concrete ballast

[kewlrunninz]

Hi all,Question what's the consensous on poured Portland cement in the bilges as ballast. What effect will it have on the wood over time.

[Andrew S/Y Rocquette]

Hi. It was very common in the first half of the 20th Century in the UK, both for commercial barges and fishing vessels, and also for yachts.

Claud Worth, in his "Yacht Cruising" (I have the 1948 4th edition) and also in "Yacht Navigation and Voyaging" extols its virtue, and claims he has never seen a well-cemented boat with rot. Which is only logical as if done properly it will prevent water ingress and therefore keep the bilges dry! Worth had both of the yachts he designed - TERN III in 1914 (definitely) and TERN IV in 1924 (I'm 99% sure) cemented. TERN IV is still around. He has a couple of pages on cementing pp.418 in Yacht Cruising. He DOES say you should be suspicious of yachts cemented some time after launch as they are likely in that case to trap in existing poor workmanship and/or rot, but in new vessels he says "Some people have written about danger of decay under the concrete: as a matter of observation it does not seem to occur. One sees many old fishing vessels which have been put ashore at the top of a spring tide and left to rot. The part which appears never to rot is that under the concrete."

His recipe is to make sure the vessel is clean of all dirt, paint the wood with very hot coal tar, and fill with concrete of one part portland cement to three parts dry sifted sand. Only enough water to make a "smooth easily worked mortar". Fill and smooth with a trowel.

Other thing to be aware of is the effect it will have on stability and the boat's motion. Spreading weight fore and aft will make the boat pitch more slowly (possibly more comfortable, but generally undesirable as she will not rise to oncoming waves so quickly). Spreading across the beam spreads the mass around the rolling axis and damps down rolling (generally a Good Thing - same reason old Cape Horners used actually to increase weight aloft in heavy seas, so as to reduce stability a bit and ease rolling motion!).

Hope this helps.

Andrew
(edited for spelling, or lack thereof)

[ 01-26-2005, 09:02 AM: Message edited by: Andrew S/Y Rocquette ]

[Andrew S/Y Rocquette]

big debate also at:

Wooden boat forum on concrete ballast (http://media5.hypernet.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic&f=1&t=000647)

[psk125]

After the procedure outlined above,I wonder if the longevity of the hull is due to the treatment with melted pitch or tar on the inside (much the same as an epoxy barrier coat, no?) . The hull may have lasted despite the concrete, rather than because of it. The lack of density , even in its densest mixes, would make rocks more effective ballast. The other thread on concrete also mentions the fun to be had if one should happen to spring a leak somewhere under there. Sounds like a "no going back" direction to take, unless you like working with jackhammers. As a sailor, I like the idea of coming back if I want to.

[Andrew S/Y Rocquette]

Personally, I agree with you! Would not do it myself.

[ssor]

The number of options for ballast is large . the vikings used round stones so that in a knockdown the stones would roll out of the boat. Sand bags have been used for years, steel punching scrap in concrete was used when available, cast iron is still found on older sailboats. I would certainly be over generous with coal tar cresote in the area that would be filled with any ballast. It is a given that access to that portion of the boat is practically impossible. Even with external ballast attached with keelbolts all repairs in that part of the vessel are terribl;y complex.

[JimD]

I made plywood boxes custom fit into the bilge between sawn frames on either side of the centerboard. They are filled with scrap iron and cement and they have nylon straps attached and are removable so there is no cement in contact with the actual hull. A very good solution it seems for a small boat that requires only a couple hundred pounds of inside ballast.

[Carl Stone]

Observation only, not to muddy the waters. I have a 45' Nova Scotia ketch w/ concrete ballast and lead pigs for trim. The hull is 2" x 2" cedar strip planking, built in 1970. Do not know the concrete mix, but it has no rot and no damage to the concrete. There are so many opinions on this subject (I am not rendering one here), that I would find a shop that has used it for a long time, and speak with them. The mix itself would obviously make quite a difference.

[Paul Stohlman]

Portland cement isn't all that heavy by itself. I have used it to fair out the areas that water flows on the way to the bilge. (Adjacent to the horn timber where the frame ends meet etc.)

