1984 Hunter 31 - Oil under floor and in bilge

Jul 29, 2016
55
Hunter 31 Comox BC
Knew there was some oil residue ending up in the bilge. The pump wasn't really working and the hose and electrical hookup was garbage, so bought a new powerful one and replaced the exit hose.
We installed it a few weeks ago, and tested it and everything was fine. I cleaned the bilge so it looked great. Walking to the boat today, noticed an oil slick on the water generally around my area of the dock. After a while I realized I was the cause. The bilge had water in it probably from the boat rocking in strong winds, and oil! It had pumped it out.
I spent all afternoon today firstly cleaning everything. I now have absorbent pads down to soak up any oil that moves through. Tried my best to see where this oil was coming from and it seems the areas between the engine and bilge where any water gets in from leaks or stuffing box under the floor and in the stringers have a coating of oil, probably from years of drips and oil changes. Am looking at cutting some strategic inspection ports to see if i can get rags in and clean it before I try flushing it. Where the ice box drain hose comes in to the bilge, I have a small grey hose that disappears up the same hole as the ice box hose. I have determined it loops around and heads under the forward part of the engine under the floor. Anyone else have this and know what its for??? This oil has been there for years, and I will always have oil in the water if I let any run through and get to the pump.
Have attached a couple of pics showing what I am talking about. The pic of the bilge is stern of the boat to the right of the image. You can just see the end of the icebox hose sticking out.
Am looking for tips, ideas, suggestions on how to clean and access this oil as I cant have a repeat in the marina as I did today. Planning a flush and drain one day as I cant think of any way to try and get rid of it. What is this grey hose for?
 

Attachments

May 24, 2004
7,129
CC 30 South Florida
The boat probably has many gallons of water and old oil trapped in the stringers below the sole. That oily water gets released with boat motion into the bilge and removing all of it might be a long process. I would turn the bilge pump off when the boat is unattended to prevent a marina spill which can get you a steep fine. If the hoses, clamps and thru-hulls have been inspected and in good condition it is all that is needed to keep the boat safe as the bilge pump is just a convenience item. Inspect the bilge every time you visit the boat and if there is oil soak it up before turning the pump on. You can lay a film of biodegradable detergent in the bilge to help breakdown oil. If you want to try and force flush some of the oil out then introduce a few buckets of a detergent solution under the sole and go sailing in brisk conditions to get all that stirred up. Pumping of gray water is not usually prohibited but before doing so make sure the water being flushed into the bilge is well emulsified.
 
Oct 30, 2011
542
klidescope 30t norfolk
Wet vac ,water hose and dawn dish washing liquid and a helper to keep running vac up to land to empty turn off bilge and remove filter from vac don't need filter if sucking water
 
Oct 30, 2011
542
klidescope 30t norfolk
After reading your post and research on internet I'm surprised the boat industry doesn't have an oil seperater. Commercial kitchens are required to have a greese trap. New parking lots have oil separators. And the elevator industry has a sensing system which would be best suited to marine adaptations but they are expensive so glad the epa is not required yet . You could make your own temp oil separator using a large Tupperware container run bilge water thru there and a drain at bottom over board water will sink to bottom only drain that then wipe oily water out and throw away
 
Jul 29, 2016
55
Hunter 31 Comox BC
Thanks for the info and suggestions. I am going to be checking every time and ensuring its clean. I did not realise so much could accumulate under the sole and in the stringers. Someone else recommended a good flush at sea, and a flush and a shop vac to suck the water out as it comes into the bilge is a good idea. Too bad they left these areas that accumulate so inaccesible. Am going to see if I can put some strategic inspection plates in to try and manually clean as well.
Thinking about it more this morning I think you are totally correct saying its accumulated in the stringers and under the sole along with water, thats what I have to address, just have to ensure I do not get a repeat of what happened yesterday again!
 
Last edited:
Jul 29, 2016
55
Hunter 31 Comox BC
No, it goes the opposite way towards the stern. I found the end under the engine compartment somewhere but I cant see the place it ended. I don't think It was connected to anything.
 
