Thread: Cleaning and sealing an oily bilge?

Don't attempt to seal these planks (none of them). This is a common misconception and one that will cause a host of issues down the road. Don't even think about epoxy.

A carvel boat has planks that "move" and this is normal, expected and required. The bilge is a place where you'll get every concoction imaginable mixed with sea water, contaminating the planking surfaces. For the most part, these can be cleaned and repainted (if desired). Personally, I don't like painting these areas, preferring to use varnish instead, so I can see what's happening under the varnish (leaks, stains, etc.), but some like paint, which can lighten up the look in a bilge, so you can see in there.

It's often the case that leaking engine oil and fuel contaminate the planks under the engine, transmission and lowest point of the bilge and that no cleaner will really do a good job. Welcome to the realities of working with a century old boat. Most boats experience this, long before they're this old.

The same route is suggested, clean the surfaces as best as you can, then paint. If you want to offer some protection to the planking, put a drip pan under the offending mechanical stuff. Yep, there's usually not a lot of room for this, but something could be rigged. Don't not attempt to "seal" the planking - you'll just screw yourself into a big repair bill a few years down the road.

There are lots of cleaning agents you can use. I use regular kitchen dish detergent and a soft brush, like a toilet brush. Get the bilge as dry as you can, then using some water, a splash of denatured alcohol and some "Dawn" or "Joy" you've stolen from the other half's kitchen, scrub it into the planks. Let it stand and hose it off. You'll have to repeat this process several times if it's bad. The alcohol will help dry the moisture out faster. After you've gotten what you can, you can attempt more caustic stuff like oxalic acid. Heat also helps bring out the imbedded oils in the planking, but if the wood is soaked or saturated, you'll make a career out of trying to remove all the oils. At some point you'll just have to surrender and move onto paint. Since it's oil soaked, you'll want an alkyd paint or varnish. Cut the paint not more than 20% with spirits or turps on the first two coats, but subsequent coats don't need this cut.

Some tricks to use are a straight up alcohol scrub down. It will lift oils and dry the surface pores of the wood, so a subsequent paint coat has good, clean wood fibers to grab onto. Use lots of box fans in the bilge to move lots of air around - it'll dry much faster and deeper into the wood's surface. Don't be tempted to use stronger solvents, like acetone, MEK, etc., they're not going to do much better then alcohol. Isopropyl alcohol works good too. Don't get too aggressive with the scrubbing part, it's easy to remove wood fibers this way, which you don't want to do.

I'm quite a fan of epoxy, but agree with PAR here. It doesn't belong for this process.
Try Plaster of Paris mixed with white spirits into a paste (both from the hardware store). Spread liberally (6 to 8mm maybe) over the affected area and leave for the white spirits to evaporate out - at least 24hrs in this weather. The white spirits dissolves the oils and the plaster soaks it up. The plaster can be brushed and vacuumed out - it doesn't go hard without water.
I use a primer called Zinsser BIN Cover Stain (local hardware store again). It's designed to cope with oils etc. somewhat, and seems to stick well.
Mark

Sprinkle a 1" (51 mm) layer of kitty litter on every thing in the bilge that's good and soaked. This will draw out the moisture quite well and can be vacuumed up easily when saturated.