This makes no sense.
It could be birthmarks.
If a vessel is unpaired, it typically means that it is not part of a paired set with another vessel. This could refer to blood vessels, nerves, or similar anatomical structures that are normally found in pairs. In certain contexts, it could also mean that the vessel is not connected or associated with another vessel in a functional or anatomical manner.
This is a case where the sailing vessel does not have the right of way. The overtaking vessel must stay clear of the vessel being overtaken. The best thing you could do would me to keep a steady course, or make any changes obvious so the overtaking sailboat knows what you are doing.
Cholesterol, blood clots, fat embolism', even plastic from a hypodermic needle that has broken off can block blood vessles.
A hyperextended blood vessel could cause a stroke
Nitrogen by itself does not support combustion. But if pressuring a vessel with nitrogen and allowing it to overpressure (beyond vessel limits) a vessel can explode by fatigue. Under pressure, for example when scuba diving, yes, but otherwise, I don't think so.
When overtaking another vessel in darkness or reduced visibility, the overtaking vessel must keep a safe distance and maintain a proper lookout. It should also ensure that it follows the navigation rules, particularly the International Regulations for Preventing Collisions at Sea (COLREGs), which dictate that the overtaking vessel must sound the appropriate signal and proceed with caution. Additionally, the overtaking vessel should avoid any sudden maneuvers that could confuse the other vessel.
Wind could knock you over or blow your vessel into a submerged (unseen) obstruction.
That could be either a ketch or a yawl, depending on location of the wheelhouse.
Could be your diet. Do you use tobacco?
No, a vessel could be a number of things, such as a containment pod or space shuttel.
No, a thoracotomy is incision in the chest for surgery