Here's something a bit different. ZEP Industrial Purple Degreaser. Available at Home Depot.
http://www.homedepot.com/ZEP/h_d1/N...splay?langId=-1&storeId=10051&catalogId=10053
Upon my purchase several years ago of my 1980 Hunter H36, it also had dark and stained interior teak from many coats of teak oil and just age. Otherwise the wood in general was in great shape. Previous owners did very little damage by picture hangings and the like.
Just on a whim, I found that Industrial Purple, which I had previously only used to clean brake dust and road dirt from the wire wheels and tires on my (no longer owned) 1989 Jaguar XJ6, also very effectively removed surface oil finish and grunge from the interior teak my sailboat. I was left with very clean wood. It was ready to take on whatever finish you finally settle on.
For stripping Teak Oil from wood, Industrial Purple must be used very strong. Either full strength or slightly diluted (its water based). I found that carefully applying the solution with a sponge worked well. Be very sure that nothing splashes around. In this respect a sponge is better than a brush. Industrial Purple will cause splotches and damage to almost any surface that it falls on. However, fiberglass/gelcoat will remain unaffected.
Also, protect your body. At full strength, it easily causes severe detergent burn. Rubber gloves, long sleeves and eye protection are a must.
Experiment in an inconspicuous area before going full out. What worked for me: Apply it with the sponge. Then let sit for only a few minutes. On vertical surfaces, be sure that you don't over-apply so that the product doesn't run down onto the cabin sole or other surfaces. Then wash/clean with fresh water -- several times.
I refinished the clean wood only with a couple of coats of a satin sheen polyurethane rub-on oil by Min-Wax. The final outcome wasn't as perfect as Tim R has posted in his pic. But it was easy to do and to my eye anyway my interior looks very nice.
Industrial Purple also completely removed all the surface grunge and stains from the vinyl bulkhead faux straw wall paper on my boat. The surface now looks as good as new.
But just to repeat. While I found Industrial Purple to be absolutely amazing ... Be Careful and BE Safe with It!