Your solution is at hand.... the window's rubber gasketing is probably 'shot' and needs to be replaced. go to drmarine.com, go to "pearson parts". D&R Marine is about the only place left on the planet which has a large stock of 'pearson parts' ... including your probably worn out 'rudder shaft bearings', etc.
Screwing around with silicone, caulk, etc. on a Pearson window is a PITA that will remedy nothing. Remove the window, disassemble and reassemble with the new gasket. If your 'mechanics expertise' is on the short side, take the frame and new gasket to a commercial glass supply .... they do such gasket replacement all the time.