Somebody out there actually knows his stuff.rancherlee wrote:Being over 20' long (and not a mono hull) it's not against Federal law to over power the boat, and the majority of states have laws based around that so check local laws. As far as insurance goes It's not too hard to get a policy writen and be covered as long as you give them the facts and tell them what size outboard is on the pontoon. That said a 115 is going to only give you 1-2mph more over a 90 on a pontoon. Going from a 60 to 115 will give you 6-7mph and double your fuel usage @ WOT, is it worth it?
And even then, the requirements are on manufacturers and dealers for construction standards and not so much on the end-line consumer. Another factor to consider is whatever warranty the manufacturer may still have in effect. Putting a higher than rated engine will most likely void any warranty claim for cracks, splits, weld or other structural failures of the logs or engine pod. Not an issue if the boat's out of warranty, though. However some boats, like Crest and Bennington, have lifetime structural warranties.
Engine size is based on a lot of factors, but stability is the primary one. My work boat, a 27' Crest Tri-toon with the upper deck, is rated at 150 hp max, while the same boat without the upper deck can go up to 300 hp. When I ordered it, I called Crest and asked if I could get it with a higher HP. They said that due to the increased (higher) center of gravity with the upper deck, they would absolutely not put anything above a 150 on it.
From my Coast Guard days I remember going through the training on how they determine HP requirements and the process is amazing. The manufacturer has to submit detailed plans and test data. It's reviewed by USCG Marine Engineers to verify the data and often even physically tested before they will issue them the certification to put it out to the public. Although rancherlee is correct that it's only required on outboards under 20', nearly all manufacturers do this to get certification, due to their own liability and insurance requirements, plus AYBC and NMMA requirements.
As far as the Lake Patrol giving grief, or seizing boats, it depends on how the various State Laws are written. For example, Arizona's law on overloading only applies to persons or cargo, with no mention of engine.
