Boat Motor

Part of the answer lies in where you'll be boating, and part lies in what activities you'll be participating in with your pontoon boat.

Some lakes only allow motors under 10 HP, and others require your to use a trolling motor only. Larger lakes have more generous motor restrictions.

For example the Iowa DNR website indicates:

"A boat equipped with any size motor may be operated at a no-wake speed on artificial lakes under the custody of the Department of Natural Resources of more than 100 acres in size."'

Furthermore:

"On artificial lakes under 100 acres, you can operate a motorboat equipped with one or more outboard battery operated electric trolling motors. There is no motor restriction on natural lakes and federal reservoirs."

Another statement that state's DNR website:

"There is no motor restriction on natural lakes and federal reservoirs."

So consider where you'll be boating, and find out the regulations and restrictions. One possible approach to doing this would be to use Google.com and enter the terms "DNR" "boat" "motors" "HP" and the state regulations you're researching. For Iowa, that would be entering into Google.com: DNR iowa boat motors HP. For Missouri you enter: DNR missouri boat motors HP.

You get the idea.

Furthermore, will you just be fishing, leisure crusing, pulling an innertube with a rider, or pulling a skier?

The answers to these questions will help you determine which size of motor (or motors) will be meet your needs.

Why spend the money on a 100HP motor when you really only need 15HP. Having extra horsepower that you'll never use might impress those who see the large numbers on the side of the motor, and only you can decide if that ego boost is worth the extra money.

Also, your gas tank is an important factor.

Some states prohibit plastic gas tanks. Check your local regulations and get the size of tank that you need. Naturally, for long cruises you'll need a larger tank than for short jaunts around the lake to a few favorite fishing, sunning, picnicing, or swimming spots.