Computers: In the swim with a laptop: Mike Hewitt on how to be cool about this season's hi-tech designer accessory

IF YOU WANT to make a splash on the beach this summer, ditch your old, under-powered beige portable and pick up one of this season's ultra-chic, high-performance laptops. Finished in an eclectic mix of greys and blacks and styled with discreetly seductive curves, these hot new machines will make you really sizzle in the sun.

That, at least, seems to be the current message from several of the leading men's fashion magazines. Portable computers are 'in' this year, they claim, set to displace cellphones as the style items to ostentatiously whip out in a public place. If they are a match for your Speedo swimming trunks, so much the better.

But before you start strolling around Clacton with GQ's 'Editor's Choice', it is worth considering the other factors, apart from colour co-ordination, that are important when selecting the best laptop for the beach.

The processor is all-important. If it is a PC-compatible, being stuck with a weedy 386SX processor, or less, when every other beach blanket is Pentium-ready, is the hi-tech equivalent of getting sand kicked in your face. There's no 'Dynamic Tension' course for silicon, so go for the most powerful laptop your credit card can afford.

Poseur value aside, it also makes practical sense. Today's Windowsbased programs are generally so hungry for memory - and getting more ravenous with each new version - that, at the very least, they demand a fast 386 or 486SX chip. Add to that a minimum of 4 megabytes of main memory (ram) and a hard disk no smaller than 100 megabytes. What this will give is something as functional as a desktop machine, compressed so it is not much bigger than a lunch box.

Here is one area, at least, where size does matter. You have got to be able to stow the thing in a standard beach bag, alongside the Jeffrey Archer and the thermos flask. Do not go for any 'portable' that has to be lugged along the shoreline in one of those massive padded shoulder bags. The ice cream vendors will think you are trying to muscle in on their trade.

By the same token, your chosen laptop should not be too small, either. Aside from looking like one of those cheap electronic organisers that Reader's Digest gives away free, diminutive machines easily get sat on or lost among sweet wrappers and tissues. Besides which, a keyboard much less than nine inches wide is not really suitable for anything other than 'hunt and poke'.

Fortunately, most of the newer 486 laptops oblige when it comes to size and functionality. The sub-notebook Toshiba T3400, for example, can easily be hidden behind a prawn sandwich and a pack of crisps. Yet, with a favourable tailwind, you can still achieve typing speeds in excess of 60 words per minute. Even the multimedia IBM Thinkpad 755C will fit into a small holdall with room to spare for the CD-roms, PCMCIA cards, external microphone and speakers. And, of course, for the additional batteries needed to give all of this a lifespan in excess of an ice cube in a greenhouse.

Here is the downside to computing al fresco. The average beach suffers from an unfortunate dearth of AC electric outlets which does rather inconvenience beach-bound laptop users when a 'battery low' crisis approaches and they need a recharge.

However, most laptops feature power management options, which allow selected parts of the unit, such as the hard disk, to be told to shut themselves down if not required. Machines equipped with the newer SL chips also selectively switch off some of the more power-intensive parts of the processor. And you can tell the processor to embark on a 'go slow', reducing its operating speed from, say, 33 megahertz to 16 megahertz.

Choosing a portable that takes Nickel Metal Hydride (Ni-MH) batteries also helps. These hold their charge longer than the old Nicads. Nevertheless, even with Ni-MHs and sophisticated power-saving niceties enabled, if you manage to get much more than about four hours from a single charge, the Guinness Book of Records will probably want to send a man round.

So the only real answer is to pack two or more pre-charged batteries. Indeed, some machines, including the new Apple PowerBooks, the 520 and 540, and the IBM Thinkpad accommodate two cells as standard. Have a care, though. A laptop's LCD display shares a common failing with a Fyffe's banana: both turn black when exposed to strong, direct sunlight. In the LCD's case, there are a number of reasons. The temperature rise can cause the screen controller to go out of phase with the display. Also, the heat causes a physical change in the reflectivity of the crystals, so reducing contrast. Prolonged exposure occasionally results in irreversible damage.

Colour displays are naturally more susceptible than monochrome because they have three times as many transistors to screw up. The best way to avoid such LCD armageddon is probably to shelter beneath a big beach umbrella, or wear a wide-brimmed hat.

On a similar note, watch out, too, if your laptop has a so-called 'clamshell' case. It could act as a come-on to any amorous bi-valves and some of the more broad-minded winkles. There are other, more obvious beach hazards. Suntan lotion applied liberally to the keyboard and tracker-ball (or mouse) soon makes a laptop greasy and unmanageable.

Then there's the ever-present danger posed by fine, air-borne sand particles getting where they should not. And if you have to keep inserting and removing floppy disks, you could find that by the end of the day you have inadvertently shovelled half the beach into the portable's innards. Finally, you might get so engrossed in your work that you do not notice the tide coming in. No manufacturer has yet guaranteed its laptops as waterproof - or buoyant, for that matter.

Such problems, however, are ultimately like jellyfish in the swimming trunks: a small price to pay for an otherwise enjoyable day out by the seaside. If you choose a robust, beach-friendly laptop, that day will be enhanced immeasurably. As Britain continues to sizzle in the summer sun, dare you risk being the only person on the beach without one?