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Overwintering afloat: what matters for the boat and the policy?
Short answer
A boat can spend the winter afloat if the bilge pump keeps running,
the lines are right and someone checks on it regularly.
Many wordings exclude frost and ice on their own, so precautions count for more afloat than ashore.
More and more owners leave the boat in the water over winter, because lift out, hard standing and transport are expensive, or because they want to keep sailing on bright winter days. In a tidal UK marina ice on the water is rare, but frost in pipes and seacocks is not, and winter gales do more harm than both. The usual dangers are frozen water systems, a bilge pump that stops when the battery goes flat, lines chafing through in a gale and water getting in through a cockpit drain or stern gland nobody has looked at for weeks.
What matters comes down to three things. The water on board: winterise the engine and domestic systems, close seacocks you do not need, and run the bilge pump from shore power with a battery kept charged, if the marina allows unattended shore power. The lines: doubled, with chafe protection at the cleats and enough slack for tide and surge. The checks: agree with the marina who looks at the boat after every gale or hard frost, and read the marina contract, since many marinas set rules on winter afloat and heaters. In the Netherlands and on inland waters, where ice does form, a bubbler keeping the water open around the hull is worth considering.
In the policy, winter afloat is a different risk from winter ashore. Many wordings exclude damage by frost and ice unless it follows a storm or another insured peril, so a hull pressed in by ice on a calm day may well fall outside the cover. Ours does: storm counts in Basis from force 8, Basis Plus and Premium set no threshold, and with our season policy there is no cover from 1 November to 31 March, afloat included. Some policies assume the boat is laid up ashore for part of the year, so check the lay-up clause and tell the insurer or broker if the boat stays afloat. Keep a short winter log with dates, checks, the state of the lines and photographs; after a claim it shows the boat was looked after.
Leaving a boat in the water over winter: pros and cons
Leaving a boat in the water over winter is normal in many UK and Mediterranean marinas, and it has real advantages: no lift out and storage costs, no stress on the hull from cradles or stands, and the chance to sail on good winter days. The boat is also often closer to hand, so a quick check after a gale is easier. Against that, the hull cannot dry out, marine growth continues more slowly, and storms, chafe and flat batteries become the main risks.
A season ashore makes underwater inspection and work far easier, so many owners alternate, or lift out briefly in spring to clean, inspect and antifoul. Whichever you choose, the decision should depend on the shelter of the berth, how often someone can check the boat, and the age and condition of the hull and fittings below the waterline.
Steel boat afloat in winter: anodes, stray current and ice
A steel boat in the water over winter depends on its anodes. Check them before the winter and replace any that are well used, because they keep working whether the boat is used or not. If the boat stays on shore power, a galvanic isolator or isolation transformer protects the hull against currents from neighbouring boats and the marina installation; the page on stray current corrosion explains the risk in more detail.
Inside a steel hull, condensation is a winter problem. Good ventilation, dry bilges and, where allowed, a low level of heating reduce it. On inland waters where ice forms, ice can abrade the paint at the waterline and expose bare steel, which is another reason to keep the water open around the hull or move the boat to a sheltered berth.
GRP boat afloat in winter and the question of osmosis
A GRP hull absorbs a small amount of moisture as long as it is in the water. That is normal and not a defect in itself, but boats that stay afloat for years without a period ashore give the laminate no chance to dry. Many surveyors therefore recommend lifting the boat out from time to time, letting it dry and having moisture readings taken, so that any developing osmosis is found early.
Leaving a GRP boat in the water over winter is not a problem in itself. What matters is the condition of the gelcoat and the antifouling, regular inspections when the boat is lifted and a record of moisture readings over the years. The separate page on osmosis covers the causes, the signs and how it is assessed.
Winter afloat in a tidal marina or on inland waters
In a tidal marina the lines have to cope with the full range of the tide and with surge from winter storms. Doubled lines with chafe protection, enough slack for the highest tides and springs or snubbers to absorb shock loads are the basics. Check that the pontoon itself is in good condition, because pontoons and their fixings also take a beating in winter gales.
On rivers and canals the risks differ: rising water after heavy rain, floating debris, strong currents and on some waters ice. Make sure lines can follow the water level, keep an eye on flood warnings for the river, and on waters where ice forms consider a bubbler or moving the boat. The pages on flooding and winter storage cover these situations in more detail.
Worth remembering
Storm
insured, in Basis from force 8
Frost and ice
on their own often excluded
Overwintering afloat takes precautions, not hope.
Questions
What owners ask us about this
Is ice pressure on the hull insured?
Many wordings, ours included, exclude frost and ice as weather unless they follow an insured storm. Read your wording on this point, and where ice forms, keep the water around the hull open.
Do I need to tell anyone if the boat stays afloat over winter?
Yes. Check the lay-up clause in the policy and tell the insurer or broker if the boat stays in the water. Check the marina contract as well, since many marinas set rules for winter afloat.
How often should I check the boat in winter?
After every gale, hard frost or heavy snow, and otherwise regularly, about once a week. Note each check with the date and a photograph.
Is it bad to leave a boat in the water all year round?
Not necessarily. Many boats stay afloat all year. What matters is a sheltered berth, regular checks, healthy anodes and gelcoat, and lifting the boat from time to time to inspect and clean the hull.
Should I run the engine during winter afloat?
Either winterise the engine fully or run it regularly under load until it reaches working temperature. Short idling without warming up tends to create condensation rather than prevent it.
Related
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