That is called a bayonet style bulb. Measure the size, determine the wattage if possible and from that the lumens then search online for an led version the same size with similar lumens. I've replaced all the bulbs in my 2003 410 Sundancer using this method. Good luck.
Worth reading this Marine Safety Alert about LED lighting: https://www.dco.uscg.mil/Portals/9/DCO%20Documents/5p/CG-5PC/INV/Alerts/1318.pdf?ver=2018-08-16-091109-630
Do you have the bulb # ? Try Amazon or 1000bulbs.com you will need the number on the bulb. I recommend leaving the halogen they are brighter especially for running lights
Wholesale Marine 147 Circle Freeway Dr Cincinnati, Ohio 45246 877-388-2628 Shipment Confirmation Invoice Number Order Date Order Number 1542914 2-Feb-2019 1803210
SKU Item Name Ordered Shipped
ATT-3530G7 Attwood Stainless Steel Led Side Light 1 1 ATT-3530R7 Attwood Stainless Steel Led Side Light 1 1