Cruising cat - sub 90 degrees tack upwind

[Factor]

Originally Posted by arsenelupiga

no idea. I come from the other end. I systematically measure sailing results and then try to explain so next time when planning route my estimate of boat abilities will be more precise so we optimally navigate route. Also helps to find enhancements to sailing technique. Do all this as part of preparation for long range sailing, so i have better idea of good and bad sides of our boat, regardless of any theories or opinions.

Seriously, aspect ratio of foils is not a theory or opinion, its fluid dynamic fact,

[arsenelupiga]

Originally Posted by Ken Fry

To illustrate the effectiveness of cracking off a little, here is what Sailing Mag had to say about the Lagoon 40:

"The key to sailing the Lagoon 40 is the 706ft Code 0. With romping fun conditions outside Government Cut just off South Beach in Miami, we unfurled the large headsail and soon found ourselves touching 10 knots of boatspeed in 16-18 knots of true wind on a beam reach. As we hardened up to 50 degrees and the true wind dropped to 15 knots, we still held onto 7.9 knots. The important thing to note here is that this cat will keep her speed even at a 50-degree apparent wind angle, making her more than just a downwind cruiser."

So, these people who are paid to make boats look good (because of advertising revenue) are suggesting that 50 degrees is a good upwind angle. The fact that they say "even at 50 degrees" suggests, correctly, that the expectation is for something greater than that. I agree completely: 50 degrees is a good showing for a fat cat. Obviously, the VMG of the test boat is far far better than the VMG suggested by the 41 degree tack experience. It is going much faster, while sailing only a slight bit further.

Looking at "450: PHRF rating?" in this forum will provide relative speeds of various cruising cats, in the second post. They sort out about as you'd expect, with nothing to indicate that one 40-ish foot cat is much faster than another.

reason for gennaker comment at 15 kn true above is because gennaker limit is 18 kn apparent. So they say 15 kn wind strength can also be used for upwind with gennaker. Once you go under 75 true, gennaker limit becomes 15 kn app and basically mean you can go to around 10-11 kn true max.

New generation cats with mast back do not perform upwind as well as older models but compensate with reaching speeds.

[Factor]

Originally Posted by arsenelupiga

New generation cats with mast back do not perform upwind as well as older models but compensate with reaching speeds.

Mast back is very old generation - it was popular on the Prouts of the 70s and 80s. Are you saying the a "new Gen" lagoon with an aft mast is faster than one with its mast in the more efficient location?

[arsenelupiga]

Originally Posted by Factor

Seriously, aspect ratio of foils is not a theory or opinion, its fluid dynamic fact,

i can see high aspect ratio works better at higher speeds. So that is why sleek, light cats have it.

In lower speeds, when pinching, maybe not functioning as well as turbulence created sooner?

Fixed long keel may be better for pinching as turbulence not such problem... And under some conditions, when abundant energy - enough wind, pinching may be optimal setting for our keel cat as all attributes come together in sync - weight,shape, rig. Say in 25 kn app, we got 7 kn thru water or thereabout at roughly 90 tack i think. Use this technique 2 mths or so, so not knowing enough and maybe some numbers are not proven enough. But tacks, i am pretty confident.

[arsenelupiga]

Originally Posted by Factor

Mast back is very old generation - it was popular on the Prouts of the 70s and 80s. Are you saying the a "new Gen" lagoon with an aft mast is faster than one with its mast in the more efficient location?

we cant do 10 kn in 16 to 18 app reaching with gennaker as in article. We are liveaboard loaded so that may be the reason.

[fxykty]

Originally Posted by arsenelupiga

i can see high aspect ratio works better at higher speeds. So that is why sleek, light cats have it.



In lower speeds, when pinching, maybe not functioning as well as turbulence created sooner?



Fixed long keel may be better for pinching as turbulence not such problem... And under some conditions, when abundant energy - enough wind, pinching may be optimal setting for our keel cat as all attributes come together in sync - weight,shape, rig. Say in 25 kn app, we got 7 kn thru water or thereabout at roughly 90 tack i think. Use this technique 2 mths or so, so not knowing enough and maybe some numbers are not proven enough. But tacks, i am pretty confident.

