Hacker News Reader

Comment by throwaway613834 | Hacker News Reader

> All ships should be keeping a physical lookout at all times

I know nothing about the military or naval practices but this sounds hard and very costly... you want someone on shift 24/7 with his head constantly rotating watching out in all directions? Or maybe 3-4 people simultaneously looking out each in a single direction? That would mean you have a bunch of people doing literally nothing productive (besides watching) at any given point in time, some of them even being asleep since you want 24/7 shifts... and they have to not get bored or look away for any nontrivial period of time. It seems very difficult.

View on HN

That is exactly what international maritime law requires. For reference, I estimate the eye height of people on the bridge and watch deck is about 28.5m above the waterline (from a picture of an Arleigh Burke-class destroyer on wikipedia), at that distance the horizon is approximately 19.1km away or a ship higher than that come into view from further away depending on the height of that other vessel which would be substantial for an oil tanker of cargo vessel (which has masts with radar reflectors and navigation lights). Now an Arleigh Burke-class destroyer is listed as having a greater than 30knot (56km/h) top speed on wikipedia, this probably means it is less than 40knot (74km/h), however it is probably not cruising at more than 56km/h so lets assume that is the common cruise speed (which is fast for a ship). So at 56km/h 19.1km takes 20.6 minutes to cover even if the other vessel is going the same speed head on that still gives more than 10 minutes to avoid a collision from when the other vessel was first able to be spotted.

So WTF was that destroyer doing for 10-20 minutes minimum that had it in a collision with another ship?

a bunch of people doing literally nothing productive (besides watching)

They are not doing "nothing productive", they are keeping watch to prevent exactly this type of accident from happening.

Do you really think that the entire ship goes to to sleep at night on a 2 billion dollar naval destroyer while it cruises in a crowded shipping lane? Even the $250M office/residential building where I work has 2 night watchmen and a building engineer or two on duty at all times... and the building is unlikely to have a collision when another building moves into its path.

> Do you really think that the entire ship goes to to sleep at night on a 2 billion dollar naval destroyer while it cruises in a crowded shipping lane?

I didn't say they all go to sleep, they probably have lots of things to do at various times. And I wasn't talking about more-sensitive points like crowded shipping lanes. I was just talking about having people on duty to literally keep a watch out over the sea the entire time. Not sure why you twist my words like that.

Or you're saying they do have watchmen 24/7 but their watchmen are just blind? How did they manage to collide 4 times this year if they had people watching the sea the whole time?

Oh, and don't forget others are suggesting sleep deprivation as the cause. Which is not exactly inconsistent with my point that keeping watch is probably difficult and costly...

The International Regulations for Preventing Collisions at Sea (1972) says in part:

Every vessel must at all times keep a proper look-out

by sight (day shape or lights by eyes or visual aids),

hearing (sound signal or Marine VHF radio)

and all available means (e.g. Radar, ARPA, AIS, GMDSS...)

in order to judge if risk of collision exists

https://en.m.wikipedia.org/wiki/Lookout

Reply on news.ycombinator.com