Another stability question

[Dpackie]

Originally Posted by smj

Not altogether correct. Think of it this way, if your motoring at 10 kts directly into a 10kt wind your apparent wind will be 20kts. If your motoring at 10 kts going directly downwind in a 10kt wind your apparent wind will be 0.
That’s a 20kt difference in wind strength just determined by the direction your boat is traveling.

I do see my error. If you're on a broad reach in a cat at 10 knots, and a gust comes that might capsize the boat, turning down wind will lower apparent wind even if boat speed remains the same, but if you don't also ease the sheet, won't you be dangerously close to a jibe? Still seems scary. Heading up will luff and de-power on a cat, even if the wind is on the quarter, right? It just seems so counter-intuitive, but I trust your right.

[smj]

Originally Posted by Dpackie

I do see my error. If you're on a broad reach in a cat at 10 knots, and a gust comes that might capsize the boat, turning down wind will lower apparent wind even if boat speed remains the same, but if you don't also ease the sheet, won't you be dangerously close to a jibe? Still seems scary. Heading up will luff and de-power on a cat, even if the wind is on the quarter, right? It just seems so counter-intuitive, but I trust your right.

The problem with heading up is you increase the apparent wind on the sails before getting to the point of luffing, a dangerous thing to do if in fear of capsizing.
Not sure of the science behind it but I believe you also increase the centrifugal force when heading up, also contributing to the capsize factor.

[Manateeman]

Hi. First, where do you get one of the devices Captain Bibot has to release a line.
Second, no responses on the Chris White foil mast...
Captain Octopus. I understand you like catamarans but don’t you feel your statement might be just a tiny bit hurtful to the owners of monohulls?
I don’t see how it was a substantial addition to the matter under discussion.
Not seeking a retraction, nor an arguement. I began sailing a long time ago and one of my best friends has a real fast cat. Being polite is yachting vs boating.
Happy trails to you.
Mark, a, too poor to own two hulls kinda manatee

[RaymondR]

Yep, love to own one but the expense and two engines.

[aqfishing]

Originally Posted by smj

The problem with heading up is you increase the apparent wind on the sails before getting to the point of luffing, a dangerous thing to do if in fear of capsizing.
Not sure of the science behind it but I believe you also increase the centrifugal force when heading up, also contributing to the capsize factor.

I have often pondered this point while sailing my Leopard 44. Admittedly my boat and seamanship experience is good as I am a commercial fisherman, but my sailing experience is very limited.

So while sitting there with the AP doing the job I was wondering what would happen if we were caught out by a sudden gust we never saw. I felt that it would be quicker to alter course than to dump the main, but I may be wrong. So my question is, do you steer up or down? Let’s say a hull is lifting and you turn up, the centrifugal force would cause the boat to lean out more, but then you would quickly have less wind/force on your sail as it luffs.
Turning down would have the opposite effect on the centrifugal force thereby putting the hull down. You would speed up, but when turning down the apparent wind will decrease and your main should then be over sheeted, thereby reducing the load as well. I am assuming you sailing square to the wind or maybe 60deg in this scenario. It would be faster to hit the plus or minus 10deg a few times on the auto than to switch to manual, but not sure this is an option.

While it’s obviously best to avoid such a such a scenario it’s prudent and fun to think about it!

Would love to hear your thoughts.

Plan for the worst and hope for the best!

[Alistair242]

The OP refers to being closed hauled, let’s assume that is 40 degrees AWA in a cat. Big gust comes and if you head up to 20-30 off the wind your sails luff just like a monohull. Or if you are in the salon run out and dump the main same result. Probably faster just to head up? Cats generally are sailing closed hauled with jib and large main. If the main is a square top it will spill a lot of that extra wind in a gust and the jib should be fine. If you are sailing 40 degrees AWA and the wind jumps from 15 to 35 as you bear away you will actually lift the windward hull further out of the water until you pass through 90 degrees off the wind one would think?
If you are on a beam reach on a cat and it pipes up then bear away to a broad reach. Not much chance of jibing unless you fall away too far.
It is really not that much different on a cat except that bigger heavier ones will not round up. Reefing early and not straying too far from the helm in squally/gusty conditions is the best bet, much the same as on a monohull.

