SailgribWR

[matt1]

I’m loving the sailgrib app And for less than £200 for the app and a small android tablet it’s pretty amazing to think I can get my own weather and tide routing. I mean, I’m guessing this is on a par with the routing that round the world racers would have been using a couple of Vendee’s ago

But, a couple of rookie questions if I may?

Whilst I can see the plot of cog and even get the cog in the “road book” table, I can’t find where it actually tells me what course to steer?

Also, when I ran it for a typical channel crossing I only got a very slight / subtle “s” so am wondering if I have the correct settings for tides. I’m set to “atlases of current” rather than “grib of currents”

 

[franksingleton]

I cannot answer your questions but am interested in Sailgrib and routing from an academic point of view. And I am not an Android user.
Do you have to feed in boat polars and how is that done?
How much GRIB data do you have to download?
For an “ordinary” cruising yacht, I am sceptical about routing for the majority doing passages mostly a few hours to a day or so. On oceanic crossings, I am also sceptical because of the limitations in predictability beyond 7 or 8 days. What might seem a great routing for the first week could put you in a difficult position for the second week. Stan Honey once said that while he used routing on RTW events, for his own 40 ft yacht, he would wait until he had a window to get clear of land and then take what came.
When I cross the Channel, my decisions are mainly concerned with tidal gates, do I have a fair wind enough to sail but not too much. On coastal passages it is mainly tidal streams, gates and harbour entry considerations. Does anyone find routing useful for that kind of sailing?
A friend of mine used a routing service to cross Biscay from the Solent. They took him through the Alderney Race at night, south of Guernsey, beating along the French coast, through the Chenal du Four at night against the tide, it was a neap. I have not checked back, but at the time, I did wonder why they left just then. I seem to remember that a day later and they could have sailed direct to Le Four. Maybe leaving when they did, had they gone west rather than east, they might have picked up a good direction for Le Four earlier. My analysis might be faulty, it was a while ago now but it did not look sensible.

 

[matt1]

Hi Frank

Sailgrib comes with a huge database of pre loaded polars for many mainstream production boats, but I believe you can upload your own as well.

I think you can download 7 day grib files but it interfaces with iridium so you can download more whilst on passage to refine the route. It does factor tides, so I could even use it just for crossing the Channel as a lazy way of calculating course to steer.

Still getting to grips with it but am impressed.

 

[Ingwe]

Whilst I can see the plot of cog and even get the cog in the “road book” table, I can’t find where it actually tells me what course to steer?

Also, when I ran it for a typical channel crossing I only got a very slight / subtle “s” so am wondering if I have the correct settings for tides. I’m set to “atlases of current” rather than “grib of currents”

In the road book it gives you COG and I think apparent wind angle (it might be true wind angle I can't remember off the top of my head) so the idea is that as long is the wind is as predicted you sail to the wind angle that it is telling you to and keep an eye on the COG that you are making on the screen to make sure that it is all roughly adding up. The snag with all of this is that it is only as good as the weather data you are getting so only ever think of it as a guide as to what you might want to do as opposed to sticking to exactly what it says, as weather forecasting just isn't that good yet, on that note if your sailing in the channel often the most accurate short term free forecast is is the "Arome" one which is the French high res 2 day forecast, the equivalent met office one you have to pay for.

The tides bit I haven't played with enough to answer your question as I have only used it for about 4 passages where that would have had an effect. I don't know this but I am guessing that the atlas of currents may well be higher res but the grib of currents will take into account the atmospheric pressure effects so would be more useful if there is either a very low or a very high pressure system nearby.

In reply to Frank there are times when routing can make a big difference over relatively short distances eg I once won a 4 hour race by half an hour because I had run the routing and found that due to a wind shift that was coming in half way through the race I should start off sailing a much deeper angle than you would have expected to, I could easily see that even for the average cruiser doing a 12 hour passage you would regularly chop thirty minutes to an hour off the passage if you had spent 2 to 3 minutes downloading a grib and running a quick routing, which isn't a bad return for a couple of minutes work.

