Firstly what do I mean by getting pressed?
Well upwind if you have too much sail up (mainsail) for the wind you can let out your mainsheet and effectively de-power your sail, a sail pointed directly into wind might flap a bit but it won’t create any power or heel on your boat.
Downwind the mainsail and boom can only rotate so far before they start hitting shrouds (wires that keep your mast up). On a catamaran this is not even 90 degrees to the boats centre line as the shrouds are angled back to support the mast (Catamaran’s do not have backstays like monohulls).
Therefore you can not completely de-power downwind because the sail will eventually “press” against the shrouds and still catch wind. This is what I mean by being pressed. At this point there will be so much force on the sail that you won’t be able to reef it, nor will you be able to de-power it without turning up into the wind.
Pressed is not a good thing!!!
On a monohull you can take a last ditch turn up into wind and the boat will heal with wind and swell but even if it broaches it has the desired effect of rounding up and allowing you to de-power and then reef before resuming course. Not ideal but not as boat threatening as it is for a catamaran.
On a Catamaran you can also round up into wind and try to get an angle that will allow you to reef and de-power (not in that order) but whilst doing this the boat will be side on to the waves and wind and it will at best be rather exciting. You’ve probably experienced this is in lesser winds and even then it can get a little exciting as you round up.
Either way avoiding getting pressed is a desirable goal for both types of boats.
So what did I learn today? Well in order to avoid becoming “PRESSED” downwind….
- Reef your main early and use your main only enough to balance the boat as needed
- rely more on Genoa and Downwind flying sails, all of which can’t become “PRESSED” and can be de-powered if need be
- Ensure you have plenty of length on your Sheets so you can get the clew fully forward if need be on these sails without having to just let them fly (you might need your engines later and lines in the water is NOT a good thing).
- Leave the Main in the sail bag if you think it’s going to blow hard and you don’t need to go upwind.