Catamaran tacking angles , really that bad???

[arsenelupiga]

Originally Posted by wingssail

arsenelupiga, Just to clarify, is your boat the Lagoon 400 that shows up in sailboat data, https://sailboatdata.com/sailboat/lagoon-400, which indicates that it is twin keel, (not centerboards)?

If so, that video you are considering should show both how you have the boat rigged and the instruments. I'd like to see TWA, AWA, BSP, and VMG, and a track showing tacking angles would also be convincing, of course current effects are always a possibility which the instruments don't usually show.

It is not that we doubt you, it's just astonishing that you can do it. We'd like to see how.

yes, standard fixed keels. I really do not get the issue here. Boat can surely do sub 90 tacks in mild sea conditions. Here is recent example of agitated seas that got less agitated as day progressed. There was some current that i believe runs north/south here. We like upwind sailing.

Done some studies of my tracks and in 6 kn boat speed drift seem to be really small upwind. It may be bigger with gennaker.

Will try to produce what you ask.

[arsenelupiga]

missing pic.

[jmh2002]

Originally Posted by Boatguy30

Here is another pic just at the gybe mark. Shows the relative loading. Probably at about 10,000 lbs vs 11,000 full load. Again, these were probably ideal upwind conditions for my boat. Reefed down into 25 knots that last 40 miles into N Minerva we were racking at about 140 degrees! Truly horrible!

Thanks for the info, nice photo too

[arsenelupiga]

and one more, wind was rotating here but one can see ~ 90 deg tacks

[arsenelupiga]

such disbelief on CF, found some more evidence. Spanish coast.

"For this delivery, there was no downwind sailing but an endless climb upwind, particularly on the Portuguese coast and along the north-west coast of Spain. Overall: the Lagoon 400 is sailing very clean, even in 30 knots of wind. Jean-Pierre has equipped his catamaran with folding propellers, the profile of the rudders has been optimised and the hull is particularly neat.

No damage or technical problems to report, which is very encouraging!"

I found this to be very informative for cruising catamaran handling in roaring 40ies.

https://www.boatsnews.com/story/2760...oesnt-scare-me

L 400 around 3 capes has not happened.

[Jim Cate]

Originally Posted by arsenelupiga

such disbelief on CF, found some more evidence. Spanish coast.

"For this delivery, there was no downwind sailing but an endless climb upwind, particularly on the Portuguese coast and along the north-west coast of Spain. Overall: the Lagoon 400 is sailing very clean, even in 30 knots of wind. Jean-Pierre has equipped his catamaran with folding propellers, the profile of the rudders has been optimised and the hull is particularly neat.

No damage or technical problems to report, which is very encouraging!"

I found this to be very informative for cruising catamaran handling in roaring 40ies.

https://www.boatsnews.com/story/2760...oesnt-scare-me

L 400 around 3 capes has not happened.

Perhaps I am being dense, but the tracks shown here don't seem to show very good tacking angles, well more than 90 degrees for sure... so what is this data in support of?

Jim

[arsenelupiga]

Originally Posted by Jim Cate

Perhaps I am being dense, but the tracks shown here don't seem to show very good tacking angles, well more than 90 degrees for sure... so what is this data in support of?

Jim

you are right. probably seas were not very pretty. However, it looks better than 50 app, which is what most people on CF believe Lagoon 400 can do at best of times in flat water, judged by disbelief around. So, yeah, it can do better than 50app, actually can do in good conditions 90 true tack, give or take. It is my belief that optimum angle for cat is actually around 110 tack most of time unless seas really bad.

[Woodgate Beach]

I think the factors that make a difference are dagger boards, rotating mast, weight, and skill with trim but not in that order. I have a 12m Schionning (light and dagger boards) but ballon hulls (rather than sharp) and I struggle above an AWA of 35 degrees. I am quite fast at AWA 40 but it falls off quickly as you push up to 30 degrees and then you have to come down again to build a bit of momentum. I need to tack through 100 to 110 degrees and then come up again. This is poor performance compared to the 14m race boat that I crew on but you can live comfortably on my boat and entertain. The race boat would be a cramped life. I can manage my boat single handed but the race boat needs 4 pob to get going.
Cats are a good choice for living and for entertaining but upwind is not their specialty. My friend has a rotating mast on a similar boat and does a good few degrees better than me but he is also a much better sailor.

[Tupaia]

Originally Posted by arsenelupiga

you are right. probably seas were not very pretty. However, it looks better than 50 app, which is what most people on CF believe Lagoon 400 can do at best of times in flat water, judged by disbelief around. So, yeah, it can do better than 50app, actually can do in good conditions 90 true tack, give or take. It is my belief that optimum angle for cat is actually around 110 tack most of time unless seas really bad.

I cannot see how you can glean anything from the plot without knowing the wind speed, direction and the speed of the boat. Your assumption of 50 app, which is pretty poor, is also meaningless without boat speed and I would be interested to know how you arrived at this figure.



A keeled cat will have a minimum leeway component of about 7-9 degrees (5 knots TWS) in light winds reducing to 5-7 (15-20 knots TWS) as the wind strengthens. The tacks shown might show superb performance if the boat speed was 10 knots and pathetic if the boat speed was 2 knots.



The key is maintaining a high boat speed and being able to achieve a small AWA. This is why monohulls appear to point higher because they have a lower boat speed. The faster a boat sails through the water to smaller the app wind angle must be to achieve the same tacking angle.



So without all of the parameters it is impossible to comment meaningfully.

