View Full Version : concrete ballast

r kemp
01-24-2000, 10:47 PM
I am looking for some advice on adding concrete ballast to the bottom of a wooden boat (marine fir plywood over laminated fir frames). Does the concrete cause eventual rot and do I need to coat the wood first (with epoxy ? , plastic ? , roofing compound ?) before pouring ?

Bob Cleek
01-24-2000, 11:14 PM
Sixteen guys are going to squawk that Ruel Parker or whoever says concrete and boiler punchings are great ballast and that some old fish boat had concrete in the bilges and lasted forever and blah, blah, blah... BUT, if you want ADVICE about concrete ballast, just one word:


You got that! No if's and's or by's about it. NO WAY should concrete go into a bilge that you care anything about.

Yes, it will promote rot. You already are 0 and 2 with fir plywood... don't push it! It is also about the lousiest ballast you can find. Sheet, if you want cheap ballast, use stones before concrete. Not only that, but concrete is really a pain to mix and pour inside of a boat. Look, you can go to your local scrap metal yard and buy lead pigs for about 25 cents a pound, or you can scrounge the lead from plumbers, tire shops (wheel weights), indoor firing ranges, battery recyclers, and so on... your creativity is the limit. You can melt it on a camp stove in an old frying pan, for Pete's sake. Pour it into a wooden box or a coffee can. Put that in your bilge. It is clean, odor free, dry, and very easy to carry and stowe. If you are really anal, you can make molds that fit between your frames just so and each pig will fit perfectly. Lead is easy to remove when you want to paint the bilges, which, of course is impossible once you've poured cement in there... as is any sort of repairs, short of getting out the jack hammer. It will take a lot less lead, volume wise, to fill your needs, than it will take cement. The weight will also be lower in the bilge with lead, and thus be much, much more effective as ballast. Best of all, when you are through with your boat, the lead can be sold for what you paid for it at least, if not more. Go lead! Forget cement... please!

[This message has been edited by Bob Cleek (edited 01-25-2000).]

01-25-2000, 06:10 AM
Another advantage of the lead is that you can adjust the amount easily. I had to take about 200 lbs out of my catboat when it was moved from Cape Cod, down to the Chesapeak where the water is not pure saltwater. Real hard to do w/ concrete. Also, you can pull the ballast out entirely if you have to store the boat on the hard. Saves wear on the planking when not supported.

Ian McColgin
01-25-2000, 08:58 AM
Sometimes people mix purposes with unfortunate confusion.

Concrete does NOT promote rot in a new boat - may even prevent it.

Concrete is very light & by itself is not a good ballast but hoeing some cement around the bilges for trimming ballast and to flatten out the waterways can work in some designs.

I personally would not concrete on a plywood and lamframe construction. Cementing spreads the load but just somehow feels wrong for what you're describing. Usually your construction is more consistant with boats that want such ballast as they have concentrated more than is possible with concrete. Try to think this one through with the designer. Regular ballast has its own problems. The plywood skins, being rotary cut, are not as happy with static crushing. Put a ceiling down over the frames so that the ballast does not bear on the hull.

Granna has a cement with punchings keel for external ballast & it's a liability that perhaps some day I'll cure. At least the leading edge is protected by a 6x6 crush beam, which at the moment is a bit cattywonkis due to an intimate discussion with a rock. I'm not lifetime Admiral of the Kedgers' Club for nothing.

Whatever. G'luck.

Bob Cleek
01-25-2000, 12:36 PM
Ian's suggestion for ceiling under your ballast is excellent. I'd consider it essential if the ballast would otherwise rest on the ply skin. If the ballast weren't absolutely rigidly secured, it will shift slightly and likely, in time, chafe right through the ply... glub, glub, glub...

[This message has been edited by Bob Cleek (edited 01-25-2000).]

Jeffrey Ward Smith
01-25-2000, 02:10 PM
Here in Florida, every morning any metal mass is covered with dew, so internal ballast needs to be better ventilated than lots of bilges are. JWSmith

01-25-2000, 03:03 PM
Just for the record. Ruel Parker recommends removable ballast.

That way when you run aground you have a pontential way of getting off.

I might add that concrete is not waterproof. As many of the bridges in Boston can attest too. The water has gotten into the concrete and rusted out the reenforcing metal inside!

The bridge that collasped in CT was caused by this!

