Opinions on premium gas

I'm sure there are all kinds of opinions on this matter. It seems as long as I've been around boats every one has always said they should run premium gas. As a new boat owner I continue rocking the high dollar gas out of habit and a little piece of mind. Recently I have read a few pieces on how premium grade gasoline is a waste of money in most cars. I know in the grand scheme of things the upgrade isn't all that much with each fill up, but cumulatively over a season it can add up. So what do you guys think, what are you pumping, and why?

this is what I know about it.
All my fords(97-2001) have said to use 85 or 87. The computer is mapped to run with that. One exception, my 99 svt coutour was a high compression motor. Needed 91. At least.
Also, boat motors are usualy high proformance. High performance with out turbos, superchargers or nitrous is done with compression. So They(our boat motors) may need 91+

Regular unleaded is what the manufacturer calls for in my boat so thats what it gets. Would not waste my money on super unless the engine warranted it. High compression, blown, turbo, etc.

Uh not really. High performance is not done with compression. Its done with cam, induction, ignition and ECM tuning.

Grades of gasoline are rated based on octane. Octane amounts to resistance to ignition, such as from heat. Compression makes heat. We want the air/fuel mixture to be ignited at a precise time by a spark, not spontaneously by heat in the combustion chamber. Higher compression gives more performance per the same volume of fuel. Thus, higher compression engines require higher octane to prevent spontaneous ignition (predetonation). Any octane past what is required to prevent predetonation does not good, and technically reduced horsepower (though by such a miniscule amount you would never notice the difference).

The limit for 93 octane fuel is about 8.7:1 dynamic compression ratio. Dynamic compression is determine primarily by static compression ratio and the point at which the intake valve closes. That 8.7:1 limit can be upped by thing such as polished combusion chambers, singh grooves, timing curve, and other methods to prevent hot spots in the chamber.

I could go on all day about compression ratio and ways to increase the compression you can run on the same octane, affects on horsepower and torque, etc. I won't... Unless anyone is really interested. Bottom line, run the octane your engine requires. You gain ABSOLUTELY NOTHING by running a higher octane than your engine requires.;

Personally I run 89 octane in my boat. I believe, though am not 100% certain, that's what my 454 was originally designed to run on. It was rebuild with some performance parts a couple years before I bought it and I don't knwo waht was put into it. I don't know what pistons or heads it has, or waht cam, what the cam degreed out at, or anything else. I run 89 octane and it doesn't detonate... So I don't sweat it. I have never heard of any ski boat being made to run on 91+ octane, so unless your owners manual says it requires it, or you build the engine to require it, you are wasting money. End of story.

The station owner at the local BP store told me that anything 89 octaine and great contains no ethanol? Now, he may have been pulling my chain trying to get me to buy the more expensive gas. BTW, it did not work, I run 87 because that is what PCM tunes their engines to.

Every engine will have a design Octane rating. At or near sea level that fuel will provide the best power and economy. At high altitudes (over 3500') you can usually drop one grade of fuel without much change because the air density is lower so the combustion pressures are lower and a lower Octane rating is suitable.
Using a higher grade of fuel than is specified for your engine will drop your power and economy slightly, and cost your more to lose that.
Using a lower grade of fuel can lead to detonation or preignition which will cost you power and economy. It might also melt or break parts. Usually very expensive.
However, if your engine has a full closed loop engine management system, which most boats do not, the knock sensors can keep the engine alive and operating efficiently by adjusting timing to stop engine damage. In doing that you lose a bit of economy but not usually as much as the price difference on fuel so you can come out ahead by using lower grades of fuel. (unless the management system fails or has a fault, in which case you're back to expensive broken parts.)
My Mercruiser asks for regular fuel and putting premium in it is of no benefit, except to the company pumping it.