Boat motor turns over but doesn’t start(no spark)?

My friend recently bought a pontoon boat. It has a 40hp 3 cyl yamaha engine. I've never touched a boat engine, however I am mechanically inclined. It's getting fuel, but no spark at all to the plugs. I can't see any loose ground anywhere. It looks like it uses a coil of some kind. What could be some reasons it wouldn't spark? contact points? a relay? Thanks.