Concrete as ballast in bilge?

My boat is a custom sailboat hull steel construction. The boat is top heavy, due to the upper structure, which is wide and high, plus has thicker steel.
The builder added an I-beam keel to the bottom and mounted about 5000 lbs ballast on it, going forward on the keel.
The boat is too tender and needs more weight at the bottom.
My first idea was to pull the boat out and weld more steel to the I-beam. This should not be a big problem, as long I have the welder and material in place, when I pull out the boat for a bottom job. However, this needs to wait due to budget restrains.
On another forum it was suggested the concrete can be poured into the bilge (permanent ballast) and left alone there forever. It also takes care of the rust in the bilge.
Anyone used this method, or hear of, to increase the ballast volume? Thanks.

In 1977 I had a sailboat built. Hull had an enclosed ballast keel. Builder dropped in some lead ingots and topped it with steel punchings in concrete. Smooth off the top far enough below the floor to leave a decent wine cellar.
No deterioration in the 11 yrs I owned that boat.

Plenty of wood fishing boats have had concrete poured in for ballast. Keel boats, however, needing more ballast, usually will have steel punchings with concrete poured around them.

Concrete itself may not be dense enough for your needs.

My dos centavos thoughts --

It is important to keep the interior of a steel hull clean, dry and hopefully properly painted. Concrete allows just the reverse, retaining moisture between the steel concrete interface. The product of choice is lead, placed on the hull interior.

Just curious though, what was BR's build plan for ballast weight and placement? An I beam welded to the hull exterior seems counter intuitive for attaining the slippery shape a sailing hull needs. Generally, the plans should take into account the construction of a sailing vessel that should ideally be self righting from a 90 degree roll. Are the top sides all steel too? I thought BR's designs used Al.

ON bulldozers the tracks are flexed around "track pins" whicg with there bushings are replaced by specialized companies.

The pins are 8 to 14 inches long (or bigger) and 1 1/2 to 2 1/2 in diameter(or bigger) and can usually be bought for scrap value , if you pay cash.

The pins will stand easily in most keels and dry pre mix concrete will fill the small spaces between pins if brushed on a couple of times. A thin file can compress the concrete to make sure there are no voids.

By using different sized track pins a very dense fill can be obtained.

The concrete is hardened by laying wet towels in the top and allowing a nice slow cure.

Steel is not as dense as lead , but far denser than just concrete to lower the ballast CG.

Steel track pins are also way cheaper than lead.

I used sand in the bow of my last boat> It had a compartment below deck in front of the engine room. I sealed it off from the bilge and emptied bags of sand in there. I figured it would come out easy enough with a wet dry vac if needed.

Early Willards had concrete with steel as ballast, the concrete swelled as moisture permeated the concrete. My vessel has fully encapsulated lead as ballast, but I think as long as it is encapsulated to prevent moisture intrusion it would be fine. Many Willards had the concrete chiseled out and replaced, you might check the Willard thread on the topic.

koliver said:

In 1977 I had a sailboat built. Hull had an enclosed ballast keel. Builder dropped in some lead ingots and topped it with steel
No deterioration in the 11 yrs I owned that boat.

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Has it been anything between the steel surface and the concrete?

sunchaser said:

My dos centavos thoughts --

It is important to keep the interior of a steel hull clean, dry and hopefully properly painted. Concrete allows just the reverse, retaining moisture between the steel concrete interface. The product of choice is lead, placed on the hull interior.

Just curious though, what was BR's build plan for ballast weight and placement? An I beam welded to the hull exterior seems counter intuitive for attaining the slippery shape a sailing hull needs. Generally, the plans should take into account the construction of a sailing vessel that should ideally be self righting from a 90 degree roll. Are the top sides all steel too? I thought BR's designs used Al.

Click to expand...

