Reading: Sailing optimization for Macs

[DaveC426913]

I think I'd like to hone my sailing game.

I think I'll find a nice fat book on sailing theory - particularly sail shape and trim. But I might as well make sure I choose one that is as relevant to the particular eccentricities of Macs as possible. Looking for suggestions.

Speed of course, is nice, but pointing is probably the single most important factor in my sailing requirements. My no-sail angle is between 100 and 110 degrees (with my 150 genny), which means beating "upwind" is a pretty generous term for what I have to do.

I want more than just tips, I think I should immerse myself in the theory as a refresher.

I guess I should check out the 'performance and tuning' sub-forum while I'm at it.

[dlandersson]

Here you go

I think I'd like to hone my sailing game.

[Ammiraglio]

I am an engineer, and a specialist in design optimization. I have all the necessary degrees and thousands of hours of experience, and I know and use optimization algorithms every day. I usually get on my Mac to get away from optimization. I am a lousy sailor, but that's OK (for me).

My suggestion is to look for books that give you qualitative tips, e.g., put more twist here, sheet in less there, etc., rather than X degrees of heel for Y knots of wind, and then go out and practice.

If you really want to go about it "the engineering way", you'll need to start with a polar diagram. I searched the forum, and I only found this viewtopic.php?p=331154&hilit=polar#p331154, so it looks like there are no polars for Macs publicly available, and you'll have to put together your own by spending a lot of time taking measurements on the water.

[Russ]

I usually get on my Mac to get away from optimization.

Same here. Otherwise, I would not have bought a Mac.

With that said, the Mac is not forgiving with regard to sail trim. It's a good boat to learn if that's your goal.

[DaveC426913]

I usually get on my Mac to get away from optimization.

Software dev here.

Yeah. Totally. My brother is my 1st mate ofttime and he's a racer. so he's all about fine trim and proper procedure, and I'm like "Dude. This is a Mac. You're not Sisyphus. Sit back."

But I've been sailing SeaSaw for 16 years - in the same waters - and I'm fine with tweaking my game.

If you really want to go about it "the engineering way", you'll need to start with a polar diagram. I searched the forum, and I only found this viewtopic.php?p=331154&hilit=polar#p331154, so it looks like there are no polars for Macs publicly available, and you'll have to put together your own by spending a lot of time taking measurements on the water.

Sunuvagun! I had no idea anyone else thought the same way I did! I was groping toward this in my head, but I had no idea such a thing really existed!

I never developed it because every time I would start to think along these lines, my practical left brain would come along and say "Dude. This is what marine computers are for. Forget PoS and speed, marine computers magically calculate VMG, and you're done!" and then I give up.

(Just like the dive tables I learned on have been overtaken by dive watch computers.)


You have opened up a whole new world for me!

[DaveC426913]

I guess there's another layer on top of this one, which optimizes the VMG for a given PoS and speed, but that's not boat-specific.

[Sheppie62]

I’m reading Sailing for Dummies, maybe too basic, but I have already got some good use out of it. What I know is little, but I learned a jib sail will help in pointing up wind a lot. Mainly because it gets pulled in closer to the mast, doesn’t have to go around the outer stay like the Genoa. You will lose some power in lite wind, especially down wind. I put these plastic strips on the outer stays (on top of the cable covers), loose so they pivot well, align luff edge of sail with these (up wind only). That’s about all my knowledge good luck

[Be Free]

I guess there's another layer on top of this one, which optimizes the VMG for a given PoS and speed, but that's not boat-specific.

The graphic basically says that there is an optimal angle to the wind and if you point above or below that angle you will go slower.

The trick is finding that (sometimes) moving optimal angle. For an "X" below 10 knots I've found that to be around 50-55 degrees (true wind). 10 to 15 knots it gradually moves back to around 40 degrees and then stays in the 40 to 45 area up to the point where you should probably not be sailing a Mac. For simplicity, I usually aim for a few degrees either side of 40 degrees apparent and call it good enough.

[Herschel]

Sheppie62 said:

I learned a jib sail will help in pointing up wind a lot. Mainly because it gets pulled in closer to the mast, doesn’t have to go around the outer stay like the Genoa.

