Atlantic in 2007.

The challenge with designing a power-sailer is that sailing yachts and planing powerboats tend to have very different hull forms for good reason, even before you consider fundamentals like the sailing yacht’s need for ballast, a rig, and foils that generate lift.

Most power-sailers have had a large outboard on the broad stern of a hull with very little rocker, leading to an immersed transom to support the outboard’s weight and create sufficient lift for them to plane.

The folding solid-wood oak table sits on top of the lifting keel housing. Credit: David Harding

In this respect they have been just like conventional planing powerboats.

The problem is that sailing yachts need rocker (fore-and-aft curvature to the underside of the hull) and a transom that’s clear of the water at rest. They don’t like a lot of weight in the stern either, so the shape of the conventional power-sailer does it no favours under sail.

An idea whose time has come?

It so happens that I have sailed (and motored) all these power-sailers over the past 20-odd years.

I was also living on the Dart in the 1980s when Ian Anderson launched his 37ft (11.3m) MRCB (multi-role cruising boat), which was powered by 165hp of Volvo Penta diesel and helped along when the throttle was opened by ‘variable hull geometry’ – essentially integrated trim tabs that flattened the stern sections.

I remember seeing the MRCB in its creamy-yellow livery charging around at high speed off the mouth of the river.

A 70hp in its central well drives the Coast at up to 15 knots – or you can stick with 10hp for displacement speeds. Credit: David Harding

Sadly the idea never took off commercially but it was unquestionably ahead of its time.

Remembering the MRCB and having tested various power-sailers as well as many of the day-sailers and small cruisers built by Swallow Yachts, I was more than a little interested when Swallow’s Matt Newland mentioned that he was planning to develop a power-sailer whose sailing ability, he assured me, would not be compromised by its motoring performance.

This was a few years ago now — such projects take time.

It was clear from the outset that this boat would be very different from the MacGregor 26 and its ilk.

Swallow’s Coast 250 was to have – and does have – the 70hp outboard mounted in a well at the forward end of the cockpit, immediately abaft the keel case.

This overcomes the need for a broad, immersed transom that creates an enormous amount of drag under sail.

An optional carbon bowsprit for the asymmetric retracts into the anchor well. Credit: David Harding

Moving the engine was the starting point.

Through CFD (computational fluid dynamics) testing with the Wolfson Unit in Southampton, Matt soon came to realise that, with an uncompromised sailing-boat hull form, this shift of weight alone was not the solution.

The boat still trimmed bow-up and created too much drag under power to achieve the speeds he wanted.

His solution was to fit trim tabs on the transom to eliminate stern-squat and bring the bow down at planing speeds.

Further CFD analysis, followed by on-the-water testing with a full-size plywood hull ballasted to sailing weight, showed that the tabs made the crucial difference and allowed efficient planing at 15 knots.

That’s how the Coast evolved, but what’s she like to motor and sail and how does she perform in testing conditions?

THE TEST VERDICT

In the words of Matt Newland, the Coast’s designer and builder, ‘this is not a perfect motorboat. It’s a sailing boat that has a big engine and some trim tabs. It’s not going to set any motorboater’s heart alight and I’m not expecting to convert any motorboaters to sailing, though I would love to.’

Whether or not Matt and the Coast succeed in introducing motorboaters to the delights of sailing, I’m sure they will gain converts in the form of sailors who might otherwise have moved to motorboating or chosen a more conventional sailing yacht.

The wide, offset companionway allows easy access to the cabin around the engine box. The head compartment is to starboard. Credit: David Harding

He might also attract former (or current) owners of other power-sailers that they have found unrewarding or plain disappointing under sail.

The power-sailer concept has always had its appeal but, apart from the MRCB, the Coast is the only one I have come across that really seems to deliver the goods in both modes.

Great attention to detail has been paid to every aspect of the design.

WOULD SHE SUIT YOU AND YOUR CREW?

In many ways it’s a simple choice: do you want a boat of this size that sails well, offers roomy accommodation, will sit on a drying mooring, can be trailed behind a large family car and motors at 15 knots?

You will find precious little else, if anything, that does all that.

Even if the planing performance under power is of no consequence to you, the Coast’s other attributes make her worthy of attention.

She’s not cheap because of what she is.

For example, the carbon rig makes so much sense under both power and sail.

A cassette system around the gooseneck simplifies removal of the boom.

A boat of this size and weight can’t be described as a trailer-sailer, but she’s certainly a trailable sailer and an extremely clever, well-conceived, versatile and practical one too.

FACTS AND FIGURES

Price as tested: £77,771
LOA (including rudders):  7.95m(26ft 1in)
Hull Length: 7.57m (24ft 10in)
LWL: 7.57m (24ft 10in)
Beam: 2.55m (8ft 4in)
Draught: keel up 0.4m (1ft 4in)
Keel down: 1.85m (6ft 1in)
Displacement: 1,300kg (2,866lb)
Ballast: 300kg (661lb)
Ballast ratio: 23%
Displacement/Length: 83.60
Sail area: 28.6m2 (307.86sq ft)
SA/D ratio: 24.40
Fuel: 75 litres (16.5gal)
Water: 70 litres (15.4 gal)
Engine: 10 or 70hp
Transmission: Outboard
RCD category: C
Designer: Swallow Yachts
Builder: Swallow Yachts
Tel: 01239 615482
Website: Swallowyachts.com