Gotta disagree with you here. Adding a more or less permanent, hard pop-top (or doghouse, or whatever you want to call it) could not interfere at all with the structural integrity of the boat. It might add a small amount of weight up high, and certainly will add windage, but won't make the boat weaker
Beg to differ. The structural integrity of the boat could easily be compromised by this heavy addition to the cabintop. If it is not solidly attached, it could be swept away or damaged by a large wave. Next wave fills the cabin. 'Bye Boyer. What is there to attach to? For an 18" high plywood "wall" I would want carlins at least 2"x3" to rabbet and screw into. This is all being attached to a cabintop that is perhaps 1/4" fiberglass? We don't know. If it IS solidly attached, the hefty dimensions of the proposed materials (3/4" ply, for starters) could lead to fractures in the cabintop itself, with the whole thing weakening until it was simply ripped off at the worst possible moment. (This is why patched sails tend to tear more around the patch - the repair is stronger than the surrounding material.) There is also the worry about the lexan ports getting punched in, though that problem could be resolved by the proper design. On a 1977 27' "pop-top" Luger we are not talking about making alterations to ISAF open ocean standards. If the expected use is daysailing on a lake in nice weather, some of these issues are moot. The aesthetic concerns remain, however, since we each have to look at what's moored next door, even if just to avoid hitting it. Changing the original design does make the boat susceptible to structural problems that could be dangerous.