Adding epoxy in bilge

[Scott T-Bird]

My bilge is narrow and constrictive. The keel bolts are mounted thru SS plates that stand about 1/4" proud of the sump floor. I also mounted my float switch on a 1/4" riser so the footprint of the switch could be laid flat, without interference from the SS plates. It is difficult to completely dry the sump because the plates fill up areas on the bottom that makes it hard to mop up the dampness.

I'm thinking about leveling areas in the bottom of the bilge with epoxy so that water flows directly to the low point at the pick-up hose. The epoxy would only be 1/4" thick to match the height of the SS plates. These plates seem to be adhered to the bilge floor because when I remove the nuts, I can't displace the plates (I've made a delicate effort). Good idea or bad?

 

[dLj]

Got pictures?

dj

 

[dlochner]

Bilge pumps will never completely dry the bilge, especially the centrifugal pumps most boats have, because they only work if there is water flowing into the pump, they push water out. Once the pump shuts off, any water in the pump and part of the hose will drain back into the bilge. You'll get better results with a diaphragm pump. These pumps suck water instead of pushing water and can continue to suck until the bilge is pretty dry.

There are "sponge pumps" (for lack of a better term) which rely on a sponge to soak up water and a small pump which pulls the water out of the sponge. I've seen a few DIY versions of this pump.

The Whale Bilge IC pump works well. It gets the water down to about a ¼" in the deepest part of the bilge and the rest is dry. The pump sits above the bilge and out of the way.

Whale Marine Catalogue

Welcome to the Whale Marine 2024 Catalogue.

docs.navico.com

 

[American_Mainsail]

Hi Scott,

I did this to my shower pan to address water not draining out of the pan effectively. It worked well. I used West System epoxy and low density filler (the purple stuff).

I don't necessarily see anything wrong with this in a bilge at all, but like @dlochner said, you will need to pair your modification with a separate pump. Centrifugal-style bilge pumps can't pickup those last bits of water left at the bottom of the bilge. On top of that, they tend to backflow the water that's left in the line that didn't make it overboard when the pump shuts off.

I did this to my bilge and it was one of the best modifications I've done to cut down on boat smells:

I installed a gulper-like pump (the Rule branded version of what @dlochner linked to in Whale's manual, without the special bilge pickup) in a separate compartment and ran a 3/4" pickup tube with a one-way valve at the lowest part extending down into the deepest part of the bilge. This does a great job getting out the last gallon or so of water that that the bilge pump can't pickup. It's controlled by a manual on/off switch that comes with the pump. I installed the switch at the nav station next to the existing bilge pump switch. I also teed into the pickup hose with a smaller, 4(ish) foot long hose and pistol-like strainer on the end and a small check valve. This lets me vacuum up any remaining water that the fixed pickup tube can't get.

 

[Rich Stidger]

I like the Whale Bilge IC pump and it works excellently for my shower sump.

But I am perplexed by the obsession to have a perfectly dry bilge. There are so many sources of water that will find its way into the bilge- stuffing box, refrigerator drain, removable speed transducer plug, etc. Trying to achieve a dry bilge seems like an exercise in frustration. Aren't there tasks that are higher on the punch list than blotting up the last few ounces of bilge water? If I am missing something, please educate me......

 

[shemandr]

I really don't know Scott's situation but to put epoxy down seems basically irreversible. On that basis I wouldn't't do it.
There's the question of whether or not the bilge could be dried enough for good adhesion. And expansion due to temperature changes of the metal backing plates and fiberglass surround might create cracks or voids that will fill with water anyway but won't dry out. That's not even counting the flex of the hull during sailing or even motoring in waves.
On the other hand, there are internal encapsulated keels made from pouring epoxy over as dense metal as possible. But there are no keel bolts.

 

[American_Mainsail]

I like the Whale Bilge IC pump and it works excellently for my shower sump.

But I am perplexed by the obsession to have a perfectly dry bilge. There are so many sources of water that will find its way into the bilge- stuffing box, refrigerator drain, removable speed transducer plug, etc. Trying to achieve a dry bilge seems like an exercise in frustration. Aren't there tasks that are higher on the punch list than blotting up the last few ounces of bilge water? If I am missing something, please educate me......

Fair question, Rich.

Bilge water starts to stink over time. It’s a musty, dank smell. For liveaboards, the smell can start to permeate everything you own. Having an easy way to keep the bilge dry keeps the smells away, keeps (potential) salt water off of your keel bolts and inner bilge, and takes the frustration out of the process.

 

[Stu Jackson]

Bilge water starts to stink over time. It’s a musty, dank smell.

I've owned my boat for over 27 years and have always had some water in the bilge. I agree with Rich. It's never smelled because there's always something replacing the water there - all the usual sources, plus I cleaned it every six months or so. The OP has a relatively flat bottomed, shallow bilge.

for SCOTT: I know you from this forum. I know your C320 is relatively new to you. I am sure you've spent time at Catalina 320 International Association I also suggest you ask there because they know the specifics of your bilge better than those of us here, like for instance the skipper who asked for a picture. He was right to ask.

