Holding tank to bilge leak?

[Angela and Tom]

On my CD28, I had an anti-siphon valve that leaked right into the wet closet behind the head. There was no hosing leading the vapors to the outside. I placed a hose from the valve to a vent and that cured the problem.

Hi Ed,

I think we have the same thing happening on our boat. Could you provide more detail on how you placed the hose from the valve to the outside? Did you have to install a new vent? What kind and where? I'm picturing a little vent like the holding tank vent, placed high on the side of the hull above the stinky valve.

Thanks,
Angela

[Ed Haley]

Angela and Tom:
On my former CD28, there was no hosing over the antisiphon valve to lead odors outside the boat. As you know the antisiphon valve is located in the wet closet behind the head. I simply took the correct size hose that will fit over the valve and lead it forward along the port bow bunk to the holding tank compartment. You might remove the plywood from the bunk to do this.

I then lead the hose into the anchor locker and spliced this hose into the existing head vent with a pvc tee. Use ring clamps to secure the attachments.

That pretty much took care of things.

The antisiphon valve was faulty in my case. At the time I couldn't find a proper replacement. If its working correctly, air is only drawn into the valve. None should escape.

[bottomscraper]

Melissa, how did you manged to get down there and do that work? Is the 36 beamy enough that the access is better? On the 31, anything down there has to be done with a long-handled something.


Dean

The 36 isn't all that beamy and access is a pain. I cleaned it out with heavy duty detergent and a long scrub brush. We let it dry out and then cleaned with acetone and lots of paper towels. I used mechanical fingers to hold the paper towels. We filled the small scew holes with thickened epoxy using a syringe but the new "starboard" bottom for mounting the bilge pump was actually glued down with lots of 5200. I used a whole tube. This was not a fun job. It's very hard to reach the bottom.

The bilge pump is mounted with short philips head screws. I purchased an extra long screwdriver from McMaster Carr. It's about 2 ft long!

[Phil Shedd]

Dean

I would think a good wire brushing of the area should be enough to get bonding. Try to wipe the area with acetone before the first coat . Have plenty of ventilation The first coat as a stick coat to hold the mat . A second coat to seal in the mat and a third to add strength and make sure every thing is sealed up.

I sure it will look funny trying to do all this while working through a 6 x 10 inch hole . Oh yes need pads

Phil

[liin]

Dean and others -

More on my 33 . . . when I initially detected my trickle of liquid from holding tank to bilge, it was right at the garboard drain plug but certainly not sea water. Liquid was not coming from bottom of bilge but rather about 2 inches above bottom at garboard drain level. I figured previous owner must have not winterized holding tank and freezing caused crack that I can detect by eye? In my situation as I've thought through the problem, the only way I could figure to repair tank was from the inside of the tank. The inspection port is woefully small to try to work through. I've thought of making inspection port larger and trying the epoxy and matt trick on the inside of tank but didn't feel I could get area clean enough etc. I certainly appreciate some of the suggestions how this might be done though.

I've thought of cutting top and front side of tank out and inserting polyethelene tank into original glassed in tank. Without ripping up cabin sole, I think I can maybe get in a 10" x 12" top dimension tank. I've also thought about a flexible tank as this would likely be easiest solution but am concerned smells would eventually permeate through this tank. Does anyone know whether flexible tank might work?

No question that sailing is much better than this!

Damon

[Dean Abramson]

Damon,

I am pretty compulsive about doing things "right." But maybe with old boats, sometimes we have to just do what's practical, and hope for the best.

My feeling, too, was that this needs to be fixed from inside the holding tank. After all, that's what's leaking. But that is a very tall order, and probably requires major boat surgery.

So I have decided that I don't have a holding tank leak which spills into the bilge, but rather a bilge leak which spills into the holding tank! Let's face it, it's all just a bunch of yucky liquid which probably doesn't much care whether it's flowing forward or aft. I know that this is a silly little mental game, but this is how I am going to approach it. I am going to fix the bilge the best I can, and hope for the best. I don't see where I have much to lose, and whatever I do will almost certainly help, if not flat work. I figure it's worth trying before getting into boat surgery.

