Illyasviel beat me to the answer, but I'll show one possible process by which that answer can be derived.
Final answer:
$$
\begin{array}{|c|c|c|c|c|c|c|c|c|c|l}
\hline&&&&&&&&\blacklozenge&&1\\
\hline&&\blacktriangle&&&&&&&&1\\
\hline&&\blacktriangledown&&&&\blacktriangle&&\blacklozenge&&3\\
\hline&&&&&&\blacksquare&&&&1\\
\hline&\blacklozenge&&&&&\blacktriangledown&&\blacktriangleleft&\blacktriangleright&4\\
\hline&&&&&&&&&&0\\
\hline&&&&&&&&&&0\\
\hline\blacktriangle&&\blacktriangleleft&\blacksquare&\blacksquare&\blacktriangleright&&\blacktriangleleft&\blacksquare&\blacktriangleright&8\\
\hline\blacktriangledown&&&&&&&&&&1\\
\hline&&&&&&&&\blacklozenge&&1\\
\hline2&1&3&1&1&1&3&1&5&2
\end{array}
$$
Begin with:
$$
\def\b{\color{blue}\blacksquare}
\def\ltri{\color{red}\blacktriangleleft}
\def\rtri{\color{red}\blacktriangleright}
\def\utri{\color{red}\blacktriangle}
\def\dtri{\color{red}\blacktriangledown}
\def\rsq{\color{red}\blacksquare}
\def\rdi{\color{red}\blacklozenge}
\begin{array}{|c|c|c|c|c|c|c|c|c|c|l}
\hline&&&&&&&&&&1\\
\hline&&\utri&&&&&&&&1\\
\hline&&&&&&&&&&3\\
\hline&&&&&&&&&&1\\
\hline&\rdi&&&&&&&&&4\\
\hline&&&&&&&&&&0\\
\hline&&&&&&&&&&0\\
\hline&&&&&\rtri&&&&&8\\
\hline&&&&&&&&&&1\\
\hline&&&&&&&&&&1\\
\hline2&1&3&1&1&1&3&1&5&2
\end{array}
$$
I use ?'s to mark spaces that are known to contain a ship segment, but when I do not know the correct symbol. $\b$ marks spaces that are known not to contain a ship.
First, mark all the spaces known to not contain a ship. In this pass, we get this from the 0's, from the 1's that already have segments them, and all spaces adjacent to a ship.
$$
\begin{array}{|c|c|c|c|c|c|c|c|c|c|l}
\hline&\b&\b&\b&\b&\b&&&&&1\\
\hline\b&\b&\utri&\b&\b&\b&\b&\b&\b&\b&1\\
\hline&\b&?&\b&\b&\b&&&&&3\\
\hline\b&\b&\b&\b&\b&\b&&&&&1\\
\hline\b&\rdi&\b&&\b&\b&&&&&4\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline&\b&&&?&\rtri&\b&&&&8\\
\hline&\b&&\b&\b&\b&\b&&&&1\\
\hline&\b&&&\b&\b&&&&&1\\
\hline2&1&3&1&1&1&3&1&5&2
\end{array}
$$
Use the 8. We have eliminated two spaces from that 8's row, therefore all the remaining spaces must contain a ship.
$$
\begin{array}{|c|c|c|c|c|c|c|c|c|c|l}
\hline&\b&\b&\b&\b&\b&&\b&&&1\\
\hline\b&\b&\utri&\b&\b&\b&\b&\b&\b&\b&1\\
\hline&\b&\dtri&\b&\b&\b&&\b&&&3\\
\hline\b&\b&\b&\b&\b&\b&&\b&&&1\\
\hline\b&\rdi&\b&\b&\b&\b&&\b&&&4\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline?&\b&\ltri&\rsq&\rsq&\rtri&\b&\ltri&\rsq&\rtri&8\\
\hline&\b&\b&\b&\b&\b&\b&\b&\b&\b&1\\
\hline&\b&\b&\b&\b&\b&&\b&&&1\\
\hline2&1&3&1&1&1&3&1&5&2
\end{array}
$$
Since there is a 1 directly below that 8, and horizontal ships cannot have a ship next to them, even diagonally, the far left [?] must be a ^.
