Coast 250 power sailer on test
What makes the Coast 250 a planing power-sailer like none we’ve seen before? David Harding finds out
Imagine this for a morning on the water. You start by motoring down the river at 15 knots. There’s no speed restriction and you want to get out to sea – for a sail. Once clear of the river, you find a brisk south-westerly kicking up a steep chop over the bar, so you throttle back to 10 knots and punch your way through it. Then you speed back up to 12 knots as you skim across the waves in the bay.
In open water further offshore, you turn off the engine. Your boat sails better than many dedicated sailing boats of similar size that would be lucky to motor at 6 knots. They would still be on the way down the river or bouncing over the bar, probably drenching you in spray or green water, while you’re having a lovely sail.
Does this sound farfetched? Until recently it probably would. You might have managed the planing under power, albeit with a good deal of slamming and banging outside the river and wondering whether your rig was going to stand it. And then you could have sailed, but rather painfully and in a boat that was heavily compromised.
The morning on the water I describe is exactly how things happened during my test sail with Swallow Yachts’ Coast 250. Here is a boat that does what no other trailable monohull of her size (or at least none I have come across) has managed to do: to zip along under engine and to sail very nicely too. Too large to be treated as a trailer-sailer, she can still be hitched up behind a large car and taken home for the winter or to new cruising grounds in the summer. Being able to motor at three times the speed of conventional trailable cruisers opens up areas you might not otherwise consider.
How, you might wonder, have Swallow Yachts succeeded where no one else has? After all, the power-sailer concept has been around for some decades so it’s not exactly new.
Moving forward
The answer involves nothing radical. It was a case of looking at the problems affecting earlier power-sailers and applying logical solutions from the worlds of both power and sail.
If you want a boat to plane under power, it needs a bigger engine than for displacement speeds. The problem is that a big outboard on the transom, as most power-sailers have, would weigh the boat down at the stern and make it squat. To support its weight you need a broad, immersed transom like a power boat, which is fine when you’re motoring at planing speeds but extremely inefficient at displacement speeds and under sail because it creates a vast amount of drag. That’s one reason why power-sailers traditionally haven’t sailed very well.
Matt Newland, the Coast’s designer and the man behind Swallow Yachts, moved the outboard forward to a well just abaft the companionway, thereby centralising the weight and obviating the need for the immersed transom. This also had the benefit of reducing pitching and ensuring full immersion of the prop in a seaway. An outboard is used because of the power-to-weight ratio: the 70hp Yamaha
weighs the same as a 10hp inboard with all its stern gear.
Computational Fluid Dynamics (CFD) testing with the Wolfson Unit in Southampton showed that moving the engine helped. In itself, however, it did not overcome the problem of squat because of the need for rocker (fore-and-aft curvature to the underside of the hull). Broadly speaking, sailing boats need rocker whereas planing powerboats with immersed transoms don’t. Sailing boats also need transoms that are clear (or largely clear) of the water at rest.
It was clear from the CFD testing that, even with the engine moved forward, the Coast would still trim bow-up and the uncompromised sailing-boat hull would produce too much drag. It was time to deploy the secret weapon: trim tabs. Further CFD analysis showed that Matt’s idea of fitting tabs to the transom would eliminate the squat, bring the bow down and allow the boat to achieve the speeds he wanted with the engine. Since relying purely on CFD would be a leap of faith, Matt built a full-sized wooden hull, added ballast equivalent to the weight of the keel, engine, rig and interior, fitted the tabs and spent many a cold winter hour getting wet on the river Teifi.
On the level
It’s by no means uncommon for ideas that appear in a new boat to have been seen before even if the designer hasn’t knowingly borrowed them from elsewhere. For example, Ian Anderson’s 37ft (11.3m) MRCB (multi-role cruising boat) was a power-sailer, albeit a much bigger one, that used ‘variable hull geometry’ – essentially integrated trim tabs – to flatten the stern sections and create an efficient shape for planing under power. I saw the MRCB charging around off Dartmouth when I lived there in the 1980s. Sadly, and despite being ahead of its time in some respects, the design never took off commercially.
