Catamarans in 50kt winds

[Jeannius]

Originally Posted by serpa4

I've only been sailing for 5 years, but you have two sails on the same fuller that when furled, both roll up?

That is correct. Twin groove furler, one in each groove.

On the rare (very rare) occasion I wasn't going downwind then the two genoas were on the same side lying flat against each other, both sheeted in. Obviously they weren't as efficient as a single sail would have been in those circumstances but it worked well enough.

[Moontide]

Haven't read all the posts on this thread, but for those interested in reading some real world descriptions of both types of boats in survival conditions read "Surviving the Storm" by Steve and Linda Dashew.



Can download (free) it from https://setsail.com/free-books/.


This is a compilation and analysis of reports from boats (and rescuers) caught in the Queen's Day Storm in November of 1994 which caught large group of cruisers enroute between Fiji and New Zealand and some Sydney to Hobart races. A little dated, but many of the lessons learned on both monohulls and cats are valuable, and still applicable.



It also includes a discussion of various drogue types, including the Jordan Series Drogue (which is my preferred).


I highly recommend this book for anyone doing offshore passages on any boat.


Bill

[44'cruisingcat]

An account of the Queens Birthday storm here:

Multihull Dynamics, Inc. - News Article

[impi]

Hi Everyone - it's been a while since we've been here on account of being busy with the sailing life.
A friend asked us to look at this thread and comment on cats sailing in 50 knot winds which we've unfortunately done a few times now, including winds over 60 knots gusting into the 70’s - (a downdraft ‘break through’ from the upper layers).
I was asked to share a link where we wrote about our storm tactics so here it is:
https://catamaranimpi.com/2019/09/29...heavy-weather/

Our recent YT video - Ep.2 - Sailing Indonesia (where we do not post as regularly as most, has some footage of Impi in rough seas. However, as sailors we tend to forget to take footage of the 'real deal' in lieu of survival tactics - lol.
Having sailed monos from a young age and eventually progressing to catamarans I can say that both boat types are equally vulnerable / safe in rough seas but the tactics are very different ... for us.
It is of course VERY TRUE that one does not want to capsize a catamaran.
I would say our tactics would also change slightly from Cat to Cat depending on how it is set up (although we would have used similar tactics on our previous cat being a Catana 471 and our current cat being a Lagoon 440).

Some boats will never experience these conditions, however, we do sail ‘out of season’ to experience some regions which we otherwise would miss out on. On this passage we checked weather models including CAPE values and in spite of everything seeming good to go, we encountered rough seas.
It actually got worse in a following passage (in one of our videos yet to be made when I eventually get around to it - lol) where we spotted aircraft spraying some ‘stuff’ into the atmosphere (probably some sort of Ozone layer protection or experiment ?) - I actually mention on camera that I hope this does not create a new weather front and rough seas and not long after that we are indeed in winds again over 50 knots. In that storm a ship capsized and 25 souls were lost at sea and sadly we sailed into the oil slick and some debris which at the time we did not realise what had occurred.
When we called the Indonesian Search And Rescue People on Sat Phone, they mentioned unusually strong weather.

Things are changing out here - this year as we sail across the Indian back to South Africa before setting out on our next circumnavigation we do realise the Indian Ocean dipole is extremely positive this year (Strongest in 6 decades) meaning that it brings excessive rainfall to the east coast of Africa and dry conditions to Australia region. It also means equatorial convection can’t move to Australia and remains around Java. In the past when it was a positive dipole this coincided with the upwelling of cooler water along the west Sumatra coast and that causes the winds to shift to the east creating bigger seas. For us in the Indian ocean - we have warmer sea temperatures in the western sector (opposite in the east), it could mean stronger sea and wind conditions too so we are mindful of this. Oh boy - a Pacific Ocean crossing during El-Nino and an Indian Ocean Passage with a very strong dipole.

Cheers everyone - stay safe




Here is a screenshot of our recent sea state - this is the back of the wave in 50 + knot winds

[NevilleCat]

Originally Posted by Jim Cate

Without wanting to stir the pot excessively, we've heard of several cats being flipped on their moorings with no sail up and in flat water. One specific incident was in Little Oyster cove (off Kettering) in Tasmania. A couple of years ago there was a sudden and fierce storm which lead to the loss of several boats, and t he near loss of a brand new >million dollar 8 meter classic yacht (written up in Afloat). During that storm, which had gusts around 80 knots according to folks who sat through it, a ~35-40 ft catamaran on a mooring was flipped. It then proceeded to drag its mooring through the anchorage, damaging a couple of boats on the way. Bad joss for sure! There were no big seas involved, for it is a well protected anchorage with little fetch, yet there it was, inverted. If it can happen under these conditions, could it not also happen at sea to a vessel with bare poles?

