cementing steel bilge

[kenpatt]

Hi

I cant get the paint to do its job on my boats steel bilge (v shaped). Every couple of years the rust returns due to water lying in the bilge. I was considering grinding as best as possible, using bilge cleaner, applying several coats of POR 15 and then put a couple of inches of cement in the bottom of the bilge were the water gathers most. Will this work. Advice please

[Jesse Holden]

I would be very concerned that water would penetrate between the hull and the concrete creating a much greater problem. Jesse

[knottybuoyz]

Our buddy Jim with the 43' Bruce Roberts in steel swears by Coal Tar Epoxy! Surface prep would be crucial before using that. Pretty sure there's other threads on here or the Metal Boat Society about that very same problem. If you use cement it'd have to be hydraulic cement IIRC.

[Chief Engineer]

I have seen it done in tugboats/////it is bad news///the cement traps moisture

where is the water coming from? Stuffing box? If so, you might want to isolate that area using a cofferdam and a dedicated bilge pump for that area.

[Alan Wheeler]

I don't recomend it either. I will not adhere to the steel. Epoxy tar is a good choice. But don't ever expect to paint anything else over the tar. It is very hard to get anything to stick to the stuff.

[Ex-Calif]

You also have to consider where the water will go if you take away it's current "home."

Unless you can convince it to find a spot where a bilge pump can get it out you are just shifting the problem around. I like Chief Engineers thinking.

My boat has one bilge pump but water tends to collect in 3-4 different places - By the time these 4 places were contiguous the boat would have to have 8 inches in the hull - It drives me nuts.

[mickmul]

I have a steel Van de Stadt, my first steel boat, and she had been coal tar epoxied in the compartment above the keel prior to purchase - however, because of the stringers in the flat hull section around this, water (drips down the mast, carried aboard on wet weather gear, spills, from cleaning the through hull log, and possibly stern gland ingress, etc, etc) gathers in the compartments under the cabin sole. After a day's run, I always sponge them out with highly absorbent cloth. The epoxy section leads to a smaller and deep section where the auto bilge pumps sits. Thing about coal tar epoxy is, I'm told, is not to use that area for storing tins, bottles, etc, as in hotter climes, the heat transfer can make them sink into the tar.

[kenpatt]

Guest it was wishful thinking that I would receive numerous posts all telling me that cement would be ideal and was the only way to go. On reflection I just could not see me hiring a cement mixer and filling buckets of concrete into the bilge only to discover in a years time it was a disaster and then have to hire a jack hammer to get it out again. I was at the boat today and think it will be easier to prepare the bilge for painting than I first thought. I am going to grind and wire brush as best as possible, clean with bilge cleaner,apply two coats of POR metal ready and finally several coats of POR 15. I will be drilling 8mm holes in the stringers and stiffeners to let all water go to the lowest level of the bilge in order that the bilge pump can do its job. The bilge was painted originally with epoxy tar and I wouldnt recommend it where water tends to lie, its great in all areas of the boat. This was my first (and last) attempt at building a boat. I choose steel as I could build it outside in my yard and I could learn the skills on the job. I ended up pleased with the final results, however, over-looked the need for water to be able to get to the bottom of the bilge and did not leave cut outs for this to happen. I would recommend anyone choose steel for a home buiid project but pay just as much attention to rust prevention inside as out. Having always owned plastic boats I didnt appreciate this at the time. Thanks for all your valuable comments

[encore]

Check out Durabak 18 at [url=http://www.cotelind.com] The smooth product is used for truck bedliners, bridges, bilge painting and a host other things. It is an atmospheric moisture cured polyurethane. I'm using the rubber granule encapsolated version for my anti-skid. It is pretty fantastic stuff. BUT you must follow the directions and like all coatings you must prep, prep, and prep to get a good bond. In the past I've used coal tar epoxy--if you go that route make sure you completely protect your skin, it's carcinogenic. I used it 15 years ago and I'm still monitoring some pretty ugly brown and black spots on my arms and face where it snuck past my tyek suit. Durabak is a much better choice and it can be overcoated if necessary.
Ellis

[GordMay]

When creating new Limber Holes*, be sure to re-seal the exposed edges of any new holes you make in the stringers.

Make sure that your Limber Holes remain clean, so that the bilge-water flow is not impeded.
A good trick is to thread one piece of small stuff (flag halyard) through, with a knot just forward & aft of each hole.
Join the forward end to a short piece of shock cord and attach this to the hull. On the aft end, tie a loop. When you need to clear the holes, one or two pulls on the loop end will clear all at once. This can be left in place permanently, and works better than the traditional small chain.

* A Limber Hole is a drainage hole, made through any hull structural member.

[hellosailor]

Ken, if you take a cement block and leave it in your kitchen oven (on low) overnight, in the morning you can smash it easily into crumbs. Cement contains a high amount of water and if you put cement in your bilge--it will attract and retain moisture. Not a good thing against the steel.

If you look at a "wrought iron" fence, this is the same problem. Cheap modern work that sets the "iron" right into a cement base, and it starts rotting out immediately. Work done a hundred years ago, set iron into a pool of molten lead, to keep the concrete and its moisture away from the iron. Today a good installer may use a pool of epoxy instead of lead in the hole--but the either way, concrete means moisture, it isn't good against steel.

If you want to use the concrete in order to raise the "floor" and encourage proper drainage, don't use concrete. Use an epoxy with an inert filler (talc, stone dust, plastics, many choices) instead. It will be more expensive short term--but it won't cost you a hull repair.

[zephyr4]

Here is a crazy idea that came to me while I was thinking those disposable plastic paint tray liners

If the idea is to keep water off the steel so a paint job will last a long time, then what about about forming a fiberglass pan that covers the surface of the bilge? It would be watertight and could hold the water until it can be pumped out? You could lay the glass right in place for a good fit.

[hellosailor]

"what about about forming a fiberglass pan that covers the surface of the bilge?"
Fiberglass, aka fiber reinforced plastic (FRP) and other names...would just be a waste of good fiber reinforcement. All you need is the plastic (the resin) and that can be done with simple epoxy or other paint. But, that won't have the bulk to level out a bilge.

[Boracay]

I don't know how long this will last but how about cleaning the area as well as possible, then degreasing, then scraping and sanding as well as possible.

Then prime with phosporic acid, leave to soak in as long as possible then dry the bilge totally. Use a hot air gun or similar to get all the moisture out.

Then get some generic epoxy resin (5:1) and mix it 50/50 by volume with penolic miroballons. It takes a while but eventually the two will mix. Limit the amounts in each batch to around 250ml so it does not set quickly.

This gives a "goo" that is almost self leveling. It might be a good idea to do a test batch first.

Pour this into the bilge and paint/spread it up the sides as far as possible.

The epoxy resin/microbaloon mix is almost flexible when cured and the lack of solvent makes it resistant to water penetration.

Don't blame me if it doesn't work!

[Ex-Calif]

Any sort of liner has the potential to trap moisture between the liner and the hull - bad news. I remember my first truck bed insert. Seemed like a good idea at the time until two years later when the bed rotted through.

If you are just barrier coating the hull, I like the suggestion of the new tuff-liner/rhino paint on stuff and would be interested to see how it works out.

But clearly the other goals are stopping the water from getting in and when it gets in getting it to one place and getting it out of the boat.