Work out your budget before you fall in love

Narrowboats are beguiling. A gleaming paint job and a wood-burning stove can make you forget you are buying a steel tube that lives in water. Start with numbers instead of dreams. A sound, unfashionable 45ft to 57ft boat with a dated but tidy fit-out typically sits somewhere between £30,000 and £55,000. Add £15,000 or more if you want a recent professional fit-out, modern electrics and a decent engine. Anything advertised well below that range usually has a reason, and the reason is usually the hull.

Then budget for the things the advert never mentions. In your first year, set aside £3,000 to £5,000 on top of the purchase price for a pre-purchase survey, craning out, blacking, anodes, a full service, insurance, a licence and mooring fees. If that makes the numbers uncomfortable, buy a smaller boat rather than a tired one.

The hull is everything – never skip the survey

This is the one place you cannot economise. Commission a full pre-purchase survey with the boat out of the water, carried out by a surveyor who works on inland waterways rather than sea-going yachts. They will use an ultrasonic thickness gauge to measure the steel at dozens of points along the hull, and the report will tell you far more than any advert can.

As a rough guide, a well-built boat starts with a 10mm baseplate and 6mm sides. Steel wears from the inside as well as the outside, so look for pitting and localised thinning rather than a single average figure. Ask:

• When was the boat last out of the water, and can the owner show receipts for blacking and anodes?
• Are there any previous survey reports, and have the recommendations been carried out?
• Is there corrosion around the bow, the stern gear, the waterline or beneath the weed hatch?

Overplating is not automatically a deal-breaker, but it should be done to a known standard with proper documentation. If the surveyor sounds cautious, listen. There is always another boat.

Engine hours matter less than maintenance

A diesel engine with 5,000 hours and a thick folder of oil changes is often a better bet than one with 800 hours and no history. These are slow-revving, marinised industrial units and they run for decades when looked after. Ask for a logbook, then verify the basics yourself.

Insist on a cold start. Feel the exhaust for smoke, listen for knocking, and let it run up to working temperature before you accept it. Check the gearbox engages smoothly in forward and reverse, and look for oil or water weeping around the stern gland and propshaft. Find out whether the engine is cooled by raw water or by a keel tank – the latter is generally less trouble. Check the alternator, the battery bank and the age of the starter battery, because replacing these adds up quickly.

Layout is personal – stern style is not

You will spend more time in the back of the boat than anywhere else. A traditional stern gives you the most cabin space but is a cramped, unsociable place to stand for hours. A cruiser stern offers a generous cockpit for guests and dogs, at the cost of internal room. A semi-traditional stern is the usual compromise, and for a first boat it is often the sensible one.

Inside, be honest about how you will use the boat. Fixed beds are wonderful until you need to change the sheets in a tight space; make-up beds are fine for weekends and irritating for months. Check the length of the bed and the height of the galley worktop – stand in it properly. Decide on a cassette toilet, which is simple and cheap to empty, or a pump-out, which feels more domestic but ties you to finding a pump-out point. A solid fuel stove plus a diesel heater is the classic British combination for a reason.

Paperwork, moorings and the running costs

A boat needs a current boat safety certificate, a valid licence from the navigation authority and insurance before it goes anywhere. Ask to see proof of ownership, and be wary of anything vague about the boat's history. If you want to live aboard, understand that a residential mooring needs planning permission; a leisure mooring does not permit year-round living, and authorities do check. Waiting lists in popular spots can run to years, so secure a mooring before you commit to a boat, not after.

Have a second viewing, then make a conditional offer

Return on a wet weekday, ideally with someone who has owned a boat before. Smell for damp, look for water stains around windows and vents, and run every tap, light and appliance. Ask the owner what they would fix if they were keeping her – the answer is usually revealing.

When you are ready, offer subject to a satisfactory survey, with the deposit held by the broker or a solicitor and returned if the survey reveals serious problems. If the hull report is poor, walk away without guilt. The right boat is worth waiting for, and the waterways will still be there next spring.