I'm no expert, but...
JP,There are 2 possibilities that come to mind in your situation: Either the wood is just stained, or it's rotted beyond repair from weather exposure. Teak is probably the heartiest of all woods, so it's probably not rotted. However, I believe your companionway doors are mahogany which WILL rot eventually if not maintained. If you think you've got rotted wood, you'll have to repair or replace to make it look good again. Here's a test: Are the dark patches softer than the lighter patches? If so, you might have rot.Assuming the wood is salvageable, I'd go to a chandlery and find some oxacylic acid to bleach the wood before applying a finish. I've never done this myself, but I've been told that this will restore old stained weathered wood to like-new condition so it's ready for stain or varnish.Good luck. Let us know how it works out.Allen Schweitzers/v FalstaffC-30 Hull# 632