I've been think about a hardtop style forward cockpit cover for my Sea Pearl 21. A type of water resistant hard cover / hatch that could be raised later like a bimini or hard top tent roof. My #SeaPearl21 has a forward and rear cockpit. The forward cockpit opens up to the inside of the entire boat. I know it's not if I ever capsize it's when I will capsize in the future. So this has lead me to think about mast head floats, filling my booms with flotation, additional interior floatation and covering my forward cockpit. Has anyone seen anything like this before?
1986 Sea Pearl 21 LBHull #109
DCA - Dinghy Cruising Association DCA # 3515
TSCA - Traditional Small Craft Association TSCA #4545
OCSG - Open Canoe Sailing Group - OC #265
ACA - American Canoe Association - Lifetime # 10773564
Sorry, no direct experience. I've not seen a DCA boat with a lifting hard top. Most go for a large stow-away cockpit tent. UK Norfolk Broads sailing cruisers sometimes have lifting hard-tops. Also, some Corsair Trimarans have a pop-up hatch with Canvas sides to increase headroom.
I guess you want it strong enough to kneel on when it's stowed but as light as possible. You could have a removable strut to help the strength of an otherwise light structure when it's down. Are you going to take the opportunity to make it full width?
Sounds a nice idea.
For a hard top 3.5mm plywood curved over a frame will strong and lightweight.
The hatch on MilliBee my Lynx 14 pocket cruiser has a similar construction. I found two lengths of pine and cut curves with a jigsaw. 2x1 softwood joined them into a rectangular frame. Then l bent 6mm ply over and held it down with clamps until the epoxy set. I used 6mm ply in case I stepped on it!
Canvas sides would not be difficult to add, as there is a 18mm upstand on the deck to keep the rain out.
I've toyed with raising the entire roof behind the mast Broads style. However the removable hatch allows one to stand up, which is very convenient. It is held down with a clever set of internal pad eyes and 3mm rope acting as rope hinges. The rope can be pull the hatch tight onto the deck or loosened so that it slides sideways.
Regarding masthead floation, I have the Secumar auto inflating device, which is compact and can be lowered on a halliard for re-arming if required. I also have a cockpit spray hood which I made myself and is useful if motoring to windward in bad weather. It does not seem to slow the boat down.