Suitable clothing
As long as the bad weather is manageable and the latitudes where you operate are mild in terms of temperatures, a traditional salopettes and jacket combination is perfect. But if the conditions become extreme, a survival suit will be essential.
Anticipate meals!
It’s very difficult to cook in severe weather. Prepare, if possible in advance, thermos of hot drinks, cereal bars and other dried fruits. Freeze-dried dishes are easy and quick to prepare; they allow you to eat hot food!
Keep the children safe
Children can stay in the cockpit as long as the seas are not too big. On condition that they’re wearing lifevests and harnesses.
Reef in time
Reducing the mainsail means positioning your multihull close-hauled or head to wind: easy when the sea is not too big, complicated with three-meter (10’) waves – even more-so at night. Take in a reef before you are caught out!
Furling the genoa
Reducing the genoa is possible at any speed. Remember to keep some tension on the sheet to prevent the sail and sheets from flogging too violently during the maneuver. The sailcloth, in this "half rolled" configuration, will suffer... It may be better to set a staysail on if you have a removable inner forestay, or simply to roll up the genoa completely.
Raise the daggerboards
The advantage of multihulls with daggerboards is that they can be raised all or part of the way in bad weather! The hulls can then slide more easily through the waves and make the helmsman's work easier.
Enough searoom?
The basic principle, in bad weather, is to move away from the area of strongest winds. Today, modern analysis of weather maps makes it possible to optimize its trajectory. But beware of the coasts: apart from some possible access in all weathers, many ports are inaccessible in very heavy seas. Allow yourself some searoom!
Heaving-to
Reefed main, jib sheeted in on the opposite tack and helm hard over: this is the classic hove-to configuration. The multihull advances and drifts in relative comfort. A good formula to avoid losing too much headway and/or rest.
Lying a-hull
If the wind and sea become very strong, it may be wise to lie a-hull, i.e. stow the mainsail and furl the jib completely. Depending on the desired course, the support of one or more motors can be useful.
Trailing lines
Sometimes, extreme conditions may require you to trail lines - provided you have enough searoom. Your multihull, with no sail up, or almost (three reefs in the mainsail ideally), practically flies downwind and accompanies the waves. To remain safe, it’s sometimes desirable to limit the speed: a looped trailing line, preferably on reels, can be very effective, provided there are reinforced anchoring points.
Protect the nacelle
Par mer forte de l’arrière, les nacelles très ouvertes sur le cockpit – ou plutôt les baies vitrées – peuvent être soumises à rude épreuve. Des batardeaux sont conseillés. A défaut, une annexe dégonflée ou un paddle – bien amarrés – feront l’affaire.
Survival equipment
Without getting bogged down in tales of catastrophe, an ingress of water or a capsize can occur under extreme conditions. A multihull doesn't sink, there's already that... However, preparation and composure will help. The key points: survival suit, access to the raft, survival ditch-bag with waterproof and fully-charged handheld VHF, knowing how to use the escape hatches.