[Sos]

As already mentioned if hit by a gust you have three options
1 - Release the sails
2 - Head up into the wind
3 - Head down wind

Releasing the sails is not always that easy especially the main and then there will be a lot of flogging, noise and possible damage.
The other two will need a decision based on the course you are sailing at the time and the condition's.
But as already said, a cruising cat is quite forgiving and if it is a light fast cat then you shouldn't be sailing it without more experience!

[fivecapes]

Originally Posted by smj

...
Not sure of the science behind it but I believe you also increase the centrifugal force when heading up, also contributing to the capsize factor.

A CF contributor Yeloya will attest to that, there's a lengthy dicussion here.

[Octopus]

Originally Posted by Manateeman

Captain Octopus. I understand you like catamarans but don’t you feel your statement might be just a tiny bit hurtful to the owners of monohulls?
I don’t see how it was a substantial addition to the matter under discussion.
Not seeking a retraction, nor an arguement. I began sailing a long time ago and one of my best friends has a real fast cat. Being polite is yachting vs boating.
Happy trails to you.

Perhaps I was insensitive, so I apologise. My comment was spoken from the perspective of someone that loves my family, not someone that loves catamarans. There have been many times I would rather be sailing a fine mono than a cruising catamaran and aesthetically monos are usually far more beautiful, however where safety is concerned I don't think there is any contest, except, perhaps, in F12 survival conditions (arguably). Faced with the choice of what boat to buy to achieve our ambition of sailing an Atlantic circuit with my wife and six children we obviously looked into the safety aspect quite closely and I'm afraid if you analyse all the key risks there just is no contest. And, as I said, capsize doesn't even enter the equation, even though it receives most of the attention.

I hope my comment was relevant to the OP's final sentence:

Originally Posted by Tsalta

From what I have read, cats are reef by the numbers so potentially there could be too much sail up. Am I going to end up inverted?
Cheers

[Manateeman]

Hello Catamaran People. The release device in the Captain Bilbot (the French Captain) where or who makes them and any comments please.
Hello Technical Catamaran People.
Chris White Foil Mast...how does a catamaran with this rig respond to a big gust.
Any different...at the helm, what is the best response to a big gust.
Lastly, are there any wind speed alarms say linked to an anemometer or an alarm that will signal you like a stall alarm in an aircraft.
I was on a research boat that had a ship rollover bell and was actually impressed.
It helped one dark and stormy night. Every time it rang I thought, yes we better say another prayer. Ding, ding. We’d rip down one wave Ding Ding..hard helm.
Ding ding. Once I got on land doorbells would make me jump. Well...
Happy trails to you.
Mark, like manatees, one hulled

[mark_morwood]

Originally Posted by Tsalta

Hi,

Thanks for all the responses.

Ok, say the scenario is Wife #1 is on watch and I’m having a kip. We are heading to windward in a steady 15kts. No expectation of anything gusting greater than 20 kts. What sail plan should we have deployed?

A general rule of thumb that I have used is on a monohull reef for the lulls, on a multihull reef for the gusts. However it really depended on conditions and whether it was daytime when you could see things coming or nighttime when you usually couldn't. So in your scenario I would probably have reefed for 20 knots. You should do whatever keeps the watch keeper comfortable. Keeping watch should be enjoyable not stressful.

It's also worth noting we were almost always reefing for comfort or to reduce the stress on all the gear, well before we were reefing for safety. For example we had a long upwind passage from Bermuda to the Azores where it was 25 to 30 knots for days, and we had 2 or 3 reefs in the main and the jib partially furled to slow it down for comfort rather than for any fear of capsize.

Should I plan contingency for 20kt, 30kt, 40kt ...... gusts and sail around under staysail forever?

For the people cruising around as a couple, how do you run the boat during passages for safety first with regards to sail plan to windward?

(Am I right to expect sailing downhill under headsail only is relatively risk free regarding wind changes?)

We spent 4 years cruising on a Catana 48 with my wife and two teenagers from Boston to the Med to Carib to Australia. All of us would stand solo watches. We generally reefed for the expected gusts, but a little on the conservative side, and more so in unsettled conditions or at night when you couldn't see.