Ken Bascom
01-26-2000, 07:42 AM
I'm certainly not going to go against the tide here, just making an observation: In his book "How to Build Wooden Boats", Ed Monk describes how to make cement-and-boiler punch *external* ballast. While this would seem to avoid the issue of deteriorating a surrounding skin, Brian's comment about concrete absorbing water suggests that your ballast might increase in weight while it hung in the water. Which hardly seems like "a good thing", to quote our esteemed friend.

r kemp
01-26-2000, 04:09 PM
It seems there isn't a clear yes or no answer to the question of concrete ballast. However , I am still leaning towards it for several reasons.

1. Many boats have been built with concrete ballast and from replies I have seen in this forum their owners stand by them . George Buehler advocates concrete ballast in his book as a simple cheap and long lasting method. Slocum's Spray had concrete ballast and it managed O.K. Concrete in the bilge would not be exposed to any where near the salt water exposure of other structures like bridges and deterioration or waterlogging would not be a factor.

2. The idea of handling molten metal to form a lead ballast is very scary (see the thread on lead ballast currently running)

3. I can buy 4000 lbs. of concrete (about 1 yard) for a little over $100 and if I'm lucky have the concrete company add it over a load that is comming my way anyway and drop it off when they are finished with the bigger job. I would have to make myself available at the concrete company's conveinience but Im sure I could arrange it.
At this cost over the lifetime of the boat I am willing to write the cost of the ballast off.

4. Concrete ballast is lighter and would take up more space. I realize the centre of gravity of the ballast would move up somewhat but wouldn't the extra volume of concrete move more fore and aft and athwatships as the bilge opens up rather than higher . This spreading out of the ballast could have the effect of a more comfotable ride. The density of concrete can be increased by adding scrap metal anyway.

5. Anchor bolts could project out of the concrete and thru floor timbers placed so that the floors were slightly embedded in the concrete. The nuts could be snugged down after the concrete has set, fastening the ballast to the floors in a simalar fashion to outside ballast.

6. As the frames heels would be embedded in concrete , the question of whether to socket them or not becomes moot.

01-26-2000, 04:22 PM
Regarding the fact that concrete takes more space than metal. If you take advantage of this you can produce a relatively larger moment of polar inertia which will give you longer periods of rock, pitch and yaw, and give a more subdued motion. If I recall, a period of about 5 seconds for roll is considered about the ideal. This is difficult to obtain.

Allen Foote
01-26-2000, 05:34 PM
I had a home built sail boat with a concrete keel. When I copper sheathed it we sealed the keel with West before painting it. 16 years later the keel was still painted and looked fine. I'd seal the plywood with epoxy first. Maybe even roll on a layer of 6 oz. cloth. Sounds like you've figured out what you want and why.....go do it. Fair winds to ya.

Don Z.
01-26-2000, 07:27 PM
Would that be the same Slocum who went to sea in Spray, and, is now partying with Amelia Earhart?

Two short tons of concrete is over 26 cubic feet. The same weight of lead is only a little more than five. You could cast ingots and put them where you like, and control both trim and polar moment that way.

Sure, there are a bunch of guys who have used concrete and reported no problems. There are also a bunch who ride jetskis and say they enjoy it. Yes, the ballast would spread out as it went up, but that is also raising the CG.

It's your boat, and it's your decision. It's not for me to say "do this" or "do that". Right now, I'm trying to do the math to convert a 275 kg cast iron keel to lead (and if I could get wings, that would be really cool), but I can't say that I would want to go with a less dense ballast. As Bob said, you would almost be better off with stone (and isn't granite denser than concrete?). My judgement is a little clouded, as I once sailed in a boat with concrete ballast, and not only did it not stay well, not point well, and was still a bit tender, I still have no clue where that leak was. That's just my two cents, but I'm a big fan of the most dense ballast you can find.

Anyone got any depleted uranium?

Ed Harrow
01-26-2000, 07:58 PM
Hey Don, I've got a friend in the right place... LOL but I don't think that I can fulfill your request.

Only three comments re concrete:

1. Roseway, an old boston harbor pilot boat built in the 20's has a poured concrete ballast. She's still floating, but as has been pointed out, I'd hate to have to find a leak.

2. Punchings, from all I've heard from anyone who's ever had to deal with ballast removal for repair purposes, are a curse

3. Mass Maritime Acad's boat Bay State had a bunch of concrete put in her hold to buy her a few more years of productive live as she was getting a bit wiggley. Ian may know more about this...

Don Z.
01-26-2000, 08:16 PM
Ed, thanks anyway. I guess I'll just shelve those double secret potato cannon plans I had for a few more years...

Syd MacDonald
01-26-2000, 09:15 PM
Forget the depleted uranium Don. They're sneaking it into Canada under cover of datkness.

