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Old 14-11-2015, 16:40   #541
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Sail Mag article

Sail magazine just recently published an on-line article,

Mainsail Furling on a Multihull
Quote:
Originally Posted by excerpt
The defining feature of most modern multihulls is a large, robustly built mainsail, typically with full battens and a dramatic roach. The sails are cut large to maximize the performance for which multihulls are renowned, especially to windward. They are heavily constructed to withstand the loads that result from the boats not heeling before the wind like a monohull.
Unfortunately, this much canvas can make sailing a multihull a real chore, especially for shorthanded crews. Not only does the sheer weight of material make a multihull’s mainsail a bear to hoist, but they can be challenging or even downright scary to reef. Batten cars, luff tracks, lazyjacks, zippered “stack-pack” mainsail covers and slab-reefing systems all go a long way toward minimizing these challenges. But handling the main on a bigger cruising cat, in particular, remains tough, even if it’s just manhandling those last few folds of errant Dacron into its bag at the anchorage. The result is the all-too-many cats you see making their way under power or jib alone, even to windward, on an otherwise perfect sailing day.
Of course, the natural solution to an unruly mainsail is some kind of roller-furling system. However, while mainsail furlers have long been widely accepted aboard monohulls, they are rarely seen on multihulls, which is too bad, given the many benefits they provide.
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Old 14-11-2015, 17:20   #542
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Re: Why Do Catamarans Motor Nearly 100%

I have a Knysna480 cat that I single hand all the time. I love to sail...and try my best not to motor unless I have to. Probably just their preference to motor.
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Old 14-11-2015, 20:30   #543
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Re: Why Do Catamarans Motor Nearly 100%

Quote:
Originally Posted by Polux View Post
I can tack on 90º, even a bit less if the conditions are good, but I agree that most boats have a bigger tack angle and condo cats mutch bigger.

Regarding Upwind sailing to be more frequent It depends on the type of sailing and place. If one voyages a lot it will use the trade winds and that's mostly downwind sailing but I agree that the vast majority of sailboats do coastal cruising with some offshore passages.

There are another reason why I sail more upwind than downwind: With my sailboat I sail with 4k wind upwind, making apparent wind and going at least at wind speed. Downwind I cannot make wind, I subtract apparent wind and that means that with light winds I can sail upwind but I have to motor downwind.

So you sail at TWS, and at angles higher than 22' apparent?

I'd like to see some video of that...
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Old 15-11-2015, 04:10   #544
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Re: Why Do Catamarans Motor Nearly 100%

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So you sail at TWS, and at angles higher than 22' apparent?

I'd like to see some video of that...
No I don't sail with and apparent wind angle of 22º. With good conditions I make 26º apparent wind but in what regards the beat true wind angles you don't need a video, you only need to look at the ORCI rating file to see what the boat can make:

With 6k TW a wind angle of 43.4º with a VMG of 3.6k
With 10 TW a wind angle of 41.6º with a VMG of 4.9k
With 14k TW a wind angle of 39º with a VMG of 5.4K

Of course this regards flat water conditions and with 14K it is almost never the case so that angle (39º) is pretty much impossible to get. On my plotter the course line, when tacking, makes an angle of 90º or a bit less, in good conditions.
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Old 15-11-2015, 12:55   #545
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Re: Why Do Catamarans Motor Nearly 100%

If, as you claimed, you tack through less than 90', and sail at 4 knots in 4 knots wind, then you are sailing at 22.5' apparent or better....
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Old 15-11-2015, 13:22   #546
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Re: Why Do Catamarans Motor Nearly 100%

44 C is correct.

Try plugging your figures into one of the many True/Apparent/speed calculators
on the net.

4 in 4 at 45 is gunboat G4 territory. (this is the multihull forum ? )

Quoting possible figures and then attaining them in the real world without the best crew , sails , minimal load and flat conditions are two different thigs.

Like your boat ,Comet 41 s ,by the way.
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Old 15-11-2015, 17:34   #547
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Re: Why Do Catamarans Motor Nearly 100%

Hey everyone.
Cats have their place. I've motored in Croatia in a cat for a week due to low winds. Great trip. Not one nice sandy beach. Backed up to sea walls and loved it. I've motored around the BVI's for an entire week in a cat. My friend's sons love to fish. We trolled off both pontoons. Exciting fishing. Fantastic trip. We beat into the wind and motored for 9 days and 8 nights in a mono fighting our way from Cabo San Lucas back to San Diego. Woa. Crazy. And I've compared the Atlantic crossing times from the ARC results, which make for interesting comparisons.
But my home screen is a picture from a cat. I seem to spend much more time at anchor (or mooring ball or sea wall) than actually sailing. And I'm pretty convinced that a typical monohull just can't compete, even slightly, with a cat when the boats aren't moving. I don't want to live in a basement on land either.Maybe I'm just claustrophobic. But I'd never actually buy a monohull.

Please note, this is just an opinion. I don't actually listen to closely to what I say. My opinions change with time. I used to be a Republican.

Thanks
Matt

P.s. Any body want to partner up on a 1/4 interest in a Lagoon 560? Med in the summer, Carib in the winter?
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Old 15-11-2015, 19:57   #548
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Re: Why Do Catamarans Motor Nearly 100%

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Originally Posted by 44'cruisingcat View Post
If, as you claimed, you tack through less than 90', and sail at 4 knots in 4 knots wind, then you are sailing at 22.5' apparent or better....
I didn't said that I tacked in 90º with 4k wind and I did not said at what angle I was sailing upwind with 4k wind doing 4k speed, only said it was upwind and I don't see what is the doubt about that. It is a normal performance from any modern performance fast yacht, not a particularity of my boat.

