About 5 yrs ago I rpld the rotted seahood on my 1982 C37 with a new one from PSC.
It was a perfect fit and they even adjusted the color to account for fading over time.At that time I think it was $900.00.
The seahood is the low-profile, fixed fibreglass cover over the sliding companionway hatch. It helps to prevent the closed hatch from leaking in heavy conditions when there's a lot of water on deck (heavy rain squalls or large seas).
The dodger of course is your canvas hood over the hatch, that is intended to shield the occupants of the cockpit from spray. It also provides an awning for the open companionway hatch, to prevent spray or rain from entering the cabin when it's open.
Not all boats have the seahood that our PSCs have. It's a nice feature. If I can find a good photo I'll post it.