Passage Planning Software

[ShinyShoe]

Am I missing a trick?

Say I want to sail from Port A to Port B. Port A has a bar on the harbour and I need to make sure I have enough water to get out. I then sail out to waypoint C, D and E to navigate round a headland before turning back in towards Port B, which also has a bar or maybe a marina that only opens its locks certain times around high water.

A plotter can handle all of that for me showing me what I'm doing and where my pre-determined waypoints are, bearings to them etc.

But while it shows charted depth... If I was at Waypoint C and and click on Waypoint D, it tells me its on a bearing of 100N but doesn't say "you wont have enough water" - why not?

• Water depth is (reasonably) predictable
• Passage times are predictable based on weather and tidal flow, both of which are (reasonably) predictable

So instead before I leave A, I make a load of predictions on paper using various sources of information. All prone to transcription error and calculation error. I leave port but as I'm heading to waypoint C I turn to avoid other shipping. The bearing to WPT is updated on the plotter for me to steer a new course. But underway, short handed, do I have time to recheck depths along the way? To recalculate not only if I can make it to Waypoint C, but if my deviation to avoid shipping has then delayed my arrival enough by "re-modelling" the remainder of the passage to affect by ability to get into B.

Its all just based on looking up information and doing some calculations. Thats what computers do well...

So am I missing a feature on some plotters that can do this? And if not why not?

 

[thommothebear]

I have often wondered about this myself, have found no answers so far though.

 

[wizard]

Navionics now have a passage planner ( not completely perfect-yet ) which is great for playing with both on idevices and the plotter. I suspect that with the feedback they are now getting it probably won't be long before they have all the bells and whistles you could possibly want, followed by all other makes of plotter.

 

[Hadenough]

Navionics now have a passage planner ( not completely perfect-yet ) which is great for playing with both on idevices and the plotter. I suspect that with the feedback they are now getting it probably won't be long before they have all the bells and whistles you could possibly want, followed by all other makes of plotter.

I'm aware of their route planner but not of a passage planner, or am I missing something?

 

[Spirit (of Glenans)]

Tidal calculations and various aspects of passage -planning/navigation are half the fun of boating. Things do not happen so fast at sea that you don't have time to review your pilotage plan.
Besides, using your brain instead of electronics keeps it active and helps to ward off the approach of dementia.

 

[[70521]]

Besides, using your brain instead of electronics keeps it active and helps to ward off the approach of dementia.

+1

I can't understand why there is this headlong charge to "trust the computer", a significant part of my enjoyment is working out a passage plan and then seeing if your calculations work and mentally making adjustments when the wind is not blowing, blowing too hard, blowing from the wrong direction or you have spent too long at the pub the night before and really, really want an extra two hours in your sleeping bag (not sure how a computer would react to that).

 

[thommothebear]

I agree to a degree, but when you in the pub or club and somebody says fancy a trip up to destination X on Saturday I usually like to take a quick look on the Nav package on my iPad, either iSailor or Navionics, both give me an outline passage plan but I still have to work out the best departure and arrival times and adjust for tides manually. I would still do my actual passage plan the old way and adjust according to actual conditions - I've had electronics and gps failures enough times now to not rely on them for anything critical.

 

[ShinyShoe]

+1

I can't understand why there is this headlong charge to "trust the computer", a significant part of my enjoyment is working out a passage plan and then seeing if your calculations work and mentally making adjustments when the wind is not blowing, blowing too hard, blowing from the wrong direction or you have spent too long at the pub the night before and really, really want an extra two hours in your sleeping bag (not sure how a computer would react to that).

Well 20, maybe 30 years ago thats what people said to GPS's and Chart Plotters. "Part of the enjoyment is working out where I am with a compass, why trust the technology?" And I absolutely agree - I love a paper chart far more than a screen. I love pulling all the info together - the tide table, the tidal atlas, the chart, working it all through.

But your situation you describe - the wind is not as strong as expected, or indeed stronger or I just CBA to get out my sleeping bag, all mean all of that needs revised. on a 2 hour jolly from A to B with few hazards along the way - fine. I might even have mentally figured some of them in my passage plan as I worked through it...

As the passage gets longer, with more variables - tidal races, hazards, more chance of weather forecasts not maturing as expected etc rather than looking at my watch constantly thinking Cr@p - shouldn't have stayed in my sleeping bag for that extra half hour I'm not going to make the bar it would surely be better that your passage plan could start to highlight "issues" ... won't make the bar - so will need to divert somewhere else... Or we will cut the corner a bit more or put the engine on to get there.

On a boat with crew its much more practical to re-calculate. Single handing - It surely becomes a bit back of a fag packet while trying to maintain a lookout, steer, trim sails, capture the latest weather etc.

Instead a computer can be monitoring position and therefore progress against the plan. Re-timing arrivals along the route and checking depths. If it had access to the "WWW" it could be getting updated weather, just like my car gets traffic updates and revises my Sat Nav routes...