Bob Cleek
01-26-2000, 10:03 PM
Sigh... Well, it looks like I was right... sixteen guys weighed in telling us that George Buehler and Ed Monk think concrete and boiler punchings are great... somebody held Slocum up as an authority again (LOL... read those past "Spray" posts when you get a chance!), we've even got an option for casting keel bolts right into the concrete, and of course, cites to any number of old wrecks full of redimix. I just knew it.

Well, there's no shortage of concrete, so go for it guys! P.T. Barnum was right!

BTW, if the brokerage business is the same as it was twenty-five years ago when I was in it, don't bother trying to list your concrete-filled boat with a broker... nobody wants 'em... they don't sell... heck, you can't give them away. But, then, that doesn't matter if you aren't going to ever sell her, does it?

Ken Bascom
01-27-2000, 07:27 AM
Gee, Bob, as the guy who raised the Ed Monk reference, I tried to be clear that I wasn't advocating it -- lord knows I'm 'way too uninformed on this issue to argue with you geezers on the pilings (well the reference in the other thread was something like that). I was mentioning it to see if anyone else had experience with external concrete ballast. The boats I'm tackling in the foreseeable future are unballasted, but there's always that dream of building something big enough to skip town in. I was just looking for some info to tuck away until then.

Stephen Hunter
01-27-2000, 09:43 AM
Syd. Aren't we nice neighbors to take that wonderful stuff off their hands?

Bob Cleek
01-27-2000, 01:17 PM
No offense, Ken... just taking a little poetic license with the Monk reference.

Come on guys! You can scrounge lead from all over for free and cast it yourself. What do you get? State of the art, top of the line ballast. External concrete ballast? Well, for openers, you will have to be good enough with the stuff and experienced enough with the specialized additives to pour a keel than won't break in half on you the first time she's hauled. Make sure all your rebar is set deeply enough so that it doesn't start to corrode and blow the concrete off... and so on.

Frankly, I'm amazed that anyone who knew enough to build any sort of boat that would float would even consider using concrete for ballast in new construction.

By the way, the fibreglass Rawson 30, a notorious "bulletproof bathtub" built in the sixties used concrete and boiler punchings for ballast and sailed like a slug. Most of the surviving examples have had the concrete jackhammered out at great expense and lead installed. The modifications sail a lot better.
[This message has been edited by Bob Cleek (edited 01-27-2000).]

[This message has been edited by Bob Cleek (edited 01-27-2000).]

Scott Rosen
01-27-2000, 06:18 PM
Lead or concrete. Hmmm. Reminds me of the old gangster movies. If you had some business to take care of you could fill 'em full of lead. Or you could drop them in the river with cement galoshes. For efficient and quick killing--lead. For unbeatable hiding--concrete. Different materials, different uses. Over the years, lead has become the material of choice. Today, no gangster worth his weight in iron ballast would use concrete. Boat builders, take note.

01-27-2000, 07:57 PM
Have you considered water ballast for your boat? Specifically a pair of tanks, one to port, one to stbd, and a fluid transfer system to move back & forth? This works, very well.

Bob Cleek
01-27-2000, 11:27 PM
Henri, what does a "fluid transfer system" that can effectively shift liquid ballast from port to starboard in a seaway LOOK LIKE anyway?

And, second question, how does water inside the boat, having the same specific gravity as the water outside, lower the metacentric height? Or, does one have to be salt water and the other fresh to make it work for ballast?

01-28-2000, 11:58 AM
Conceptually it looks like a windward rail full of overweight former linemen. Ones that don't bitch about being cold, wet, and hungry. Motorized pumps probably do the leeword to windword transfer work. At least they would on any boat I'd care to work. Probably not the solution of choice when short tacking up a narrow channel. It gets used by the likes of singlehanded round the world race boats. Obviously not a traditional seamenlike idea. It looks like a way to get more stability in a light, non lead mine, monohull. Whatever one's theoretical preconceptions, it seems to be a workable engineering solution for the narrow problem it addresses. Maybe if you used a liquid at normal tempratures metal like mercury as the fluid.... http://media4.hypernet.com/~dick/ubb/wink.gif

