Newb Multihull wind angle question

[Don C L]

I think to answer your question, I have yet to enjoy the pleasure of a boat that is so fast that it creates this problem, well, except for Hobie cats long ago, but when you get back on that Crowther, I believe you'll find that as you point higher into the apparent wind the boat will slow (sails luff as it adjusts to the new speed,) and the apparent wind will move closer to the true wind of course. So you can can point higher relative to the true wind, but you'll not enjoy that same speed. Hence the irresistible desire to spend obscene amounts of money on more perfect airfoils
So, to save yourself, get a nice old slow boat now before you get sucked in to the vortex of speeed! I neeed more speeed!

But before you do that, can I get a ride on that cat too?

[Dsanduril]

We can sail between about 50TWA and 65TWA with almost no change in AWA. What changes is boat speed. As we get closer to the wind the boat slows down. As posted above, it's all about VMG. That's just basic trig, for us, in nice 12-18 knot trades that's about a 110 degree tack. When it gets windier we point higher to keep boat speed about the same so the ride doesn't get too bouncy. Flat water sailing is a different animal, there we may open things up a bit more.

[unbusted67]

Originally Posted by Don C L

I think to answer your question, I have yet to enjoy the pleasure of a boat that is so fast that it creates this problem, well, except for Hobie cats long ago, but when you get back on that Crowther, I believe you'll find that as you point higher into the apparent wind the boat will slow (sails luff as it adjusts to the new speed,) and the apparent wind will move closer to the true wind of course. So you can can point higher relative to the true wind, but you'll not enjoy that same speed. Hence the irresistible desire to spend obscene amounts of money on more perfect airfoils
So, to save yourself, get a nice old slow boat now before you get sucked in to the vortex of speeed! I neeed more speeed!

But before you do that, can I get a ride on that cat too?

Haha, you will notice I haven't given up the identity of this charter boat because I hope to buy it and ruin myself financially!

[Just Another Sa]

Originally Posted by 44'cruisingcat

I was told this by one of the F50 sailors in Sydney. But what would he know?

He would certainly know what the instruments showed him. And he might very well use that instrument for something useful while sailing the boat.

But the truth is that The GPS system and telemetry on those boats was far more accurate and precise than any wind instrument reading on board. The analyses done onshore by the teams to learn the best angles for performance was certainly based on that info.

[44'cruisingcat]

Originally Posted by Just Another Sa

He would certainly know what the instruments showed him. And he might very well use that instrument for something useful while sailing the boat.

But the truth is that The GPS system and telemetry on those boats was far more accurate and precise than any wind instrument reading on board. The analyses done onshore by the teams to learn the best angles for performance was certainly based on that info.

How do you know he based what he told me from on board instruments?

Have you sailed an F50? Ever?

Are you seriously claiming you know more about them than the people who sail them professionally?

[44'cruisingcat]

Originally Posted by unbusted67

So let me see if I am getting this right: Multihulls, because of the nature of their design do not generally point as high as monohulls.

That info aside, in a fast multihull, you may find yourself close hauled even with the TWA well aft of the AWA due to the boat speeding up and therefore bringing the AWA forward. As the multihull points higher though, boat speed will fall off as you get the bow of the boat pointing closer to TWA 45, therefore it is important to have a good indicator of VMG.

Does that sound right? Am I way off? I guess what I am wondering is, since you could be close hauled with the TWA aft of the the beam, then what happens when you point higher? Certainly you don't go into irons because TWA is actually well aft of your AWA irons point right?

Fast cruising catamarans are generally also good to windward.

They point about as high, in terms of AWA, as fast cruising mono's. We generally sail at around 30' apparent. A degree or two lower if it's light, a little higher if it's fresh.

What makes them appear to not point as high is that they sail faster. The faster you sail, the greater the difference between AWA and TWA. Which results in bigger tacking angles.

You could sail higher still, go slower, tack through tighter angles, but it's not the best way to make VMG on a cat.

[Just Another Sa]

Originally Posted by 44'cruisingcat

How do you know he based what he told me from on board instruments?

Because of what you wrote to this thread. Go read it if you don't remember it.

Originally Posted by 44'cruisingcat

Have you sailed an F50? Ever?

No. And that is not relevant at all.

