MIGHTY MICRO CRUISER
Producing a boat that planes under power and sails like a thoroughbred has been an elusive quest for decades. Has Swallow Yachts’ Coast 250 succeeded where others have failed?
We put Swallow Yachts’ Coast 250 powersailer through her amazingly rapid paces
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 motorsailers, 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. 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. 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. 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 powersailer 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 (multirole 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. 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 powersailer 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.
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?
PERFORMANCE UNDER POWER
On the day when a weather window coincided with workable tides on the Teifi estuary, home to Swallow Yachts at the southern end of Cardigan Bay, a fresh and gusty south-westerly was kicking up a steep chop over the bar.
Since we started in the river, from the drying mooring off the slipway leading to the yard, it was a good opportunity to see what the Coast would do under engine in flat water. We started by opening the ‘doors’ in the bottom of the engine well that ensure a flush bottom under sail when the engine is retracted. Made of a hard plastic, they’re opened upwards by a manual purchase pulling against gas struts. Then we lowered the 70hp Yamaha, fired it up and got going, with the twin vertically-lifting rudders raised in their cassettes.
At 2,600rpm we made 6 knots. That’s roughly what you would expect from a conventional boat of similar size, only the Coast kicked up very little wash and made it feel like a gentle stroll. Matt was growing impatient. ‘When you’re used to doing 12-15 knots under power, 6 knots feels boring because motoring is boring and I want to be out there sailing!’
I wanted to see how the boat behaved at speeds between displacement and full tilt, so I opened the throttle progressively. At 7.5 knots the bow began to rise slightly and the turbulence to break away from the transom. The interesting change occurred at 8 knots: the bow rose a little further and it felt an inefficient speed, as though the boat were trying to climb over the ‘hump’ that afflicts most planing hulls. At this point it took only the briefest nudge of the button that lowers the tabs to bring about a remarkable transformation. The bow came down, the revs increased and the boat accelerated to 13 knots over the ground against the incoming tide as it was
The boat punched and sliced her way through the unforgiving seas with remarkable composure
funnelled through the mouth of the river. And we hadn’t touched the throttle. That’s the power of the tabs, which are Matt’s own design based on an established principle. In their sailing position they look just like a small sugar scoop extending the stern.
Out in the estuary the sea was distinctly lumpy. Throttling back from 4,600 to 3,900rpm still gave us 9.5 knots over the ground and a surprisingly comfortable ride to boot. I have found other powersailers slamming alarmingly in a much easier sea, their rigs jarring, waving around and looking as though they might come down at any moment. Everything felt perfectly relaxed with the Coast. Perhaps because the carbon rig is lighter and stiffer than a relatively spindly aluminium rig, it didn’t seem to mind at all and its inertia would have thrown the boat around a good deal less.
There’s no doubt that the Coast motors remarkably well. In terms of the minimal wash and the virtual absence of a hump (assuming the tabs are used appropriately) she’s more impressive than many powerboats. Of course she’s carrying a rig and 660lb (300kg) of ballast, and a 70hp engine on a boat of this size and weight is small by powerboat standards. It weighs about the same as a 10hp inboard with all the stern gear, and that would most certainly not push the boat along at 15 knots.
Leaving a few inches of the swing keel down improves directional stability under power and, in shallow water, affords the engine some protection. You can reduce draught further by trimming up, just as you would with a transom-mounted outboard. At full chat the engine drinks around 20L per hour, so three 25L tanks (which will fit in the locker beneath the cockpit) give a range of 55 miles or so. Throttling back to 6 knots should take you 90 miles. If you have no interest in motoring above displacement speeds you can save weight and cost by choosing a 9.9hp
outboard instead. Whichever engine you choose, you can – if necessary – lift it out with the help of the mainsheet attached to the boom, though routine maintenance can be carried out in situ.
PERFORMANCE UNDER SAIL
If you were to look at a Coast with a smaller engine, you would quite possibly have no idea that she was anything other than a pure sailing boat. Any concessions – if you can call them that – to powerplaning performance are of minimal significance. The high aspect-ratio keel is a profiled, reinforced composite moulding with a lead bulb at its tip, giving a draught of 6ft 1in (1.85m) when fully lowered. That’s deep for a 25-footer and places the ballast a long way down for a healthy righting moment and an AVS (angle of vanishing stability) of 130°. A switch in the cockpit activates the winch and the keel can also be raised and lowered manually from the cabin. When the keel is down you could be sailing a fin-keeler: there’s none of the slop, play or juddering you sometimes experience with swing keels. The short, sharp chop would have shown up any there was. It did, however, make it hard for the Coast to get into her stride in a breeze that had moderated to a gusty 10-18 knots.
Despite the unforgiving seas, she punched and sliced her way through them with remarkable composure for a 25-footer, up to 4.8 knots showing on the GPS against the north-going current. Tacking angles were hard to assess with the shiftiness of the wind but interpolation suggested they were within 80°.When you’re sailing upwind in a breeze using the tiller extension, the windward coaming makes a comfortable perch and you can lean back against the guardwires, bracing your forward foot against the engine casing if you need to. A positive and direct feel is transmitted to the tiller from the twin rudders and, if you feel inclined, you can play with the helm balance by raising the keel a little.
As soon as you crack off the wind, a self-tacking jib inevitably twists open too far. That’s something you have to trade against the convenience, though Matt is contemplating the use of a permanent jib-stick of the type used by the K1 single-handed keelboat for example. We quickly hit 7 knots on a reach, when our speed over the ground would not have been influenced by the tide.
There’s no doubt that the Coast’s hull form, combined with her carbon rig, modest weight, efficient keel section and low centre of gravity make her a more-than-competent performer under sail.
BELOW RIGHT: With the keel projecting a few inches below the hull when raised, the Coast dries out at a slight angle
‘Motoring at 6 knots is boring and I want to be out there sailing’
She’s responsive, fun, eager to surf, probably capable of planing in a breeze, easy to manage and quick enough to worry racy boats of similar size.
ACCOMMODATION
At 5ft 7in (1.70m), headroom is more than generous for a shallow-hulled 25-footer. An interior moulding forms the basis of the layout up to the top of the bunks, then tongue and groove plywood and foambacked vinyl complete the simple trim. The keel case, inevitably a dominant feature, is used as a base for the table with its hinge-out leaves.
A flush hatch in the foredeck is over the forward berth, which can be extended from day-time mode to its full length of 6ft 5in (1.95m). Beneath it are the water tank, the battery and one of the Coast’s three buoyancy compartments.
If you don’t have the optional fridge aft to port under the slide-out galley with its cooker and hob, the seating is long enough to allow two six-footers to sleep head to head so you can have five berths. Opposite is the heads compartment, housing a chemical loo or a sea toilet.
Our test boat was the rather hastily-finished prototype. Production boats will see a number of refinements and neater trim. There was little to complain about all the same. It’s a roomy, light and airy space below decks and the layout should work well for weekending and coastal cruising.