Catamaran tacking angles , really that bad???

[fxykty]

Originally Posted by arsenelupiga

Fast boat sailing at 34 app, say 8kn in 10 kn true, sailing at 60 degrees, can simply slow down at same app angle and will sail at 45 degress say throwing in water by small parachute.



At 8 kn it makes 4 kn VMG. Slowing down to 3.7 kn it will sail at angle 45 true and make 2.6 VMG. Although only 46.5% speed of fast boat, VMG is 65% of fast boat. Speed upwind is game of diminishing returns. This may get handy when crew tired or wants to eat, or just relax.



So, dropping app angle say to 30( instead of slowing by parachute) will slow down boat, so that speed thru water say halves will decrease VMG for 1 kn or 25 %.

But remember that dropping speed too much for higher pointing will also increase leeway, so the optimum angle for max VMG really depends on the particular boat, wind and sea conditions. The larger areas of mini keels vs daggerboards could mean that your Lagoon has less leeway in lighter winds at higher angles and slower relative speeds than a cat with daggerboards. So for you, maybe 90 degree tacks are optimum for VMG; for our boat 100-110 degree tacks are optimum.

I certainly remember sailing an IOR two tonner and often upwind as tactician I would tell the helm to slow down, i.e. point higher, for better VMG, based on the polars. Downwind, it was split 50/50 depending on wind strength whether it was better to go slower near DDW or to reach up and go for more boat speed.

[arsenelupiga]

Originally Posted by fxykty

But remember that dropping speed too much for higher pointing will also increase leeway, so the optimum angle for max VMG really depends on the particular boat, wind and sea conditions. The larger areas of mini keels vs daggerboards could mean that your Lagoon has less leeway in lighter winds at higher angles and slower relative speeds than a cat with daggerboards. So for you, maybe 90 degree tacks are optimum for VMG; for our boat 100-110 degree tacks are optimum.

I certainly remember sailing an IOR two tonner and often upwind as tactician I would tell the helm to slow down, i.e. point higher, for better VMG, based on the polars. Downwind, it was split 50/50 depending on wind strength whether it was better to go slower near DDW or to reach up and go for more boat speed.

i have a feeling you nailed it

of course if lagoon is well prepared for sailing so hydrodynamics works as per architect plan. Else one has to go to 45-50 angles.

Your boat is designed for higher speeds and draggerboards are better option as they develop less drag and same/better bite at higher speeds.

Outremer will also have to be in good trim to achieve expected/designed speeds else you get too slow and lose the edge as daggerboards do not function optimally.

[AllenRbrts]

I'm a little nervous about commenting on this thread given that folks have some strong opinions, but here goes.

It seems to me people are making unequal comparisons. arsenelupiga post was about sailing angles with TWS at 22K, and yet others were comparing monohull performance at 10K TWS. Certainly tacking angles will be very different between those conditions. At 22K TWS and SOG at 8K, AWA of 40, tacking angles of 100 would seem to be possible, but at 10K TWS those angles would become more like 160 (assuming SOG is still 8K).

I certainly don't what arsenelupiga's actual conditions were, but on our production cat (FP44), when sailing upwind, we typically will have a reported adverse current of about 2K. That is not real current, but instead a calculated current based our heading being higher than our COG and that our water speed is higher than our SOG. This "current" is due to leeway due to our minikeels. Again I don't know what arsenelupiga's conditions were, but some folks they might think they had adverse current, but it actually only the effects of leeway.

We can usually keep pace with our buddy boat which is a Hylas 49, but we have feathering props, very clean bottom and carbon sails. I do know that Joli at 61' sails circles around us

[Bullshooter]

Originally Posted by Dave_S

It is easy to assume a tight tacking angle is the goal.

IT'S NOT.

If you are sailing well and high at a point before speed drops off, i.e. without pinching, then, the wider you can make the angle between AWA and TWA while maintaining your AWA the better your VMG.

That's a fact. So the objective to improve VMG is to try to INCREASE the TWA as much as you can while maintaining the same AWA.

Forgive my ignorance but I don't follow the above bolded point. How can INCREASING the TWA increase VMG? ( I assume by VMG you refer to velocity towards the wind). I understand that your speed increases as you bear off, but the increased angle would decrease VMG. Wouldn't it drop to zero once TWA was 180?

