What boatspeed should I expect, as a percentage of True wind?

[Tupaia]

You need to have COG and boat speed to determine your actual tacking angle and leeway. You could be almost stalled with a tiny AWA but a huge leeway. If you look at your plot your tacks are more like 95 degrees over the ground.

Your TWA is calculated from the measured AWS, AWA and boat speed not SOG.

A better way to find how well you point is to set a GPS WP a long way away (say 500-1000NM) directly to windward and then sail to maximize your VMG recording your CMG.

Remember this will all change with wind speed hence the use of polar diagrams.

Good navigation software like (OpenCPN) will generate polars for you.

[Sparx]

Very nice results Paul. Actually brilliant performance. Someday I want to see this boat.

For faster tacking I drop the windward board just before shifting the helm, which gives the boat a firm pivot point. Just a small point to play with as you dial in your boat.

[GRIT]

Thanks to you both for the advice. I'd like to really test it one day soon, but we were just arriving from an overnight and I was too tired to be too fussy.

Agreed, I didn't think about COG. However, I'm still fairly pleased, as the boards were only half down.



I will try as you both said . I'm still new to cats, and the boat isn't finished yet.

10 minutes before the last video...

https://youtu.be/gERfh1P4jvE

Cheers.
Paul.

[GRIT]

On the second video, when I show the instrument panel, the cog is the same as my heading...
So it must be fairly close.

Am I missing something there? Someone with more knowledge about this stuff can tell me if I'm missing something...

Only one data point, but it must count for something.

Cheers.
Paul.

[django37]

Originally Posted by GRIT

Thanks Brent.

The board tweaking might help, but where I really need help is on mainsail trimming. I heard flat tops are easy to trim, but I can't believe they're as easy as it seems. I'm sure I'm doing something wrong.

The tell tales are most often doing just what I want them to do. I'm going to try to get them to flip to leeward more often, as I read that the mainsail should possibly be trimmed a little tighter than what the tell tales show. Though, every time I try it, I lose speed.

I'm also having luck with a very tight leech, and the main far to leeward, in 12 knots or so.

I've got to pay more attention to the foot tension too. I know I can do better.

I'm forever trimming the darn thing. On my old boat, I'd adjust it once an hour or two, or once a day offshore. On this one, I can't seem to stop tweaking! All of a sudden, a quarter of a knot means something...

I'm looking forward to sailing on a reach or a close reach, to see how things go.

Cheers for now.
Paul.

Why do you have so many data doubled? This is what I like to see.

[Tupaia]

Originally Posted by GRIT

I'm forever trimming the darn thing. On my old boat, I'd adjust it once an hour or two, or once a day offshore. On this one, I can't seem to stop tweaking! All of a sudden, a quarter of a knot means something...

I'm looking forward to sailing on a reach or a close reach, to see how things go.

Cheers for now.
Paul.

You are getting some excellent results for a first timer which is a testament to the boat. TW tacking angles of 86 degrees!

Unlike a boat limited by hull speed, that a whole range of adjustments will achieve, removing this limitation means that each tiny adjustment can give just that little bit more, or less.

It is rare to have constant sailing conditions, wind and waves, for any length of time but when you do it is good to play each control, out-haul, traveller, board, etc, one at a time and gauge the response. Every adjustment will not result in an instant change so give it time for the instruments to settle.

It once took 6 hours of an 8 hour night watch (full moon) to tweak a friends cat from an erratic 8-11 knots to a sustained 13 knots. The fastest passage the owner had ever made.

Mono's and most chartermarans don't have that zone above hull speed which is why so many are disappointed by catamarans. Sailing a performance cat well, by the numbers is a technical skill, where a few inches of movement on the traveller can gain an extra half a knot.

You have years of fun ahead, enjoy.

[GRIT]

Originally Posted by django37

Why do you have so many data doubled? This is what I like to see.

AWA of 12??? Wow, I wouldn't have thought that possible!

