help! looking to build poly pontoon boat 60ft 2 levels, ideas/advice/plans any help

any help much appreciated

 

I think some could help a lot but it is necessary that you give us more details of what you want. For example, a 2 level pontoon is not well understood. Without knowing anything more, it seems impractical to make a 60-foot boat on several elements, it is better, easier and cheaper to build a "mono-hull". Need pontoons to have cargo holds?. Are there any limitations in the draft? ... endless questions.
I'd like to help. Please, more data

 

The pontoon is to float on a lake and the idea is a floating venue, drive out to middle of lake and hold wedding receptions, buck/hens, corporate functions so I'd like it to hold 100 people

 

The reason I thought poly was I'm a polywelder and it would be light and very durable

 

You mean polyethylene obviously, and you intend to use plain sheet material to fabricate it ? It lacks stiffness, and the poly boats you see have moulded shapes that incorporate shape to give rigidity.

 

I was thinking poly pipe to float on and aluminium
Frame

 

PVC ? I don't think that will be suitable, what diameter and wall thickness are you envisaging ?

 

Pe pipe

 

OK, PE, but what diameter and wall thickness ?

 

So 10 tons of people, plus boat, it's super structure, equipment, etc., 60' seems a bit small, unless quite beamy. Obviously, this will require an NA and professionally done plans, assuming you'll want any municipality or insurance company to take you seriously, in regard to the safety of 100 wedding goers.

Simply, hire an NA, there's no way you'll "wing it" with this one. The same will be true of the build, where certified construction techniques will be required.

 

There are standards if you are taking passengers, even to the middle of a lake.

Take a look here, you would fall into "new vessel:"

https://www.amsa.gov.au/domestic/quick-guides/vessels/index.asp

•A new vessel needs to be surveyed or is ‘in survey’ if it is ≥7.5m, or carries passengers, or operates beyond sheltered waters, or is otherwise high risk. These vessels must be designed and built (NSCV Part C, Design & Construction), operated (NSCV Parts D (Crew Competencies) & E (Safe Operations)) and surveyed to meet national standards. See the Applicable Standards and Requirements for Vessels table for more information.

Being on a lake will not make construction much easier, and I doubt you will be able to use anything flammable for vessel construction

Like PAR said, you need an NA