01-28-2000, 07:25 PM
Firstly, in re concrete in/for boats. The most definitive book I have seen on this subject is FERRO CEMENT DESIGN, TECHNIQUES AND APPLICATION , Bruce Bingham, C1974, Cornell Maritime Press. This is a tough one to find, and you'll probably need to use an inter-library search request. Its also dated, but a quick read will give you the message that there's quite a little more to this than meets the eye. There is an excellent very recent book on concrete formulation by Some US concrete assoc, which I think is in Ohio, someplace. I can get you the citation if you want it. You do not use plain old reddy mix out of the back of any old truck. This becomes quite sophisticated when specifically for boats. The state of the art is military aircraft bomb shelter dome material, using Dramix ZC 30/.50 (metric) steel fiber reinforcement. You can find this at >bekaert.com< . I also refer you to >masterbuilders.com< . go to the canoe project, thence into press releases, thence to the teams photo, where you will see a photo of 23 concrete racing shells built by 23 university engineering groups using Kevlar fiber reinforcement and who knows what else. If you have proximity or acess into any of these U's, I would refer you to them. To find state of the art ferroconcrete construction, you will have to go to Europe. I don't know how many of you know it, but REDDI MIX is a UK entity out of Birmingham.
Secondly, in response to Bob Cleek's questions, I will make a new post on movable water ballasting in this subject group.

Bob Cleek
01-28-2000, 07:48 PM
My hunch is the ferrocement book is hard to find because it was the first one they reached for as soon as the corn cobs ran out! Ferrocement? You don't even wanna go there!

Dale Harvey
01-29-2000, 06:35 PM
If you must use concrete inside a boat, first red lead prime the bare wood, then hot tar to above the proposed level of the concrete. Under no circumstances should ferrous metal be used. Every piece of concrete I've ever seen thats been exposed to saltwater was destroyed when the expanding iron oxide burst it. Use a granite aggragate instead of limestone. Use the new glassfiber additives sparringly, they make it real tough to jackhammer the stuff back out if you have to repair. Few boats built useing the plans, materials and methods advocated by Bhueler, will ever be worth the cost of major repairs. Simpler and cheaper to just build a new one, as I suspect he intends.

r kemp
01-29-2000, 10:43 PM
I'm not sure whether the designers of boats who allow concrete ballast intend them to be
rebuilt rather than repaired or not but I doubt it. In addition to the designers already mentioned in previous posts ,William Garden also had at least two designs that allowed for concrete ballast and at least for the Spice Island Cutter indicates no difference in performance for either inside or outside ballast.(The other design is Porpoise) I doubt Mr. Garden would allow for concrete ballast if he had serious reservations about its effectiveness.
Nevertheless I do get the impression that for the DIY concrete is better but ideally lead is preferred. Which brings me to the next question - how does one find a foundry that will pour a lead keel for me and what does it cost (the boat is a 28 footer with 3000 lbs. ballast) Do I have to costruct the mold myself or will they.

Bob Cleek
01-29-2000, 11:24 PM
Ah, we are finally down to the short strokes!

Answer: A) Any foundry in the Yellow Pages will cast a lead keel that size for you. They would make the mold if you wanted to pay for that service (not likely) and they had a patternmaker (likely). Generally, you supply the mold, if they are sand casting. If poured into a wooden mold, it would probably be necessary for them to build it in place there. There is an outfit that advertised in WB classifieds or ads and will cast a lead keel and ship it anywhere. (For a price.) B) You cast one yourself. (Check the recent lead keel casting thread.) A keel your size is no problem at all! A LOT cheaper to cast your own, especially if you can scrounge your lead for free. No transit costs, etc. Really the ONLY way to go. Frankly, if you can't get past casting the keel of the boat, you probably aren't going to have what it takes to build the rest of it. Bigger the keel, bigger the boat... it's self-limiting... never try to build a boat bigger than a keel you can cast! LOL

Ken Bascom
02-04-2000, 07:39 AM
Things are getting too quiet around here, so...

I just checked in at another discussion forum - the "Boat Building" forum page at www.boatbuilding.com (http://www.boatbuilding.com) - and stumbled across a thread on concrete ballast. Short but interesting discussion you might want to check out; there's one guy over there who details what seems like a fairly good system for installing easily removeable poured concrete ballast.

Not advocating it, Bob, just trying to stir some poop.

Matt J.
02-04-2000, 12:12 PM
OK, I'll bite. I used to work for a national concrete assocation research lab. while there I lead a team of U Maryland students to build 2 concrete toboggans. I also developed the concrete for this purpose. Also helped with a couple of concrete canoes that went to the Masterbuilders / ASCE competions. Concrete is not only ready-mix. our concrete mixes ranged from 35 pounds per cubic foot to near 200 pounds per cubic foot. Concrete made with those fibers can be a great material to work with. Our concrete matrix failed but the fibers held everything in place during testing.
Steel (ss if you want) can be used in many ays to strenthen and and mass to the mix. One of our professors had the idea to use a steel (kind-of-a) powder to the extent that the concrete can be polished to look like a dirty steel.

