I spent some time considering how you might even start forming an ocean of blood.

Mammal blood is out of question because it would coagulate. It would probably end up with rocks made of blood crust separating from watery plasma and pus. If you were sailing on an ocean of pus, any stars you'd see on the surdace of the ocean would be the result of intoxocation.

In the case of non mammalian blood you would have no coagula, so it may take a while longer for pus to happen. But even then it would require all the blood to just materialize out of thin air below your boat.

Thw problem with blood is that it is plasma filled with living cells. If you just let blood pour into a container and wait for a few days the cells will die and rot. Do not try this at home. The whole thing smells pungently of feces after some time. I have personally felt it when I had a freezer full of chicken fail due to a circuit breaker being open, then leaking blood throughout a whole weekend because there was a hole in it. The monday after that weekend was one of the worst days of my life. That blood filled a large puddle for a couple days. Now imagine how long it would take to form a sea.

You may as well be describing hell in a way that not even Dante Alighieri would imagine.

I spent some time considering how you might even start forming an ocean of blood.

Mammal blood is out of question because it would coagulate. It would probably end up with rocks made of blood crust separating from watery plasma and pus. If you were sailing on an ocean of pus, any stars you'd see on the surface of the ocean would be the result of intoxication.

In the case of non mammalian blood you would have no coagula, so it may take a while longer for pus to happen. But even then it would require all the blood to just materialize out of thin air below your boat.

The problem with blood is that it is plasma filled with living cells. If you just let blood pour into a container and wait for a few days the cells will die and rot. Do not try this at home. The whole thing smells pungently of feces after some time. 

I have personally felt it when I had a freezer full of chicken failing due to a circuit breaker being open, then leaking blood throughout a whole weekend because there was a hole in it. The Monday after that weekend was one of the worst days of my life. That blood filled a large puddle for a couple days. Now imagine how long it would take to form a sea.

You may as well be describing hell in a way that not even Dante Alighieri would imagine.