Trailable power-sailers have fared rather better. Best-known by far is the MacGregor 26 in its various guises. Then there was the Odin 26, later re-born as the Imexus 27, and Legend’s Edge 27. These would hop up on the plane when the throttle was opened but, having tested all of them over the past 20-odd years, I would be struggling to say that their sailing performance was anything to get excited about. The most competent sailer by a country mile (or should that be a nautical mile?) was the Tide 28, which made the headlines when a 14-year-old Michael Perham sailed Cheeky Monkey across the Atlantic in 2007.
So, what is the Coast really like as a motorboat and as a sailing boat? Since our test began in the river, on the drying mooring just off the slipway leading to Swallow’s yard, it was a good opportunity to see how she performed under power in flat water. We started by opening the ‘doors’ in the bottom of the engine well that create a flush hull in sailing mode. Then we lowered the engine, 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 with the outboard working flat out, 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!”
Easy does it
Despite Matt’s eagerness to crack on, 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 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.
‘It’s not a motorboat. It’s a sailing boat that has a big engine and some trim tabs’
Out in the estuary the sea was distinctly lumpy. Throttling back from 4,600rpm to 3,900rpm still gave us 9.5 knots over the ground and a surprisingly comfortable ride to boot. Perhaps because the carbon rig is lighter and stiffer than the relatively spindly aluminium rigs seen on some power-sailers, it didn’t seem to mind the boat bouncing at speed underneath it. Its inertia would also have thrown us around a good deal less.
As Matt says: “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’d love to.”
Converts or not, there’s no doubt that the Coast motors remarkably well. In terms of the minimal wash and virtual absence of a hump she’s more impressive than many powerboats. You have to bear in mind that she’s carrying a rig and 300kg (660lb) of ballast and, of course, that a 70hp engine on a boat of this size and weight is tiny in powerboat terms. By any standards, however, her power-tospeed ratio is pretty good.
Leaving a few inches of the swing keel down improves directional stability when you’re motoring and, in shallow water, it affords the engine some protection. You can reduce draught further by trimming up, just as you would with a transommounted outboard.
At full chat the engine drinks around 20lt per hour, so three 25lt 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 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 see a Coast with a smaller engine, you would quite possibly have no idea that she was anything other than a pure sailing boat, albeit one in the modern style with high and near-vertical topsides. Any concessions – such as they are – to power-planing are of minimal significance.
The high aspect-ratio keel is a profiled, reinforced composite moulding with a lead bulb at its tip, giving a maximum draught of 1.85m (6ft 1in). That’s deep for a 25-footer and it places the ballast a long way down, giving 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 judder you sometimes experience with swing keels. The short, sharp chop during our test 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. With a keel of that depth, a few degrees has a significant effect on the boat’s CLR (centre of lateral resistance).
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. Twist notwithstanding, 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 (thanks in part to the foam-cored topsides), efficient keel section and low centre of gravity make her a more-thancompetent performer under sail. She’s responsive, fun, eager to surf (even though I wondered at times if a little more bow-up trim might have helped), probably capable of planing in a breeze, easy to manage and undoubtedly quick enough to worry some pretty sporty boats of similar size.
Accommodation
Below decks it’s very much a matter of the pictures telling the story.
At 1.70m (5ft 7in), 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 T&G plywood and foambacked vinyl complete the simple trim. The keel case, inevitably a dominant feature, supports the table with its hinge-out leaves.
Seating is comfortable and eye-level ports in the hull-sides let you see out.
A flush hatch in the foredeck is over the forward berth, which can be extended from day-time mode to its full length of 1.95m (6ft 5in). 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, there’s length for 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 hastilyfinished prototype. Production models will see a number of refinements and neater trim all round. 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.
PBO’s verdict
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 won’t find much out there apart from the Coast that does all that.
Even if power-planing is of no interest to you, the boat’s other attributes make her worthy of attention.
She’s sure to gain converts in the form of sailors who might otherwise have moved to motorboating. I would be surprised if owners of older power-sailers don’t take more than a passing interest too, because here’s a boat that really does deliver what it promises. With the Coast 250, the power-sailer has finally come of age.