Inter 20 - an awful lot of cat for the money

This is just about the ultimate in machinery for those who like main-lining raw speed.

Sunday December 17th 2000, Author: Peter Bentley, Location: None
Speed ...The genesis of the Inter 20 (and the Formula 20 rule that it’s drawn to) seems to stem from the pathological desire of the hard-core catamaran sailor for more speed. And longer means faster - first there were Formula 18s, now there are Formula 20s; first there were Inter 18s, now there are Inter 20s.

Experienced cat sailors Stuart Gummer and Steve Mellors put the Inter 20 through its paces for the madforsailing scoreboard in some brisk conditions. The Inter 20 is a two-person, two-trapeze, three-sail cat with a generous area of asymmetric spinnaker. In short, it’s a beast. Drawn by accomplished multi-hull designer Gino Morelli, we were expecting something special from a boat that’s already taken line honours in the Round Texel Race two years running.

The reviewer wasn’t disappointed - from the moment we had trouble keeping up in the RIB, as the Inter 20 blasted away at speeds in excess of 20 knots. Just a shower of fast fading spray left for the camera. So it’ll come as no surprise to you, dear reader, that the Inter 20 scores magnificently on performance. Small sailboats just don’t go much quicker.

But it does well elsewhere too; once up to speed, upwind steering is fingertip light and precise, bear-aways are instant. Fully powered up on a two-sail reach, the boat goes where you point it. There is no hint of cavitation or stalling and remarkably, never a hint of loading up in the rudders. The hull shape provides the excellent control, and the critical fore and aft distribution of buoyancy is near perfect.

Tacking is straightforward even in short seas, provided it’s done at a reasonable speed. Gybing is not too scary and getting the kite up and down is reasonably easy. And once the spinnaker is up and sheeted in, performance hits the red-line Ferrari league. The systems are well designed, and the smooth running Harken fittings make the beast easy to master. And for a big, powerful, high-tech cat, the Inter 20 is straightforward to assemble and rig, and is inside the maximum European towing width.

There were a couple of niggles and low point scores. The jib sheets can be tricky to release from flat out on the wire, though a small modification to the cleat angle would probably sort it out. There was also the suspicion, although not tested, that the hull shape performance could be lacking in flat water and light airs. But hey, who wants to sail this baby in light air?

This mighty machine still manages to retail at under ten big ones (at the time of review), including VAT and assembly help from UK importer, Don Findlay. The hard work is paying off, and the Inter 20 has already been successful under the Formula 20 Rule. It’s also been chosen as the catamaran for the awesome Worrell 1000.

There were only 29 in the UK in mid-2000, but they are just about all owned by serious, adrenaline-addicted racers. Only one of those 29 is not attending this year's Nationals. Not for the faint of heart, the Inter 20 is a demanding and seriously quick boat to sail. But it may well offer the ultimate speed rush delivered by a production multi-hull dinghy.

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The Nitty Gritty

Ease of Sailing

Solid marks here, especially for such a wicked looking piece of kit. As with any big cat, getting off the beach requires reasonable manpower to keep the boat head-to-wind in the surf, but once into deep water both the rudders and centreboards slip down effortlessly to provide some bite and the fun begins. The delicate-looking design of the tillers gives a hint that rudder loads are minimal, but it's only at speed that the true nature of this boat's directional control can be fully appreciated. Upwind, it really is fingertip light with a beautiful feel and lack of play. The rubber couplings between the tiller bar and the tillers provide the barest hint of self-centring, and more importantly, a precision, silky smooth feel.

Tacking is drama free, provided reasonable speed is carried into the tack there is no need to back the jib. This remained true even in the short seas that were building as we approached the end of the test. In a gybe the kite swept through the relatively narrow gap between headstay and luff without any difficulty. The fore and aft positioning of crew weight is important, but not as critical in the Inter 20 as some high performance catamarans. On a powered-up two-sail reach it's important to get the weight right back, but at other times downwind it proved necessary to move weight forward.

