Sail trim apps

[postoaca]

Are there any apps that can describe the most optimal sail trim based on some input data such as wind speed, direction, sail types etc? preferably connected to a B&G or Garmin device?

[wholybee]

Finding the optimal sail trim is far more complicated than what can be determined by a few parameters. One of the most important "inputs" is going to be what the sails look like. Another is how the helm "feels." So no, there aren't any apps that will give you optimal sail trim.
"Good enough" trim, if you are cruising and not racing is pretty easy and doesn't require an app. Ease the sail until it just starts to luff, then trim until it just isn't. Getting from good enough to optimal requires some study and practice.

[pdx_sailing]

before there where apps, we had books
I found this guide useful and easy to understand.

https://sailtrimproducts.com/

[Alan Mighty]

Originally Posted by postoaca

Are there any apps that can describe the most optimal sail trim based on some input data such as wind speed, direction, sail types etc?

Welcome to Cruisers Forum, postoaca! Hope you find a lot of happiness here.

Jolly good question.

Not even all human brains are capable of optimal sail trim. Big mobs of experiential learning, with perhaps a dollop of neuroplasticity, seem to be required. Seems that not everyone carries enough CPU power in their heads.

In addition to data of the sort you've mentioned, short term local weather forecasts, sea state data, and of course the sort of data captured in a polar diagram for a specific sail plan and hull are necessary. Change the sail plan, such as from a sloop to a cutter, and you have a different game.

At the America's Cup level of racing, several applications were devised but each also required the addition of human judgment. Big money was involved.

Since then, America's Cup racing has moved away from boat designs likely to be used by a cruiser.

North U, a part of North Sails, made attempts at applications (for smartdevices and for PC/Mac), at reasonable prices (i.e. either free or for about US$10).

The North U apps were called 'simulators', and were restricted to (1) upwind work using a sloop sail plan; (2) a relatively small set of hulls with polar diagrams from velocity prediction programs; and (3) without dealing the complexity of capturing and responding to a full suite real data. Perhaps better for optimising human performance than a replacement?

Some of the roadblocks on the way are quite difficult. Consider for yourself how to generate instantaneous genuine true wind vector given easily measured apparent wind vector plus leeway data plus waterspeed data etc. And then add the job of mapping that true wind vector across all sails and at all heights above sea level. Repeat for different points of sail.

It's a bit like nuclear fusion. Always one or two decades away. Perhaps.

And then, what's the point?

Have a look at:

https://northu.com/sailtrimsimulator/

[Spindrift NH]

Originally Posted by pdx_sailing

before there where apps, we had books
I found this guide useful and easy to understand.

https://sailtrimproducts.com/

These trim charts are a great reference, and I think the author is on this forum

[sailorboy1]

And here I thought that "app" was called tell tails

[Snore]

Sail trim is an art. I do not believe a chart can apply to every boat in every situation. Stated differently there is no Magic solution. The only way to master sail trim is to understand what a sail does, and then adjust your sails to perform that function best.

I would suggest to start by reading Arvel Gentry's works. Arvel Gentry was a research specialist in aerodynamics at the Skunkworks run by the McDonnell-Douglas company. Because a sail is fundamentally an air foil or wing turned on its side, Gentry's training and profession were incredibly relevant. IMFO Arvel Gentry's works provide the best education. Best of all-- his works are available free! See Gentry Sailing | Theory and Practice

Once you read his works, you will understand the importance of tell tales on the BODY and leach of the sails, and why adding an outhaul/barber haul to the jib on your catamaran, in many conditions, can add 1/2 a knot.

Finally, after you have read Gentry, try to get a ride with someone who does around-the-bouys races. Or lure them onto your boat with rum.... Someone who is competitive will impart a treasure trove of info---- if you have taken the time to learn the basics with Gentry.

Yes some of those guys are fanatics, but

[belzamail]

What you can get is your performance in relation to optimal speed in given wind speed, for this there is built in features in some of the more high end systems from B&G, usually given as a percentage number. (This is built on a polar data for your boat, that can be either calculated or then recorded from your real time practice data) But you need to know what to do in order to increase speed. But at least you will know you should do something to the sails.

[postoaca]

I really appreciate the answers I got. I agree sail trim is an art but as a resonably new sailor I take all help I can get and an app that would recommend the best sail set-up based on my available sail set would help. I have B&G and will explore more what is available within the chart plotter first. Once again, thanks for your time and answers! Much appreciated!

[Montanan]

Don't forget to include the comfort and safety of the crew and passengers on board into the parameters of sail trim. Those are my primary considerations, whereas performance is a longways down the list, but then I have long since given up racing.

[Snore]

Originally Posted by postoaca

… … the best sail set-up based on my available sail set would help. … …

Check the owners manual. Every cat I have run has an owners manual that states the sail configuration for various wind speeds. That is different than trim

[Montanan]

Originally Posted by sailorboy1

And here I thought that "app" was called tell tails

So not to be confused with Tattle Tells.

Although I admit to having some tattered tell tails on some of my older sails.