Concrete can be cast into the entire bilge or cast (in a dense mix) into smaller bars or cylinders (plastic ones can be had for cheap) and then placed like the lead pigs in our bilges. Concrete is certainly not a bad choice - it will take creativity and some good planning, but it can work just as well.

The rust that some of you mention in bridge concrete is not only that concrete is permeable, it's that salt water carries the salt into the concrete, deposits it, more goes in, etc then freeze / thaw cycles take care of the rest. Simulations of freeze thaw are interesting and mean you will need more research than the local-yocals will (can?) give you.

Stephen J
02-04-2000, 02:58 PM
I am also attempting to make the decision of what to use as some ballast in a much smaller vessel (12' Swampscott) and think that I will likely use lead, and have found where I can obtain it in strips (8 oz. per strip). I will laminate the strips in-between the layers of the daggerboard I will glue up. The one thing that I am uncertain about is what amount of weight would I be likely to use given the length and beam (4'4") of the boat. I can't imagine what kind of task it would be to put the one proposed with concrete into dry dock without being able to remove the ballast first, and then to remove it as chunks of concrete, versus lead would seem extreme, whereas ingots of lead would be more mallable and easily molded to areas within the bilge to be removed at will to permit maintenance.

Don Z.
02-04-2000, 06:42 PM
I still don't get it. Even with the really heavy stuff, you would need over three times the amount of concrete than with lead. In the time it has taken us to decide all the extra steps we would have to take (ceilings, boiler punchings, etc) we could have cast ingots, and been done.

05-29-2001, 04:36 PM
OK, I have a concrete keel that weighs, by estimation, approximately 3,200 lbs. I am guessing, but the plans state that ballast is 3256, Herreschoff's "Prudence", a similar plan, has 3,150, though the senile old fellow who last owned her tells me the concrete weighs 2380, and he didn't pour it. So I am thinking 3200 lbs. Or just follow the plans and say 3256. It's heavy.

This thread has sufficiently scared me to lop off the concrete and pour lead (this is a five+ year construction project, boat has not yet been in the water. Cedar on oak, full shallow keel cruiser, 24'LOA, 8' beam).

So my question is, how do I calculate the new shape of the lead ballast keel? I know I'mm gonna have to come up with some combination of lead and wood that add up to the same weight as exists now, or dang close to it. How much of the volume of space becomes lead, and how much is deadwood? http://media5.hypernet.com/~dick/ubb/confused.gif

I need to scan a picture, maybe that would help.

Thanks for thoughts and apologies for reviving an old thread.


05-29-2001, 07:35 PM
Just for the record....On Slocum's Spray and concrete ballast....
The hull of Spray was new when launched in 1895 and the concrete ballast added. In less than 5 years there was rot in the hull below the ballast. Slocum did EXTENSIVE rework about every five years until he could no longer afford it, and without hauling the boat went to sea the last time knowing it would probably fall apart....

05-29-2001, 08:57 PM
This is an old thread, and I imagine the original poster has long moved on with his decision...but:

I once had to remove poured internal concrete and punchings ballast from a steel Rhodes motorsailer to get at an area that needed repair. I spent three days with an air hammer jacking away at that stuff before the yard manager decided it would be cheaper and faster to cut away the hull on the outside, drop the offending ballast out, repair, reframe, replate and repaint. I could have kissed him. It was among the most backbreaking jobs I'd ever had.

I can't imagine using even a small pickaxe, much less a jackhammer to remove concrete in a plywood planked boat! http://media5.hypernet.com/~dick/ubb/eek.gif

J. A.Tones
05-29-2001, 11:32 PM
Well here it goes again and I just know Mr. Cleek is going to have words to say but - I have an ex commercial fishboat which I converted to pleasure use 12 years ago. The lower extremities of the bilge are filled with a concrete mix which appears to be sand and not gravel agregate. This has been in place since new (1969) and during my current re-configuring project I had need to remove small portions of the concrete in order to add a bulkhead. In surveying the hull the only place that ANY weakness in the oak frames showed up was in the area which held the original fish holds. In these areas there is a short area of each frame (about 3 inches) that extends ABOVE the concrete, where I surmise fresh water leakage from the hold would collect. Even in these areas the frames do not really need replacing but as a precaution I am laminating new wood in to replace the weak areas.
When the concrete was removed, the "rot" stopped immediately below the original surface and NO "rot" was found under any of the random test areas.
I don't know what the secret mixes were that the original builders had, as there does not appear to be any coating on the planking or ribs where the concrete was poured.
In effect what this concrete appears to mainly do is level the bilge out fore/aft to allow drainage from the fore cabin bilge aft to the bilge sump, at the stuffing box.
Well, there's one boat's story for what its worth. I do know for certain that almost every commercial (wooden) fishboat that you look at out here in the PNW has concrete in the bilge.
John Tones MV Penta
Victoria BC

