Signal a ship RAR!

[Hawkwings]

Imagine you are in a situation similar to the movie Cast Away, where you are stranded on an island with minimal resources. Imagine also that you decide to try your luck on the high seas by building a raft and hoping a passing ship sees you. One day, you get lucky and spot a big container ship on the horizon. What have you prepared in order to signal it and let them know that you are there and need help?

[Zaune]

A great big pile of dry wood, some kindling and some means of starting a fire.

[Zor]

If i remember correctly, three fires in a triangle is the signal for distress.

Zor

[Korto]

A great big pile of dry wood, some kindling and some means of starting a fire.

I think you missed something...

Imagine also that you decide to try your luck on the high seas by building a raft and hoping a passing ship sees you.

Apparently, you're on a raft. A wooden raft. In the middle of the ocean.

[The_Saint]

Reflected or created light... in sets of three

[Enigma]

A great big pile of dry wood, some kindling and some means of starting a fire.

I think you missed something...

Imagine also that you decide to try your luck on the high seas by building a raft and hoping a passing ship sees you.

Apparently, you're on a raft. A wooden raft. In the middle of the ocean.

So? Set the raft on fire.

Or if you have anything reflective, use it to signal the ship.

[Sea Skimmer]

You could bring a second small raft to light a fire on, but the difficult part is keeping any fuel you bring dry enough to rapidly ignite. This would be near impossible in the movie setting when the raft is smashed by large waves before the ship is sighted. Merchant ships also have utter crap for lookouts on the high seas, so you'll need one heck of a fire to get noticed at a long distance. Depending on resources, it would be very worth exploring that you could do to build a radar reflector. Even a corner reflector made of wood would have some effect if you kept it wet.

[Sarevok]

You could bring a second small raft to light a fire on, but the difficult part is keeping any fuel you bring dry enough to rapidly ignite. This would be near impossible in the movie setting when the raft is smashed by large waves before the ship is sighted. Merchant ships also have utter crap for lookouts on the high seas, so you'll need one heck of a fire to get noticed at a long distance. Depending on resources, it would be very worth exploring that you could do to build a radar reflector. Even a corner reflector made of wood would have some effect if you kept it wet.

Modern merchant ships do seem to have very tiny crews. I wonder if ones chances of catching attention from a passing ship during a disaster would be higher in the past ?

[Sea Skimmer]

Tiny crews and no lookouts. You'd be lucky if more then one person is even on the bridge all the time. Odds of being spotted would certainly have been higher in the era before GPS, and higher still before radars with automatic target detection, best to be in the no radar at all era. Earlier arlier merchants were smaller with lower bridges, so actual visibility for people would be worse, but then in such an era ships were also more numerous.

The fact is though merchants mainly steam in just a few narrow point to point shipping lanes on each. They are not evenly spread across the ocean, not even remotely, so you can drift some awful long distances and see nothing at all. Fishing boats are more likely to see you since they are a bit random in distribution, but they also tend to be small, low and low on lookouts too. Back in WW2 a Chinese guy drifted for 133 days in a raft in the Atlantic Ocean before washing up in Brazil. In that entire time, he was spotted just twice, once by a freighter that didn't pick him up, one by a US plane which lost him after a storm set in. It isn't for nothing that so many ships have sunk with all hands lost. The ocean is a vast cruel place to be.

[Sky Captain]

Depending on resources, it would be very worth exploring that you could do to build a radar reflector. Even a corner reflector made of wood would have some effect if you kept it wet.

What are the chances that the guy on watch is paying proper attention to radar or seeing a blip on radar if it is not on collison course bothers to identify it? I sail a small sailboat for recreational purposes and from what more experienced sailors have told me I have got impression that typical comercial ship crews are pretty careless and often don't pay proper attention to the surroundings of a ship once out on the high seas. I have been told that if you see a freighter that may be on a collision course with your boat always assume the freighter don't see you and take evasive action yourself.

[Sea Skimmer]

Yeah rule of thumb is always give way to the law of gross tonnage. Especially when the disparity is in the factor of a thousand or more. Doesn't matter if your on the high seas or not, since its not like a freighter in a shipping channel on a river has many options to turn to avoid you anyway.

Odds of being noticed on radar still beat odds of being noticed visually if you are so far away it would take binoculars to be spotted. They might not be good, but it'd be stupid to discount it. Problem is these days if you did get noticed in many parts of the world, the ship might well turn away out of fear of some kind of small pirate boat.