How hard is it to reteak a swim platform? boats a 85 an the woods gray would like to make it look like new again. whats a good way an or product to use;

carefull pressure wash, sand and teak oil

West Marine sells a cleaner (mild acid), followed by brightener (bleach). Then rinse with lots of water, allow to dry, and put on several coats of teak oil.
Badly blackened areas may need sanding.

Just re-did mine... Used teak cleaner twice... Then followed up with a bleach water mix. Light sanding in some of the ruff areas.. Followed up with 3 coats of teak oil..
SWEEEEET..
Now if you want. you can skip the teak oil and use a good urethane for outdoor/wet use... like for front doors on a house.
I have done that and it lasts for about 4 years...and looks great and no maint. The only problem is it will start to crack in about 3-4 years and then you will have to sand to re-finish..
Just looks better longer but more work at the tail end..
flip a coin...