Trowel the cement where water will accumulate, so it can flow uninterrupted.

Lead (custom cast if need be) is great for internal ballast. It takes up the least space, and won't rust.
Be careful to protect the planking (no point loads) and secure it from movement.

[Buzz73]

In his book, "Backyard Boatbuilding", George Buehler mentioned using various combinations of concrete ballast with great success. He even wrote of concrete ballast keels surviving severe groundings unscathed.

I, myself, have seen concrete ballast used with a tar bedding as well as directly onto bare wood (internal ballast). As long as it is applied to new wood, I haven't seen any rot associated with this technique. For some reason, there is a social stigma about concrete ballast in boats, and the resale value of the boat may suffer because of it. That's the only drawback I can think of.

[rbgarr]

I once had to remove the poured concrete/metal ballast 'bits' from the inside of a Rhodes ketch in order to repair the centerboard box. It took several days of very dusty/uncomfortable/awkward/loud work with a handheld jackhammer. Never want to do that again.

[nedL]

It's still the norm in steel fishing boats. I put 9 cu. yards in the hold of an 80' dragger I was involved in building (lots of fun shoveling that around on a hot summer day smile.gif ).

[ssor]

posted 01-27-2005 12:10 AM
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I once had to remove the poured concrete/metal ballast 'bits' from the inside of a Rhodes ketch in order to repair the centerboard box. It took several days of very dusty/uncomfortable/awkward/loud work with a handheld jackhammer. Never want to do that again.
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Posts: 2726 | From: Maine and Georgia | IP: Logged

I wonder if it would have been easier if it had been five hundred pound custom cast lead blocks set bedding.

[rbgarr]

Not to highjack, but I just read about something that L.F. Herreshoff supposedly did when the J-Boat "Whirlwind" was built. He was wary of the Lawley Yard's set of ways, so he had the lead keel cast with deep, empty cones in the top. Lloyd's of London made repeated demands to change the design, and when she was launched the hull was down on her lines ten inches at the stern and eighteen inches too high at the bow. She was 130' long, so this may sound worse than it really was, perhaps. Lead set into the cones helped trim the hull.

On another aside, early in her working up for the Cup trials the syndicate moved her mast forward six (!) feet because they decided not to use LFH's double foresail rig.

[ 01-27-2005, 12:17 PM: Message edited by: rbgarr ]

[George.]

I used concrete ballast in Dalia's bilge, with 5 tons of scrap iron pigs mixed in. I coated the hull with epoxy and then with a waterproofing compound sold down here used for the inside of swimming pools, and I mixed another compound into the cement which makes it impermeable. And I left a "trench" down the middle, right down to the keel, to serve both as a bilge and to collect any water that does find its way into the concrete.

[Roger Cumming]

This concrete in the bilge question makes me wonder why none of the great yacht designers nor any of the great wooden yacht builders used this technique. Were they all ignorant of a wonderful new idea? I doubt it. Why was this technique not used in first class construction in new yachts? Concrete has been around for a long time. It sets under water. It can be made very strong by varying its formula. It's cheap.

Wooden yacht construction techniques reflect the need for strength, constructability and economy but also repairability. The comments above concerning the mess involved in repairing a boat with concrete ballast, i.e., the wood obstructed by concrete in the bilge, would suggest that it may not be a worthwhile construction technique.

[RonW]

http://media5.hypernet.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=009412

I followed with great interest when the above thread was going on.It makes perfectly good sense, because concrete has tremendous wicking action, and will redistribute the moisture throughout the slab, then release it through evaporation into the atmosphere.
If I was going to use it inside a wooden hull, I would put it in only about 8 inches deep, and then a thin layer of sand with another slab on top and so forth. The sand would keep the slabs from bonding into one large mass, making removal if needed a lot more reasonable instead of trying to jack hammer out a 2 foot thick layer of concrete.

