I just had to get in on this topic as it is very interesting....guess i still remember the days when i had to build model boats as CHEAPLY as possible...soooo...Im the first to absolutly agree that aircraft ply is the BEST type of wood to build a model boat with..hands down..HOWEVER doorskin or luan which i do believe is very similar if not basically the same will work if one wants to build a boat on a tight budget! It can be a little more difficult to work with and will compress but so will plywood if one leans on the wrenches hard enough. I knew a great guy by the name of Charlie Lockett who scratch built 20 and 40 tunnels and inboards with nothing but luan..he even SKINNED em with the stuff and his boats lasted for YEARS. Ive built a number of Dumas boats using nothing but the material that came with the kit and by SEALING the luan with epoxy inside and out i still have a 20 Pakynpak that is 28 years old and is still in one piece! Ive even seen Classic Thunderboats built with doorskin and they seem to work fine. The areas that take stress such as the transom or turn fin area can be backed up or skinned with plywood but whatever is used it must be sealed because even plywood will swell if it isnt protected, and one takes the time to DRY the boat out as well as possible after a days running... The other kinda good thing about a softer wood such as luan is that it does absorb vibration slightly better than harder woods. As long as I can afford to, ill build my wood boats with a/c plywood, but if times get tough (and that can happen anytime in this lousy economy) Id build a doorskin boat in a heartbeat!! Just my penny and a half cause thats about all my opinion is worth!!