Upwind there wasn't much difference between watch standers. Downwind when you have more sail options it depended who was on watch. There is maybe more risk downwind as it's not hard to get caught out as the true wind slowly picks up without much change in apparent wind. It's easy to suddenly find yourself trying to get the spinnaker down in 20 knots true. So we generally flew whatever the watch stander was comfortable with taking down or reefing.

We also changed as we gained experience to usually dropping the main entirely on long downwind legs. It was only a fraction slower, but made everything much easier without having to tame the boom, and keep the main off the shrouds. With a furling jib, furling code 0, and asymmetric spinnaker in a sock, there was no problem reducing or bringing down any of them as conditions picked up.

I would occasionally fly the spinnaker at night in settled conditions, but we would switch to the Code 0 which could be easily reefed when one of the kids or my wife came on watch. We never hesitated to wake some extra hands if needed. As above, the goal was for the watch stander to feel comfortable handling whatever came up.

It is worth noting we had fairly large sails (90m2 main, 100m2 code 0, 200m2 spinnaker) on the Catana so we could keep sailing in light winds rather than motoring, so reefing or changing down was common and normal.

If you're cruising, keep it comfortable and fun.

[Naughty Cat]

The original question is one that has made me think a bit. In particular why, as the owner a so-called performance cruising catamaran - lighter than many others with daggerboards - it did not particularly concern me.

The answer, I have concluded is threefold:

Firstly, most cruising cats are not sailed in the same way as something like a Farr. They aren't being taken around the cans for fun and they aren't (sadly) being sailed close hauled. There are some exceptions of course.

Secondly, we would either have put in a reef already if the gust forecast was dicey, in which case a shift/increase would not phase us and we would happily go in and have a cup of tea, or I would be at the wheel with a very big smile on my face with an AWS of about 22-24 watching the rigging for signs of getting overpressed. A 30 degree shift would either take the wind onto our nose, in which case we would stall and use the opportunity to get the solent in, or it would take it to around 90 true, both sails would lose some power and we would accelerate, resulting in an apparent wind increase of about 10 knots. The daggerboards would simply shear if we had too much board down (they are designed to do this) and our leeway would increase. As someone already said, the sea state is far more important and we view gust forecasts as much as prevailing wind. The summary being, we would have to have done a lot of things differently to be concerned about being caught short by such a scenario.

The third is that, in my unfortunate experience, the rig of the cruising cats would give before wind could ever turn them over. It happened to me, and made me realise how difficult it is for a catamaran rig to cope when a heavy hull starts to dig in with the ensuing and extraordinary forces that accompany that.


For the record, we liked the accommodation of a cat but were very frustrated chartering cats, getting straight off them and going to find a Hobie or similar to do some propoer sailing. So the requirement was a cat that we would also enjoy day sailing i.e. sailing just for the sheer fun of it, as well as extended cruising. The choice is quite limited (and expensive).

[Tsalta]

Hi all,

Thanks again for your answers. Especially the last couple from mark_morwood and naughtyCat.

PreCovid we were on track to being able to afford our dream cat but that has not been pushed back a bit. We will have to settle for a share mono for the time being to scratch the itch. Hopefully purchasing a share in the next week or so.

I'll go and hunt around the marina and hassle some big cat owners to take me for a sail. Boat shows are great for comparing the space but aren't quite the same as the real thing.

From what I have read and watched on youtube since, it seems quite common for people to not even use the main and just head downwind as much as possible under headsail only. I guess that would be super relaxing and extremely low risk unatended.

Thanks again for taking the time to anwer. I certainly appreciate it.

Cheers
Jeff

[Naughty Cat]

Sounds a good plan and you're right, if you do go down the cat route make sure you can have a big gennaker and preferably another downwind sail as well. I have seen more mono's in recent years under headsail only as well. I think it's because most boats now have a second furler enabling them to carry a gennaker/code sail, and this gives decent boat speed at little to no effort. If you can why not?

[chrisr]

i think the trend on both monos & cats towards sailing under headsail alone is because of the furler it's easier to roll in / roll out, than to set / reef / drop the mainsail.

on the other hand boats with in mast furling like us actually find it easier to set the mainsail as it rolls out / in at the touch of a button, rather than having to pull one of those nasty ropes...

cheers,