Points taken. Put this in mind though, the dominant mobs in thi

are drug dealers.  I believe those gangs have more than just light weapons & they are ruthless to mistreat any unfortunate individual.  However, they are very careful when coming to deal with the governments.  They will try not to provoke the officials unless the governments infiltrate their territory & threaten their business.

The patrols in this case serve to secure the waterway & to protect the safety of travellers.  There is no major conflicts between two sides.  Hitherto, I don't see the reason the big bosses will risk official retaliation to attack the river patrols. 

Simply put, the patrols are more like some warning signs.  They don't face hostile guerilla like in Iraq but some Mafia groups that tend to avoid confrontation with governments.  I would say that the patrols are safe as long as they don't bump into the drug deal transporters. 

Your point is still valid though.  Safety of the troops is the primary concern.  They need better protection regardless of the risks on their job.  I hope that the improved patrol boat can be put in service sooner.