Using Luan for Boat Building is probably not a good idea, for the reasons I list below:
In fact Luan Wood has never been graded by the American Plywood Association.
Marine ply is also going to have more plies than typical construction ply, you want to be on the look out for higher numbers, greater than 7 in my opinion. Marine ply is going to be lighter than ext ply and especially pressure treated ply. For your boat I would go with the Home Depot pressure treated varieties. Your best bet is to get 2 sheets of 3/4 pt ply, let them dry for a week, then glue them together.
Marine Grade plywood is usually considered good for uses that will involve a project getting wet, such as Marine Applications and Boat Building. Marine plywood is a specially treated plywood that is designed to resist rotting in a high-moisture environment. Marine plywood is frequently used in the construction of docks and boats. Luan Plywood, is not shown to react well to moisture exposure.
Oriented Strand BoardSterling board (UK and Ireland) and by the proprietary eponym Aspenite in Canada and the Americas. It is also an engineered wood particle board made by layering strands of wood in specific orientations. In appearance, it may have a rough and variegated surface with the individual strips of around 2.5 x 15 cm / 1 x 6 inch, lying unevenly across each other -
WBP Plywood ----
WBP plywood is so called because it is Weather and Boil Proof. During manufacture this product plywood is constructed with weather resistant adhesives which allow it to endure maximum humidity levels. It is often used for outside construction projects by do-it-yourselfers for decking furniture and landscaping. It is also useful for exterior protection on small frame structures such as sheds, and garages. It will require a coat of paint or a varnishing to bring it to full protective values and strength.
MDF Plywood : Description
What is MDF Plywood? Well I'll give you a brief description of it's background here. MDF Plywood is actually an acronym for Medium Density Fibreboard. It is a specially engineered product which is created when hardwood or softwood is broken down into fibers and then combined with wax in a resin. This then forms panels (plywood) by applying high temperature and pressure. MDF Plywood is actually denser than regular plywood, but can be used in the same applications or those that might call for greater strength than run of the mill plywood
Using Marine Plywood in Kitchens and Baths
Applications for Marine Grade Plywood
What are the Differences in Marine Grade Plywood
Is Dynea Plywood Considered Marine Grade Plywood?
Do you Need to Waterproof Marine Grade Plywood?
How to Install Marine Grade Plywood
Installing Marine Grade Plywood for Boat Building
Boat Building Plans Available Online
Luan and Marine Grade Plywood?
What is Marine Grade Plywood