 

[aidancoughlan]

Somehow deleted my post as I was typing it ! ... anyhow, have to agree with the OP. PC Plotting software has had tidal calculation capability including course to steer, best time of departure etc. for at least 8-10 years I think. (Euronav, PC Plotter etc. ) I can't understand why commercial hardware plotters costing thousands still don't have this capability (or do they now?). Perhaps it's a hardware processing limitation (cant imagine it being that intensive though), or perhaps just a market status quo. It's very handy in strong tidal water to quixckly calculate several departure scenarios in the pub the night before, and would be invaluable if it were supported and automatically recalculated on your hardware plotter at regular intervals. Even better if it checked anticipated depths etc. - what a help this would be when you are short-handed in marginal weather, and nearing the later stages of a long passage where you are missing tidal gates and considering options.

 

[[70521]]

Well 20, maybe 30 years ago thats what people said to GPS's and Chart Plotters. "Part of the enjoyment is working out where I am with a compass, why trust the technology?" And I absolutely agree - I love a paper chart far more than a screen. I love pulling all the info together - the tide table, the tidal atlas, the chart, working it all through.

What are these GPS and Chart Plotters you talk about? Joking apart the GPS has totally changed the way that people navigate these days. If only I could get the hang of these new fangled Cardinal Markers.

I did my Day Skipper when I was a spotty youth and when returned to sailing about 25 years later took it again. I do love working out a position usuing the traditional methods and like to check how close to the GPS fix I am.

 

[prv]

I can't understand why commercial hardware plotters costing thousands still don't have this capability (or do they now?). Perhaps it's a hardware processing limitation (cant imagine it being that intensive though), or perhaps just a market status quo.

Another factor is that sailing software engineers are relatively thin on the ground. I work with an ex-Navico guy (worked on Simrad and B&G plotters) and he's a good software developer but has no real boating experience.

Pete

 

[Keith-i]

I thought I saw in a Garmin manual an option to set minimum depths for its route planning feature. Presumably it is quite feasible for manufacturers to extend this to depths over bars etc. However, I think all plotters have a welcome screen which in essence says not to be relied upon for navigation so they are probably cautious about it becoming too easy to avoid being blamed for when it goes wrong.

 

[ylop]

Some Garmin plotters do have an auto navigate feature. I *think* it uses low water for its calcs though. AFAIK it doesn't plan for tacking or leeway either so I see it as more of a MOBO tool.

 

[KellysEye]

If there had been passage planning software when I was sailing I wouldn't have used it, it's a simple task to work out a passage plan and the tide height you want on arrival.

 

[ShinyShoe]

If there had been passage planning software when I was sailing I wouldn't have used it, it's a simple task to work out a passage plan and the tide height you want on arrival.

It is. You are absolutely right.

But I think it depends a LOT on your waters. If you are crossing the channel you only care about start and finish. If you are sailing round the IoW you might want to know about depths over various sand banks etc.

If you then add in the effect of tidal flow you might find the half hour delay caused by avoiding a ship, wind being slightly less than forecast or being late out of harbour then affects your progress by more than half an hour because you are now against a tide you had been hoping to be at slack. Understanding how all that plays into each other is what passage planning is about.

My work involves calculations on a daily minutely basis. I can do all that by hand if I need to. But 99% of the time a computer does it.

The fact that you wouldn't have used it- doesn't mean no-one would use it.

I suspect the legal issues may be part of it... ..."Your honour, Mr Garmin said there was enough water so I sailed on and broke my boat, I now want £1m compensation" "Your honour, Mr Garmin clearly stated in the 83 page disclaimer that came in the box with it that it will tell you if there is not enough water, rather than there is enough water"...

Can it be done in OpenCPN? It would need vector charts - which has been a limitation till recently in UK waters. OpenCPN can alert to landfall using a plugin.

I guess the other issue is scale of the chart - a small scale chart wont show enough detail to know there isn't enough water?

For tacking etc - I was anticipating that it would know the weather, know you'd be tacking and so would need to create a 1/2mile wide 'zone' rather than a thin blue line. It would need to identify any depth issues in the zone... This is what we do with our eyes without really thinking about it - we scan for obstructions...

 

[Playtime]

There is one useful feature on many (most?) modern chartplotters that goes partway to solving the OPs problem.

If a route is set up on the plotter (e.g. from A to E via B,C and D as per the example cited) and the route is 'activated' on the plotter, a continuously updated reading of ETA can be provided. This uses current average speed and the remaining distance along the route. It can't, of course, make any allowance for tacking or deviation for other shipping etc. but if the speed drops or the distance from the next waypoint increases then the ETA will be adjusted accordingly (upwards in this example) in real time. The plotter has no knowledge of depths but, if there is a tidal constraint at the destination, the time window can be pre-planned and the ETA can then be (manually) checked against it very quickly.

I use this facility all the time for longer passages. The routes are pre-prepared (often at home) using OpenCPN and then uploaded into my Simrad NSS8 before departure.

It works for me.

