What is Weather Routing Vs. Vessel Performance Monitoring?

You’re kidding right? Of course by then I knew enough to keep my mouth shut.

Like my AB told me; third mate gets no respect, second mate gets a little respect, chief mate gets his due respect and the captain gets his ass kissed all day long.


I thought you might. Still you see my concern for later.

Vessel particulars. It’s a made up vessel pick any you like. Fairly typical of a small geared bulk carrier, mine was a laker, at 580 ft long 76 beam and up to 30ft draft. Service speed typical about 15 knots.
more common to be chartered slower at best economic 12 or 13 knots.

Box boat bigger faster particularly faster 20 knots changes things a bit. Less uncertainty.

My point is you can advise me to go North but your advising me to take a lot more risk for a small possibility of a gain in efficiency.

Deck cargoe is vulnerable. Particularly to bad weather.
Timber particularly, I will be down near my marks and with minimal stability. Possibly negative stability with an angle of lol.
even strong winds and spray on one side for an extended no of days could have an impact.

Hence my desire to get south.

It’s as they used to say a “slow boat to China” or in this case Japan.
At the speed of the question. Even an average loss of a knot or half a knot is going to start tipping the scales.

Are we talking the kind of weather routing I use sometimes where I get advice and feel free to ignore it or is someone making you follow it?

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An accurate 10 day surface forecast is not needed. The upper-air charts can be used to determine surface storm track patterns. Ten days out it’s not required to know exactly where the ship is going to cross through the zone of bad weather. Can wait and use the 2 or 3 day surface forecast and cut between the lows.

Depends on who you are. Very similar I suppose. With slightly different purpose or goals.
The theory is to avoid adverse weather. Taking advantage of shorter routing when the weather warrants rather than using traditional routing based weather trends for time of year.

Often the difference is in who’s choice is it. I was never “The Master” its his choice or certainly was until some buffoon of a UK Judge made a ruling otherwise.

Often its not the Master or the ship owner who hires the routing service. Its the Charterer who hired the ship to do the job.
The Charterer naturally expects the ship to do as he wishes. Meanwhile the Master has the actual responsibility. The Master can choose to take the advice or not.
Not taking the advice is probably going to take some explaining. Particularly since the Charterer is often paying a daily hire rate and the fuel.

I’ve sailed with different Masters who have done both. I usually as a OOW certainly as a 2nd had some impute but it wasn’t up to me.
My personal observation. It usually didn’t work out well for us. We would take the northern route and take a beating.

The example above, todays weather and charts posted. The Northern route does look like a good option.
Making my argument why would be reluctant to take it, would be a tough sell.
The owner I worked for, always backed his Master or Captains decisions even when charterers disliked the decision. It was a small company and the owner knew and trusted his Masters Captains.
He had also been one himself.

My experience makes me sceptical, sometimes it works. I found more often than not it didn’t.
The Shipping company, Found more often than not it didn’t.

I will admit my experience may be a bit out of date. I quite that life quite a long time ago. Technology may have improved but weather has also gotten worse

The issue is speed-distance-time.

For example a 4000 mile trip at 18.0 kts is 222 hrs. Add say 20 miles for a diversion and now distance is 4020 and the speed required bumps up to 18.1.

Get too smart about routing and the other ships that left later will arrive earlier. The stories are always about out smarting the routers but in practice it’s like trying to beat the house in Vegas. Not easy.

My experience with weather routing has been a mixed bag. For the most part, it is fairly accurate and minimizes the risk to my ship. I have chimed in over the years to protest skirting me too close to the ice edge or taking me down across the bay of Biscay in winter. I agree that the best course of action is to analyze every source you can get your hands on and make your own informed decision. The 500mb map is quite a useful tool indeed.

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I agree you should consider all sources.

Yes the 500mb chart can be very useful

Sure, but the relationship we find ourselves in as captains with the professional meteorologists is similar to many other situations. Captains are by nature generalists.

For example dealing with the agent, a pilot or with the engineers, we have some level of understanding. However in each case a specialist in their field should have a deeper understanding.

So as captain I should be able to develop a voyage plan on my own, however if in fact the plan the routers propose is better I should at least have the skills to be able to evaluate that plan.

This is where understanding of the upper-air charts comes in. My understanding is not very deep. But it is sufficient such that when the problem with the route I planned is explained in upper-air terms I can understand it even if I would not have seen it on my own.


