So How High Will a Cat Point?

[tsmwebb]

Originally Posted by Curmudgeon

...How much higher can a daggerboard cat point than one with keels?

I don't understand what he bases this on but Gregor Tarjan claims up to 5 degrees higher and 2 to 5 degrees less leeway while comparing cruising cats with boards to ones with low aspect keels.

Tom.

[44'cruisingcat]

Originally Posted by catty

Thats so funny. I just checked out the weather obs for yesterday and there was very little wind so I'm guessing you had the motors running. Here Latest Weather Observations Port Macquarie Airport.

You guess wrong. Maybe YOU would motor a zig-zag course to try to look as if you were sailing, not me. While the breeze was light, it was mostly around 10 knots - ample to sail on. In our boat, if not yours.

I'm wondering exactly how you think you can figure out how fast we were sailing from a GPS track.

Oh, and by design, airports aren't usually placed in the most windy location available. There's quite often more breeze out at sea than inland.

Even funnier: checked out the weather observations for the time I was sailing - early afternoon - and the breeze is pretty well exactly what I described - NE around 10 knots. What's up catty, doesn't your boat sail in 10 knots of breeze, even to windward? Must be quite a pile... a real steamer, so to speak.

[Factor]

Who is laughing now !!!

[Southern Star]

44'cruisingcat, I'm with you. Catty has been asked before to tell us what kind of boat he/she sails and has thus far refused to answer. But if he/she must motor on a zig zag course upwind in only 10 knots and it suffers from the sort of leeway he/she estimated, then I gather it doesn't sail upwind at all. Maybe its a square-rigger cat.

C'mon Catty, help us out here. My boat is admittedly on the low end of the performance scale (something which I have repeatedly acknowledged), but even I can do way better than that.

Brad

[daddle]

Originally Posted by 44'cruisingcat

Yesterday: Sailing northeast in a northwesterly, which turned NE. On autopilot, so angles aren't quite as good as hand steering, but still in the 90-100 degree range.

Well, those tacking angles are pathetic. But maybe the VMG was good, as tacking angle has little to do with "How High Will a Cat Point". Here's a recent track of mine. Singlehanded, 10kts of breeze, small waves in the lagoon at Palau. My AWA, or pointing was about 30 degrees. Tacking angle around 70.

[Captain Bill]

Originally Posted by daddle

Well, those tacking angles are pathetic. But maybe the VMG was good, as tacking angle has little to do with "How High Will a Cat Point". Here's a recent track of mine. Singlehanded, 10kts of breeze, small waves in the lagoon at Palau. My AWA, or pointing was about 30 degrees. Tacking angle around 70.

Clearly going windward very well, but what kind of boat?

[Joli]

The OP's question "how high can a cat point" is rather meaningless. The real question should be: "what is the upwind VMG of a cat".

Below we have two examples from this thread, of upwind VMG's on boats with mini keels. Are the owners happy with those numbers? They certainly seem to be and that's really all that matters.

Palarran stated he would rather motor 14 miles in two hours then sail that distance in 6. So upwind VMG for the FP 56 is a bit over 2 knots.

Sailingaway221 listed the numbers below. His VMG, based on these number is 2.5 knots.

Report True Wind

Originally Posted by sailingaway221

Windier it gets higher I point... 7 to 8 knots 15 knots of wind and 42 - 43 degrees off the wind. St. Francis 43... flatish water....Choppy rough..... 20 - 30 k I slow the boat down by pointing higher if its comfortable... 39 - 42deg...apparent.... if uncomfortable, 45 - 47 but have to reduce sail to slow it down.

[tsmwebb]

Originally Posted by Joli

Sailingaway221 listed the numbers below. His VMG, based on these number is 2.5 knots.

Report True Wind

Are you sure? I believe he is giving true wind speed and apparent wind angle. Assuming that is the case then the reported VMG at 15 true is about a knot faster than your result. If he was giving true wind and true angle his VMG is over twice what you calculate. If he was reporting apparent for both then the result is for a breeze under 11 knots.

Tom.

[Joli]

Tom, generally you use apparent (ie boat speed, apparent wind angle, apparent wind speed) unless you have very expensive instruments (B&G 3000, Ockam's...). The data sampling rate of stand alone instruments is not fast enough to give you meaningful "true readings" without the central processor. And really, all you care about is what the boat sees anyway, you reef for apparent wind.

That said, he states he's using apparent wind angle. This yields tacking angles of 140 degrees if the wind is 15 apparent. VMG is 2.5 knots.

Let's assume that the wind speed is 15 true or 20 apparent. If that is the case the tacking angle is ~62 or 124 degrees. VMG is 3.46 knots.

Report True Wind

When you add lumps, bumps and leeway then sailing to the weather mark can be a time consuming event.