Otherwise, if it was my boat, I would definitely NOT do what you're suggesting.

 

[JoeWhite]

To keep the water off of the keel bolts I used 4200 caulking and placed cups around the keel bolts to prevent water coming in contact with the bolts and in addition it stops water from going down from the edges of the keel bolts resulting in Catalina Smile. See images here

Catalina-Smile | Catalina 36 MKII Album | Sail La Vie Home

mei1970.org

 

[Scott T-Bird]

I have a diaghragm pump and the hose pick-up is at the low point so after pumping there is very little water remaining. I typically have a dry bilge based on the external environment. I typically have water from the A/C condensate, defrosting the fridge, or the leaky vent line from my forward water tank - all things that I could fix or modify. I'll have to admit that I'm a bit obsessive about drying the bilge every time I leave the boat. I typically wipe down the bilge with a rag to get every last bit of water. I get frustrated by the water that gets blocked by the plates.

The bottom photo shows the area that I would smooth out with epoxy. The top of the photo shows the lowest point in the sump where the hose pick-up is (not there in the photo). I wouldn't put any epoxy there because it is the low point. My intention is to just pour it high enough to be flush with the top of the plates so the water would flow just across and not be trapped.

The only thing that bothers me about the water sitting in there is because the fiberglass is typically uneven and the plates surely don't sit evenly, unless there is a bedding of material underneath the plates (which I'm pretty sure there is). My mind would be eased if I felt like the bolts were not exposed to latent water underneath the plates.

 

[Scott T-Bird]

The middle fiberglass plate is where I mount the float switch. It is epoxied in place.

 

[dlochner]

If you're going to fill this, gel coat might be a better option. First it is cheaper. Second, if it ever needed to be removed it would chip out more easily than epoxy. Third you could easily tint it, anyone for Hot Pink? Neon Green?

 

[dLj]

@Scott T-Bird thanks for the photos.

In my opinion, this is not a good idea to fill with especially epoxy. There are two fundamental problems:

1) It would be impossible to get a perfect seal - especially between the plates and your fill material. This could cause the creation of localized corrosion locations that would be invisible and more damaging than your current set-up. This could happen no matter what kind of "fill" you might choose to use.

2) If you needed to address this in the future - it would be really hard to remove that epoxy and then pull those plates.

The phrase "The enemy of good enough, is better" comes to mind.

dj

 

[Stu Jackson]

>>>>>>>>>>>>>>>>>>>>>>>>>>>

I typically have water from the A/C condensate, defrosting the fridge, or the leaky vent line from my forward water tank - all things that I could fix or modify. I'll have to admit that I'm a bit obsessive about drying the bilge every time I leave the boat. I typically wipe down the bilge with a rag to get every last bit of water. I get frustrated by the water that gets blocked by the plates.


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

My mind would be eased if I felt like the bolts were not exposed to latent water underneath the plates.

Let's see: water comes from things you could fix, but you haven't and remain frustrated. Golly...

Isn't this like the guy who complains about getting wet in a rain shower because he keeps leaving his umbrella at home?

I applaud your honesty about this, Scott, but find it difficult to understand. Levelling out the low point will not stop the sources of your described water ingress and, as you point out, the "water underneath the plates" may not even be an issue anyway. You'll still have mop-up duty.

My keel remains firmly attached to the bottom of my 1986 boat, that's FORTY YEARS, with lots more water over the keel bolts that your few drips.

If your fridge drains that much water you need to fix the seal of the opening. You also know what else needs to be fixed.

Good luck, 'cuz epoxy sure isn't the answer.

 

[American_Mainsail]

Alright - I see what you're trying to do here and I'm getting gunshy. The glaring problem I see is that you're not going to have a good surface to bond the epoxy to where the sealant is potentially squeezing out around the keel bolt backing washers. I think there's a decent chance for water to get around that area, which isn't great. On top of that, it will make this area essentially uninspectable for water intrusion; also not great. You're kind of shooting yourself in the foot by trying to make a fair surface around the keel bolts/washers to drain water, but introducing joints between sealing materials that probably won't perform well over time. This is exactly what @dLj is saying. I think to do this right, unfortunately, you would need to drop the keel, or at least pry off the backing washers (which I wouldn't mess with to solve a nuisance problem like this), fair out the whole area, and reseal the bolts. Even then I think this project would take a fair bit of forthought and planning since you'd be potentially starting to get into how the keel bolts transfer force into the hull.

Epoxy is generally pretty workable with sanding/grinding tools, especially when it's modified with fillers. But in this case the geometry is so restrictive and you're dealing in such close proximity of the seal with the backing washers, I'm just not sure that it's wise to refair this area.

Consider putting the effort into rerouting condensate drains to shower boxes and maybe fixing that leak you spoke to? Your bilge won't be 100% dry still, but there will be a big improvement in how much water you take on down there over time.

