Cat rounding up despite counter helm

[HabibiDah]

I had an interesting event in our Lagoon 46 that I thought I’d share.

I’m not inexperienced, but not an old salt either. (old, just not that salty!) Most of my experience has been in mono’s years ago, but we've moved to a cat and I’m still learning the ins and outs of cruising cat performance.

We were on a broad reach, starboard tack, AWA about 130-135. Winds were steady about 15 knots. Boat speed about 5-6 knots. Comfy. Quiet. Lulled into a sunny day not-a-care-in-the-world mood. Full main, no jib. (I know some people will stop reading here and say “well, that was your problem,” and they are probably right. More on that in a minute.) At the time, it felt like the self-tacking jib was flailing a little too much and not contributing to our forward motion, so I just furled it.

Comes time to Gybe. I sheet in the main and throw the helm over to port. We pass through the wind and the main fills on the new port tack. I spin the helm almost full to starboard and…nothing. The boat keeps turning to port. In a matter of what seemed like about 8 seconds, we rounded from a port tack broad reach to being close-hauled and heading on about a 70 AWA.

At this point in time, I settled on the close haul for about a minute to gather my thoughts, then deployed full jib, and tacked to a starboard tack letting the boat go all the way to a broad reach and settled in there while I thought about what just happened. Luckily, we had plenty of room and the gybe was more to stay on course than any obstacle avoidance.

I finally bore away again to our original broad reach. Later when I decided to gybe again, the gybe went as I would have expected, and we went from about a +130 AWA to about a -130 AWA.

I am taking this as a learning episode and welcome anyone’s thoughtful input on what happened.

My thoughts:

First: Unbalanced sails. Even if the jib is not doing a lot, it is there to balance the boat, especially when changing points of sail. I am now paying a lot more attention to how much helm I’m using and paying attention more to my sail plan and its balance, not just in the current configuration, but in any configuration that may come up. I think the boat settled in at the 70 AWA because the sheeting of the main was such that it was depowered enough at that angle to stop the turn while adding enough forward vector to gather speed and give us more rudder authority.

Second: The Lagoon 46 mast has been moved aft from other designs. This puts the mast almost squarely in the center of the boat. That means that rotational torque has a greater effect than if it were off center. This allowed the wind to force the boat around regardless of rudder position. Again, sail balance was off. A jib would have countered this torque with a nice counter force on a long arm from the mast, as it did during the second gybe.

Third: at 5-6 knots there isn’t a huge amount of rudder authority, and certainly not enough to overcome the torque of the main by itself. There is a lot of power in that main!

What are your thoughts? Am I missing anything? This quick event was both surprising and humbling. It took me a while to figure out what I think happened, but like I said, I'm open to other's insights as well.

This does have me thinking though about heaving to in the cat with a self-tacking jib. While some claim that you should secure the clew to windward before tacking, others have claimed that it can be done on a cat without the jib and counter helm after tacking. After this experience, I think that might be possible, to an extent, but the sheeting on the main needs to be just right or it will overpower the helm. This seems like a good afternoon of trial and error one weekend…

[Chotu]

I remember my switch from monohulls to Catamarans.

I think you had a combination of factors and you have pretty much guessed them all.

biggest difference in sailing a catamaran is that you have to carry the momentum yourself. If you don’t have enough speed, The rudders tend to stall out on hard maneuvers. (Especially tacking)

if you were only at 5 knots and you had that big sail with all of the power behind the center of the lateral resistance, but you were going so slow the Rudders weren’t creating much lift, that would cause this to happen.

it could further be exacerbated by turning the rudders all the way because at the high angle of attack with low speed through the water, they are going to stall instead of grip.

[smj]

After you gybed did you release the sheet or was the main still sheeted in hard.

[Snore]

I have moved a fair number of cats very long distances, and taught new owners how to sail them.

Balancing the rig is critical. If you are not familiar with that phrase, it would be prudent to google it to understand the forces involved.

To achieve balance you need the jib!!!! At the risk of sounding rude- the boat has an owners manual. It is important that you read and understand the manufacturer’s guidance on sailing the boat. I can honestly say 50% of the used cats I move failed the sea trial due to a cracked ferrule. My personal opinion is that the ferrules failed because of overloading. So knowing the design limits is important.

FWIW I NEVER EVER gibe a cat. The rig has no backstay, and one shroud on each side to take the shock of a gibe. Even a gentle give in 15kts will slam. Instead ‘chicken gibes’ are the SOP on my deliveries.

PS- learn to rig a barber haul on the jib. It will take out that ugly hook and add 1/2 a knot.

[thomm225]

The mainsail causes the rounding up.

The sails are stronger than the rudder.

Think steering with the sails rather than the rudder

Rudder is for trim.

I raced Beach cats for 15 years and 2 of them had spinnakers

Good example of rounding up.

I screwed up here and had too much mainsail up but couldn't leave the helm to reduce sail except for furling the jib to keep the bow from burying itself under the waves

It still went under as the boat was overpowered but it was doable

I had my one reef in but the winds were gusting to 35 knots.

Video is 3 hours in after things had calmed a bit. I could barely control the rounding up by sailing DDW

Had accidental gybe right after video

https://www.youtube.com/watch?v=-nXfjcCuiPk

[thomm225]

Originally Posted by Snore

I have moved a fair number of cats very long distances, and taught new owners how to sail them.

Balancing the rig is critical. If you are not familiar with that phrase, it would be prudent to google it to understand the forces involved.

To achieve balance you need the jib!!!! At the risk of sounding rude- the boat has an owners manual. It is important that you read and understand the manufacturer’s guidance on sailing the boat. I can honestly say 50% of the used cats I move failed the sea trial due to a cracked ferrule. My personal opinion is that the ferrules failed because of overloading. So knowing the design limits is important.