 

[matt1]

Thanks - that’s really helpful. I’ve been vicariously sailing all manner of passages over the Xmas break and it’s fascinating. Best one was a trip from the solent - Portland that started to plot a route taking me well south and into the channel before then showing me the tack on a wind shift that bought me nicely in to Portland. If I were sailing that passage for real there is no doubt I would have just taken a direct course and ended up headed! (Yes, I get that it is just a guide and the wind shift may not have materialised)

To be fair, I’ve mainly bought the app for longer 3+ day passages, but it occurred to me with the ability to add motoring parameters and tides it could be useful even for crossing the Channel. Especially if sailing to a wind shift could make the difference between motoring the passage or not

 

[Ingwe]

I use it for pretty much all passages no matter how short. If you program in all the passages that you do regularly you can download the latest grib, run the weather routing and press play it will show you a rough passage plan, show you what the wind is likely to do and what the tides are doing all in under a minute. Just look at it as a way of looking up the weather / tide info that you are going to do anyway that happens to give you the routing info as a bonus! As another tip if you also own the navionics app you can download any of the charts that you own to view them within sail grib so that you don't have to switch between apps.

 

[matt1]

I use it for pretty much all passages no matter how short. If you program in all the passages that you do regularly you can download the latest grib, run the weather routing and press play it will show you a rough passage plan, show you what the wind is likely to do and what the tides are doing all in under a minute. Just look at it as a way of looking up the weather / tide info that you are going to do anyway that happens to give you the routing info as a bonus! As another tip if you also own the navionics app you can download any of the charts that you own to view them within sail grib so that you don't have to switch between apps.

navionics app next on the list )

 

[franksingleton]

Thank you. My direct contact with routing was as a provider in the very early days of NWP. Obviously forecasting was hardly adequate but our impression was that, even with far better prediction, routing a 10kt ship on an Atlantic crossing was virtually impossible. Forecasts are often pretty good out to 7 or 8 days but predictability decreases quickly after that.

What experiences does anyone have of other providers? Predictwind is big in the area. Are there any comparisons?

I assume the the £200 to Sailgrib is a one off. What sort of data costs are there? Obviously not a great problem when still ashore or close to land but a possible problem if using Iridium, I guess. Using PW, presumably you avoid data download costs but what does PW cost? Which is more cost efficient? Does PW have a cost per routing?

On an ocean crossing, I would want to update routing daily. Does anyone do that?

I am too old to start routing now. I must say that I have always doubted it’s efficacy. But, your real experiences certainly interest me.

 

[matt1]

When I referenced “under £200” that included an Android tablet I had to purchase. The app itself is £75 to buy outright or £25 per year to subscribe. I can’t comment on predictwind but that and sailgrib were featured in an article by Pip Hare on routing sw. Unfortunately I can’t for the life of me did the article now. It may have been a review she did in Yachting World.

I’ve only just got the app and haven’t connected it to iridium so can’t comment. There are some videos from sailgrib on YouTube, including one where the founder “shadow” routed an imoca racing across the Atlantic. His route and the imoca’s actual route were strikingly similar.

One feature I love is the way you can adjust the polars for nightime / daytime or upwind / downwind and two different wind threadsholds.

If I were B&G or Raymarine I’d be trying to acquire Sailgrib and integrate it into the plotter range. I think there are lots of benefits to be had for regular cruisers

 

[franksingleton]

When I referenced “under £200” that included an Android tablet I had to purchase. The app itself is £75 to buy outright or £25 per year to subscribe. I can’t comment on predictwind but that and sailgrib were featured in an article by Pip Hare on routing sw. Unfortunately I can’t for the life of me did the article now. It may have been a review she did in Yachting World.

I’ve only just got the app and haven’t connected it to iridium so can’t comment. There are some videos from sailgrib on YouTube, including one where the founder “shadow” routed an imoca racing across the Atlantic. His route and the imoca’s actual route were strikingly similar.

One feature I love is the way you can adjust the polars for nightime / daytime or upwind / downwind and two different wind threadsholds.

If I were B&G or Raymarine I’d be trying to acquire Sailgrib and integrate it into the plotter range. I think there are lots of benefits to be had for regular cruisers

Thank you.

 

[Ningaloo]

I took a reduced price offer on "savvy navvy" (awful name!) as a less expensive alternative to predict wind.
It produces an impressive passage plan with some beautiful graphics but under the skin it is pretty basic. No polars so the only may to "manage" boat speed is very crudely by altering boat length.
It also recommended me putting the engine on rather than tacking in 20kts with a cross tide. I had specified engine use at less than 3kts, but maybe it used VMG rather than boat speed. Even so with a 14m boat I'd expect to significantly exceed 3kts VMG in those conditions. I raised this with the supplier who advised turning off the "use engine" feature and this did give a reasonable passage plan but they didn't come back to me on why the initial plan required engine.
All in all this is interesting to play with but I won't be renewing my subscription unless real world use (rather than winter armchair dreaming) gives better, and more controllable results.

Unfortunately I can't see B&G implementing anything similar as they already have a relationship with predict wind who will presumably supply this functionality in time. Hope I'm wrong...