NOTE: This article is intended for catamaran skippers with good command of sailing terminology and maneuvers.
As much as owners of the Lagoon 42 catamaran love this model, most of us accept the reality that it is not an easy boat to sail (or at least to sail well). The aft mast design created a difficult-to-balance boat that experiences significant weather helm (and loss of speed) if the sails are not properly balanced and trimmed. We have talked about this frequently and we have a dedicated article on sail trimming and weather helm on this catamaran.
This boat is also a bit more difficult to tack than similarly-sized catamarans. Most often, owners blame the self-tacking jib. Indeed, the standard self-tacking jib without modifications can’t be backwinded, so it offers no help when tacking the boat. Being able to backwind the jib is a commonly used and desired feature in catamarans because it can help when tacking in difficult conditions or to compensate for other mistakes.
For example, one of the most common mistakes skippers make is using too much rudder when tacking (i.e., turning the wheel hard and all the way to make the tack as sharp as possible). The problem is that this creates a rapid deceleration of the boat that in some cases can slow down the boat’s momentum so much that it can get stuck in irons. Backing the jib could help in these situations, but that is not a luxury we have in the 42 given the self-tacking system.
But there is another issue that makes the 42 difficult to tack even when skippers use a more gradual tack angle with proper speed. As you see in the figures below, when we are sailing close haul (Figure A) and we are properly trimmed, the wind is creating greater pressure on the aft of the boat producing some desirable weather helm. As we begin to tack (Figure B) this weather helm helps us turn the boat initially as the boat wants to turn towards the wind.
The problem happens when the bow crosses the wind (Figure C). As the jib can not be back-winded, it does not help push the bow to leeward. Worse, the wind is now hitting the mainsail on the new windward side before the jib fills, creating a counter force making the boat rotate back into the wind. If you do not have enough speed/momentum, that pivoting force will make the boat turn back into the wind and you will end up in irons. If you recognize that you don’t have enough speed early enough, you can quickly turn back into the original course and try again. If you don’t react quickly enough, it will be time to turn on the engines with a bruised skipper pride.
So how can you avoid this issue?
The most common trick is to make sure you gain as much speed as possible before the turn. The faster you go, the greater the momentum of the boat, which is often enough to fight the counter-turn force of the mainsail. How do you increase speed? First, you can gain speed by bearing away a bit before the tack. We never try to tack in less than 5.5 knots of speed or from higher than 50AWA. Second, your tack should be gradual (not sharp) so you must use just the right amount of helm during the turn. As mentioned before, one common mistake skippers make is to use too much helm too fast (e.g., turning too hard into the wind). The rudders then act as a break that can dramatically slow down the boat risking getting into irons. So, think of your tacks as a graduate curve as opposed to a sharp turn.
However, in some conditions, even when doing the turn correctly, the main will try to turn the boat into the wind and keep the boat from completing the tack. So you need to depower the main during the turn. We use an unorthodox method to depower the main: we simply “backwind” the main before the tack.
When we are in big seas in moderate winds (when tacking is most difficult) we use the backwind trick. Seconds before the tack, we move the boom about 20cm to windward of the center line (note the location of the boom in Figure D). Yes, we mean to windward of the centerline – as in back-winded!
In our case, because our traveler would already be 30-60cm to windward of the centerline in these conditions (see our sail trimming and weather helm articles that speak to why the traveler should be to windward of the center line), we simply tighten the mainsheet. This brings the main closer to the traveler and across the centerline to windward. We then start the tack.
Why do we do this? As we begin to turn, the initial whether helm is maximized by the new mainsail location (Figure E) which speeds up the initial acceleration of the turn when I turn the helm. But most importantly, when the bow crosses the wind, the counter rotation force of the main is minimized because the main is depowered and not yet exposed to the wind (Figure F). The depowered main allows the boat to continue to turn and the jib to fill, which helps complete the turn. Now, you may be wondering why I want a rapid acceleration of the turn when above I mentioned the tack should be gradual? The reason is that this acceleration is not rudder dependent and it will not have as much deceleration effect on the forward progress of the boat. It allows the boat to keep moving rapidly while accelerating the momentum of the turn.
So, what we are doing by pre-emptively moving the boom to windward before the tack is depowering the main on the new tack so that it reduces whether helm (on the new tack), which allows the boat to complete the turn with the help from the filled jib.
This trick is not always needed. Sometimes just having the right amount of speed and doing a gradual tack is enough to tack the boat. But if you have a hard time tacking the Lagoon 42 in some conditions, give this trick a try and you will be surprised at how easy the boat will tack.
There are other ways to depower the main after the turn. For example, you can simply ease the main during the tack. By easing the main, you are depowering it on the other side of the tack, which prevents the main from stopping the turn and pivoting into the wind. You can then repower the main once the jib is filled. This requires a bit of coordination by the person handling the mainsheet but it is a trick also worth a try. You can also depower the main with the traveler. Before the tack the leeward (lazy) line of the traveler is put on a winch and the clutch is left open. After the bow crosses the wind, that traveler line becomes the working side and it is eased so that the traveler moves to leeward on the new side. This creates the same depowering effect preventing the main from turning the boat into the wind. Both of these approaches should work, but they require significant coordination during the tack and you run the risk of depowering the main too much so you may lose too much speed on the other side of the tack. Although that should not matter much on a tack unless you are racing.
Now, do you know what is even better than these tricks? Modify your jib traveler so that you can backwind the jib!
Leave a comment below if you have any questions