M_Boats: Best Sealant to use

Hello All: I am doing some re-bedding, etc, on my M15. The boat store recommends silicon sealant, some on this site recommend 5200, while others recommend some variant. Could someone please give me the rule of thumb, if there is one, concerning when to use what sealant. Thanks Mike Hall M15 #167 Dreki Sent via BlackBerry by AT&T