A sea anchor
and a drogue
should be standard equipment
on multihulls venturing offshore. For the sea anchor
go by the manufacturer's recommendations for your size and type of boat. I have a 16 foot parachute for my 40 ft tri and a Sea Squid (also know as the Seabrake) drogue
. I have never had to use them in storm conditions but I have tried them out for practice.
The sea anchor should be deployed with very long nylon line 300-500 feet. It needs to be in the crests and troughs at the same time as the boat. The drogue is just the opposite. You want it in the trough when the boat is on the crest. Both are attached to the boat with a bridle
. This is where the wide beam really helps as varying tension on the bridle
greatly enhances directional control. John and Joan Cassanova used a surplus military chute as a sea anchor to survive a force 11-12 storm near Cape Horn in a 38 foot Horstman Trimaran. The anemometer broke after it pegged 100 m.p.h. That's enough to make me a believer.
Lying ahull is a tactic for less severe conditions without large breaking waves. The main factor in a boats ability to resist being rolled over by large waves is its roll moment of inertia. The cat has the edge over the trimaran here so it may be more successful lying ahull in severe conditions. Any cruising multihull will have a higher roll moment of inertia than a monohull
due to the weight of the hulls located far from the centerline.
Running off is also a very effective tactic as multihulls have very good control at high speed in large waves. They don't broach like a monohull.I have run off at speed in large waves in my tri. If the waves start getting too steep or the surfing speeds start to get unnerving reduce sail to quiet things down. You don't want to drive off a crest and stuff your bows into the trough. In storm conditions the hull
and rig may provide enough windage to get the boat up to surfing speed so then its time to put out the drogue. The widely spaced bridle will help hold the boat on a steady course. The problems with running are that you need plenty of searoom, an alert crew, and hopefully it does not take you in the wrong direction. Running before the wind
in a cyclonic disturbence may take you into the most dangerous part of the storm. You have to know your postion in relation to the storm center before you run off. If you are in the dangerous quadrant you need to go to windward or stop.
Heaving to may work well with some boats and not with others. You need to try it out in your boat to see how it behaves. My old Searunner Tri heaves to quite nicely but some of the lightweight multis may be a little unsteady while hove to.
In a nutshell. Lying ahull or running off if the waves are not breaking severely. In larger breaking waves you may try heaving to or you can run off using your boat speed and control to avoid the worst breakers maybe using a drogue to help control your speed. Your sea anchor is your ultimate weapon if it gets really bad out there.