I think Palarran was completely honest stating he would rather motor 2 hours to an upwind destination then spend 6 hours sailing there. It also sounds like Palarran is completely thrilled with his boat. Every boat is a compromise, you give and you get.



"St. Francis 43... flatish water....Choppy rough..... 20 - 30 k I slow the boat down by pointing higher if its comfortable... 39 - 42deg...apparent"

Originally Posted by tsmwebb

Are you sure? I believe he is giving true wind speed and apparent wind angle. Assuming that is the case then the reported VMG at 15 true is about a knot faster than your result. If he was giving true wind and true angle his VMG is over twice what you calculate. If he was reporting apparent for both then the result is for a breeze under 11 knots.

Tom.

[Joli]

I believe Daddle sails a Santa Cruze 50?

Originally Posted by Captain Bill

Clearly going windward very well, but what kind of boat?

[tsmwebb]

Originally Posted by Joli

Tom, generally you use apparent (ie boat speed, apparent wind angle, apparent wind speed) unless you have very expensive instruments (B&G 3000, Ockam's...). The data sampling rate of stand alone instruments is not fast enough to give you meaningful "true readings" without the central processor. And really, all you care about is what the boat sees anyway, you reef for apparent wind.

I do? Are you sure?

I think depends on the context. When someone says they are sailing in 15 knots of wind I think that usually means true wind as estimated from the sea state . Certainly, when reporting into nets it is expected that true wind either from instruments or estimates will be used (also averaged COG in true degrees and TWD in true degrees or true points). In any case when I say that I am sailing in 15 knots of wind I mean true wind speed. FWIW, I use B&G Hydra 2000 and they produce true wind readings. But, I find Adm. Beaufort's method is about as good as it gets for comparative purposes given the difficulties of calibrating integrated instruments. IMO, an awareness of true wind is important to safe sailing. So, no, I do not only care about apparent wind.

Tom.

[Joli]

Oh, do you carry more sail up or down? Do you carry the same sail area in 20 knots regardless of point? App is what we sail in.

Regardless, the OP questions stands. "How high can a cat point?" or as I said, a more accurate question is "what is a cats upwind vmg?" Those numbers are known.

Originally Posted by tsmwebb

I do? Are you sure?

I think depends on the context. When someone says they are sailing in 15 knots of wind I think that usually means true wind as estimated from the sea state . Certainly, when reporting into nets it is expected that true wind either from instruments or estimates will be used (also averaged COG in true degrees and TWD in true degrees or true points). In any case when I say that I am sailing in 15 knots of wind I mean true wind speed. FWIW, I use B&G Hydra 2000 and they produce true wind readings. But, I find Adm. Beaufort's method is about as good as it gets for comparative purposes given the difficulties of calibrating integrated instruments. IMO, an awareness of true wind is important to safe sailing. So, no, I do not only care about apparent wind.

Tom.

[tsmwebb]

Originally Posted by Joli

Oh, do you carry more sail up or down? Do you carry the same sail area in 20 knots regardless of point? App is what we sail in.

This is very Zen of you. If you sail only in the moment then apparent is all you need to know. If you want to anticipate future possibilities then having a good idea of true is important. It is also critical to understanding the weather, for communicating to others and for understanding yacht performance among other things. I think most sailors are aware of both most of the time.

Originally Posted by Joli

Regardless, the OP questions stands. "How high can a cat point?" or as I said, a more accurate question is "what is a cats upwind vmg?" Those numbers are known.

The variance for both "pointing" (and I still don't know how the OP is defining that) and upwind VMG are greater for multihull designs than they are for monohull designs. We may know or be able to estimate numbers for specific designs. A couple of sets of polars have been posted in this discussion. For similar boats they should scale reasonably with the sqrt(lwl). Generalizing from there is unlikely to yeild valid results. Making assumptions about an unknown sampling of approximated data where even the units that the reporter intended to use are not known with certainty and then reporting them to two decimal places as fact seems like a bit of a stretch to me.

Tom.

[boatman61]

A cat like most boats will point all the way into the wind if asked to...
How fast... and how long they'll stay there is another matter....

[44'cruisingcat]

Originally Posted by daddle

Well, those tacking angles are pathetic. But maybe the VMG was good, as tacking angle has little to do with "How High Will a Cat Point". Here's a recent track of mine. Singlehanded, 10kts of breeze, small waves in the lagoon at Palau. My AWA, or pointing was about 30 degrees. Tacking angle around 70.

AWA 30 degrees, tacking angles of 70 means a TWA of 35 degrees. Even if we allow for zero leeway. In 10 knots of breeze, the only way your AWA could be so close to the TWA is if you were going pretty slow.

I'm sure Catty can crunch the numbers for us!