Darn I had this whole response typed out and now I'm seeing what you're proposing and kind of changing my tune. I guess I'll keep what I wrote out below for people that might stop by and just be looking for general info about epoxy:

It sounds like you're pretty adament about filling this area with something. Myself, I would probably leave it alone since there's some prep and finishing work associated with this project and probably wouldn't be worth it to me. But that's me, I'm not in your shoes. It's sounds like you're pretty adament about fairing this area out.

I guess I'm going to be disagreeing with the group here on this one. I don't think there's anything wrong with filling this area with epoxy that's thickened with the right filler. This is done very often on the outside of hulls to fair various surfaces. It's even done to fair keel joints, and to make the seal between hull and keel joints.

Epoxy with filler is a pretty ideal material for something like this. It will stick tenaciously as long as the bonding surface is clean and prepared (sanded to give it tooth), which will keep any chance of cracking around the edge and water getting under the material down . It's unlikely that it will crack since epoxy generally has a higher tensile elongation than polyester resin-based GRP.

I did a little more research on this on the side, and it may be wise to call up West System, or the technical support line of whatever epoxy system you would use, and ask them about what filler to use in this application. A low-density filler that would make this easy to sand would 'probably' be OK, but I would double check since this area is under some stress and probably needs to breath a little bit. I would be very surprised if a naked epoxy ever cracked since its tensile elongation is probably 2x what the tensile elongation of the underlying GRP is, but once you start modifying the epoxy with filler it can make the epoxy more brittle. The key is striking a nice balance between pour consistency and sand-ability after it cures. Epoxy is very flexible in allowing you to come up with the best end material using different fillers and proportions of said fillers.

I have had a lot of great luck with West System's tech support staff. They have usually been very helpful and are very experiened in boat-specific applications.

 

[william24424]

How about butyl tape or plumbers putty?

 

[Scott T-Bird]

@Scott T-Bird thanks for the photos.



The phrase "The enemy of good enough, is better" comes to mind.

dj

That line is priceless!

Yeah, that's basically the reason I asked this question. It's not really a big deal. I would just like to make my periodic bilge clean-up a bit more satisfying. I'm not that concerned about creating a condition that may seal in a bit of moisture. In my mind, the moisture is latent around those joints anyway. I'm just trying to make it easier for the little bit of moisture to make its way to the low point. Gel coat could work just as well. But the amount is so small, the expense isn't a consideration.

@American_Mainsail mentioned thickened epoxy as a consideration. I have Thixo that can be applied and formed just as easily as caulk ...

I'm still mulling this over. It's not a high priority and I'm not trying to fix any damage.

Those photos really make the bilge look awful! I really want to clean it up a bit more and eventually apply some Bilge Kote!

 

[Project_Mayhem]

Have you considered an alternate tank or bucket for water from appliances to go so it's not sitting in your bilge? If you do this, then you can use a container with a pump at the bottom so all the water is sucked up. I'd use the bilge as an overflow

 

[BAD ORCA]

I like the Whale Bilge IC pump and it works excellently for my shower sump.

But I am perplexed by the obsession to have a perfectly dry bilge. There are so many sources of water that will find its way into the bilge- stuffing box, refrigerator drain, removable speed transducer plug, etc. Trying to achieve a dry bilge seems like an exercise in frustration. Aren't there tasks that are higher on the punch list than blotting up the last few ounces of bilge water? If I am missing something, please educate me......

It helps to let you know when you have a leak you should not have. My bilge is dry and whenever i see water in the bilge, i need to go and look for the cause. It helped me find a very badly leaking dripless shaft seal that could have become a real problem. Also helped me find leaaking fresh water connections, dripping thru hull and a couple of other issues.

 

[BAD ORCA]

I really don't know Scott's situation but to put epoxy down seems basically irreversible. On that basis I wouldn't't do it.
There's the question of whether or not the bilge could be dried enough for good adhesion. And expansion due to temperature changes of the metal backing plates and fiberglass surround might create cracks or voids that will fill with water anyway but won't dry out. That's not even counting the flex of the hull during sailing or even motoring in waves.
On the other hand, there are internal encapsulated keels made from pouring epoxy over as dense metal as possible. But there are no keel bolts.

Its no that hard to remove if necessary as long as its not fiber glassed in. I did exactly as OP is proposing to level the bilge to get new backing plates and new mast step to sit flush and it has been a non-issue. Most builders poured a thick layer of polyester filler into our bilges originally, threw on some backing plates with sealer and called it good. They have mostly held up reasonably well, but many boats/bilges are getting tired and the gelcoat/ bilge resin / sealer around the old bolts may starting to be compromised. I think trying to keep water away from old bilge keel bolts is a good idea to consider. I don't think most bilges flex enough to crack epoxy unless its a small, light sailboat. If he can get it dry enough I think its a good solution, however if its always been wet, it may be damp down below the surface and may need some help drying out, not to mention it probably has a wax layer if it was gel coated and painted over. A small 1/2" Makita belt sander will make short work of and bilge resin that needs to be ground and faired.