 

[ylop]

But you,ve suddenly gone from a very simple set of estimates to knowing the weather (needs intenet connection on the boat) and no use for planning more than 48h ahead. Then knowing how close to the wind the boat will sail, how often we will tack , how much sail we will put up, the possibility we might run the engine, etc, in my experience those thing vary depending on who is on board, the wind v tide condition and even the swell height, how much of a rush we are in, other traffic etc.

It's perfectly calculable and contrary to the assertion above that there aren't many sailing software engineers I can name three or four and you only need one , actually you don't need any so long as the sailor can clearly explain the process. Life becomes complex when u have too many choices, and you will want to sail on the ground as you see it not as the software calculated.

 

[ShinyShoe]

But you,ve suddenly gone from a very simple set of estimates to knowing the weather (needs intenet connection on the boat) and no use for planning more than 48h ahead. Then knowing how close to the wind the boat will sail, how often we will tack , how much sail we will put up, the possibility we might run the engine, etc, in my experience those thing vary depending on who is on board, the wind v tide condition and even the swell height, how much of a rush we are in, other traffic etc.

It's perfectly calculable and contrary to the assertion above that there aren't many sailing software engineers I can name three or four and you only need one , actually you don't need any so long as the sailor can clearly explain the process. Life becomes complex when u have too many choices, and you will want to sail on the ground as you see it not as the software calculated.

This is no different from me wanting to know how long it will take to drive from Leeds to Glasgow. I punch the two into the computer and it gives me an estimate based on available info. I may tell it I need to be there by 3pm on Thursday and it can back calculate based on "normal" traffic on a Thursday at those times. On Thursday when the weather is awful and there are accidents, it updates its estimates on the sat nav as I set off. If it then didn't have internet that is as good as it will be, but probably a better estimate than the general guess. If I have internet on the sat nav it can further update as I go.

So I'd expect the same thing. I'm sat in the pub pontificating a passage in 6 weeks time. It can model the tides etc based on the normal predictive models etc. But either it can't do weather or it needs to vaguely use general weather for that time of year. The night before I head off it can download a new grib and check the estimates. Suddenly it says I need to leave earlier... no problem. No grib because I'm out of site of the internet and don't have Sat Phone. I can enter in a F4 NE veering 5 later from the inshore forecast. Wont be as good as the grib, but would be better than a general estimate.

It would know what boat speed I would expect at different angles to the wind and conditions. It would let me configure that but could then learn that from me over time. I'd be able to tell it I will be cruising (e.g. 70% of max potential speed) or racing (100% max speed). I can tell it I can supplement speed with the engine or not. (It could even know fuel consumption and fuel tank state!)

None of this is any different from you do on paper passage planning... is it? OK some of it is a bit rough and ready on paper - but you all have an expected speed for a reach, a shade less for a run etc. When you hear the forecast and the wind is less than expected you say - best leave a tad sooner... the advantage with the software doing that is it is recalculating what leaving sooner actually means for passage into tides etc.

If you have internet you can get an updated grib on passage. If you don't it wont update, but it could know if the current wind is lighter than expected from your instruments and it could know why you are progressing slower...

...I think that's the flaw with ETA values. In simple terms you are travelling 100 miles, at an expected 20 miles per hour. Your ETA at departure is 5 hours from now. You travel the first hour but have only managed 15miles; does your ETA show the remaining 85miles at 20MPH or 85miles at 15MPH? - that depends why you are only making 15MPH for the first hour... Those will be two very very different ETAs. But if you could feed in sufficient data you can work out why and seek info on will those things change...

 

[Polly's Kettle]

The traditionalists are right - it's fun to calculate. But I have a boat full of kids, a job list waiting, and frankly don't have time to do everything I'd like to. Sometimes life's too short, and it would just be helpful not to have to waste the time.

If I use Navionics as an example it will struggle sometimes to create a route because of depth, whereas I know that anything above half tide is OK. Going into Bembridge Harbour is a good example. So I have to trick it by telling it I have a draft of 10cm. Then it's happy, and creates a route in moments. Yet quite separately, the same package has tidal heights, tidal streams built in, and a clock. So all of the data is there, andI use it to manually check what time I have to leave to get there with enough water. It won't be long before they wake up to this. But I agree - Plotters cost far far more - why on earth don't they do this?

So I agree with the OP - it is functionality that would be easy to deliver for a half-decent developer, and I'd expect to see it soon.

 

[Playtime]

...I think that's the flaw with ETA values. In simple terms you are travelling 100 miles, at an expected 20 miles per hour. Your ETA at departure is 5 hours from now. You travel the first hour but have only managed 15miles; does your ETA show the remaining 85miles at 20MPH or 85miles at 15MPH? - that depends why you are only making 15MPH for the first hour... Those will be two very very different ETAs. But if you could feed in sufficient data you can work out why and seek info on will those things change...

This of course is nonsense. Any active ETA calculation worth anything uses the real time average speed (not the "expected" speed) and the total distance still to run. OK chartplotter ETA calculations can't properly cope with tacking but in all other situations they do give a useful indication of arrival time.