Late
Sorry for the late reply but have been off this board for awhile. Pontoon boats are built many different ways. They do all look alike but from the floor down there are major differences. If your going to use the pontoon as a floating living room at low mph all the boats made today will do that well. If your going to add a 200+hp outboard motor or a high HP I/O then you need to know more to make a good choice. The main problem with pontoons is the flex of the hull-the toons shifting and moving at higher speeds. So I suggest if your interested look at the following-
Floor- what is it made of-composite,aluminum, or plywood. If it's plywood is it individual sheets or one contunious sheet and the thickness.
Floor attachment- screwed or bolted
Floor Joices- what is used (guage and type) and the spread- 12",16" or 24" on centers.
Pontoons-
Thickness of the aluminum material- .08,.09,.10,.125 etc.
Shape-Ushaped or round-Ushape eliminates the M brackets. The M brackets are used to connect the round tube to the floor joices and is a major failure point. Ushaped pontoons bolt directly to the floor joices.
Filled or unfilled pontoon-Is it filled with styrofoam or does it have baffles.
Both are used to prevent the sides of the toon from oil canning(caving in)
Pontoon Nose cones-these hit the waves first and take alot of stress.
How heavy are they built and do they have strong splash shields on them.
Undersheilding- are the floor joices covered by aluminum sheeting to keep the waves from catching the underside of the floor. Is the floor completely covered or just a partical covering?
Lifting strakes-where located, thickness,shape-they really affect the handling and performance.
There are a few pontoon mfg. that make very good pontoon boats that are built to handle unlimited power- single double and triple outboards and big block single and dual i/o's. They can also handle the big water on the big lakes/rivers without failure. There are other pontoon mfg. that stick lifting strakes on their toons,add a third toon and put racing stripes on them and call them performance toons. I've seen the failures.
For me I like the one sheet plywood floor(stronger than individual sheets)Utoons(bolt directly to the floor joices)filled with close cell foam for strength,floor joices on 16" centers at the least and a fully covered underside.
I like the high end models of Playcraft & JC.
But there are round toon mfg. that make heavy duty toons also. The high end Premier, Bennington Southbay and Manitou come to mind.
BTW- if you read all the performance tests done by third parties the best boats are topping out at 50-53mph gps. (Saw one test with a Verado 350 that did 60.2 )To go beyond that you need dual outboards(Premier,Bennington,Southbay and Playcraft)or a Big Block IO(
Playcraft and Southbay). Just remember when you go looking for a toon crawl under it and check it out. If the sales person starts talking about the wine rack or the power lounge seats first I'd leave asap.