FWIW, there were several monohulls damaged at their moorings, but none actually knocked down as far as I heard. The tin roof was ripped from a shed on shore... flew through the air and dismasted a moored boat (timber mast, just launched after a refit) and then nearly sliced an automobile in half. Not a nice day on the water!

Please don't take this as cat-bashing! This was a well documented incident, and I'm trying to relate it to the realities of multihull sailing as discussed in this thread.

Jim

Actually from speaking to an eye witness, my understanding is that the cat didn't actually invert at the mooring but simply picked up the mooring and dragged out of the harbour into the seas with the weight of the mooring pulling the bows down until it was overwhelmed by the seas.
This is quite a different scenario yes?

[arsenelupiga]

bit of physics


wind speed at which cat is flipping at mooring or anchor is function of cat weight and cross section size under the bridge. Larger weight better, smaller crossection size better.

Estimating that Lagoon design flips at 150 kn gust, one can calculate that cat 1/2 of the weight and 2x area size of bridge crossection compared to that lagoon will flip at 1/4 of the energy representing 150 kn gust, which is 1/2 wind speed ~ 75 kn.

Lots depends on design... in this case low bridgedeck clearance is asset.

[fxykty]

Originally Posted by NevilleCat

Actually from speaking to an eye witness, my understanding is that the cat didn't actually invert at the mooring but simply picked up the mooring and dragged out of the harbour into the seas with the weight of the mooring pulling the bows down until it was overwhelmed by the seas.

This is quite a different scenario yes?

Would have to have been some serious seas to have an effect I think. Even so, wow.

There was also the Schionning cat named Rosella that flipped at its marina berth in Auckland a little while ago during a microburst. The flip may have been caused by the main sail partially raising itself during wind gusts earlier.

In the threads about that there was speculation that lighter, more aerodynamic cats are more susceptible to extreme wind inversion. Not sure we have enough samples to make that conclusion. Even if true, though, I sure don’t want to spoil my boat’s sailing capabilities to prevent an extremely unlikely possibility.

[yeloya]

Here is a screenshot of our recent sea state - this is the back of the wave in 50 + knot winds


[/QUOTE]

So, you had almost 2/3 of yr genoa unfurled in 50+ kts of wind ??

Yeloya

[InsuredApple]

Originally Posted by yeloya

Here is a screenshot of our recent sea state - this is the back of the wave in 50 + knot winds

So, you had almost 2/3 of yr genoa unfurled in 50+ kts of wind ??

Yeloya[/QUOTE]

Wow, I'd think a storm jib would be out. We couldn't have 2/3 of our genoa out in 50+ knot winds... and as a side note, I don't want to ever be in 50+ knot winds

[impi]

Originally Posted by InsuredApple

So, you had almost 2/3 of yr genoa unfurled in 50+ kts of wind ??

Yeloya

Wow, I'd think a storm jib would be out. We couldn't have 2/3 of our genoa out in 50+ knot winds... and as a side note, I don't want to ever be in 50+ knot winds [/QUOTE]

Absolutely - We very seldom use a storm jib although we have one - mostly because we find it’s dangerous to put it up in rough seas and mostly the storms we’ve encountered catch us by surprise and weren’t predicted. We’ve always found it safer to ‘play the Genoa’ and and we’ve found it safer than setting up a storm jib in strong seas. The trick is to keep the boat active and work the Genoa .we would use the storm jib if the Genoa failed
Cheers

[S/V Adeline]

Originally Posted by Moontide

Haven't read all the posts on this thread, but for those interested in reading some real world descriptions of both types of boats in survival conditions read "Surviving the Storm" by Steve and Linda Dashew.



Can download (free) it from https://setsail.com/free-books/.


This is a compilation and analysis of reports from boats (and rescuers) caught in the Queen's Day Storm in November of 1994 which caught large group of cruisers enroute between Fiji and New Zealand and some Sydney to Hobart races. A little dated, but many of the lessons learned on both monohulls and cats are valuable, and still applicable.



It also includes a discussion of various drogue types, including the Jordan Series Drogue (which is my preferred).


I highly recommend this book for anyone doing offshore passages on any boat.


Bill

+1

Purchased it new when it first came out, lost that hardcover in a nasty divorce. Downloaded the free version and still refer to it often. Many real eye opening accounts of just how fast the tide turns and lives are lost. I strongly recommend it for anyone before venturing offshore.

[Palarran]

Impi, I read your post on storm tactics and think it's pretty well thought out. Nice job.

Yeloya, How are you? We need to exchange e-mails to catch up sometime. Anyway, if you look at Impi's post you can see the sea state isn't that bad at the time the screen grab was taken.