Originally Posted by 44'cruisingcat

Are you seriously claiming you know more about them than the people who sail them professionally?

I don't claim what someone else knows or not. I was commenting on what you said someone sailing on those cats has told you. I assumed you were telling the truth, if you lied here or that sailor lied to you, that's not my problem.

The fact remains that AC50 cats were capable of sailing awa < 14 degrees at optimum downwind course, and that there is no reason to assume sailGP cat would be any slower in equal conditions. The fact also remains that anyone who wanted to posess publicly available telemetry data from AC50 cats at bermuda has the data now, and adding some elementary level trigonometry allows to calculate correct awa from that data.
Nothing you or some sailGP sailor says can change any of that.

[44'cruisingcat]

Originally Posted by Just Another Sa

Because of what you wrote to this thread. Go read it if you don't remember it.


No. And that is not relevant at all.

..

No, in your personal looneyverse, internet experience beats real world experience every time.

I said they sailed at 13 and 19 apparent. Never mentioned on board instruments. That's your imagination at work again.

[44'cruisingcat]

Originally Posted by Just Another Sa

The fact remains that AC50 cats were capable of sailing awa < 14 degrees at optimum downwind course, and that there is no reason to assume sailGP cat would be any slower in equal conditions. The fact also remains that anyone who wanted to posess publicly available telemetry data from AC50 cats at bermuda has the data now, and adding some elementary level trigonometry allows to calculate correct awa from that data.
Nothing you or some sailGP sailor says can change any of that.

Maybe in your little loonyverse.

On planet Earth, sailing at 14' apparent at THREE TIMES TRUE WINDSPEED, you'd still be sailing UPWIND. Tacking through about 120 degrees.

Gee, maybe the guy who actually sailed the F50 knows something after all?

[44'cruisingcat]

Originally Posted by Just Another Sa

In some wind speed perhaps, but certainly not in all windspeeds.
During AC35 in Bermuda, ETNZ sailed at 3 times windspeed with TWA of 150 degrees, which results AWA as 13.19 degrees.
I don't think sailGP is any slower in similar conditions.

Of course the wing causes upwash in front of it, so any wind instrument could show some other numbers, like 19 degrees caused by that source of error, but that really doesn't matter, does it?
13 degrees awa sounds pretty close correct for upwind case in similar conditions, but not in the heavier stuff.

The wind transducer on F50s is not fitted anywhere near the wing. It's out on the tip of the prodder, well forward of even the forestay, and probably about 25 feet in front of the wing.

Just another mistake....

[unbusted67]

woh guys. settle down.

[44'cruisingcat]

Originally Posted by unbusted67

woh guys. settle down.

I dislike being accused of lying.

It's notable that the person making the accusation has, after being proven wrong repeatedly and running off wailing to the moderators, failed to answer any of the factual points I've made.

[unbusted67]

Originally Posted by 44'cruisingcat

I dislike being accused of lying.

It's notable that the person making the accusation has, after being proven wrong repeatedly and running off wailing to the moderators, failed to answer any of the factual points I've made.

I know but it’s just sailing man. i’m just gonna chalk it up to a misunderstanding. 10 posts later and I still don’t know wtf either of you are arguing about.

[longjonsilver]

Originally Posted by unbusted67

I know but it’s just sailing man. i’m just gonna chalk it up to a misunderstanding. 10 posts later and I still don’t know wtf either of you are arguing about.

"hear hear" as they say in the British Parliament.

[44'cruisingcat]

Originally Posted by unbusted67

I know but it’s just sailing man. i’m just gonna chalk it up to a misunderstanding. 10 posts later and I still don’t know wtf either of you are arguing about.

It's pretty simple. When the SailGP was in Sydney, we (TP 12 and myself) went to Cockatoo island, where it was based, to check out the boats.

I asked one of the F50 sailors what angles they sailed at. He said 13' apparent upwind, 19' apparent downwind.

When I posted that here Just another sa said that was wrong, he knew better, they sailed downwind at less than 14' apparent and that either I or the crew member was lying. Obviously the crew member would have no reason to lie, which would just leave me...

Unless, of course Just another sa was wrong....

And it turns out, at 3 times windspeed, even at 4 times windspeed, a boat sailing at 14' apparent isn't sailing downwind at all.