What if, Optimum course time to mark to sail calculator?

[jbinbi]

I am sure that this SW exists, I wish my B&G had this.

Here is what I want to know. I am sailing to a mark. I have polars to my boat. I am currently travelling at X kts at Y degrees off the mark. Should I fall off and pick up boat speed but increase my distance to the mark, should I head up , possibly lose a bit of boat speed but decrease my distance. Which option (course) will get me to the mark fastest.

If I have polars for my boat, standard instruments (TWS, AWS, TWA, AWA, SOG, STW, etc. etc.), all loaded and being observed, a piece of SW should be able to calculate TTM for any course I am on and give me the best course I should be sailing on. It should be able to say, fall off 5deg and you will get to the mark 3% faster.

I haven't raced in 40 years, but I have to believe that the larger boats with a crew that has a tactician have this SW. Does this SW exist?

[s/v Jedi]

Originally Posted by jbinbi

I am sure that this SW exists, I wish my B&G had this.

Here is what I want to know. I am sailing to a mark. I have polars to my boat. I am currently travelling at X kts at Y degrees off the mark. Should I fall off and pick up boat speed but increase my distance to the mark, should I head up , possibly lose a bit of boat speed but decrease my distance. Which option (course) will get me to the mark fastest.

If I have polars for my boat, standard instruments (TWS, AWS, TWA, AWA, SOG, STW, etc. etc.), all loaded and being observed, a piece of SW should be able to calculate TTM for any course I am on and give me the best course I should be sailing on. It should be able to say, fall off 5deg and you will get to the mark 3% faster.

I haven't raced in 40 years, but I have to believe that the larger boats with a crew that has a tactician have this SW. Does this SW exist?

If you have enough sensors then your displays show VMG Velocity Made Good which is the number you’re looking for… kind of.

If you want to see if you’re doing 80% or 100% of your possible speed, using your polars, then you need B&G Hydra computers.

[jbinbi]

Thanks. Yeah, I have VMG on the Zues. But what I am looking for is a what if on the course for best time to mark.

What course with current conditions will give me best time to mark. It would say to me , fall off or head up by X degrees. Glad to see Hydra from B&G has this, I just cruise so not going to spend on new instruments, but would assume this is straight forward SW and someone would have a program or app that you could purchase that does this.

[SailingHarmonie]

A crewed ocean racing boat is almost surely running a B&G Hydra, or custom computer doing the same thing. That will certainly do it what you are asking for. Although a calculated course is really is only a start, since the optimum AWA for maximum VMG is highly dependent on sea state.

Current versions of the Zeus (the 3, #s, and S) MFDs will report boat speed as a function of target speed in polars, but that is not really the answer to optimizing VMG.

A VMG display is almost useless to a human (at least one like me) trying to make progress to windward. The problem is if you head up, the VMG ALWAYS goes up... at first. When most helmsmen try to steer to the highest VMG they quickly find the boat in irons.

I have an AC42 B&G Autopilot that does optimize an upwind course, but has a much better ability than I do to look at time averaged VMG to make decisions. When sailing close hauled you can ask the AP to optimize the AWA for the current sea state, wind, and sail trim. Over the next 5 or ten minutes it tweaks the set AWA until it picks an optimum. I know the Hydra Autopilot can do the same. Note that the AC42 still needs the Hydra if it is going to optimize SOG/COG to windward. Without the external computer it ignores any effects of current.

I find the AP's optimization function quite helpful. I know about what AWA it will normally settle down to. If it ends up farther off the wind than I expect, then I immediately check for what I missed on sail trim.

The problem with most recreationally sailed boats, and especially cruising boats, the instruments are almost never calibrated well enough to give accurate numbers for the derived data, like VMG, or even TWA. Small errors in boat speed, wind angle, wind speed, and heading quickly accumulate and blow up the derived values.

[jbinbi]

Yeah. Appreciate the info. I am a scientist engineer and that part of me is just always wondering if I am on the optimal course to get where I am heading, even though I am really just daysailing, not racing. Doesn't make a difference in reality if I tack 3x or 4, I usually set the AP to wind so I don't even have to trim my sails.

But I just wonder, and part of the wonder was, isn't there some SW/app or instrument to give this best course for best time to waypoint. 40 years ago when I was writing code every day, I would have given this a go. These days, not so much, but figured some other coder/sailer would do this...Or someone would write a plugin for opencpn