I guess some could argue that we do have some special vocabulary for cars too.

E.g. you don't call it the front/back door, you call it the bonnet/boot (or maybe hood/trunk depending where you're from) though that probably is stretching the definition of a door a little bit... but then you also have nearside and offside for passengers/drivers side, though that's probably a bit more of a technical term.

I always get confused by nearside and offside. Is it "near to the driver" or "near to the roadside"?

Near the roadside.

> though that probably is stretching the definition of a door a little bit...

It is, but then so is the stupid "3-door" / "5-door" / etc. car classification, which is really 2-door / 4-door / etc. with the trunk being counted as additional door for some reason.

I think it makes sense for hatchbacks, where there's no real trunk/passenger cabin separation.

The trunk is considered a door when it opens into the main cabin instead of a separate compartment.

> We don't do this with cars. You have a left rear door, not a port rear door.

“Driver side rear door” or “passenger side rear door” are pretty common, at least in the US and UK, where they mean the opposite.

“Nearside“ (passenger side nearest curb in a right-hand drive vehicle driving on the right) and “offside” (driver side furthest from curb) are also used in the UK.

If you ever went 4x4 driving, you use driver / passenger to indicate the direction someone has to go to. This is because the navigation often is done from someone standing outside the car, where using left/right can be rather confusing.

In UK a [experienced, older?] driver gives another driver instructions with "right hand down" and "left hand down". That is, you give directions to move the steering wheel.

I've the vaguest recollection that sailing/steam boats used to say which side to move the wheel towards to steer; that begging opposite of the way the boat will go??

For repair instructions this actually causes a lot of confusion for someone in a right hand drive market. Half the time the repair instruction gets it wrong and would have been better saying left or right. Occasionally it is correct though if dealing with a part that's different in each market.

I don’t know how widespread this is but I don’t do this for the very reason you bring up with differences between countries, I drive in both the UK and Canada most years.

Cars are small and for the most part everyone in the car faces the same direction as the car itself. When you have a ship, you have 3 frames of references to contend with (self, ship, cardinal)

Four, actually. You also have the wind frame of reference, which is actually the most important (for sail boats). You don't turn left or right, you turn upwind or downwind.

For wind there is leeward (downwind) and windward (upwind). I don't think there are common terms for the 2 crosswind directions though?

I'm not familiar with sail vocabulary in English, but in Portuguese there is only downwind (sotavento) and upwind (barlavento). Functionally you don't need the other two, so I imagine it's similar in English.