We already had speakers installed in the cockpit, but they were so badly UV damaged that the membrane fell apart. I decided to replace them with some new 5" marine speakers. Fortunately I found a model (LTC Promarine 52) that fits perfectly. They're placed under the sprayhood windshield and raised from the deck a few centimeters by a round wooden frame. I also removed the frames, sanded and painted them, and installed them back with a new marine sealant.
The cockpit speakers can be turned on/off with a switch at the charttable, next to the radio.
Our VHF radio is installed at the chart table too and it would be good if we could hear it more clearly while under way, so I also installed a new external VHF speaker in the cockpit. The wire goes below deck at the speaker's flange and the VHF speaker is fastened with velcro, so it be easily moved if needed. It can be turned on/off in the VHF radio's menu.