[Zzmeyer]

The definition of vmg is the cosine of TWA times boat speed. As you increase TWA your vmg will increase or decrease based on how much your boat speed increases. For example vmg will be 71% of boat speed at 45 degrees and 64% of boat speed at 50 degrees. If your boat speed increases from five to six knots by falling off your vmg would increase from 3.5 knots to 3.8 knots. At 90 degrees VMG will be 0 no matter the boat speed.

[arsenelupiga]

Originally Posted by AllenRbrts

I'm a little nervous about commenting on this thread given that folks have some strong opinions, but here goes.

It seems to me people are making unequal comparisons. arsenelupiga post was about sailing angles with TWS at 22K, and yet others were comparing monohull performance at 10K TWS. Certainly tacking angles will be very different between those conditions. At 22K TWS and SOG at 8K, AWA of 40, tacking angles of 100 would seem to be possible, but at 10K TWS those angles would become more like 160 (assuming SOG is still 8K).

I certainly don't what arsenelupiga's actual conditions were, but on our production cat (FP44), when sailing upwind, we typically will have a reported adverse current of about 2K. That is not real current, but instead a calculated current based our heading being higher than our COG and that our water speed is higher than our SOG. This "current" is due to leeway due to our minikeels. Again I don't know what arsenelupiga's conditions were, but some folks they might think they had adverse current, but it actually only the effects of leeway.

We can usually keep pace with our buddy boat which is a Hylas 49, but we have feathering props, very clean bottom and carbon sails. I do know that Joli at 61' sails circles around us

I have described conditions -10 to 20 kn true, fluky winds, one reef in main. It is true that better angles can be sailed at higher speeds and we held 41 true at 15 kn true or higher, from memory. At lower wind speeds had to go up to 45 true.

It is possible i was so lucky that there was eddie (currents never rest here) and speedo showing too much, and helped with speed and angles. As I have repeated this 'achievement' couple times now, I have more confidence that it is not because of luck. But I will continue doing it and I will report back if i find out it was just a lucky streak. However there is no doubt in my mind that I have improved my windward technique for good.

We only have 360 W solar on davits (wind cannot 'see' it when windward) and no famous 'tent' above driver seat. That may also contribute positively to weatherness of the boat.

[arsenelupiga]

this is what wind see, ignore shade covers. See panels hidden behind, no tent, just roof above driver seat that produces almost no drag force, boat sitting high -> reasonably light, no tilting hulls back due to heavy batteries which is major drag.

So you can compare to your boat.

[GRIT]

It just so happens that we had to pinch quite high today, to get to our destination. We did a few tacks, and I managed to get some of it on video.

I'll forewarn you all, the audio is terrible, I'm wearing earplugs so I can't always hear my wife, I'm not used to videoing, and I'm a terrible "multi tasker". The mainsail sheet controls are on my right, and I'm filming with my right hand, and frankly, we don't have our sh*t together yet. But that last tack was pretty well executed.

We're pinching to about 40-45 TWA, with a few minutes of slightly more, or slightly less. Some of you are experienced enough racers to be able to tell me if this is considered "good" performance, and I'd like to hear your opinions. I'm pretty sure we were tacking at less than 90 degrees, once I got her pointed in the right direction again. If I was concentrating on sailing, rather than filming, I'd have done a better job.

We've really not practiced much on this boat, and are usually lazy sailing, unless the wind is just right. We'll get there.

In the mean time, let me know if this video shows what you'd call good performance, VMG and all that jazz.

https://youtu.be/sNDzTQYxwYE

Cheers.
Paul.

Oh, and can someone tell me why this next video is mirrored? It's not taken with the selfie camera.

https://youtu.be/qUsBVVau6VY

Thanks.

[smj]

Looked to me like you were maintaining a good speed pointing 40-45 of the true wind? I would think that is hard for any boat to accomplish.

[Dave_S]

Originally Posted by Bullshooter

Forgive my ignorance but I don't follow the above bolded point. How can INCREASING the TWA increase VMG? ( I assume by VMG you refer to velocity towards the wind). I understand that your speed increases as you bear off, but the increased angle would decrease VMG. Wouldn't it drop to zero once TWA was 180?