$$
\begin{array}{|c|c|c|c|c|c|c|c|c|c|l}
\hline&\b&\b&\b&\b&\b&&\b&&&1\\
\hline\b&\b&\utri&\b&\b&\b&\b&\b&\b&\b&1\\
\hline&\b&\dtri&\b&\b&\b&&\b&&&3\\
\hline\b&\b&\b&\b&\b&\b&&\b&&&1\\
\hline\b&\rdi&\b&\b&\b&\b&&\b&&&4\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\utri&\b&\ltri&\rsq&\rsq&\rtri&\b&\ltri&\rsq&\rtri&8\\
\hline?&\b&\b&\b&\b&\b&\b&\b&\b&\b&1\\
\hline&\b&\b&\b&\b&\b&&\b&&&1\\
\hline2&1&3&1&1&1&3&1&5&2
\end{array}
$$
Since the ? fills that column's 2, we can close it as a $\dtri$ and block out the rest of that row.
$$
\begin{array}{|c|c|c|c|c|c|c|c|c|c|l}
\hline\b&\b&\b&\b&\b&\b&&\b&&&1\\
\hline\b&\b&\utri&\b&\b&\b&\b&\b&\b&\b&1\\
\hline\b&\b&\dtri&\b&\b&\b&&\b&&&3\\
\hline\b&\b&\b&\b&\b&\b&&\b&&&1\\
\hline\b&\rdi&\b&\b&\b&\b&&\b&&&4\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\utri&\b&\ltri&\rsq&\rsq&\rtri&\b&\ltri&\rsq&\rtri&8\\
\hline\dtri&\b&\b&\b&\b&\b&\b&\b&\b&\b&1\\
\hline\b&\b&\b&\b&\b&\b&&\b&&&1\\
\hline2&1&3&1&1&1&3&1&5&2
\end{array}
$$
Now, the 4 row can be filled in, since six spaces have been blocked out.
$$
\begin{array}{|c|c|c|c|c|c|c|c|c|c|l}
\hline\b&\b&\b&\b&\b&\b&&\b&&\b&1\\
\hline\b&\b&\utri&\b&\b&\b&\b&\b&\b&\b&1\\
\hline\b&\b&\dtri&\b&\b&\b&&\b&&\b&3\\
\hline\b&\b&\b&\b&\b&\b&&\b&\b&\b&1\\
\hline\b&\rdi&\b&\b&\b&\b&?&\b&\ltri&\rtri&4\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\utri&\b&\ltri&\rsq&\rsq&\rtri&\b&\ltri&\rsq&\rtri&8\\
\hline\dtri&\b&\b&\b&\b&\b&\b&\b&\b&\b&1\\
\hline\b&\b&\b&\b&\b&\b&&\b&&\b&1\\
\hline2&1&3&1&1&1&3&1&5&2
\end{array}
$$
Now we can fill in the rows above that 4, by the same elimination.
$$
\begin{array}{|c|c|c|c|c|c|c|c|c|c|l}
\hline\b&\b&\b&\b&\b&\b&\b&\b&&\b&1\\
\hline\b&\b&\utri&\b&\b&\b&\b&\b&\b&\b&1\\
\hline\b&\b&\dtri&\b&\b&\b&?&\b&?&\b&3\\
\hline\b&\b&\b&\b&\b&\b&?&\b&\b&\b&1\\
\hline\b&\rdi&\b&\b&\b&\b&\dtri&\b&\ltri&\rtri&4\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\utri&\b&\ltri&\rsq&\rsq&\rtri&\b&\ltri&\rsq&\rtri&8\\
\hline\dtri&\b&\b&\b&\b&\b&\b&\b&\b&\b&1\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&&\b&1\\
\hline2&1&3&1&1&1&3&1&5&2
\end{array}
$$
Finally, we can place the last two patrol boats, in the only empty spaces remaining.
$$
\begin{array}{|c|c|c|c|c|c|c|c|c|c|l}
\hline\b&\b&\b&\b&\b&\b&\b&\b&\rdi&\b&1\\
\hline\b&\b&\utri&\b&\b&\b&\b&\b&\b&\b&1\\
\hline\b&\b&\dtri&\b&\b&\b&\utri&\b&\rdi&\b&3\\
\hline\b&\b&\b&\b&\b&\b&\rsq&\b&\b&\b&1\\
\hline\b&\rdi&\b&\b&\b&\b&\dtri&\b&\ltri&\rtri&4\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\b&\b&0\\
\hline\utri&\b&\ltri&\rsq&\rsq&\rtri&\b&\ltri&\rsq&\rtri&8\\
\hline\dtri&\b&\b&\b&\b&\b&\b&\b&\b&\b&1\\
\hline\b&\b&\b&\b&\b&\b&\b&\b&\rdi&\b&1\\
\hline2&1&3&1&1&1&3&1&5&2
\end{array}
$$