05-30-2001, 05:36 AM
Well...to start with....cement used for ferro-cement boats or for marine construction ain't the same cement used for building bridges. The proper stuff (type 2 if memory serves) is a slow setting cement to which are added 10% graded fines and a latex bonding agent which makes it impervious to water. Additionally, the metal used is well rusted rebar and mesh, no oil or galvanizing. Then a small amount of chromium trioxide is added to the water to prevent the reaction of the galvanizined or metal coatings from chemically reacting with the cement and forming bubbles around the reinforcing material. Cement ain't necesarily cement. I have several books from the great war years where this type of construction was used for Liberty Ships.

05-30-2001, 08:28 AM
Sheesh, all this head scratching about cement brews and all one really needs to do is mix a slurry of epoxy and lead shot....


05-30-2001, 09:02 AM
Well, mine is all external, so at least I won't have that to deal with.

05-30-2001, 09:59 AM
Right, Norm.
Sheet metal bent to an airfoil section, or wood coated with waxed paper, a glass shell built around it, slid off, filled with old wheel weights and reject lead shot and epoxy is easier, heavier, cheaper in the long run, and performs better.....

Ian McColgin
05-30-2001, 10:25 AM
For an external keel, start with the designed keel shape and center of fore and aft trim. Imagine just cutting away enough wood that you have lead on the lower leading edge of the keel - a wonderful shock absorber for Kedgers' Club wannabes - and enough back to keep the CoB in place.

You may compromise a bit on the issue of long and low, which puts a lower righting moment but a longer pitching momemt, versus chunkier but more centered, which is generally better for sailing as you don't have such a fierce pitching moment to argue with the headseas.

Some designs that are meant to dry out on their own bottoms (CB or leeboard) have the lead in a kind of horizontal keel or skid pad which gets the weight as low as it's gonna get on such a design and protects the bottom.

Lot's of choises here, depending on the design.

For what it's worth, Mr Cleek is right that in today's world and today's prices, lead is the more cost-effective way to go and is almost always the most design effective manner.

Goblin had a cast iron keel - build in the '20's when lead was dear and the first owner owned an iron foundry anyway. It was great for holding the boat together. She was the only CB Alden 43'er I knew of to hold up. All the Goody & whomever CB 43's I knew of had to have the CB removed and got keeled over as the wood and lead structure just didn't have the guts for more than 40 years of that use. I'm not aware of that problem in regular lead and wood keel structures that do not have a centerboard trunk weakening the structure.

The iron was fun - put holes in rocks rather than the other way around, but it transmitted the shock something fierce and started the seams every time I hit the little ridge just south of Fiddlehead Rock. (I'm a guy who likes to learn from my mistakes. To make sure I'm really learning, I usually commit them over and over . . . It's a little bit like love.)

05-30-2001, 10:53 PM
Well I am glad that John pithced in there. I was about to go dig up all of the dead shipwrights out here on the puget sound and tell them that they were wrong. Heck I could even get Mr Cleek to email them and tell em why!

Bob Cleek
05-31-2001, 07:41 PM
Hell, Norm, melting the lead and pouring it into the form is easier than mixing the epoxy for the same job! And costs nothing! LOL

Anywho, Michael dredged this thread up with a few serious questions which we may have overlooked answering.

