The Honda requires premium fuel to make 100 hp (it is a very high compression motor). When run on 87 octane, the engine's computer will retard timing to avoid knocking. It will run just fine on 87, but it will probably produce something more like 90 hp.
Same thing with Yamaha's 2.8 liter 200... run it on regular and it detunes to avoid knocking, and likely puts out power similar to the Yamaha 175.
Most marina's that have non-ethanol fuel will be selling mid-grade or premium fuel. I personally would avoid a motor that required premium to make full power, but mostly because I burn a lot of fuel in the summer. With a 100 gallon tank, $2.45 cent regular is a lot less painful than $2.99 premium, or $4.00 marina fuel.