Oct 29, 2016
1,915
Hunter 41 DS Port Huron
Have you looked at the manual? pressure relief / drain from the HW heater?

Manuals may be found at Forums/Hunter Owners/Ask a Hunter Owner
 
Nov 26, 2014
51
HUNTER h31 Northport L.I.
Does your Bilge Have any holes in it? I have a 87 h31 and the area under the Bilge had long term water/oil that would only show up from certain boat motion ie healing etc. I saw mods on this forum and others to release the water to drain and clean it out. Basically holes in front and aft of bilge at bottom to release water , There is space under bilge bottom that can not accessed otherwise. I simply drilled holes and was able to release water and flush from stern and from bow. I now no longer have water , and the boat smells a whole lot better after flushing with bleach water. Might be worth investigating. Good luck
Eddie
 
Dec 28, 2014
61
Hunter 280 Mandeville, LA
Couple suggestions. I have used newspapers in their plastic bags to absorb oil, just poke some holes in the bags and toss them in the bilge - will soak up water also, but pick up oil with it. Also the "Purple Cleaner" available at HD/Lowes is a fantastic degreaser, put it in a spray bottle and can stream it into little nooks & crannies. Just be aware if disposal regs. If the buildup has developed over time, it will take awhile to gradually wash it out from the areas you can't just wipe or scrub.
 

HMT2

.
Mar 20, 2014
899
Hunter 31 828 Shoreacres, TX
I have an 83, that gray hose, nor the hole it goes through exists on mine. The water and oil that comes through the engine area drains to an area under the grate where you step,down from the companion way steps.. That area does not drain to the bilge, so what little oil or water ends up in there I soak up with pads then a shop vac. I think Hunter designed it that way so that what happened to you does not happen. I believe that to be a not well thought out modification made by a PO, but yours is a year older.
 
Jul 29, 2016
55
Hunter 31 Comox BC
Like these new thoughts and ideas, will be working on that over time. Have to be careful in the marina, as I can't flush anything outside unless its contained, I could rig up something I guess.
Someone cut an opening between the blue access under the engine and the area under the removeable grate where the stern keel bolt is and crap was draining in there and just sitting there. Thats getting plugged.
Am going to look at holes in strategic points to get access so I can either use a spray or manually clean. Have been contemplating that cleaner and using a pressure washer in places I can access, may expediate the process. May also put absorbent pads in areas I can access to see if that will remove above any.
Interesting what that grey hose is, sounds like its unique to me, who put it there or why remains a mystery. I may just haul it out as I found the end, and it doesnt appear to have been connected to anything.
 
Oct 22, 2014
20,989
CAL 35 Cruiser #21 moored EVERETT WA
Glenn consider yourself lucky. When I took possession of my Cal35 I discovered a neglected bilge full of water from a dripping shifting box and all types of unknown engine fluids. I pumped over 150 gallons of bilge fluids out 4 gallons at a time in 5 gallon buckets. The marina has a tank for bilge water so we carried it to the tank 3 four gallon bucket visits at a time. Took most of a Saturday. Got it all out, stopped the leak, sealed the engine, and working on cleaning up the neglect of previous owners. Be careful on pluging up holes. These boats are meant to drain water to the bilge where it can be pumped out of the boat. My pump out really improved the smell of the boat. Dawn soap has become an important tool on my boat. I figure if its good enough to clean up oily birds it can be used on my boat to help clean the mess.
 
May 24, 2004
7,129
CC 30 South Florida
Oil floats in water. Manually skim the oil from the top of the water in the bilge into a bucket before turning the pump on. The water being pumped out should be relatively free of oil and should not create a visible slick. Turn the pump off and allow the bilge to refill. Repeat the procedure as many times as needed until the water flowing into the bilge seems adequately clean. Do not allow the pump to run in automatic
 
  • Like
Likes: jssailem
Jul 29, 2016
55
Hunter 31 Comox BC
Oil floats in water. Manually skim the oil from the top of the water in the bilge into a bucket before turning the pump on. The water being pumped out should be relatively free of oil and should not create a visible slick. Turn the pump off and allow the bilge to refill. Repeat the procedure as many times as needed until the water flowing into the bilge seems adequately clean. Do not allow the pump to run in automatic
Thanks, great tips, appreciate the help!!
 