I can see cracks in my bilge, so I am fixing them! Maybe your bilge needs fixing too. :-) Come up several inches from the bottom on the sides with glass and epoxy, and maybe that fixes it. Good luck.

Dean

[Dean Abramson]

I did the food coloring test today, and sure enough, shortly after I put the dyed water in the holding tank, it started seeping out the bottom of the bilge. At least now we know for sure why it stunk so bad.

I poured lots of bleach into the holding tank, then filled it with water and let it disinfect for a while, then I pumped it out, and then I vacuumed out the last standing water in both the holding tank and the bilge. The holding tank got amazingly clean, but...

This is the first time I have actually seen the bottom of my holding tank. Right in the bottom, right in the vee formed by the hull, is a long crack or dark line running fore to aft for the entire distance that I can see with a flashlight. My guess is this is where the water migrates from. I need to feel with a wire or something to ascertain for sure if it is a crack, but I am pretty sure it is.

Question: does anyone know if the 31's hull was molded in one piece, or two? Hopefully what I am seeing is actually just a seam. But it does not look good. Have any of you with similar arrangements ever seen the bottom of the holding tank? Is there a crack or dark line there?

I am thinking that we might have to cut a hole in the side of the hull in order to get in there and deal with this. It is pretty depressing. I am going to have a surveyor look at it.

This boat has turned out to be a booby prize, but all we can do is press on. It is kind of embarrassing to write about all of this, but I am hoping to get the usual good advice, and also hoping that others might learn something from our travails.

Damon, right now I am not sure what I am going to do!

Dean

[Michael Abramson]

After hearing what the surveyor says, you may be able to consider using a waste bladder in the holding tank space. There may be a structural reason for a major repair, but hopefully not. I would think even a custom bladder may be less expensive than going through the hull, and it would be removable for cleaning and leak testing at a later date. You would lose a little volume however.

[Oswego John]

Dean,

Sorry to hear about your troubles.

I have a suggestion. Before you start cutting a hole in the hull, there is a product that may be worth trying. The stuff is called Captain Tolleys Creeping Crack Cure.

It is a water based fluid with a very light viscosity. It will ferret out and creep into the smallest hairline cracks, some that are invisible to the naked eye.

I have used it on deck cracks and port lights, with good results, but I can't comment on it's use for a condition such as yours. I feel sure that a call to customer service will give you any needed info on it's use.

It might be worth a try.

Good luck,
O J

[Russell]

Wow Dean, hearing of this discovery of yours makes my sympathy go out to you, hopefully cutting a hole in the side of the boat does not become nessisary. I would be tempted to just pour epoxy with no filler down in there, without filler it should flow well and evenly, and using enough to create a resonably thick "floor" above this crack. But that is only a superficial fix, it will not give you any confomfort in structural concerns. No CD I am aware was built as a 2 peice hull, one of the reasons we chose cape dorys is because of this quality one peice hull construction.

I would call Robinhood and talk to them, maybe even if the hull is not two peices, somehow the holding tank was? Someone there would know and be able to tell you. Keep in mind that they are a buisness, even though many there are origonally from CD and know the boats well, they are not there as a free support center for CD owners. The problem your looking at may need more advice then a simply quick answer off the top of their heads, they may have to look at old design and building specs. I would call them, explain the situation, and ask if they are willing to work on this for you as a remote consultant for a fair fee. They stand to be able to offer good advise and insight, but may not want to do it for free (and I dont blame them).

[Dean Abramson]

I spoke to a very nice gentleman at Robinhood named Tom, who believes that this is just another Cape Dory too-thick gelcoat problem. He seriously doubts that there is a structural issue, since no water is coming out of the outside of the hull below.

I may be going to hire them to fix this right next winter, but in the meantime, I am going to attack the symptoms, using some of the suggestions from you folks out there.