The screen I showed was nearly the default screen. I haven't yet had time to play with it to have it show the data I want (when I figure out what I want). We're still building the boat, my wife works on week-days, and we're trying to get south on the week-ends. There really isn't much time to get things set up yet.



It'll get there, but not soon!

Cheers.
Paul.

[GRIT]

Thanks Tupaia.

I really do have lots to learn, thanks for figuring out my tacking angle for me. I have many skills to develop, and I'll get there, but in the mean time, it's good to hear from those who know.

We have a fair bit of experience, on slower boats, having taken our Corbin 39 to Europe and back, but once we hit hull speed, there's no sense in tweaking anything. Most of our sailing has been cruising, and lazy cruising at that!

After being a lazy cruiser, in regards to sail tweaking, I'm quite surprised at how much I enjoy trying to get that extra 1/10 of a knot out of this boat. My wife is very understanding about it, but I'm sure she must be shaking her head when I'm not looking.

Cheers.
Paul.

[smj]

I find this an interesting subject but can’t comment as I don’t have a wind speed/direction indicator, and on a performance cat I find it hard to give solid numbers as the speeds are so erratic as compared to a monohull.

[Tupaia]

Originally Posted by smj

I find this an interesting subject but can’t comment as I don’t have a wind speed/direction indicator, and on a performance cat I find it hard to give solid numbers as the speeds are so erratic as compared to a monohull.

ultrasonic amenometer https://lcjcapteurs.com/en/ a revelation after my old wizzy, wizzy, flappy thing at the top of the mast.

[GRIT]

Hi SMJ.

I'm happy to hear generalities, or whatever input you have.

Tupaia: How long have you had this on your boat? I've looked at similar units, but reports were hard to find.

Cheers.
Paul.

[GRIT]

I ordered a Code 0 last week, which I should be able to pick up in December. We've also ordered a prodder and roller furler for the Code 0.

Travis, at Mack Sails, thinks the Code 0 will be about 100m2 in size. I asked for the biggest he thought would fit.

We're also talking about a 55m2 screecher for upwind work, but that will have to wait until I see how happy I am with the code 0.

We have a smallish symetrical spinnaker aboard, which we'll likely end up selling. I doubt it's even 80m2. So that's going to be on our shopping list too, a symetrical spinnaker of about 140m2.

That should round up or light air arsenal, but I'd appreciate any input anyone would like to give. The code 0 comes first, because I'm told that's a good "all rounder" to have.

Cheers.
Paul.

[smj]

Here’s my take on the last trip we took.
With winds at 8-10 and flat water we would make 7-9 at about 70 degrees true, and 6.5-8 with about 85 degrees between tacks.
On a beam reach in 10-12 gusting maybe 15 with 2-3’ seas on the beam and also another wave pattern of 2-3 from about 70 degrees we were making 8.5-11 hitting 13’s in gusts, that was with full main and 110% jib. With a reef in the main we dropped to 7-9 hitting 11 in the gusts.
This is without wind gauges but accurate on the speed.

[jmh2002]

Originally Posted by Tupaia

ultrasonic amenometer https://lcjcapteurs.com/en/ a revelation after my old wizzy, wizzy, flappy thing at the top of the mast.

This might be interesting too for a cable free installation (although there are some caveats, see the tech specs). Not cheap, but endorsed by the pros.

https://sailmon.com/max/

https://shop.sailmon.com/product/ult...e-wind-sensor/

They also have some other pretty cool stuff on their site too (but none of it is cheap either, it's all race grade stuff).

PS: @Grit, Paul your boat is great, any chance we can see some more photos? Thanks

[GRIT]

SMJ:

Thanks for those numbers. If you see me on the bay, please turn in the other direction. That boat's QUICK, in my books.


JMH2002:

Thank you for the compliment, we really appreciate it. We don't take a lot of photos, but here's a couple that I like.

Those instruments look pretty good, thanks for that too. I wonder how far the transmitter can be from the receiver? I seem to remember that Tack Tick had issues with tall masts... Just something to consider.



Cheers.
Paul.