Cruising cat - sub 90 degrees tack upwind

[arsenelupiga]

watching video of O 55 Great Circle and it just happened they go upwind in 16 kn true at 55 true doing 9 kn. I am sure it can do better once they learn, but comparing to Django 5.4 VMG (mine 4.5 kn) in same conditions much smaller boat .... who says again lagoon cant go upwind ?

that is the calc and video at the time.

[arsenelupiga]

above example clearly shows that one needs to learn the boat, no matter how good boat is.

Most people switch the boat way before they reach full potential in performance leaving 20-30 % on the table. Pretty wasteful, especially if they pay premium for performance with more money, less space and less carry capacity.

[smj]

Originally Posted by arsenelupiga

watching video of O 55 Great Circle and it just happened they go upwind in 16 kn true at 55 true doing 9 kn. I am sure it can do better once they learn, but comparing to Django 5.4 VMG (mine 4.5 kn) in same conditions much smaller boat .... who says again lagoon cant go upwind ?



that is the calc and video at the time.

That’s a great speed for the Outremer 55 Great Circle considering she is still in the shed being built.

[fxykty]

Originally Posted by smj

That’s a great speed for the Outremer 55 Great Circle considering she is still in the shed being built.

Perhaps they went sailing on one of the three earlier O55s?

[cwjohm]

Originally Posted by arsenelupiga

watching video of O 55 Great Circle and it just happened they go upwind in 16 kn true at 55 true doing 9 kn. I am sure it can do better once they learn, but comparing to Django 5.4 VMG (mine 4.5 kn) in same conditions much smaller boat .... who says again lagoon cant go upwind ?

that is the calc and video at the time.

You make the common mistake in assuming the instantaneous readings of a plotter are accurate. In fact given the way the software works they are not. This is where you get these silly statements of maximum SOG which are in fact the result of instantaneous readings over short intervals resulting from inherent delays in both the GPS and speed readings.

The only way to get truly accurate readings is to use the average function over a reasonable period. Use several minutes, but in regard to VMG these periods should be longer and should incorporate at least two tacks, as the software measures VMG in relation to true wind direction which will vary continuously with time.

In regard to Django's data it is simply beyond belief that any normal boat will achieve 5.5kn VMG in 8kn TWS on average. However, it is entirely believable that you could get such an instantaneous reading on the displays.

If you want to be credible you need to state that you made two marks at least 1kn distance to direct windward x distance apart in y time and thereby calculate VMG.

The same considerations apply when one considers SOG. You often hear from owners that my boat can do 15Kn max and 10Kn consistently, but when you ask them for average SOG over 6, 12,24 hours their speeds look nothing like this on average. Try setting your plotter to average SOG and watch it consistently drop over time.

[arsenelupiga]

Originally Posted by fxykty

Perhaps they went sailing on one of the three earlier O55s?

my understanding same boat as theirs another owner, but already in water.

[arsenelupiga]

Originally Posted by cwjohm

You make the common mistake in assuming the instantaneous readings of a plotter are accurate. In fact given the way the software works they are not. This is where you get these silly statements of maximum SOG which are in fact the result of instantaneous readings over short intervals resulting from inherent delays in both the GPS and speed readings.

The only way to get truly accurate readings is to use the average function over a reasonable period. Use several minutes, but in regard to VMG these periods should be longer and should incorporate at least two tacks, as the software measures VMG in relation to true wind direction which will vary continuously with time.

In regard to Django's data it is simply beyond belief that any normal boat will achieve 5.5kn VMG in 8kn TWS on average. However, it is entirely believable that you could get such an instantaneous reading on the displays.

If you want to be credible you need to state that you made two marks at least 1kn distance to direct windward x distance apart in y time and thereby calculate VMG.

The same considerations apply when one considers SOG. You often hear from owners that my boat can do 15Kn max and 10Kn consistently, but when you ask them for average SOG over 6, 12,24 hours their speeds look nothing like this on average. Try setting your plotter to average SOG and watch it consistently drop over time.

you read it wrong. It is 16 kn wind and not 8kn. His display is in m/s this is 8 m/s = 16 kn.

