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Old 29-05-2016, 07:07   #1
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Tacking under mainsail alone

New to cats, but been sailing for many many (too many) years in monos. Raced lasers to offshore as well as cruising, just adding this in so you know I have some experience.

Too my boat out yesterday for a daysail with about 8 people. 4 or 5 wanted to be up front on the tramp, bow seats etc. Was blowing about 18T with gusts to about 22.

My typical way to do this is to pick a course that goes the long way across the bay, tack back, etc. We are not going anywhere, just out to enjoy the day.

So I went out under main alone, figured better for the guests who want to be upfront, and less effort for me to tack, didn't have to work the jib. Typical conditions on what I would do on a mono as well.

I am sailing at about 55deg AWA, and try to tack. No way I am close to making it. Need the engine to complete it. Do this several more times. Never complete the tack. In one situation, I am on port tack, turn wheel hard over, almost make it. But don't make it. But notice as we drift backwards, turn wheel hard to to stb , since I am moving backwards, turns back of boat to stb, front of boat is now moving CCWise, and sail fills! Bingo, think I have a solution. However, boat was going in reverse. As it picks up speed going foward, I turn wheel to port, but boat just rounds up into irons again.

When tacking with genoa up, I normally just backwind it until I am well past where I normally would on a mono, say all the way to 30deg AWA, and then let the jib sheet fly, and haul in on the other side.

Was hoping for tips from experienced multi sailors on how to tack with main alone.
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Old 29-05-2016, 08:09   #2
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Re: Tacking under mainsail alone

With just the mainsail up, the boat has weather helm. The boat wants to turn upwind due to the forces on the sail and underwater hull. You need to build up enough speed speed on the new tack so that the rudder becomes effective enough to counter the turning force back into the wind.

Starting with the backing around to the new tack, once you back up far enough to be head to wind, ease the traveler out (or mainsheet) so that the sail doesn't fill until you are on a deeper reach. The sail is now pulling more forward and less sideways, giving the boat a chance to accelerate enough for the rudder to become effective.

Is the 55 degree app. wind as close to the wind as you can sail without losing a lot of speed? Starting your tack close hauled to minimize the turn without power in the sails can help. Maybe to the point where you don't have to back up. (You still want to ease the main past head to wind as above.)

If you try to sail a course closer to a close haul, you can try easing the traveler out a foot or so. The genoa changes the direction of the wind that the main sees, so it is operating in wind more from the front of the boat. Without the genoa it is possible to be trying to point higher than the boat will sail. Many cat rigged (boats with only a mainsail.) boats do not center the mainsail for going close hauled.

Done this a lot in beach cats, keelboats, and dinghies. Never thought to try on the couple of charters I've done on big cats in Caribbean, so the above might not be enough to work for certain designs.
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Old 29-05-2016, 08:17   #3
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Re: Tacking under mainsail alone

A good boat of any amount of hulls should tack under main alone in a good breeze, the lighter the wind the bigger the challenge, but I have never had to backwinded a jib/genoa on a good multi.

In your case, try bearing away getting some speed, and then easing the main a lot. What is happening to you is the centre of effort is so far back that is virtually on top of the the centre of lateral resistance.
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Old 29-05-2016, 08:27   #4
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Re: Tacking under mainsail alone

On some, well, many boats actually. Both mono's & multi's. It's a trick that's pretty much impossible to pull off. As with only the main up, there's not enough lead between the CE of the sailplan, & the CLR of the hulls & foils.
Plus, with a multii, you don't have the momentum of several tons of lead down low, to aid you in such a manuver, via it's massive momentum.
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Old 29-05-2016, 13:17   #5
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Re: Tacking under mainsail alone

Another explanation:

The rate of rotation of the boat when luffing causes a change in apparent wind: the sails before the mast see the apparent wind drawing aft, this makes it possible for these sails to keep drawing. On the contrary, the sails aft of the mast see the apparent wind heading, so they stop drawing early.

Without a jib, if the boat isn't sailing really close hauled before tacking, it loses too much momentum when luffing.

The obvious solution is to gybe.

Alain
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Old 29-05-2016, 16:28   #6
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Re: Tacking under mainsail alone

On my boat, in light wind it's very tricky. In more breeze it's a bit easier, but still involves some planning.


Put simply, at low speed, the weather helm overpowers the rudders. So before the tack you need to sail lower and go faster, set up the traveller so the main will be quite well eased on the new tack, then tack way past where you'll be sailing on the new tack, so you recover speed quickly. It's all about getting enough flow over the rudders. Once you're moving fast enough on the new tack you can raise the traveller again.


