Sierra wrote:
If it's the C or E series Raymarine, after you carefully remove the the plastic faceplate of the unit there are four screws fixing it to the helm.
The transom locker issue has been well documented and is one of the few design flaws in these models that really annoys me. Mine bows out slightly as well and I am planning on attempting some sort of weather stripping or gasket to keep out the water.
This is right on the money. To get the bezel off the chartplotter you may want to pick up an upholstery's tack puller tool. The tool has a split fork in the tip, and a bit of an angle to it. This lets you get leverage under the edges of the bezel to pop it loose. If you use a screwdriver alone you'll risk leaving a gouge in the plastic. When you use the tack puller you'll also want to slip something like a matchbook cover behind the tool where it gets leverage against the dash surface. Just something to cushion the pressure point to avoid leaving a mark. The bezel clicks on there TIGHT and really can't be removed without some sort of prying tool. I believe the Raymarine install manual shows the setup. There are four slots, two each on the left and right, that you use to pry the bezel off. Just make sure you only insert the tool about 1/8" inch. You'll just popping off the bezel, not prying the whole unit out. Once the bezel is off there's four screws at the corners.
This is what that sort of tool looks like:

I got mine as part of a 20 or 30 piece set from Harbor Freight. They're cheap tools and not very good quality. But given the harsh environment on the boat I'd rather have cheap tools getting ruined rather than really expensive stainless ones. That and I've lost at least 3 screwdrivers going overboard, long before they'd have rusted out.
I put some thick white weather stripping around the top of my transom door. It put it in a U shape, with about 4" coming down along the port/starboard sides. I did have to adjust the door striker clips a little. I had to replace the screws holding them in with bolts as the screws had stripped. I sloped the stripping a bit to encourage better drainage. It's slightly higher at the middle.
This is what I used and how it's set up:


Also note I've removed the shelf inside that locker. I found it was better to hang some loops for the lines instead of leaving everything piled onto the shelving. I bought the kind of loops designed to fit over bow rails. I cut them in half and then screwed the 2 remaining loop parts to the back of the locker area. Works nicely for keeping the lines organized and gives them a chance to hang-dry instead of sitting in a musty pile.