All three boats in 16 kn, we have moments displays and can comapre, knowing there is envelope of error present.

You are right about moment displays also but thats what we have and there is no interest to display these.

However, i was achieving 6 kn at 41 true in around 16 kn wind which is 4.5kn VMG consistently. Yeah, could be sneaky current, or speedo or wind instrument that helped (or opposite) but GPS was in line more or less...

And Django 5.4kn is therfore believable as he has carbon sails and main is quite larger than standard and he is also racer.

And O55 managed 5.12kn with totally inexperienced crew. Seems believable to me. Just hull length advantage comes at 20 % faster, and then leanlines better sails etc adds probably another 20 % so I think this boat should do in these conditions around 40 % better than say L 400 and achieve 6.3 kn VMG. This would require 9 kn at 29 app in 16kn true.

[smj]

Originally Posted by fxykty

Perhaps they went sailing on one of the three earlier O55s?

Yes, I forgot the smiley face emoji again.[emoji1]

[django37]

Many nonbelievers here. A VMG of 5.4 knots and at 45 degr. TWA is 7.56 boatspeed over the gound. This is slightly less than the 380' hullspeeds: 1.25*(LWL)^0.5 = 7.6 knots, and max wave resistance at 1.78*(LWL)^0.5 is 10.8 knots. In winds above 15 knots, we can do between 7.5 to 8 knots boatspeed. If the wind gets over 20 knots we pull the sails harder and point higher, we dont try to go faster by pointing lower. Belove 15 knots its bad, because the boat is undercanwassed: in 11 knots (6 m/s) we can point 45 degr. and do 6.4 knots boatspeed, but then comes leeway, which increases with lower boatspeed, so we are doing over 50 degr. On the B&G a current of about half a knot is against us. In Greek waters, there are no tides, but often a weak current in the same direction as the wind.
Yes, I have done a lot of races, but consider myself a cruiser now, having lived on the boat for 5 years now and sailed round the world.

[44'cruisingcat]

Hull speed on a catamaran?

[cwjohm]

Yes, I now understand these displays were in m/s, not kn.

Accordingly, the performance stats quoted here by django are reasonable.

What, therefore, is the point made in this thread. Sub 90 degree tacks are possible at low SOG but not optimal for VMG. As django says at low SOG leeway pushes 45 degree tacks to 50 degrees.

The comparison to O55 is meaningless due to beginner crew with new boat.

It seems a whole lot of discussion over nothing of any substance.

[jmh2002]

Originally Posted by 44'cruisingcat

Hull speed on a catamaran?

It might actually be relevant for a Lagoon...

[smj]

Originally Posted by jmh2002

It might actually be relevant for a Lagoon...

Did you go there? Oh no you didn’t.......[emoji1]

[jmh2002]

Originally Posted by smj

Did you go there? Oh no you didn’t.......[emoji1]

It seems that I did (but all in good fun)

[arsenelupiga]

Originally Posted by cwjohm

Yes, I now understand these displays were in m/s, not kn.

Accordingly, the performance stats quoted here by django are reasonable.

What, therefore, is the point made in this thread. Sub 90 degree tacks are possible at low SOG but not optimal for VMG. As django says at low SOG leeway pushes 45 degree tacks to 50 degrees.

The comparison to O55 is meaningless due to beginner crew with new boat.

It seems a whole lot of discussion over nothing of any substance.

point of this discussion is for keeled boats approach upwind. It seems keeled boats can do quite well upwind by pointing higher and actually having better VMG as leeway is less than what is commonly accepted. Most people on this thread here have daggerboards, looking to me they are a bit surprised about the numbers that can be achieved by keeled boats.

Standard advice go 50 app with condocat turns out total rubbish = attempt by performance cat manufacturers to artificially lower the hurdle and they look better.

eh well, we can only expect more fake disbelief.