I fully understand why the old time wooden boatbuilders did not readily use it.
First off concrete is relatively light compared to lead, about 1/6 the weight.
And then it is basically a product of the early 1900's and really wasn't that readily available till the 30's and more like the late 40's.These bag mixes that you can buy anywhere, like sakrete, these companies where just started in the 30's. Ready mix concrete companies didn't spring up till after world war2, so concrete was still the new kid on the block,while the boat business was already changed to steel hulls, and the old time wooden builders continued as best they could in the old ways, just trying to survive, so why experiment.

[kc8pql]

Originally posted by RonW:

And then it is basically a product of the early 1900's.......so concrete was still the new kid on the block,Actually, the Romans used concrete extensively. The Coliseum is concrete.

I don't see anything particullary good or bad about concrete ballist. It's just another option, depending on the type of boat and how much money you have to spend. The old designers didn't use it because they where designing for wealthy clients. Besides, when your fee is based on a percentage of the cost of the boat it's not in your own best interest to cut costs.

[Ken Hutchins]

The boat JOAN designed and built by Atkin in 1927, this is the boat about which Atkin wrote "Of Yachts and Men" had concrete in the bilges, that boat is still sailing, I was told by the person who restored it about 15 years ago that the concrete was chipped out for surveying and the wood under the concrete was great, so new concrete was put back in.

[RonW]

Ken - sounds like hard core info to me.
Atkin thought outside the box, that is for sure.

KC8pql- Concrete was the new kid on the block.I have heard the (theories) of the romans, egyptians and chineeses. But those where slurries, kinda like mexican adobes, bricks of mud and clay.Here is the history of concrete, as we know it to be today.

http://matse1.mse.uiuc.edu/~tw/concrete/hist.html

1824- english patten on portland cement.
1871- american patten on portland cement.
1891- first concrete street.
1903- first concrete highrise.
1936- first major dam.
It would appear that when Atkin put concrete in the bilge of the Joan in 1927 , he was definitely thinking outside the box.

[Ed Burnett]

Concrete in the bilge of many working craft is practically normal this side of the Atlantic. In many cases its density was inceased with the inclusion of scap iron or lead.

I have had most involvement with this in original Bristol Channel Pilot Cutters where it was considered standard practice from the latter part of the 19th century onwards. One hears all sorts of stories of builders including empty bottles or cork in the concrete in the ends of the boat in an attempt to reduce the weight.

Cleary then it was considered to have value other than ballast or they would simply have not put any in the ends at all. This seems to be borne out in what one sees of old boats that have been ballasted in this way as the structure under the concrete is often the best preseved in the boat.

From a technical point of view, these old boat types tend to be shaped to carry large volumes of internal ballast. Concrete as an external ballast keel would not be a very efficient choice.

[George.]

I have read that the concrete acts as a wood preservative - perhaps because it is alkaline. It would also stop bolts from rusting, as long as no bits are sticking out. And you would think it would render the bottom of the boat pretty much immune to structural damage, even after a hard grounding.

And I have never heard or read of a boat having rotted or had any other sort of problems underneath the concrete - the typical anectdote is of a great effort to take out some concrete for a survey of an old boat, only to find a perfect hull under it, as in Tilman's Mischief .

[kewlrunninz]