Downwind, maximum thrills are definitely achieved with both crew out on the wire. But the best VMG speed was probably achieved by doing the wild thing. There is some speed loss with the helmsman in and the crew to leeward, but the benefit is a much deeper course. As the pressure builds through 18 knots the crew needs to move to windward to keep things moving. It's hard to tell exactly what the optimum angle is with just one boat, but race conditions should tell you the fastest option pretty quickly. Whichever route you choose, it's as controllable as these things can be at speeds in excess of 20 knots.

The Inter 20 is undoubtedly a powerful boat, but it is also a forgiving one. Stuart reckoned that anyone with a moderate amount of multi-hull experience ought to be able to master it without too much difficulty.

Systems and Layout

The Inter 20 is by no means complicated to assemble. The UK importer, Don Findlay (who assembles every new boat for the first time before delivery), reckons the job can be undertaken in just a couple of hours. The really good news is that with the boat inside the maximum European towing width, it's a job that won't have to be done very often. Unless you live very close to the beach, or sail from just one club, the rig does have to go up and down pretty regularly. Fortunately, even this presents few problems. The light carbon tube is easy to handle and Don regularly rigs the whole thing himself without any assistance. The trampolines slide into exceptionally neat grooves in the hulls and there is very little to do in the way of lacing and tensioning - a time-consuming task that afflicts so many old cat designs.

Once on the water, the Inter 20 benefits from a simple layout, superbly designed systems and a full Harken fit-out. The result is that everything runs freely and works virtually to perfection. Upwind, the kite stows in a highly effective zip bag and getting it up proves pretty simple, as does dousing it. Just one line serves to activate the halyard and the tack-line. All the necessary tackle is hidden out of harm's way inside the bowsprit. It runs very freely, but we felt that a 1:2 reverse tackle could prove a good idea. It would reduce the amount of halyard that had to be pulled to get the thing up, making for an even quicker hoist.


This is a demanding and seriously quick boat to sail. As with all multi-hull, the fore and aft distribution of buoyancy is critical. Morelli has put his experience designing big offshore boats to good effect, producing a hull form with plenty of reserve buoyancy forward. The result is near to perfection, safe handling at ridiculous speeds. For the experienced it offers something near to the ultimate performance available in a production multi-hull.

Build Quality

As might be expected, the Inter 20 construction is about as hi-tech as it is possible to get, within the constraints of the International Formula 20 rule. The two hulls (which are marginally asymmetrical) are each moulded in two halves and joined along the centreline in a manner that leaves the join barely perceptible. The mast comes from Omahundro in the USA, while the sails are by Performance Sails of Holland. It is all one-design, with just a single approved supplier for each item.

The attention to detail is almost impeccable, with our test crew reporting just a couple of tiny malfunctions on what is a big powerful boat. We’ve already mentioned that the jib sheets were tricky to release from flat out on the wire. The only other grumble was that Steve thought the - otherwise excellent - non-slip might be better extended further round the deck edge, to provide more support for the crew's feet. As might be expected, the pristine trampoline proved slippery. But given that this was a brand-new boat, we couldn't quite bring ourselves to take up Don's suggestion and chuck a handful of sand on it to calm things down.

Anticipated Durability

Well-built and well-designed, there’s no reason to think that the Inter 20 is going to give you any trouble.

Quality of Race Circuit

The Inter 20 has already established itself as a serious contender under the Formula 20 rule with numerous regatta wins. The boats are selling well, and there’re plenty of other designs within the Formula 20 rule to race against. Add in selection for the Worrell 1000, and the Inter 20 has the credibility and the support to be around for a while. There should be no shortage of race competition.

Value for money

All this for less than £10,000 (mid-2000), and the Inter 20’s value for money takes some beating. An excellent boat at a great price, we were seriously impressed.

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