Steel Sailboat - deep bilge

[Delfin]

Originally Posted by qwert

Faced with a similar problem I sandblasted and epoxy painted the steel sides then coated the side with 1/4 inch of sikaflex (here in aust there is an identical product parfix much cheaper). Then I filled the hole with epoxy bog. The theory of the sikaflex was to give a flexible permanent seal so there wouldn't be cracking between the steel and the bog letting water into the microgap.
Seems to be working.........

No oxygen, no rust. I'd clean, prime and topcoat the area with two part LP like Awlgrip. Then coat with an elastomeric like Flex Seal, then pour in foam, which I would use in preference to epoxy because of you really had to remove it, you can dig it out easily enough.

[psk125]

Originally Posted by MicHughV

Here is what I did on my steel Roberts 38......the back portion of the keel cavity was not meant to have ballast, but I had no idea how I could get in there and apply any kind of sealant.
So, I filled the void full with a concrete mix....you buy a bag of pre-mix concrete at Home depot..mix with water and in it went.
I filled to near the top inline with the other ballasted voids.
After the concrete hardened, I coated it with coal tax epoxy ( as per the rest of my interior) to seal it all in and prevent any water from dripping down the sides.
After many years of sailing it never leaked.
Alternately, you can go to Home Depot and buy several cartridges of foam sealant, you can can also get this 2 part foam sealant, you just place the cartridge in a regular cartridge sealant gun and squirt the foam in there. Follow immediately behind with a trowel to flatten it out.
If you get the 2 part foam, let it expand to the top and trim it after with a saw blade. It will cut real easily. Then seal it with the coal tar epoxy.
Hope these suggestions guide you.

Pouring concrete into a steel bilge, even under a tar (or other) barrier sounds like a recipe for rust. What happens to the water you use to mix the concrete? How often do you check for leaks? How do you check for leaks? How do you know what's going on in there? Any water will not be visible, as it will soak into the concrete like a sponge, which will hold it in constant contact with the steel. Yikes!

Another cautionary tale: My father's center console skiff had poured foam in the entire bilge under the sole, where it was supposedly "dry". Water got in anyway over the years. The foam soaked it up (it wasn't closed cell) and ended up weighing the boat down by at least a ton. We had to remove the whole deck and dig out the foam with a spade, dripping wet 20-pound chunks at a time. If you use foam, get the right kind.

[MicHughV]

let me clarify....the concrete was not poured into the bilge per se...but into the keel cavity.
Anticipating that there might be some residual water while the concrete hardened, I drilled a single 1/4" dia. hole in the keel side at the vary back bottom of the keel. Keel plates were 1/4".
Indeed, some water dribbled out of that hole in the first two week or so.
I left the hole open for the duration of the rest of my build, probably another year or so, during which time I could visually tell when water stopped dribbling out there. Like I said, after about 2 weeks, the dribbling stopped. for another few weeks, the hole appeared " wet" and then dried up completely. Prior to blasting and painting the bottom I welded the hole shut.

During the course of owning that boat, I placed two different engines over that keel cavity, which allowed me a thorough inspection of the keel cavity, which remained as the day I first coated it.

I sailed that boat for well over 15 years without a single hint of rust before selling. Recently, I was able to re-locate that boat, now approaching 40 years of age and near as I can tell, there is not a lick nor hint of problem with the steel rusting.

The forward keel cavities were filled with a mixture of steel punchings over which I melted lead ingots with an acetylene torch. These cavities too were coated with coal tax epoxy after filling with the ballast, but as they were not under the engine, I could view them every time I lifted a cabin sole hatch. Dry as bone and rust free all the time.

The coal tax epoxy was painted on quite thickly in the keel area.
The next owner stripped the entire interior down to nothing and rebuilt a different interior. I have tried to attach a photo.

Like I said, after 40 years, still going strong.