FWIW I NEVER EVER gibe a cat. The rig has no backstay, and one shroud on each side to take the shock of a gibe. Even a gentle give in 15kts will slam. Instead ‘chicken gibes’ are the SOP on my deliveries.

PS- learn to rig a barber haul on the jib. It will take out that ugly hook and add 1/2 a knot.

Actually you don't need the jib if you will reef, travel out, and sheet out the main.

And over rotate or de-rotate the mast if you have a rotating mast

Think of steering the boat with the sail(s) only

Winds 18-20 here. (in photo of Nacra 17 beach cat) We don't have reef point on our sails in beach cat racing

No jib. Boat weight 300 lbs

Mast overrotated to break up smooth wind flow over sail. main sheet eased and I'm pinching up

If the winds get too strong, sail with jib only.

No rounding up in video below and the autopilot can handle it. wind gusting to 29 knots or so

https://www.youtube.com/watch?v=agtdrmAqojs

[Snore]

Originally Posted by thomm225

Actually you don't need the jib if you will reef and travel out

And over rotate or de-rotate the mast if you have a rotating mast

Think of steering the boat with the sail(s) only

Winds 18-20 here. We don't have reef point on our sails in beach cat racing

No jib. Boat weight 300 lbs

Have YOU ever sailed a big cat?

Beach cats and big cats are rather different. My guess is the rudder on a beach cat is the same size as some 38-40’ cruising cats.

[Factor]

Really simple - it's all about centre of effort, without a headsail the centre of effort moves aft, the silly aft rig arrangement on some of the lagoons only exacerbates that situation. If your better of effort is behind the centre of lateral resistance then physics will win, as it always does.

Quick article from North sails - https://www.northsails.com/sailing/e...your-sail-plan

[thomm225]

Originally Posted by Snore

Have YOU ever sailed a big cat?

Beach cats and big cats are rather different. My guess is the rudder on a beach cat is the same size as some 38-40’ cruising cats.

If you can sail a 300 lb beach cat with around a 75% SA/Disp ratio in big winds you can sail a slow, low performing heavy big cat

Not sure why some of you guys don't seem to get it

The mainsail causes the sailboat any sailboat to roundup. There are many ways to control rounding up.

To steer a sailboat with the sails use the jib to move the bow off the wind and the main to bring it back in.

This is how we hold our position with beach cats on the starting line when the boat isn't moving sometimes for 2 minutes

Use this knowledge to control your boat and remember its the main that is causing the rounding up ....probably too much main as compared to the jib

Practice by securing the rudder centered and steering with the mainsheet when you are on a long tack in steady winds

An inch or so of sheeting is all it takes to stay on course.

[Snore]

Originally Posted by thomm225

If you can sail a 300 lb beach cat with around a 75% SA/Disp ratio in big winds you can sail a slow, low performing heavy big cat

.

Let’s start with ice sailed both. Taken cat transatlantic, trans Caribbean, up and down the east coast. I have also played with beach cats.

You can sail a big cat. But it takes a few thousand miles to sail them well.

Originally Posted by thomm225

Not sure why some of you guys don't seem to get it

The mainsail causes the sailboat any sailboat to roundup. There are many ways to control rounding up.

.

With all possibel respect - I TEACH sailing! If this was SA, I would be MUCH more direct.

My original post said to use the jib to balance the rig. Your original post said you don’t. Now in a subsequent post, you agree with me that you need the jib AND find a way to criticize me.


FYI moving a main sheet a few inches on a 50’ cat doesn’t do anything.

[smj]

I’ve never had a problem gybing a catamaran. Center traveler, tighten main sheet, ease the sail through the wind then drop the traveler.
The main sheet and topping lift acts as a backstay and gives the mast some support.

[thomm225]

Originally Posted by Snore

My original post said to use the jib to balance the rig. Your original post said you don’t. Now in a subsequent post, you agree with me that you need the jib AND find a way to criticize me.


FYI moving a main sheet a few inches on a 50’ cat doesn’t do anything.

My post said you don't need the jib as I tried to demonstrate with the photo of one of my beach cats that was a main only boat (plus spinnaker)

So I guess this means you don't have enough experience to sail a boat like this with main only

Maybe in a few years with a bit more experience you too can understand.

Also distance sailing doesn't teach you much. You have to race to get good

How could I ever control this boat? You too can learn!

[Factor]

It's how I heave to on a Cat, reach along, roll up jib, centre and tighten mighsheet, tack, lock helm, job done. its not complex, centre of effort behind centre of lateral resistance and the rudders will never win.

[HabibiDah]

Originally Posted by Chotu

it could further be exacerbated by turning the rudders all the way because at the high angle of attack with low speed through the water, they are going to stall instead of grip.

I forgot to mention this, and this is definitely another point of learning for me. On the mono's that I sailed, they were like fighter planes compared to big transports. (Former military pilot) I'm used to the rudder having almost instant response.

I had heard others comment that too fast on the helm on a cat just puts big speed brakes on as the rudders stall and create nothing but drag with no lift. Didn't really think about that until this day.

Now I treat the cat more like a cargo plane than a fighter, and we seem to get along a lot better! Having said that...I truly WANT a boat that is a long-haul, comfortable, work horse and not a fighter plane. I'm ok not feeling every wave, every gust, but it also means being more subtlely aware of what is going on. The clues are more subtle, and you need to pay attention.

[HabibiDah]

Originally Posted by smj

After you gybed did you release the sheet or was the main still sheeted in hard.

It happened fairly quickly. I was wondering what was going on and didn't have time to change the configuration, so I was still sheeted hard on the main.