Good points, though I still believe it’s largely smoke and mirrors.

In my world today, I don’t use routing service, I do on occasions call and speak to a meteorologist about the fo forecast conditions.
“Should I Go or should I stay now”

Ultimately the decision is mine and I have to answer for it.

Or as the old Fishermen say,
“the wind will drop when the tide changes”.

Tough go mid-Pacific next couple of days… Northern Route !

Details http://oceanweatherservices.com/blog/2019/12/08/hurricane-force-wind-warning-north-pacific-2/

As a Meteorologist and a boater who has crossed the Atlantic twice on my own 42 ft bottom, I think Uricanejack and KC are both right.
There is no skill in a 10-day forecast over the middle of the ocean. In fact, I think probably 5 days is the max one could expect.
Simply put, a lot more effort is put into a forecast for the 100 million people living on the east coast USA than the ocean where nobody lives and even fewer are going to complain about a bad forecast.
In practice, I’ve found it best to just worry about my departure wx, a go, no go decision, but once underway, I don’t even listen to NOAA wx radio while in range because it makes no difference.
At my boat speed of 150 nm/day, lows ate moving 3 times my speed. Thus even a slight error in forecast can make a significant difference. And perfect forecasts don’t exist on the open ocean.

I have been using Heavy Weather Avoidance and Route Design: Concepts and Applications of 500 Mb Charts by Ma-Li Chen and Lee Chesneau

This illustration gives a good sense of routing design:
Fig 8.1

Here it recommends small sail boats stay in Zone A. Container ships with 20,000 to 100,000 hp and at 400 - 500 miles day is a different story

Great Circle ocean transits will usually involve crossing what the book calls the specialized strong wind belt between 5400 meters and 5700 meters


Hi wxman22

Much of the time that I was actively routing ships we only had forecasts out 72 hours for the Northern Pacific and Atlantic so I relied heavily on storm track patterns, daily hand plotting of ship reports for winds and waves and the limited 500 mb forecasts is designing routes. We offered route suggestions based on these patterns with general wind/wave conditions to be expected. I only added specific wind/wave forecasts when route changes were being considered to allow the master some better input as to the why.

To KC - Yes indeed “Heavy Weather Avoidance and Route Design: Concepts and Applications of 500 Mb Charts” is an excellent and useful book.


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I found HWA and Route Design to be tough sledding in places, had to take it a little at time, very useful though.

Not much hand plotting deep-sea now. A few years ago the routing service started emailing the suggested route by file which could be opened using the ship’s routing program. Shoreside can also see the daily updates entered ship-side.

The Norther Route did look good this time.
Turns out it did work out favourable. It may even have been more efficient.
It still had more risk.

I found hand plotting of the 500mb map to be required if trying to make specific forecasts for specific areas or places with limited data, like oceans and Alaska.

The only problem with HWA, Route Design and similar products is that they are touted as tools anyone can use.
Yea, anyone can use them, but one could spend hours trying to figure out the best route on any given day, come up with an answer, good or bad, but have no idea if the underlying assumptions were correct in the first place.
Meanwhile, someone like Fred wx, would probably take 10 minutes to make a better forecast because they are looking at the wx in those areas constantly.

There’s no way I’d try this by hand plotting. It would kill me, too tedious and time consuming. Don’t have the time or the horsepower. I use knowledge gained from the book to evaluate a route, not to design one.

The mechanical steps of routing are done by a computer program running on the master’s and/or bridge desktops.

The program is set up by entering sea height and wind speed limits, ship’s draft, rpm. There are various tweaks and options such as shortest time, min fuel etc.

A route is generated using the 10 day surface forecast and beyond that long-term average. The program uses a model which estimates SOA/ETA based on forecast wind and sea conditions

Once a route is created various alternatives can also be generated and compared, for example trans-Pacific north of the Aleutian Chain vs south.

At that point the route(s) can be evaluated by clicking through the various layers, 500 mb, surface winds forecast then finally sea conditions and the waypoints can be moved around with the mouse to compare ETAs etc.

If the trip is using professional weather routing the router will send their recommended route about 24 hrs before departure which I can also evaluate using the same program.

Good example today looking at today’s 500 mb analysis shows clearly at least where not to go.

The risk for gale force or higher winds is fairly high all the way to 40N (even southward over the western half of the North Pacific - From December Atlas of Pilot Charts (highlighted risk 12% or more)

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