oil soaked wood, paint coming off

[Flying Dutchman]

Last year I stripped and sanded my Swedish sloop (lapstrake) down to the bare wood as I wanted to give her a completely new varnish and paint job.
The boat is from the forties and was covered in a variety of paints, tars, varnishes and woodstains. And although it gave me the opportunity to inspect every inch of the boat, reapplying the paint has been a major headache.
Decades of oil and grease leakage has seeped through the wood from the bilge especially in the area where the planking joins the keel. I spend ages trying to get rid of it with acetone, TSP and drying it out with a hot air gun.
After that I applied five coats of primer ('primocon' by Interlux) and two layers of antifouling (also Interlux).
This week I had the boat taken out of the water to check on the paintwork below the waterline and to reapply the antifouling.
Much to my disappointment though I found that all the paint in the problem area had completely gone and the wood laid bare again.
Not one yachtpaint specialist seems to know the proper way to treat this.
Has anyone of you ever had a similar problem?
Some help and advice would be greatly appreciated.

[Concordia..41]

TeKa two-part wood bleach did a wonderful job in the engine bilge and for the lower ceiling boards that were covered with oil and gook from our bilge.

It's a little different from your application, but after cleaning with TeKA, the engine supports took CPES and red lead like a dream and the ceiling boards are still in the shed, but it's been about two years since I bleached and varnished them.

[John Blazy]

I'm not a specialist on this, and haven't ever run across this in a boat, but an obvious thing comes to mind in reference to using a heat gun. A heat gun will vaporize oils that are below the surface and bring them back to the surface after you've cleaned the surface with solvent. Use solvents only to remove the oil. I would get the oil off by flooding numerous times with mineral spirits, then chasing with toluene, let air dry, then find a primer designed to lock into an oily surface. Maybe a thinned epoxy, or CPES as they often lock into contaminated surfaces.

[warwick]

I was told this works, but I am sceptical, however, an elderly shipwright told me he used to paint oil soaked areas with methylated spirits and burn it. Not a great uncontrolled burn obviously,duh!!, small piece at a time, he reckons it removes oil.

[Scott Rosen]

Was anything growing on the bare spots? Barnacles, mussles, grass, etc.?

If not, you maybe shouldn't worry too much about this problem.