Do I understand you correctly that you do not recommend pouring concrete into the bilge? What if the bilge is cleaned and rust sealed with POR-15 ?
I do have lead bricks in the forward bilge area. I could not access anything midship, yet. There is no extra weigh the engine room, because the boat was already aft heavy. They had to weld on an air tank to the aft, for this reason. Buoyancy was messed up.


This was a custom built. BR design was used for the hull only. The top structure was altered, I think. The top was built out of steel, too. It is actually a bit thicker steel than the hull.
The I-beam keel is all the way at the bottom. It also protects the prop and the two keel fuel tanks.

FF said:

Steel track pins are also way cheaper than lead.

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I like this idea. I think it is doable. Now, I just need to find the place where they sell these pins.

Bud said:

I used sand in the bow of my last boat> It had a compartment below deck in front of the engine room. I sealed it off from the bilge and emptied bags of sand in there. I figured it would come out easy enough with a wet dry vac if needed.

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Does this sand volume move around? How do you secure it? What about moisture?

AKDoug said:

Early Willards had concrete with steel as ballast, the concrete swelled as moisture permeated the concrete. My vessel has fully encapsulated lead as ballast, but I think as long as it is encapsulated to prevent moisture intrusion it would be fine. Many Willards had the concrete chiseled out and replaced, you might check the Willard thread on the topic.

Click to expand...

I have some lead already, too. It seems that not enough volume. Back then, lead must have been more affordable. Today, that is not the case.

I agree with the no concrete against steel.


A Google search had several hits where it was denied use on European boats.


A thin paint or epoxy coating in my mind would not be enough.

Sell it and get another boat.

Nomad Willy said:

Sell it and get another boat.

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I like the boat. I’ll keep it.
There is always a way to solve problems.

Just remember that adding any significant amount of ballast will decrease the freeboard and thus the safety on your boat. It also will increase the draft. Can you also reduce weight aloft to compensate?

Keep the boat but find an alternative to concrete. I remember when local steel fish boats grounded, a breech in the steel would put saltwater between concrete and hull. Company owner would sell those boats quick..

sunchaser said:

My dos centavos thoughts --

It is important to keep the interior of a steel hull clean, dry and hopefully properly painted. Concrete allows just the reverse, retaining moisture between the steel concrete interface.

Click to expand...

What sunchaser said. This used to be a fairly common practice, but in the long run can cause serious problems that will remain hidden until they perhaps become dangerous.

And, if the rest of your boat is well maintained I assure you that some day someone will have to remove that concrete to replace hull plating, not a pretty or inexpensive undertaking.

Class like Lloyds, RINA, ABS do not allow this technique, and for the same reason spray on insulation is not recommended either, you need access to your hull plating for inspection and maintenance.

Do not ask me how I know

"Now, I just need to find the place where they sell these track pins."

Google in your area shops that repair bulldozers or cranes , call and ask if they rebuild tracks .Who does?

IF they do drive over and ask if you can purchase their scrap rack pins for cash.

This will allow you to go thru their piles of scrap metal, and take only the size pins that are useful.

Last time I bought 7,000lbs I had a Porsche powered dune buggy , got everything home in 3 trips with pins laying on the floor.

Discussing cash purchases is far better done in person rather than on phone , never with E mail.

Enjoy! Its boating at its best!

Was wondering if old elevator weights would do the trick? Some years back, I found a couple in an old house we bought. They seemed to be solid steel or iron and very heavy. I would guess they were close to 100 pounds each. The elevator companies probably recycle them nowadays but you might want to contact one and see if they would sell you a few.

The key here is how much ballast by weight do you need.

I have a hard time visualizing the OP situation so can only comment on my experience with concrete ballast. Not the most preferred ballast, but adequate and I do not worry about it. I have owned two Willards over the last 25-years, both with concrete ballast. I have had zero problems personally.