It is dificult to find data on polars at 4k since they normally are only presented after 6k wind, but I found this one about the Pogo 12.50. The weaker performance of the Pogo is upwind, close to the wind with weak winds and even so you can see that the boat with 4k true wind is making 4k speed at about 45º true wind angle and almost 4.5k at 60º TW.

I don't have data regarding the VPP of my boat at 4k but you can see that the 5.52K speed at 52ºTrue wind angle with 6K speed (from the ORC file of a Comet 41s) is consistent with the data from the Pogo 12.50 polar speed, as it would be the data regarding speeds and angles with 4k winds. A small difference can exist for one or other boat but we are talking here about considerably more than 4k speed at 60º true wind angle with 4k wind.

That was what I was talking about. Regarding tacking in 90º or less and sailing with 4k wind at 4k what I said was:

Quote:
Originally Posted by Polux View Post
I can tack on 90º, even a bit less if the conditions are good, but I agree that most boats have a bigger tack angle and condo cats much bigger.

Regarding Upwind sailing to be more frequent It depends on the type of sailing and place. If one voyages a lot it will use the trade winds and that's mostly downwind sailing but I agree that the vast majority of sailboats do coastal cruising with some offshore passages.

There are another reason why I sail more upwind than downwind: With my sailboat I sail with 4k wind upwind, making apparent wind and going at least at wind speed. Downwind I cannot make wind, I subtract apparent wind and that means that with light winds I can sail upwind but I have to motor downwind.
Here you have a Polar speed from a Condo cat, a Lagoon 38:

You can see that at 60º of true wind with 8k wind the cat will only makes 3k speed and that with 10k wind only makes 4.8K. The VPP for my boat with 6k wind at that wind angle is 5.9k (more than 1k over the Lagoon with 10k wind) and with 10k wind at that angle is 7.66K, almost 3k faster than the Lagoon.

I don't see the point in this, I am stating the obvious. Condo cats have a weak upwind performance but if well sailed can go quite fast downwind, as it was proved several times on the ARC, and this year one more time, precisely by a Lagoon 38, that was faster than some performance cats.
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Old 16-11-2015, 00:04   #549
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Re: Why Do Catamarans Motor Nearly 100%

Oh, OK I misunderstood. By the same token, we've sailed to windward at over 10 knots in 10 knots TWS, and tacked through less than 90'..... on a cat, and a cruising cat at that.
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Old 16-11-2015, 01:01   #550
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Re: Why Do Catamarans Motor Nearly 100%

Dear Mr Polux, why on earth are you comparing the performance polars of the
Finot designed fast cruiser/racer? with a block of flats?.A very comfortable block of flats I must add.

I simply don't understand your point. Are these polars generated by the advertising department of the respective companies or are the derived from real world data.

Historically computer generated polars have proved worthless.
Remember the Gunboat.

Please explain what "nds" stands for after the TWS (true wind speed) on the lagoon polar diagram. ie what unit of measurement is a "nds"

Thnx
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Old 16-11-2015, 03:30   #551
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Re: Why Do Catamarans Motor Nearly 100%

nds = noeuds (French).
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Old 16-11-2015, 03:35   #552
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Re: Why Do Catamarans Motor Nearly 100%

Quote:
Originally Posted by Seaslug Caravan View Post

Please explain what "nds" stands for after the TWS (true wind speed) on the lagoon polar diagram. ie what unit of measurement is a "nds"

Thnx
It's an abbreviation for "nœuds", the french for knots.
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Old 16-11-2015, 05:05   #553
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Re: Why Do Catamarans Motor Nearly 100%

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Oh, OK I misunderstood. By the same token, we've sailed to windward at over 10 knots in 10 knots TWS, and tacked through less than 90'..... on a cat, and a cruising cat at that.
We were talking about sailing upwind. Any data to support that? Polars from your boat?

Upwind with 10K wind doing 10K speed wind is a much better performance than doing 4K with 4K wind. Here you have the polar speed of a Outremer 45, a very fast performance cat:
As you can see it is needed 23K true wind for the Outremer 45 to be able to sail at 9K speed at 70º of the true wind and even at 90/100º the speed is only a bit over 10K. Is your boat so much faster then an Outremer 45 to be able to sail at 10K with 10K wind? That is truly the performance of a carbon top racing boat, not the one of a cruiser racer.
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Old 16-11-2015, 05:10   #554
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Re: Why Do Catamarans Motor Nearly 100%

Quote:
Originally Posted by Seaslug Caravan View Post
Dear Mr Polux, why on earth are you comparing the performance polars of the
Finot designed fast cruiser/racer? with a block of flats?.A very comfortable block of flats I must add.
...
I was replying to another poster regarding two different points:

One that a performance monohull (call it a cruiser-racer if you want) in that case my own boat can do 4K speed in 4K true wind.

The other, that a condo cat has a poor performance upwind and I was not comparing the performance of a Lagoon upwind with the one of a Finot cruiser racer but with the one of my own boat.
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Old 16-11-2015, 05:22   #555
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Quote:
Originally Posted by Polux View Post

We were talking about sailing upwind. Any data to support that? Polars from your boat?

Upwind with 10K wind doing 10K speed wind is a much better performance than doing 4K with 4K wind. Here you have the polar speed of a Outremer 45, a very fast performance cat:
As you can see it is needed 23K true wind for the Outremer 45 to be able to sail at 9K speed at 70º of the true wind and even at 90/100º the speed is only a bit over 10K. Is your boat so much faster then an Outremer 45 to be able to sail at 10K with 10K wind? That is truly the performance of a carbon top racing boat, not the one of a cruiser racer.
I think Polux has far too much faith in polars, which in my experience often have little relationship to reality.

However, I agree with his point here. Upwind at 10 knots in 10 knots true? I think that cat should be entered in the next America's Cup.
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