Are you an ELT? If so, don't cover for the guy. Not for a second. This kind of crap gives ELT's across the fleet a bad name; makes people say "ELT's, no way!" when the Hampton guys can't do a primary. An RL Div that does its job to the letter works harder than any other division on board (unless M-Div actually does all of their stuff), and gives the ELT's the right to a serious elitist attitude. You want that more than to be part of a division with a dirt bag reputation.
If you have this question about speaking up you might be new on your boat. If you are new and this guy is "senior"(since we think we are senior with two years experience in this program), it might be hard to pressure him in any direction on your own. Especially if the division likes him and doesn't know you. They might just take a great big dump down your throat.
I guess I don't know what department climate is like where you're at, but I came from a boat where we didn't tolerate people who didn't do their jobs. I know that in certain places (prototypes - I was a SPU there and the sleaze was unbearable, but the climate made it the norm) the acceptable pattern of behavior is to gaff/blaze/radio/gundeck everything you can with the knowledge that you will be CIVLANT before it hits the fan. Then you read the message that comes out about a Guam boat that had Cl in a certain fresh water system for the engine room (vague enough?) for six months after an availability at PHNSY, to have it logged OOS for the first time when a guy comes back from LIMDU.
Let the guy know that he sucks. Peer pressure can be a helpful thing on a boat. If he sucks enough the rest of the division could be upset about it, and a Shaft Alley counseling session could take place.
If it is culturally acceptable to suck at your job where you're at it puts you in an awkward position. You could address the issue with the guy and not only will nothing happen, but you will be ostracised. You could formally address the issue via the CoC and you will be ostracised. You could sit quietly and say nothing about it until it gets caught, and then you are a part of the problem and you can kiss your job good-bye. Even if you hate it where you're at I'm sure you know that it's best to finish your commitment and make the transition to civilian life.