VMG = Velocity Made Good, from your starting point to the destination or next marker. If your marker is directly upwind from your start point then as you tack the marker is no longer directly upwind, so VMG measures your speed to the marker not necessarily directly upwind depending on where you are in your tack. When discussing here, I have assumed the marker was directly upwind from the starting point, it almost never is of course.

Increase the TWA while maintaing the same AWA. There is a limit to this at which point VMG decreases. e.g. if you are at 35° AWA then increasing TWA will increase VMG until you reach about 63° TWA at which point you are making progress at 37% of TWS, passed that point you start decreasing VMG. Depending on conditions we can make that but if I go over 63° I am loosing VMG.

If I point up to 30° AWA at my best I can make 54° TWA if we were better and could sail faster our tipping point would be 60°TWA but I'll never get there. On the angles and speeds I can make we are at around 47% of wind speed towards the mark, the best anyone can do at 30°A and 60°T is 50% of wind speed VMG.

To increase your TWA while maintaining AWA you have to go faster. Adjust dagger boards, trim sails, reduce rudder angle, bear away slightly and see if the extra speed brings your wind angle back to 30, repeat, reduce windage, weight etc.

[GRIT]

Originally Posted by smj

Looked to me like you were maintaining a good speed pointing 40-45 of the true wind? I would think that is hard for any boat to accomplish.

Thanks SMJ. I'll put your comment on the "pretty good" list.

There's so much lore around catamaran sailing abilities, that I'm really at a loss to decide what's good, or not good. We have no cat experience, other than this one. Our monos weren't very fast, so I'm trying to learn the definition of "fast".

We built the boat to be a fast sailing boat, but who knows if it is? This thread shows a Lagoon 40 to point as well as a j-boat.

What's true, or not, or fast or not, is difficult for me to decide. Everyone's boat is fast, as they tell the story.

Thanks for your comments SMJ.

Cheers.
Paul.

Oh, and I fixed the aforementioned video.
https://youtu.be/w0W4DZMdnY8

Thanks.

[smj]

Originally Posted by GRIT

Thanks SMJ. I'll put your comment on the "pretty good" list.

There's so much lore around catamaran sailing abilities, that I'm really at a loss to decide what's good, or not good. We have no cat experience, other than this one. Our monos weren't very fast, so I'm trying to learn the definition of "fast".

We built the boat to be a fast sailing boat, but who knows if it is? This thread shows a Lagoon 40 to point as well as a j-boat.

What's true, or not, or fast or not, is difficult for me to decide. Everyone's boat is fast, as they tell the story.

Thanks for your comments SMJ.

Cheers.
Paul.

I would put the comment on the “good” list as I think it’s hard to maintain a good speed while pointing that high.
We don’t have wind instruments or a speedo so my observations on our boat speed per wind speed are purely guessing on both wind speed and current. Your observations are way more accurate than ours.
I also think it takes quite some time to learn ones boat, especially coming from a monohull background. It will only get better!

[GRIT]

Thanks SMJ.

I'll rub that out, and re write it under the "good" list.

We're working on it. We'll get better, as we practice.

I'm not trying to compete with your rocketship, but I'm looking forward to folks commenting, and deciding whether or not the boat's "fast"; using their individual definitions of that term.

Cheers.
Paul.

[smj]

Originally Posted by GRIT

Thanks SMJ.



I'll rub that out, and re write it under the "good" list.



I'm not trying to compete with your rocketship, but I'm looking forward to folks commenting, and deciding whether or not the boat's "fast"; using their individual definitions of that term.



Cheers.

Paul.

I’m in the same “boat” as you, trying to learn a new catamaran to us. I can’t give accurate figures for our cat but we are really happy with the performance even being fully loaded.
If you are passing everyone else and no one is passing you then I would say your cat is fast. And I believe this will be the case with your cat.

[GRIT]

We haven't had much opportunity to pass boats. We passed three monohulls, in the middle of the night, while doing 12 knots in 16-17 knots of wind around Cape Canaveral.

And today, we passed a Hans Christian towing a hard dinghy! Made me proud!

Cheers.
Paul.