thinking of upgrading the stereo and speakers in my boat (17 ft bowrider) and was wondering if the new stereo has to be a marine unit? aside from water resistance, are there other considerations?
In theory the marine units are better protected against moisture and vibration. I've burned up a couple of regular car units in our boat and eventually went to a marine unit. It really hasn't faired all that well either and is on it's way back for warranty repair. Read the fine print on your warranty. Some units require that it be mounted in a pod or case specifically for that unit.
Without a doubt use marine speakers. Automotive speakers will not stand up to the UV rays and moisture. I love the Bose Environmental series. Sound awesome and you can dump a glass of water on them while playing with no damage.
Been using automotive head units for over 10 years with no problems. But as Fishman says, make sure you use marine speakers, many automotive speaker cones will die quick in the marine environment.
The coatings used in marine applications are well suited for salt water although fresh water and the amount of humidity a boat stereo will see over the years will take a toll. If you use a "car stereo" it will work fine for you for many years. Just get a water proof housing to keep it in or if you install it in the dash a water proof cover for the face at the very minimum.
You can find these housings and covers on iboats as well as many other marine stores.
I enjoy every watt of my 400W system. Its all marine, wired with 12 ga. tinned speaker wire.
I too enjoy the Bose 151Es paired with a set of kappas.
In 20 years as a car audio tech I never installed anything but auto stereos in boats. Just use a housing or water proof cover and you will be fine.
As for speakers, use marine. If you had a cuddy or cabin regular speakers are fine inside.
After I repowered with a four stroke, I decided to add a sound system. I mounted a Sony radio/CD player in a good housing under the bow and located a pair of marine speakers in the rear of the boat. I also installed one of those fancy remote control units (Sony Marine Commander I think its called.) I'm usually in salt water so the speakers and the remote control get a bath every time we come back in. It's been great.
Been using automotive head units for over 10 years with no problems. But as Fishman says, make sure you use marine speakers, many automotive speaker cones will die quick in the marine environment.