Jul 29, 2016
55
Hunter 31 Comox BC
Th
Glenn consider yourself lucky. When I took possession of my Cal35 I discovered a neglected bilge full of water from a dripping shifting box and all types of unknown engine fluids. I pumped over 150 gallons of bilge fluids out 4 gallons at a time in 5 gallon buckets. The marina has a tank for bilge water so we carried it to the tank 3 four gallon bucket visits at a time. Took most of a Saturday. Got it all out, stopped the leak, sealed the engine, and working on cleaning up the neglect of previous owners. Be careful on pluging up holes. These boats are meant to drain water to the bilge where it can be pumped out of the boat. My pump out really improved the smell of the boat. Dawn soap has become an important tool on my boat. I figure if its good enough to clean up oily birds it can be used on my boat to help clean the mess.
The hole I want to plug drains into a sealed compartment that was not meant to collect bilge water. Plugging up this wont affect water draining to the pump, just water draining to this compartment under the grate below the stairs. If it gets in there is no way out other than a manual removal. I do not want the keel bolt and the cast iron flange to be half submerged in bilge water. I cleaned it up and drying right now and plan to seal the hole a PO drilled.

Update: Added a pic showing the patch I did to reseal this compartment at the base of the ladder down into the cabin. It connected through to the engine compartment. PO had drilled a hole for some reason and water came in here but couldnt escape. Started bilge cleaning today, first of many attempts I am sure!

Update Dec 12: This area is bone dry and the seal is tight. No need to worry about cleaning this spot up any more.
 

Attachments

Last edited:
Feb 6, 2013
437
Hunter 31 Deale, MD
The pan under the engine is not supposed to have any drains in it for this very reason. If you have an oil or fuel leak there will be no containing the mess.
 
Jan 22, 2008
1,654
Hunter 34 Alameda CA
When I had a prolonged diesel leak (secondary filter ring unscrewed) the fuel passed out of the engine pan and into the stringers and the bilge. I made sure that the pump was disabled then I tossed in some oil absorbent pillows into the fuel/water mix. The pillows preferentially absorbed the oil and clarified the water. It took overnight. Then they can be disposed of normally. I followed up with lots of detergent and water blasting the grid system through every available hole. Once emulsified the water/oil mixture in the bilges was easily cleared with more pillows. Eventually it was all gone. Now I keep two pillows up tight against the front of the engine pan where the water heater hoses go through the stringer.
 
Last edited:
Jul 29, 2016
55
Hunter 31 Comox BC
Thanks for all the info everyone. I have been using absorbent pads, and spraying bilge cleaner in any spot I can get access to and I also have pads in the bilge that any water entering the pump out zone has to pass through first. Getting better but will be an ongoing process until i can do a good flush next year. I leave a pad under the engine now all thr time, however the engine isnt leaking at all. The oil is coming from residues already in the stringers and under the floors over three decades of accumulation. At least I am dealing with it and over time I know it will get better until I get all of it.
 
  • Like
Likes: HMT2
Jul 29, 2016
55
Hunter 31 Comox BC
The pan under the engine is not supposed to have any drains in it for this very reason. If you have an oil or fuel leak there will be no containing the mess.
Good point! There is a large hole at the fore front of the pan under the engine, obviously to allow drainiage and I had no idea if it was made during the boat build or added later.
Your thinking seems quite correct to me, anything that gets in through there is going places I cant get to. Anyone else have this? If not I think I will glass it and seal it and not let anything get into the stringers or under the floor from the engine bay. I suspect over the years this has been a main source for the problem.
Thoughts anyone?