I think that using a long drill bit extension I bought, with a wire brush attachment, I can prep the bilge fairly well, and maybe even the holding tank bottom too, then vacuum and swab with acetone. I am going to try to station a mirror and a light right in each space somehow, and I will have to fashion some long-handled gizmos to work with. I think I will first go with penetrating epoxy or Captain Tolley's. Once that cures, I will go with regular epoxy. That will be it for the holding tank, but in the bilge, I may then go with one layer of fiberglass cloth, then a final epoxy layer. After that, I may paint with bilge paint.

My guess is that that should stop the leak or make it fairly inconsequential. The odd thing is that after several days of having the holding tank's water level at a much higher level than the bilge, the bilge had only accumulated an inch or two of liquid. It does not seems as though it is prone to ever equalize. Makes me think that the crack on the holding tank side may be higher up than on the bilge side of things. Which might of course complicate the repair.

I will try the above. Then I am going to stock up on bleach and go sailing.

Thanks for all of your help. I will keep you posted if anyone is interested.

By the way, Tom said that what they would probably do is take up part of the cabin sole for access, then remove the bulkhead between the bilge and the holding tank, then install an actual tank in that space. I forgot to actually ask him, but I got the impression that he might have seen my type of situation before.

Dean

[John Vigor]

Dean, be cautious about using epoxy on top of Capt. Tolley's Creeping Crack Cure. Tolley's is a one-part, water based, acrylic polymer penetrating sealant and I don't know how well epoxy would bond to it.

A thin true epoxy, like Git-Rot, may provide a better base, but in my experience, not all epoxies will bond to each other, especially if there's blushing involved on the first coat.

I know this isn't much help, but it might stop a bad situation getting worse.

I must say this business of putting food in one end of humans, and getting it out of the other, causes an awful lot lot of problems for sailors. But at least you can be thankful you're not an astronaut.

Cheers,

John V.

[Oswego John]

Dean and John V

I'm sorry. I guess that I didn't explain what I had in mind to a greater degree.

My initial thought was to apply (pour ?) Captain Tolleys inside the holding tank on the crack that runs along the center line, fore and aft. Since it is a one part sealer, there shouldn't be any worry about blush.

Then I would consider using Git-Rot, or preferably, using plain, two part epoxy, and then epoxy and glass cloth in the bilge. Since either of the latter two set up exothermically, it would be possible to remove any blush residue outside of the tank.

I have used both Git-Rot and Captain Tolleys with good results. Both are fine products. If I had to pick one over the other, I think that Captain Tolleys is of a lighter viscosity and thereby able to penetrate and diffuse more readily in the porosity between the tank and the bilge area.

I have never used Git-Rot when working on fiberglass or other man-made substances so I can't comment on it. I don't see why it wouldn't do the job. I imagine that it would penetrate porous material better than plain, two part epoxy

I have used Git-Rot several times on dry rot with good results. I had always been under the impression that the formula for it was developed to be osmotically absorbed into cellulose material (wood) to repair and strengthen it. It would be interesting to find out how it would work with fiberglass, etc.

Whatever course of action Dean takes, I am looking forward to a positive conclusion. This should be interesting and educational for all.

Best regards,
O J

[Dean Abramson]

Gentlemen,

Thanks for the input. But I don't know what you mean about "blush." Could someone elaborate?

Also, how much thickness of just epoxy can I apply without worrying about it generating too much heat during curing? I have never done glass work, and my only experience with epoxy is out of a tube.

Dean

[John Vigor]

Dean, amine blush is a wax-like bloom that occurs on the surface of most good epoxies when they cure. This bloom is water-soluble. It must be removed before the next layer of epoxy is applied on top of it, otherwise the two layers will not bond.

You can buy epoxies that won't blush, but the West epoxy people seem to think that the properties that make good marine epoxy also favor the formation of blush, so you should always presume it has occurred.

Here is a link to the West site:

http://www.atlcomposites.com/pdf/west-amine_blush.pdf

Cheers,

John V.