View Full Version : Cleaning Bilges
10-16-2001, 03:10 PM
I just bought a 1959 36 foot wood powerboat that has two diesels. The motors are removed and I am going to remove the transmissions and v drives. The bilge is dirty and oily. What is the best way to remove the oily residue and can I repaint over the oily wood?
10-16-2001, 08:00 PM
RWS42,Cant say alot about painting the bilge cause I'm agginit.
You can clean by scrapping first and then using a strong household cleaner.I like TSP when taking on grease and oil.That will get the surface stuff,and cut down on the fire hazard,but you will never get oil out of the wood.
My advise is don't paint!Yes it looks pretty but it simply provides a film that will hold moisture against the wood and will not let the wood breath.
Strictly opinion , not science!
10-16-2001, 08:52 PM
I'm with Das. Just finished going through the same thing on a 37' Egg Harbor and found a selection of scrapers to be the easiest and least messy. The mahogany planking actually cleaned up pretty well, even under the engines, and a shop vac took care of the stuff that wasn't flopped into a bucket. I bought TSP, but haven't used it yet- didn't want to get things wet, and I'm not sure how much more it could do. It took about 12 hours. Fun, fun, fun!!
10-16-2001, 09:14 PM
I have always taken the view that all that diesel and oil is actually good for the wood - no scientific reasoning for this - mere opinion that it probably presents a good barrier coat in itself.
I'd be thinking along the lines of rinsing the bilges thorougly with a mild detergent and fresh water leave for a short while pump out and then suck up the funky stuff left behind (it is the funky stuff which tends to smell) with a wet and dry vac. Your wet and dry vac will not be good for much else other than use on the boat after doing this but I have found mine to be one of the more useful boat tools I have.
Other than that I would be tempted to leave as is.
10-17-2001, 12:36 AM
First off, not all oils are equal. Petroleum based oil (crankcase or diesel) is NOT GOOD FOR WOOD!!! This is true particularly of the used stuff since it has any number of acids diluted in it. I know that fishermen have oiled their decks with the stuff for ages but it does erode the wood.
Second, the purpose of painting the bilge of an inboard is not looks but safety. Diesel boats aren't so much of a problem in this respect so you can actually get away with not painting the bilge of a diesel boat. With a gasoline powered boat, however, you absolutely must paint the bilge of the engine compartment. Neglect this and any gasoline spilled is going to soak into the bare wood until you heat up the compartment with the engine and then . . . . BOOM! I have seen case studies of exactly this happening. Mind you, only the engine compartment needs to be so protected.
10-17-2001, 05:16 AM
I am more than happy to stand corrected on the painted bilges issue - exactly what acids are you concerned with and how do they attack wood (a worrying thought in itself) - assume that they attack the fibers ?? Does the damage to the wood depend on the type of wood used to build the boat in question ? Assume so. Perhaps I should add that I have a diesel engine and that I have painted bilges throughout- it was the builder who has continually stressed that the muck in the bilges was good for wood !
10-17-2001, 10:39 AM
Thanks for all the advice. The bilges are painted and I started cleaning last night. The insulation has fallen from above and combined with the oils and is easy to scrape off. I will clean and use TSP and than decide to repaint or not. Great forum and great advice. Thanks a lot
10-17-2001, 03:51 PM
Puget,The oil I think I understand.I have never heard that before,about the gas saturation.Seems like gas in the bilge would be a bomb,painted or not painted.
I didn't realize gas once evaporated would still be explosive.Are you saying that the wood will still give up enough vapor to be dangerous.?
I will certainly change my tune on this topic.
Alan D. Hyde
10-17-2001, 04:02 PM
If it did, it should set off your sniffer alarms.
10-17-2001, 07:35 PM
Once clean, I'd be more inclined to put my money into effective drip pans than painting, if I had to make a choice, and check regularly for any leaks.
10-18-2001, 05:03 PM
I'm in the same boat as you.... My bilges are soaked with 38 year+ of oil and diesel to the point where the lower ends of the white oak frames are soft enough to let the #18 screws for the planking spin! Pretty much have scrapped out all the sludge and used TSP which gets it off of the surface but don't get much deeper (used hot water as well to help soften things up a bit). I'm in the process of sistering/replacing these soft sections of framing. A fair number of floors are in the same condition. You can see a few pics of the project here:
(the site is a bit slow)
10-18-2001, 06:21 PM
You sure wern't kidding when you said the site was slow. http://media5.hypernet.com/~dick/ubb/smile.gif
Well worth the wait though.Nice pictures and one daddy of a project.
Your lucky to have that lumber.Bet it's sweet stuff if it is that old.Probably straight as a surveyors line.
I recognize the saw.We helped our son in law build his home by slicing up doug fir,larch and lodge pole with that very saw model.Had to repower it,but boy did it cut straight once we got the hang of it.
Keep us posted,and good luck.
10-19-2001, 12:11 AM
The damaging acids in crankcase oil are standard products of combustion. So carbon dioxide, nitrogen compounds, sulfuric compounds combine with that other product of combustion -water- to form acids. Some woods may be more resistant than others but I doubt that you'd want to count on it. Basically, any internal combustion engine is going to get some combustion products in the crankcase oil. Aside from that, any used crankcase oil is going to have tiny bits of metal suspended in it and these metal bits are going to form more acids as they corrode.
Mabey fresh petroleum oil is not so bad for wood but why would you want to use it that way?
I remember reading about a case (complete with pictures) in which some fishermen had a small express cruiser with an inboard engine. They stopped to refuel and spilled some fuel into the unpainted bilge. Being responsible types, they cleaned up the bilge and then waited a couple of hours for the bilge to air out. It was mabey an hour after they took off again that the bilge blew... investigation revealed that even in the short time the gasoline was in the unpainted bilge it had soaked into the wood such no amount of airing out would remove it. It wasn't until the whole compartment heated up that it was cooked out of the wood. The fishermen were lucky to have been blown clear of the boat so there were no casualties.
10-19-2001, 07:46 AM
Gasoline is only combustible (at atmospheric pressure) as vapor between a 2% - 5% mixture with air. As a SWAG, this would be about a tablespoon or two of liquid gasoline vaporized in an engine compartment.
10-19-2001, 12:25 PM
Thanks Puget.Based on what you and Andrew have added,it seems reasonable that a small spill could produce "delayed vaporization" as an engine room heats up.
Sounds like another very good reason for a drip pan.Any time the motor is out,if a drip isn't present,one should be installed if possible.
10-19-2001, 12:40 PM
Question for Pugetsound. When replacing bottoms (I have done a few) I have found that oil soaked wood is incredible weak. I can take an oil-soaked plank and easily break it over my knee where as a non-soaked plank next to it would not break. I assumed that the oil somehow attacked and weakened the lignum in the wood but I have never heard otherwise. Is this a result of the acids that you speak?
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