Mike, it's easy, maybe, and maybe it's not. It depends on what your boat looks like and whether or not you have the plans. You are going to have to do some lofting, probably, in order to develop the ballast keel shape. First, you have to get some tech books. Skene's Elements of Yacht Design will have what you need, as will most any engineering manual. You need to know the weight of lead and the volume you need to equal your 3200 (or whatever) pound ballast keel. As I recall (but do look it up to be sure), lead weighs about 740 pounds a cubic foot, so you would need about four and a third cubic feel of lead. You need to shape that amount of lead so it fits on the bottom of your keel. it will be a lot smaller than the concrete, so you will have to fair out the remaining area with deadwood. You will have to determine the center of fore and aft balance and make sure the ballast keel is properly placed to achieve that. If the lead keel is too heavily weighted forward, she will be nose heavy and if too heavy aft, she will squat. Engineering wise, you will also have to make sure that your keel and/or floor timbers will support the lead ballast. You may have a shorter length of ballast with lead, meaning that you may have to hold it on with fewer ballast keel bolts. If you had a dozen holding the concrete on spread over ten feet of keel and with lead you are only going to manage seven or eight over six feet, they have to do the job of holding the same weight and will have to be accordingly heavier. You will find the scantling rules (bolt diameters and timber dimensions) in Skenes' or in Larry Pardey's wooden boat building book, "Classic Yacht Construction - the Hull" or something like that. If your keel shape is sharply raked or tapers radically, the calculation of the necessary volume will get a bit tricky and you will have to find somebody who was awake in calculus class the day they covered that topic, which I wasn't. On the other hand, if you are lucky enough to find the plans for the boat, it is possible that you will find the ballast keel specified. Some designers will give a couple of dotted lines on the lines plans, one for lead and one for iron... never saw one for concrete, though. You can also spend a few bucks and have a real naval architect do the design work for you. I would consider this money well spent and it shouldn't cost all that much, particularly if you have some kinds of lines for the boat. Once you have the offsets to loft the pattern and mold for the keel, melting and pouring the lead isn't any big deal if you approach it with common sense and care. It's certainly the way to go and would greatly increase the value of your boat. If the boat was originally designed for a concrete keel, however, I'd make sure a naval architect checked it out to make sure the existing structure will support the more concentrated weight of the lead keel.

Bob Cleek
05-31-2001, 07:50 PM
Oh yea, and about those fishboat builders in the upper left hand corner... Nothing at all wrong with lining the bilges of a fishboat with Portland cement. No question about it. Your basic fishboat will be worked to death long before the bottom rots out of her on account of the concrete, so it's a cost effective solution. Additionally, there is a world of difference between the shape and purpose of concrete ballast in a fishboat hull and concrete ballast in sailboat. On a trawler hull, you want the weight well distributed all over to get her down and solid all around so she won't wallow and roll. On a sailboat, you want the weight concentrated and as low as possible so she will stay upright under a press of sail. Concrete, being less dense and easier to spread out inside a hull than lead, makes sense in a fishboat. One shouldn't confuse fishboats with much else, though. For them, life is nasty, mean, brutish and short. An old one is just lucky.

05-31-2001, 08:29 PM
good on you bob, however most of the fishing fleet here is anywhere from eighty to fourty years old, and I have yet to see rot under concrete unless is was added later over rotten wood.. I would not put it in a plywood boat either.

Stan Derelian
05-31-2001, 10:46 PM
For What It's Worth Department: I recently took the concrete out of the bilges of a 70 y/o Monterey (fish boat) using a hammer drill and cold chisel (about 3/4 day's work). Found absolutely no rot, and the iron fastenings that had been covered by it were corrosion-free unlike those elsewhere in the boat. The concrete was dry, and had sand with no aggregate, and no metal.

The planks and floors under and next to the concrete looked like they had been painted with red lead, and then a pitch or light tar coating.

I am planning on putting it back if I can find out the additive that will keep it from absorbing water.

06-01-2001, 09:03 AM
Thanks for your thoughts, Bob. You da man! I have a copy of Skene's on order from abebooks. I do have some plans but the designer didn't put his name on em (on purpose?) But I believe somewhere back in there is a lofted drawing of the keel. Need to check. Oh, and how about longleaf yellow pine for deadwood? Bud McIntosh says that's OK and it's local (Gulf of Mexico).

We're a little busy at home lately, daughter number three is to be born Tuesday morning.

[This message has been edited by Michael (edited 06-01-2001).]

[This message has been edited by Michael (edited 06-01-2001).]

Bob Cleek
06-01-2001, 03:33 PM
Congratulations on your bundle of joy! I remember when my daughter was born. That was just about the last time I felt free to play on my boat as much as I wanted. She turn's 20 next month. LOL

As for the "old" fishboats... yep, if they are coated with a lot of honest red lead like they did in the old days, and then slathered with hot tar, they are going to last and the concrete won't be such a problem rot-wise. Of course, nobody building them back then ever had any idea we were going to be jackhammering the rock out of them to "preserve" them for posterity! LOL THAT'S the biggest catch! Additionally, the apparent longevity of some fishboats is no doubt attributable to the fact that they are so well salted down in use. Perhaps there is some as yet undiscovered rot preventative enzyme in fish slurry. At least it smells better than antifreeze, but not by much! Obviously, the builders long ago recognized the pitfalls of concrete because they took care to insulate the wood from it. It would be interesting to know the history of cement as an ancillary material in wooden boatbuilding. Portland cement has been used as a sealer and as a seam compound as well. This seems to be a Northwestern Pacific phenomenon. I don't get the impression that cement was used in vessel construction on the East Coast to the same degree it was out here. Maybe "back when" lead was too expensive in the Northwest? Who knows? Bottom line, for my money, given the investment in a wooden boat these days, if you can afford lead, it is a better option than cement.