Too much sheet too soon and you're in irons though.
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Old 29-05-2016, 19:37   #7
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Re: Tacking under mainsail alone

What 44C said
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Old 29-05-2016, 20:52   #8
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Re: Tacking under mainsail alone

There are many factors at play. My F-31 will tack beautifully on main alone unless fitted with an oversize(high roach)main in which case not so much.What is the condition of your sail? If too much draft you will have trouble. Is your bottom clean? Because of less weight, less momentum and all negative factors are multiplied. Dave
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Old 30-05-2016, 06:11   #9
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Re: Tacking under mainsail alone

Build up speed, boom to centre and turn to start tack. Once boat is head to wind you need to let out some traveller so the boom can move to the lee side of the boat. If you have enough momentum you will make it onto the next tack.
If you get stuck in irons reverse rudder like you did and let the boat reverse onto the correct tack. Once you have come around enough pull the traveller in halfway only to allow the boat to build some forward speed. If you pull the boom to centre before you are moving forward you will just spin head to wind again.
Just like trying to turn a cat rigged hobie 14☺.
I always found it harder in a strong wind as well.


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Old 30-05-2016, 06:20   #10
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Re: Tacking under mainsail alone

We struggled to sail our Catana 48 under main sail alone, but were surprised to find we could sail her easily on jib alone, including tacking.

I agree with the suggestions above for tacking in general, make sure the main is eased on the new tack until you get up some speed. With our long traveler, we would just bring the traveler above centerline before tacking, so after tacking the main was automatically eased. We'd then bring the traveler up once we had some speed up.

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Old 30-05-2016, 08:42   #11
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Re: Tacking under mainsail alone

The difference from your 'old' mono to the 'new' cat is that you have relatively much larger mainsail with larger roach as well.
This cause weather helm more powerful than on the small mainsail on the mono.

AND - do you have daggerboards on the cat? The keel on the mono serves as a pivot. The cat just tries to slide away.

AND - there is a fine tuning to the rate of turn of the wheel while tacking. Too slow or too fast both are leading, (to complicate it more, the proper rate changes with wind speed...)

IMHO - the easiest way out of the conundrum is to put up the jib and let it catch the wind on the 'old' tack and release the main traveller (or sheet at least) once the boat is head to wind. Once the bows are on the new tack, change the jib to the new tack as you did on the mono.
But, the freeing of the mainsail is much more important then on the mono due to its huge relative size.
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Old 30-05-2016, 09:04   #12
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Re: Tacking under mainsail alone

Many good comments. I think what it all boils down to, on any type of boat, is that a sail bends the wind forward for any sail aft of it. In other words, with a jib up, the main should be trimmed in more than the jib, to account for the more windward flow of air it experiences. The corollary is that, on any boat, when you furl or drop the jib, the main must be let out in order to keep sailing at the same apparent wind angle, because the main is now getting air flow that has not been bent forward. Fail to ease the main and you are over sheeted with a stalled main. You slow down, loose maneuverability and start making lots of leeway. On my Leopard 45 cat, I can almost go sideways if I try. But, by easing the main, I can point just as high as with both sails, and I can tack without problems, too. It feels a bit counter intuitive, seeing the sail eased out quite a bit more than normal, and still sailing close hauled, but that's the aerodynamics of sailing with just a main.

It's more important with a cat, because, as some have said, you don't have the momentum of that lead keel to carry you through over-trimming errors. Without that momentum, you can easily wind up in irons if you are over-trimmed and then stall. That's when you go backwards, but it shouldn't be necessary to do that deliberately.

I frequently sail through mooring fields, and onto moorings, and my tactic is always to furl the jib, and ease the main accordingly, which slows me way down and gives me good maneuverability. At that point, I pick my way through the mooring field, steering and tacking (or gybing) as need be, until I head up into the wind to pick up the mooring, at which point I sheet right in. The main usually comes down after I pick up the mooring, This works in even quite light winds, and under good control, although under those conditions, I make sure to keep my speed up and not pinch too much, sometimes falling off for a bit to get things going. But tacking is no problem.

So sailing with just a main really comes down to getting used to the fact that the correctly trimmed main is eased considerably, compared to a correctly trimmed main that is lined up behind an unfurled jib. And, while this pertains to all boats, it's somewhat more important on a cat. Best of luck.
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Old 30-05-2016, 09:10   #13
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Re: Tacking under mainsail alone

Just need speed to come about. Faster is easier. Otherwise you will fall into irons. Could also just do a controlled jibe. Although in strong winds a controlled jibe tends to become uncontrolled quickly with all the horrible results that can entail. Also try to come about at the top of a wave, not at the bottom. Can also drag the boom to windward to get a bit more lift through the turn. Depending on how fat your crew is, you can also shift the weight right before the turn. In any case, do it quickly. Quicker the better.
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Old 30-05-2016, 09:27   #14
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Re: Tacking under mainsail alone

Most sailors try to turn the boat to fast, I have found that multi-hulls like a nice gentle turn, often about half of what hard over gives you. Most boats have a turn radius that they like, once you find it, tacking gets much easier.
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Old 30-05-2016, 09:56   #15
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Re: Tacking under mainsail alone

For everyone that's saying he should fall off to build speed, he said he's at 55 AWA. This seems to me that he is already on a reach. What's your AWA for close hauled and what is it when you have just borne off just enough to build some speed?
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