With short waterline and fat hulls and slab front cabin, your boat has way too much drag to perform at that speed in the sea conditions that accompany 20 knots TWS (for 25 knots AWS), unless you are in sheltered waters. Light ship or not, form drag matters, especially in stronger winds and their accompanying waves (and also in very light wind due to wetted surface). With your square top you’ve added sail area, so you’ve got more power to help overcome all that drag. Does that mean you have beefed up the rigging and structure to handle the additional loads of that extra power?

I don’t know about your offshore experience (and excluding downwind irrelevancies like the ARC), but from our own experience we subtract about 25% from near shore and coastal performance to plan our offshore performance. However, the offshore from (and to) New Zealand is tougher and more on the wind than most other passages in the world, so that often excludes the moderate conditions when we could match inshore performance.

Regarding keels, the only benefits to long keels are tracking and less propensity to stall. There is too much chord to have a proper hydrodynamic shape, therefore excessive wetted surface and form drag, plus more drag from the long end plate. None of that helps going upwind, which is why there are no race boats of either mono or multi persuasion with long keels.

Contrary to your supposition, short chord daggerboards and keels do not have more drag at any speed as they can have perfect foil shapes. But as they are shorter, they can stall out more easily, particularly at lower speeds. So they are more suited to faster boats that don’t pinch. The longer keel does help. But not enough to overcome the other drag factors in more wind and waves.

Regardless of all else I’ve written, it’s great to hear about the sailing performance that you have worked for and enjoy, and the other Lagoon owners that have chimed in. You are to be commended as you are definitely against the grain; the vast majority of condo cats that we see around the Hauraki Gulf and beyond are motoring to windward, and often any other wind direction.

Bravo

[arsenelupiga]

Originally Posted by fxykty

With short waterline and fat hulls and slab front cabin, your boat has way too much drag to perform at that speed in the sea conditions that accompany 20 knots TWS (for 25 knots AWS), unless you are in sheltered waters.

That is my experience, yes. However, we find that around 1/3 of time we can max it, sometimes on open seas.


Light ship or not, form drag matters, especially in stronger winds and their accompanying waves (and also in very light wind due to wetted surface). With your square top you’ve added sail area, so you’ve got more power to help overcome all that drag. Does that mean you have beefed up the rigging and structure to handle the additional loads of that extra power?

L 400 can use either sail, square or not - no rig adjustment required. However I beefed up top two cars.


I don’t know about your offshore experience (and excluding downwind irrelevancies like the ARC), but from our own experience we subtract about 25% from near shore and coastal performance to plan our offshore performance. However, the offshore from (and to) New Zealand is tougher and more on the wind than most other passages in the world, so that often excludes the moderate conditions when we could match inshore performance.

WE always used non-upwind weather to make day passage. However lately I concentrated on upwind to see if comfort and meaningful progress can be achieved. Use 3 kn VMG for direct upwind for passaging and seem to work fine. No complaints from crew. We had 2 days or so upwind passaging on multiday passage and sailed some, motored some. No, i would not be comfortable/too adventurous in NZ weather.

Regarding keels, the only benefits to long keels are tracking and less propensity to stall. There is too much chord to have a proper hydrodynamic shape, therefore excessive wetted surface and form drag, plus more drag from the long end plate. None of that helps going upwind, which is why there are no race boats of either mono or multi persuasion with long keels.

Contrary to your supposition, short chord daggerboards and keels do not have more drag at any speed as they can have perfect foil shapes. But as they are shorter, they can stall out more easily, particularly at lower speeds. So they are more suited to faster boats that don’t pinch. The longer keel does help. But not enough to overcome the other drag factors in more wind and waves.

Regardless of all else I’ve written, it’s great to hear about the sailing performance that you have worked for and enjoy, and the other Lagoon owners that have chimed in. You are to be commended as you are definitely against the grain; the vast majority of condo cats that we see around the Hauraki Gulf and beyond are motoring to windward, and often any other wind direction.