06-02-2001, 09:05 AM
It was not just the fish boats out here. A lot of the yatchs have it too, espcially the power vessels. I have seen it in the frame bays of sail boats but it is not really done for ballesting because it is so light compared to lead or iron ingots.
Really the only place I have seen much rot in assosiation with concrete is where care was not taken to insure that water drained away from the hull.
The general opinion here is that something in the concrete, perhaps the lime, kills the rot spores. I dont know any one in Port Townsend who feels that Cement causes rot. But that is the great thing about opinions, everyone can have a different one.

Dave Hadfield
06-03-2001, 10:24 AM
Norm, why use epoxy? You hardly need its strengths here. Wouldn't ordinary fiberglass resin be adequate? I think you could line each bay between the frames with a piece of plastic (laying a dowel under it first for a limber hole?) pour in wheel weights to the right level or weight, and then pour in fiberglass, probably in layers to avoid heat buildup. You'd also cast a handle or a couple of bolts into it so you could lift it out as required.

Wouldn't this work, assuming you can put up with the smell of the Obnoxious Material in your boat? You could paint each block of course, to take the smell away.

Frankly, I be more inclined to make lead "bricks" that fit more loosely into each bay, but are still roughly beveled to fit. Make a line of wooden molds, melt a pile of lead, pour or ladle it in, and you're done. (Or make the molds yourself, and take them to the foundry to be filled.)

Another way might be to use lead sheets (can you buy it in half-inch?) and have it cut in pieces that fit between the bays. That would be simple. You could even bolt thicknesses together.

Question, does uncoated lead in the bilge discourage rot?

Just some ideas.

Good luck,


06-03-2001, 12:44 PM
I can't defend lead shot/epoxy slurry for casting ballast. Truth be told, I probably just threw the idea out for orneriness. However, Sam Devlin specifies it in a couple of the plans I studied prior to selecting the boat I'm building. I thought exotherming would be a serious problem but Kern Hendricks at System Three said their slow hardener would not. That is as far as I studied the method.

The only thing I know for sure about casting lead is that the iron in my blood seems to be turning to lead (Chemist, no other explination but is this possible?) and settling in my rear.


Andrew Craig-Bennett
07-14-2004, 10:05 AM
Well, the folks who built my boat back in nthe 30's must have read Bob Cleek, because they missed the cement flushing out of the bilge.

Result - thirty years into her life - rot in the heels of the bent frames (pocketed, CRE)and a stinky bilge.

Cure - by the yard that built her - slip her, steam clean the bilges, drop the garboards off and scarph new frame ends in, put the garboards back and follow Claud Worth's recipe:

1. A`coat of pine tar, put on as hot as the brushes will stand.

2. A rich Portland cement mixture, to cover the floors (iron strap) and fill all crevices, with greased tobacco tins over the heads of the keelbolts. The tins were then removed and these spaces filled with white lead paste.

Result, after another 37 years - the shipwright who ran the cement in after repairing the frame heels was called in to help fit a new mast step -this involved yours truly smashing out the cement with a cold chisel (NB - if doing this, you want a long, thin, cold chisel and a 3lb club hammer - this is quicker than a wide chisel and a heavy hammer) to reveal absolutely pristine metal and wood.

We put the cement back again...

Russell Sova
07-15-2004, 06:13 AM
Get some concrete mixed, get drunk and start shootin' that shot gun at the wet mix. Any questions?

Russell Sova
07-15-2004, 07:08 AM
rkemp, I have never used cement as a ballast but I can tell you the lime in the cement will soak into the wood and help prevent rot. I've used cement as a water soaker-upper in a boat that had a leak at one time and there was no rot anywhere the cement was. Slocum's boat should have been hauled annually not every five years; it was carvel planked.
We used stainless steel fibers to reinforce concrete on an offtake breach on a 7 hearth incinerator. It will withstand temperature extremes, weight and whatever. It was mixed with readymix! I can't imagine a keel will have more stress than that.