OK, let us go on a little trip….

The Wiseman Steamship Company has a great reputation for punctual sailings.  Every day at noon (Greenwich time) one of its ships leaves Southampton for New York.  At exactly the same moment another ship leaves New York for Southampton.  The crossing, in either direction, takes seven days and follows the same course.  So, whenever a ship leaves either Southampton or New York, another ship is just docking there having arrived from the opposite direction.

You are lucky enough to get a ticket to travel Southampton to New York, how many Wiseman ships will you meet during your voyage to New York?

As ever, please do NOT post your answers, but do say if you think you have solved the puzzle and how long it took.  Solution on Monday.

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.

I only THINK I know! If I’m correct it took me 90sec after reading.

2. JimC says:

I must have read this wrong, because it seems very easy.

3. I reckon I have an answer. I decided to draw it all out, worked out how to do that, then did it, then realised I made an error in judgement and have now arrived at an answer. According to the twitter timestampl, around 10 minutes.
I think there may be a little bit of leeway depending on what is meant by “met”.

1. I also think if I hadn’t drawn it out I would have got it wrong. My diagram shows a number quite different from what I had assumed.

2. Michael Sternberg says:

Yup, putting it in a diagram will be quite convincing. The results are easily expressed in algebra after that, and then one can discuss the fencepost issue.

4. Chris says:

after about a minute I got to two answers. I’m pretty confident, there’s just a little question over what counts as meeting ‘during your voyage’.

1. Agreed, there’s a slight ambiguity there unfortunately.

5. neil j says:

I don’t fancy going to new York on a Mississippi river boat Richard.

6. Frank filskow says:

7. Gerard Engelage says:

If on the same course, you only meet 1: a terrible crash while leaving the port of Southampton.
I found another answer in about 1 minute which may survive the weekend.

8. I wouldn’t see any ships because I’d be using the time to catch up on my reading list!

9. I had a hunch, but thought I’d better check with a diagram. The hunch was wrong, it was more than I’d thought. Then I realized that with some clever thinking I wouldn’t need my diagram – I knewthe answer! – but I finished the diagram just to check.

10. Think I have the answer – 5 min with pencil and paper – but I suspect I’ve missed a Wiseman quirk somewhere

11. Sari1967 says:

Now I have a second answer which is totally different from the first!

1. Sari1967 says:

Pressed send to early which I got as I was reading the question

12. Richard says:

I spent time drawing it out. Agree with the ambiguity around ‘met’. Assume that, when you leave and the other one docks / you dock and the other one leaves, that counts as met.

1. Yeah, that can make a difference of 2 in the answer. In any case I just drew a diagram to get the answer(s).

13. Richard says:

Wait, that Richard isn’t the same Richard that writes the blog. 🙂

14. Mat says:

Well, I imagined myself doing all that, and the answer is a nice number. It took me 1 minute.

15. Capn Sparrow says:

It is highly implausible that the ships will leave and dock at precisely the same time. You need to take into consideration weather conditions, tidal flows, wind speed and direction, tonnage weight, Channel traffic, industrial disputes, piracy etc etc.
I also question whether a daily steamship service is commercially viable in the present economic climate.
Also in the US the clocks change on November the 6th, whereas in the UK, its on October 30th. What happens to the timetabling in the days between those two dates?
So, all in all, a pointless excercise and you would be better off working on the two flagpole problem.

1. I bet you’re a hoot at parties.

2. Anonymous says:

Is your other name Mr Logic?

3. Jack says:

What Dave said!!! 🙂

16. Anonymous says:

As per last weeks puzzle, would you get the answer if it was a FRENCH company? (HINT?)

17. Oooh, an interesting one here… More complex than it first appears! I’ve got a good diagram now, fairly sure of the right answer. Probably took me around 30 mins, but most of that was starting up a drawing program and making the image!

18. ivan says:

There will be a ship arriving at precisely the moment you leave, and another leaving at precisely the moment you arrive. Do you “meet” either of these?

The concept of relative speed seems to me a quicker way to the solution. Using that, I had the answer, modulo the end conditions (the problem above) within a second.

19. Kristian says:

After a couple of minutes I realised a very important aspect of the matter, and I think I’ve arrived at the correct solution.

In the department of not so important considerations, the solution may very a bit depending on the interpretation of “meeting a wiseman boat”.

20. Al says:

Got the answer in around a minute.

It definitely helps to draw a quick sketch.

Of course, it depends on whether or not you are counting the ship that’s arriving at the same moment you are leaving and vice-versa.

1. astro says:

in other words, there are three possible solutions, depending on whether you count the ship that’s arriving when you leave southampton, and the ship that’s leaving when you arrive in new york.

or four, if you count the ship you’re on as one you’ve “met.”

the puzzle may be easier to visualize if you replace ships on the sea with buses on a highway that leave/arrive precisely every hour, and take 7 hours for the trip.

21. Alessandro I. says:

Nice question… do the Earth rotate clockwise? 😉

22. Lazy T says:

Methinks I know, but if the ships pass each other to starboard I won’t meet any of the others on the way to NY, I always travel POSH

23. Solved after making a little paper band model to confirm an unintuitive answer.

24. exactly the same route eh..? – sounds like the first meeting would be a fatal collision.

25. Mickey D says:

About a minute, thought I had it after 30 secs but then saw my mistake and got it!

26. AMWhy says:

Ambiguous question. I have three answers which all depend on the definition of ‘meet’ and ‘Wiseman Ship’.

27. drupp says:

4 minutes – definetily needed a diagram. Gut reaction was wrong. Darn that gut reaction.

28. Anonymous says:

If the ships take the same course, one. The one your ship collides with, then it sinks and you drown. 🙂

29. Anonymous says:

I think I got it, after I drew myself a flip note illustrating the scenario took a few minutes.

30. ruthslavid says:

If the Mississipi steamer sinks, then the answer will be zero … or depend on how far it got. Otherwise, fairly straightforward depending on how you treat the ‘ends’. I am assuming that meeting has to be done at sea …

31. Jon says:

It took me a little over a week and a pretty substantial steamship investment, but I’m pretty sure I have the right answer.

1. Sarah says:

A week? It took me a fortnight, and I’m guessing a more substantial steamship investment.

2. Jon says:

It can be done in less than two weeks, you just need the steamships delivered to very specific locations–the tips to all those delivery men cost me almost as much as the ships themselves!

It’s a good thing I’m filthy rich in my hypothetical world.

3. Brava

32. I’d say the answer depends on whether there are one or two Wiseman ships in the same port at any one time.

In other words, does the journey take exactly 7 days, in which case a ship arriving in port would be able to wave to the ones departing; or does it take slightly less than 7 days, in which case the ship arriving in port is also the next ship to depart port.

33. Guy says:

34. Alan says:

How long did it take me? Well, I started at noon, Greenwich time….

35. Gordon says:

So what’s the minimum number of ships that the Wiseman Steamship Company needs in its fleet in order to maintain a daily schedule?

1. Michael Sternberg says:

Very good question!

It’s a bit easier to solve since it can be done from the perspective of just one port, working out one full cycle time. Not to forget, of course, time at ports.

36. majikthijs says:

37. Jan says:

5 minutes

38. Anonymous says:

0.237 seconds. So easy