Willards did indeed use concrete and steel punching for ballast. My 1970 W36 has around 5000 lbs of ballast that is going strong after 50-years, though this is a fiberglass hull vs steel (not sure it makes a difference). I recently had about 1000lbs removed to make room for an expanded holding tank (pic is a bucket full - some rust, but nothing serious). Best I can tell, lead is about 3x-4x more dense/heavy. For this area, I will get some lead ingots and shot to place beneath the holding tank and bond it in place with floor leveling compound versus concrete as it is more akin to epoxy and does not absorb water and shrinkage is nil

I have moderated the Willard owners group site on Yahoo for 20+ years (all are welcome, BTW). Of the 175 or so 30 and 36 foot boats with concrete ballast, I know of a handful that have reported issues with the ballast shifting after 50-years or so. The one I have direct knowledge of had an owner who made zero effort to keep standing water in his bilge for many years which is an Achilles heel of concrete. In my opinion, once concrete is properly set into a bilge and allowed to cure for a month or two (depending on dimensions of concrete), I would encapsulate with either fiberglass or leveling compound (or both).

The lower the better for ballast. Some sailboats had half "sausages" of led added to each side of the keel. I wonder if you could cast concrete in a similar shape and bolt to each side of the keel.

Hard to tell from the pix but that keel doesn't look very wide or heavy.

Donsan said:

. The key here is how ballast by weight do you need.

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This is where the rubber meets the road. On an altered home build there are a few ways to determine where and how much. Protocols and methods are known and used once the boat is cruise ready and in the water. I'd recommend going back to the original NA for assistance.

sunchaser said:

This is where the rubber meets the road. On an altered home build there are a few ways to determine where and how much. Protocols and methods are known and used once the boat is cruise ready and in the water. I'd recommend going back to the original NA for assistance.

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The NA who was involved in solving the buoyancy problem told the builder to put on at least 5000 pounds ballast. He did add those steel bars to the keel. It was not enough for the buoyancy, so the air tank addition was suggested, which he did put in place.
Since the last email exchange, I have not heard of the NA. I don’t know ,if he is still around.
At this point, my main concern is the ballast. Skippers more knowledgeable than me have suggested adding more steel bar ballast to the keel, on both sides. If the boat is pulled out next year at the yard, this can be easily done. I already have the welder, who would do the job.
The concrete idea was also suggested. I could do it myself easily, little by little. I was not sure about the concrete and steel surface together. This is why I asked.
So far, more comments are on the side not to use concrete, but not everyone.

bayview said:

The lower the better for ballast. Some sailboats had half "sausages" of led added to each side of the keel. I wonder if you could cast concrete in a similar shape and bolt to each side of the keel.

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Not a bad idea. I could certainly mold these myself and place them. I suppose I still need to include scrap metal for density?

I did see lead bricks in the bow area, but I could not open the mid section bilge, yet. I am working on it.

bayview said:

Hard to tell from the pix but that keel doesn't look very wide or heavy.

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The keel is just for protection. The steel bar were mounted on each side later.

I guess it depends on how much weight you need and the space available but a lot of uncoated steel would probably subject the concrete to rust cracking.
A wild thought is to lower the keel into a canoe shaped mold and pour concrete around it. With some cross bolts of course.

I don’t think that I would put concrete against a steel hull. The concrete will absorb moisture and that isn’t a good thing up next to a steel hull. Maybe on a fiberglass boat it would not be an issue. I put in about 1500 pounds of lead in a previous boat trying to change the trim fore and aft. We glassed it in so it wouldn’t shift.

bayview said:

The lower the better for ballast. Some sailboats had half "sausages" of led added to each side of the keel. I wonder if you could cast concrete in a similar shape and bolt to each side of the keel.

Click to expand...

I guess, I just go back to the original idea of welding additional steel bars onto the side of the keel. There is one on each side already (see photo).
The concrete idea is more affordable, but I don’t want to risk any damage to the hull from inside. Besides, this is not very urgent. For few years, I will not venture out to the open sea. Inland sailing is much smoother.