We were in a pretty strong storm for quite a long time once. It really scared the poop out of me but in the end the old saying that the crew breaks before the boat was basically true. But the point is that I had an old salt listen to my tale once and he asked "If you looked at the swells, were the waves at the top breaking forward, or did the wave outrun the crest and break behind it?" After thinking - Behind. Then he said, "You know, almost all boats will survive a storm where the crest breaks behind the wave, but almost none will survive if it breaks forward."

I've watched about every heavy weather catamaran sailing video ever made and by far most are not even close to severe conditions. But the one of the couple sailing the southern Indian Ocean in a Leopard was for sure the best I've seen. That was some serious stuff.

[Sos]

Originally Posted by fxykty

Would have to have been some serious seas to have an effect I think. Even so, wow.

There was also the Schionning cat named Rosella that flipped at its marina berth in Auckland a little while ago during a microburst. The flip may have been caused by the main sail partially raising itself during wind gusts earlier.

In the threads about that there was speculation that lighter, more aerodynamic cats are more susceptible to extreme wind inversion. Not sure we have enough samples to make that conclusion. Even if true, though, I sure don’t want to spoil my boat’s sailing capabilities to prevent an extremely unlikely possibility.

There was a Prout that flipped while at anchor, in Greece.
Heavy boat with low bridgedeck clearance!

[impi]

Replying to Palarran



Nicely said Palarran
It's quite a topic to cover and very difficult to cover all the angles.

I agree with the 'old salty' stating the relevance of a wave breaking ahead of or behind it's swell - something we do look at closely and try to avoid the parts of the swell where the wave will collapse ahead of it - why we like to keep the boat active and position it whenever we can.

What we've found is that cresting collapse in waves in open ocean 'swells' (and wave period) tends to be very different to closely spaced steep waves in shallower seas also influenced by the geology of land, the tidal flows etc.
In many deep ocean passages the crest breaks well before the trough whereas in shallower seas the crest can break closer to the trough etc. (I'm really nervous of those - kid you not).

Sailing off the east coast of south Africa for example where the deep ocean becomes shallow, delivers some waves that can be very intimidating. The wave shape changes dramatically from deep to shallow and steepens quickly. All interesting stuff and an interesting topic that I'm sure would make a terrific post.

I agree about the video of the couple at sea on the Leopard - they really caught it well. I think you are referring to the video Kenneth & Carolina were delivering (South Africans) - sailing open ocean Cape Town to Australia ( the 40's / 50's).
Another video we quite enjoy is the fella off Southport Australia who surfs his cat on a breaking wave in shallower seas - WILD RIDE - not sure if you seen that?



Anyway - of course these are conditions we try our level best to avoid but as you mention - sometimes it just happens.

On any given passage we make sure the weather models align (are similar), we check local conditions, we check upper level winds eg 500hpa layer and ALWAYS check CAPE values.
I recall when we were departing with a number of yachts from French Polynesia for the Cook Islands - we called them in the morning to say we would not be following the same route and were altering course based on CAPE values - they held potential for severe storm development. No models / Gribs picked this up.

The fleet told us they were keeping to the plan as a weather router had said it was 'good to go'. We altered for Samoa instead and although we had some sporty conditions the fleet that went south all took damage in a massive storm - one boat broke a boom and the whole fleet turned back for FP. Fortunately we were able to reach Samoa in good shape.

After that we noticed the weather router was starting to use CAPE in his routing predictions, something we had learned when I asked a professor (also a sailor and pilot) at Stellenbosch University in Cape Town to teach us about weather (we had no clue before we left South Africa back then).

He also explained the significance of looking at upper level structures which took us a long time to fathom and gets quite technical but has helped us hugely - especially the potential for weather to break through to the surface.

These days of course - we all look at CAPE, and programs like Windy display it well.
However, when one is sailing every day for years on end in different parts of the globe, it's quite telling that no matter how careful one is, there is always the potential to be in conditions that are not be predicted - especially when sailing in some areas out of cruising season.


I hope you don't mind the lengthy reply to you, but hoped to cover perhaps some other reactions or thoughts by others as we seldom are on CF.


Nice to hook up with you again ... keep well
Brent

[mglonnro]

Just to make it easier for the rest of you

Originally Posted by impi

I agree about the video of the couple at sea on the Leopard - they really caught it well. I think you are referring to the video Kenneth & Carolina were delivering (South Africans) - sailing open ocean Cape Town to Australia ( the 40's / 50's).

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

Another video we quite enjoy is the fella off Southport Australia who surfs his cat on a breaking wave in shallower seas - WILD RIDE - not sure if you seen that?

https://www.youtube.com/watch?v=qp9WvZzxdR8