If you sail, cruise, or voyage more than 100 miles offshore of a 1st world nation, then it is these ships (these points / streaks of light), near your route that will render assistance or rescue, NOT a "coast guard", etc....Assuming you DO have both a VHF-DSC radio and HF-DSC radio to signal these vessels!!!
(other than "rescue", there are other things they can provide: weather info/forecasts, fresh water, fuel, food, medical advice/supplies, mechanical assistance/advice, repair assistance, long-range communications relay, etc....but you MUST have both VHF-DSC and HF-DSC radios to contact them...)