Bravo

Thanks, pleasure is all mine One can live modestly/simply on Lagoon as well, which is the part of sailing i really enjoy. Bit of extra performance is a bonus.

[Ken Fry]

Originally Posted by jmh2002

This thread, I guess?

https://www.cruisersforum.com/forums...ng-171394.html

Yep, that's the thread.

[arsenelupiga]

After a while couple of boats reported sub 90 upwind tacks. They all in performance cruising club.

After some thought this is what is going on here

Performance cats like outremer, Atlantic and similar have thin hulls and draggerboards and aerodynamic shape above and below water on expense of space. They use speed to propell them upwind.

Lagoons that reported great tacks (it appears smaller only ?) use fixed keel size and to propell them upwind at best VMG. Their shape above and below water is not as aerodynamic. So they go slower but higher true angle thanks to keel.

For example my measurement 17 kn true, at 41 true wind angle going 6 kn, means 31 apparent wind and VMG ~ 4.5kn. With drag that seem to be around 3 degrees true VMG is 4.25 kn.

Performance cat holds same apparent wind angle but goes say 9 kn at 31 in 17 kn true wind. And assume same leeway = 3 degrees. They make 5. 8 kn VMG

So although performance cats go 50 % faster than lagoon at same apparent wind, their VMG is 36 % faster as speed at same apparent wind angle is game of diminishing returns.

Looks like some people push speed at all costs when upwind for condo cats, this is only true for fast cats. If performance cats use lagoon receipe, their VMG is not that good. For lagoon, slow and sharp seem to produce best VMG, and speed first produces lesser VMG.

Anyway, something people should try for themselves and see if my theory has legs. It works for us.

[Sos]

Set a waypoint dead upwind and then if you sail an oppy, AC72 or a cruising catamaran, VMG is what matters. Everything will then depend on wind strength, sea conditions and tide. I don't see what tacking angles have to do with it? Everything is variable except VMG.

[arsenelupiga]

Originally Posted by Sos

Set a waypoint dead upwind and then if you sail an oppy, AC72 or a cruising catamaran, VMG is what matters. Everything will then depend on wind strength, sea conditions and tide. I don't see what tacking angles have to do with it? Everything is variable except VMG.

you absolutely correct. However see this from for example https://www.katamarans.com/lagoon-400/ about lagoon 400, which is also mainstream opinion

" But don’t pinch her too tight. Just like any keel cat, she’ll sail up to 45 degrees apparent, but you are best off bearing away 5 degrees or so to keep your speed up and minimise the leeway. If you head too close to the wind, you might see the leeway build up to 20°."

that is totally wrong advice, except for really rough seas which we get around 1/3 of time. See my tracks and speed. If people listen to them, they will never enjoy full potential of the boat. And this is for L 400 to sail sharp angles and produce better VMG and more comfortable drive when conditions allow which we find around 1/3 of time when upwind.

[44'cruisingcat]

Here ya go

The recorded track is 11 miles at 7.3kts average.

[Sos]

Originally Posted by 44'cruisingcat

Here ya go

The recorded track is 11 miles at 7.3kts average.

Good to see you back!

[arsenelupiga]

Originally Posted by 44'cruisingcat

Here ya go

The recorded track is 11 miles at 7.3kts average.

nice to see you back. i though you are sitting at home, collecting some job seeker/keeper and losing sailing skills

in meantime i was practising/improving and preparing for long trips.

Your track looks very good, although we do not know the tide. But believe you would not post 'biased' track.

Your cat is really in performance category with daggerboards. Interesting that you could hold sub 90. Let me guess.

Apparent 28 deg

so you had 16 kn true wind ?

We can compare this to Django result. He was also doing 90 deg, at 28 apparent and 5.4 kn VMG. Meaning his speed was around 7.3 kn and wind 16 kn true. His has strengthened sails so I cant compete with him.

[Apollo19.5]

Originally Posted by 44'cruisingcat

Here ya go

The recorded track is 11 miles at 7.3kts average.

My home waters. Can be tricky with the tide direction. Good overall speed. Nice boat you have too.