Depends
There are two approaches. One is the varnish route, other is the non-film forming oil/silicone route. To me, I am a paint chemist, the varnish is temporary and is a pain to remove and redo. The product I use on my 27 is Teak Wonder. The kit comes with a cleaner, a brightner, and and oil. Just did mine this weekend for the first time this season. I go back over it with the oil bout every 2-3 weeks(20 min max). To me, this is less bother than the varnish approach. But hey, to each his own.My '78 wood was so weather worn that I removed it all and used a joiner or router or sander as needed to restore the wood to like new. Bought new coaming box moldings from Catalina as those were far gone.Enjoy!