{"product_id":"sierra-marine-ignition-switch-mp39780-bayliner-7-8-inch-short-body-3-position-15a-30a","title":"Sierra Marine Ignition Switch MP39780 Bayliner — 7\/8-inch Short-Body, 3-Position 15A\/30A","description":"\u003cp\u003e\u003cstrong\u003eThe Sierra MP39780 Bayliner marine ignition switch is a three-position, marine-grade replacement switch rated for 15A ignition and 30A solenoid control, designed to fit a 7\/8\" dash hole with a short reach housing.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eThis compact ignition switch is built for recreational and small commercial boats where space, corrosion resistance, and reliable electrical control matter. Molded from glass-filled polyester and fitted with brass backup hardware, the MP39780 provides a sealed interface between the cylinder and contact plate to minimize oxidation and electrical faults in salty, humid environments. It’s a conventional three-position unit with three screw-tab terminals for simple wiring and straightforward replacement or retrofit installations.\u003c\/p\u003e\n\n\u003ch3\u003eHow does this switch fit my boat’s dash and wiring?\u003c\/h3\u003e\n\u003cp\u003eThe switch is designed for a 7\/8\" (22.2 mm) mounting hole and a short-length body that accepts panels up to 5\/8\" thick. It uses three screw-tab terminals that match common marine ignition and solenoid wiring layouts, making it compatible with many Bayliner and similar small-boat installations. You can swap it into existing dash cutouts or use it during refits where space is limited.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eMounting hole: 7\/8\" diameter\u003c\/li\u003e\n  \u003cli\u003eMaximum panel thickness: 5\/8\" (short housing)\u003c\/li\u003e\n  \u003cli\u003eTerminal type: 3 screw-tab terminals for ignition\/solenoid\/battery\u003c\/li\u003e\n  \u003cli\u003eDrop-in replacement for many Bayliner-style switches\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat materials and protections prevent corrosion and electrical shorts?\u003c\/h3\u003e\n\u003cp\u003eThe housing is made from marine-grade glass-filled polyester to resist moisture and mechanical wear, while a brass backup nut adds secure, corrosion-resistant fastening. An inner seal between the cylinder lock and the contact plate limits water and salt intrusion, and the non-conductive housing reduces the risk of accidental shorts against the dash structure.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eGlass-filled polyester housing for weather resistance\u003c\/li\u003e\n  \u003cli\u003eBrass backup nut and hex black plastic face nut\u003c\/li\u003e\n  \u003cli\u003eInner seal to limit oxidation at contact points\u003c\/li\u003e\n  \u003cli\u003eNon-conductive housing to prevent stray shorts\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat are the electrical ratings and how should I use them?\u003c\/h3\u003e\n\u003cp\u003eThe ignition circuit is rated at 15 amps at 12 V DC, suitable for starter circuits and ignition systems on small engines. The separate solenoid terminal is rated to 30 amps at 12 V DC, accommodating standard starter solenoids. These ratings guide correct wiring: keep the starter load on the solenoid terminal and use the ignition terminal for accessory\/ignition loads within the 15A limit.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eIgnition rating: 15 A @ 12 V DC\u003c\/li\u003e\n  \u003cli\u003eSolenoid rating: 30 A @ 12 V DC\u003c\/li\u003e\n  \u003cli\u003eThree-position conventional operation (off\/accessory\/start)\u003c\/li\u003e\n  \u003cli\u003e3 screw-tab terminals for clear wire connections\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow easy is installation and maintenance?\u003c\/h3\u003e\n\u003cp\u003eInstallation is straightforward: push the switch into a 7\/8\" hole, secure with the included brass backup nut and face nut, and connect wires to the three screw tabs. Periodic checks of terminal tightness and seal integrity keep the switch performing well; if corrosion appears, cleaning contacts and replacing the seal will extend service life.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003ePush-in mounting with brass backup nut and hex face nut\u003c\/li\u003e\n  \u003cli\u003eSimple screw-tab wiring — no special connectors required\u003c\/li\u003e\n  \u003cli\u003eInspect terminals and seals during routine maintenance\u003c\/li\u003e\n  \u003cli\u003eCompatible with standard Bayliner dash panels and wiring harnesses\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for: The Sierra MP39780 is for boat owners, marine electricians, and repair shops replacing worn or corroded Bayliner-style ignition switches on small to mid-sized boats. It suits anyone needing a compact, sealed, and rated three-position switch with straightforward wiring and good resistance to marine environments, especially where panel depth is limited and reliable solenoid control is required.\u003c\/p\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: What hole size and panel thickness does the MP39780 require?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: It fits a 7\/8\" mounting hole and supports panels up to 5\/8\" thick with its short housing.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: What are the electrical ratings for ignition and solenoid?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Ignition circuit is rated 15A at 12V DC; solenoid terminal is rated 30A at 12V DC.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48086158311582,"sku":"B0000AXQML","price":45.29,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/sierra-mp39780-front-facing-switch.jpg?v=1785887419","url":"https:\/\/northtrailauto.ca\/products\/sierra-marine-ignition-switch-mp39780-bayliner-7-8-inch-short-body-3-position-15a-30a","provider":"North Trail Auto","version":"1.0","type":"link"}