[arsenelupiga]

Originally Posted by Tupaia

I cannot see how you can glean anything from the plot without knowing the wind speed, direction and the speed of the boat. Your assumption of 50 app, which is pretty poor, is also meaningless without boat speed and I would be interested to know how you arrived at this figure.



A keeled cat will have a minimum leeway component of about 7-9 degrees (5 knots TWS) in light winds reducing to 5-7 (15-20 knots TWS) as the wind strengthens. The tacks shown might show superb performance if the boat speed was 10 knots and pathetic if the boat speed was 2 knots.



The key is maintaining a high boat speed and being able to achieve a small AWA. This is why monohulls appear to point higher because they have a lower boat speed. The faster a boat sails through the water to smaller the app wind angle must be to achieve the same tacking angle.



So without all of the parameters it is impossible to comment meaningfully.

My analysis of track suggest that your numbers for leeway for kelled cat are too large. At least for our boat - assuming that you can keep hulls glued to sea.

Regarding boat speed in 15 true we do 30 app at 5.5 kn and we get sub 90 deg angle. And drive is pleasant. At 20 true we flirting with 7 kn at 30 app. 12 true we get around 5 kn at 30 app . Increasing to 35 or 36 gets faster, but often one does not want to go faster in bumpy conditions.

I am very happy with these numbers and allows us to choose upwind days for passage making. These numbers are bit lower than what Monte was reporting - see his 6000 nm review - if you really interested. So, no I am not making it up.

[Factor]

I would love to see your boat is a WAGS style race where like could be compared with like. I know the Lagoon 39 that runs occasionally in WAGS in Brisbane literally cannot make way to windward on windy days. It and the Nautitech 40 keep each other company at the back of the pack. I am aware that the Lagoon 400 is regarded as a much better boat than the 39, certainly it has a better sail plan. It would be good to see a well sorted one up against some other boats in similar conditions.

[Tupaia]

Originally Posted by arsenelupiga

My analysis of track suggest that your numbers for leeway for kelled cat are too large. At least for our boat - assuming that you can keep hulls glued to sea.

Regarding boat speed in 15 true we do 30 app at 5.5 kn and we get sub 90 deg angle. And drive is pleasant. At 20 true we flirting with 7 kn at 30 app. 12 true we get around 5 kn at 30 app . Increasing to 35 or 36 gets faster, but often one does not want to go faster in bumpy conditions.

I am very happy with these numbers and allows us to choose upwind days for passage making. These numbers are bit lower than what Monte was reporting - see his 6000 nm review - if you really interested. So, no I am not making it up.

You should be happy with the numbers. I am not disputing your figures for wind and speed in fact they are pretty good. When beating in a flat(ish) sea up to about 16 knots TWS you should aim for a boat speed of 50% TWS for a keeled cat and 70-75% TWS for a cat with boards so you are a little below that.



Based on your figures, your TWA 41 +/- 43°, without any leeway gives a tacking angle of 82 - 87°. BUT - The slower your boat speed the greater the leeway. The theoretical "most" efficient mini keels will result in a leeway in this wind range is 6° minimum giving you the best possible track angle of 94 - 98°. This ignores any wave action on the hull sides and aerodynamic drag of the hull/cabin profile the later I would suggest is a significant factor on your Lagoon. Anything better than this must be attributed to other factors like tide or current.



As Factor suggested you would benefit from joining in a few WAGS events.

[arsenelupiga]

Originally Posted by Tupaia

You should be happy with the numbers. I am not disputing your figures for wind and speed in fact they are pretty good. When beating in a flat(ish) sea up to about 16 knots TWS you should aim for a boat speed of 50% TWS for a keeled cat and 70-75% TWS for a cat with boards so you are a little below that.



Based on your figures, your TWA 41 +/- 43°, without any leeway gives a tacking angle of 82 - 87°. BUT - The slower your boat speed the greater the leeway. The theoretical "most" efficient mini keels will result in a leeway in this wind range is 6° minimum giving you the best possible track angle of 94 - 98°. This ignores any wave action on the hull sides and aerodynamic drag of the hull/cabin profile the later I would suggest is a significant factor on your Lagoon. Anything better than this must be attributed to other factors like tide or current.



As Factor suggested you would benefit from joining in a few WAGS events.

I thought to repeat upwind exercise to ensure I am not missing something an here you go, well performing again. So it must be true. L 400 perform pretty well upwind for its size.

We had nice upwind sail, second part recorded 2 kn current against us. Winds 10 to 20 kn. 1 reef in main. Flattish water. And one can see tacks are pretty good.
We managed 5 to 6 kn boat speed over water at true wind angle 41. SO that shows leeway is less than what you say, as early tacks are sub 90. Must be less than 4 deg.

Obviously you have not sailed Lagoon to full potential yet. Probably just charter boat, which is world apart from well setup Lagoon for sailing.

[arsenelupiga]

Originally Posted by Factor

I would love to see your boat is a WAGS style race where like could be compared with like. I know the Lagoon 39 that runs occasionally in WAGS in Brisbane literally cannot make way to windward on windy days. It and the Nautitech 40 keep each other company at the back of the pack. I am aware that the Lagoon 400 is regarded as a much better boat than the 39, certainly it has a better sail plan. It would be good to see a well sorted one up against some other boats in similar conditions.

that will never happen. I am just a skipper. Boss does not like anything to do with races.

Unless happens we sail same way on a multiday passage. Only then I get free hands. "Speed is safety" trick works.

[Factor]

Originally Posted by arsenelupiga

that will never happen. I am just a skipper. Boss does not like anything to do with races.

Unless happens we sail same way on a multiday passage. Only then I get free hands. "Speed is safety" trick works.