Yes, I switched to my jib within a year or so of buying my X back in 2003. I have stayed with it all these years. Plus, you have a little better visibility and smoother tacking.

[Be Free]

An "M" or "X" with a jib does not point well compared to many other sailboats; with a genoa it points even worse. Your only hope for any type of pointing is going to be with a jib.

[DaveC426913]

The mishap from last week that tore a length of the jenny's solar cover off has turned out to have quite the silver lining.
Today, I put up the jib that has been in by stern berth since I bought SeaSaw 14 years ago.
In fact, the PO never had it out either. It was still in the bag, with its bow* on, and a little note from Doyle about Care and Feeding of your new sail.

*bōw

Anyway, I ran my sheets inside the shrouds and took her out for a spin.

I achieved goal I've been trying to achieve for 14 years: I made a tack through 90 degrees. Not 110. Not 100. Ninety.
And I made both PoS's at 4.0 knots. (didn't drop below 3.0 during the tack).

I'll play with it while my genny gets better.

[dlandersson]

Ok, I have a 150% RF Genoa on my 26X, I routinely can "point" 30-40 degrees. I didn't start out that way, it happened over many hours (including many becalmed) of attempting to "sail"

I think I'd like to hone my sailing game.

I think I'll find a nice fat book on sailing theory - particularly sail shape and trim. But I might as well make sure I choose one that is as relevant to the particular eccentricities of Macs as possible. Looking for suggestions.

Speed of course, is nice, but pointing is probably the single most important factor in my sailing requirements. My no-sail angle is between 100 and 110 degrees (with my 150 genny), which means beating "upwind" is a pretty generous term for what I have to do.

I want more than just tips, I think I should immerse myself in the theory as a refresher.

I guess I should check out the 'performance and tuning' sub-forum while I'm at it.

[Be Free]

The mishap from last week that tore a length of the jenny's solar cover off has turned out to have quite the silver lining.
Today, I put up the jib that has been in by stern berth since I bought SeaSaw 14 years ago.
In fact, the PO never had it out either. It was still in the bag, with its bow* on, and a little note from Doyle about Care and Feeding of your new sail.

*bōw

Anyway, I ran my sheets inside the shrouds and took her out for a spin.

I achieved goal I've been trying to achieve for 14 years: I made a tack through 90 degrees. Not 110. Not 100. Ninety.
And I made both PoS's at 4.0 knots. (didn't drop below 3.0 during the tack).

I'll play with it while my genny gets better.

Out of curiosity, how much wind were you doing this in? I'm guessing north of 15 knots.

[DaveC426913]

The mishap from last week that tore a length of the jenny's solar cover off has turned out to have quite the silver lining.
Today, I put up the jib that has been in by stern berth since I bought SeaSaw 14 years ago.
In fact, the PO never had it out either. It was still in the bag, with its bow* on, and a little note from Doyle about Care and Feeding of your new sail.

*bōw

Anyway, I ran my sheets inside the shrouds and took her out for a spin.

I achieved goal I've been trying to achieve for 14 years: I made a tack through 90 degrees. Not 110. Not 100. Ninety.
And I made both PoS's at 4.0 knots. (didn't drop below 3.0 during the tack).

I'll play with it while my genny gets better.

Out of curiosity, how much wind were you doing this in? I'm guessing north of 15 knots.

5 knots.

[Be Free]

The mishap from last week that tore a length of the jenny's solar cover off has turned out to have quite the silver lining.
Today, I put up the jib that has been in by stern berth since I bought SeaSaw 14 years ago.
In fact, the PO never had it out either. It was still in the bag, with its bow* on, and a little note from Doyle about Care and Feeding of your new sail.

*bōw

Anyway, I ran my sheets inside the shrouds and took her out for a spin.

I achieved goal I've been trying to achieve for 14 years: I made a tack through 90 degrees. Not 110. Not 100. Ninety.
And I made both PoS's at 4.0 knots. (didn't drop below 3.0 during the tack).

I'll play with it while my genny gets better.

Out of curiosity, how much wind were you doing this in? I'm guessing north of 15 knots.

5 knots.

Just to be clear: the wind was five knots, you are going into at at 4 knots over ground (assuming gps measured) and then tacked through it never falling below 3 knots?