House Boat Roof ideas

Hey everyone, i have a late 70's Sumerset 55' x 14' houseboat. Steel hull (before i get thrown under the bus for a steel hull, its paid off and we love it, in fact its getting all new steel put on the hull now.) Here is my question, it has a few week spots in the top roof/deck. and had some leaks etc. so i was going to put new tongue and groove plywood on the entire room. around 1/2" maybe 3/4" not sure yet. i was going to put it right over top the old room. So my questions are:
1. is putting the wood right over top the old ok?
2. What type of covering do i put over the wood? EPDM rubber sheets, epdm liquid rubber, durabak, or something else?
3. Do i need to treat the wood before hand or can i just cover it up?
4. The inside ceiling is the kind where you can see all the studs (studs are in great shape, there were laquared or something so the water has not affect them at all were the leaks where and are 2x5".) but the white panels inbetween the studs are looking bad, any ideas of how to replace the white, it looks like the white board was put on the top before the roof, so without taking all the old wood of the roof, there is no way to change it, does anyone have ideas of what i could put over the white to make it look better, or am i going to have to put up a whole new ceiling and cover up the studs.

thanks for the help.

Re: House Boat Roof ideas

Some pictures would be nice to see what we're working on

Generally covering up rotten wood with fresh usually makes matters worse.
Think of it when you have a pot of boiling water on the stove, and you put a lid on it. Your holding in all the steam. Same thing with water soaked wood. You put a fresh layer over the top of it, and all it does is hold in the water to fester. If you plan on keeping it, do it right!

Re: House Boat Roof ideas

I have attached a picture of the roof, you can see where patch work has been done now. By doing it right you are saying to take all the old wood off?? and replacing it with new right? ok, if i do that, what do i put on the new wood? EPDM, Fiberglass?? thanks