WELL NEVER THOUGHT THAT THE RESPONSE WOULD BE SO CROWDED, LOL. ANYWAYS MY QUESTION CAME ABOUT BECAUSE I MADE A HEAVY SAND TO PORTLAND CEMENT MIX AND PENCIL VIBRATED IT BETWEEN THE RAILWAY TRACK THAT IS IN THE BILGES OF MY "LITTLE DANISH SHIP" (64' 1903 SAILING TRAWLER).
I DID THIS IN 1989 WHEN I DECIDED TO REINSTALL AN INSULATED FISH HOLD INTO HER AND TO PUT HER BACK TO COMMERCIAL FISHING. TWO WEEKS AGO I REMOVED THE FISH HOLD AND CHIPPED AWAY APPROX. 3 INCHES DOWN AT THE CEMENT/SAND AROUND THE FRAMES TO SEE WHAT THEY LOOKED LIKE AFTER 16 YEARS OF FISHING. THEIR CONDITION IS AS THEY WERE BEFORE THE CONCRETE WAS INSTALLED, I TOOK PHOTO'S OF THE THOROUGH PREP OF THE BILGES AND FRAMES (REMOVING OF RAILWAY TRACK AND SCRAPING/CREOSOTING ..ETC.ETC.)BEFORE THE JOB WAS DONE IN '89 SO HAVE A RECORD OF THE CONDITION OF THE ENTIRE BILGES.
AT THAE SAME TIME I REMOVED EVERY THIRD CEILING STRAKE AND POURED CLOSED CELL URETHANE FOAM IN ALL THE FRAME BAYS FROM COVERING BOARDS TO CONCRETE. THERE WERE NO AIR POCKETS LEFT.
OVER THE YEARS I HAVE REPLACED A FEW OUTER PLANKS AND HAD THE OPPOURTUNITY TO INSPECT THE FRAMES (5"X6" DOUBLE SAWN) WHICH SHOWED THE CONCRETE AND FOAMING TO BE COMPLETE AND TIGHTLY FILLING ALL THE SPACES. AT LEAST IN THE WAY OF THE PLANK'S THAT WERE REPLACED.
MY DECISION IS TO LEAVE THE CONCRETE WHERE IT IS AS WELL AS THE FOAM BETWEEN THE CEILING AND PLANKING. I WILL REPLACE THE MISSING CEILING STRAKES AS THE "HOLD" IS TO BE CONVERTED TO A MAIN SALON.
IF IT IS POSSIBLE I COULD POST SOME PIC'S IF INTERESTED....THANKS TO EVERYONE FOR THE REPLIES.........PETER

[DLC]

please do

[paladin]

The Romans invented hydraulic cement....and the reason the mix was so dense, they used volcanic ash in the mortar. Cement does not bond well with new steel or iron mesh because of the mill scale...so let it stay out in the weather for a while ot clean it, then mix a 1 percent by weight of Chromium trioxide to the water mix to reduce the chemical reaction to any zinc particles that are on the metal.

[Chan]

If concrete works so well with wood, why is it that FMA and FHA require that wood in contact with concrete be pressure treated?
I wouldn't do it. The fishing boats and commercial boats using it have a life expectancy of 20 or so years. Probably why most commercial craft are frp, steel, or aluminium nowadays.
At 144 # /cu.' you would need quite a bit of concrete to equal 700 some odd #s / cu'.

[Nordicthug]

Almost every wooden workboat I've had any experience with in my 35 year stint in repair yards in the Seattle area has had concrete ballast. Many yachts, both sail and power, as well.

Limit seiners in particular use concrete ballast to fair the bilges and fish holds to assist in keeping things clean and gurry free. There seems to be a bactericidal effect to concrete as most fishboats I've had to do with that have cement ballast tend to smell pretty clean, as opposed to some that had loose ballast covered with pitch / tar ("Jeffrey's Marine Glue") that stunk to high heaven.

Quite a few have boiler punchings in the mix in place of gravel to increase the weight.

Where the wood is in contact with the concrete it tends to be nearly rot proof.

Gerry

[George Ray]

google (books): concrete bilge

Practical Shipbuilding: A Treatise on the Structural Design and Building of ...
By A. Campbell Holms

http://books.google.com/books?id=qHuQcI0SrrIC&pg=PA455&dq=concrete+bilge&ei=IKF9R9j0NZ-4tgOY1aTFBA

[Jay Greer]

In the fifty so odd years I have been in the boat building game, I have come across many boats that had cement poured in their bilges as added ballast. Most of these were Monterey Fish Boats that were in need of repairs that did not relate to the concrete ballast. In all cases, there was no evidence of structural deterioration*or rot in the areas of the cement fill!
Jay

[kulas44]

In a sailboat you can mount the auxilary diesel engine to a concrete pad and never feel it running. In the process duing away with engine beds etc. as long as you are able to rod it to the stringers. The 15 kw jenny in my trawler sits on about a ton of concrete....no vibration at all to the hull.

[andrewe]

Ed´s comments about bottles, cork being added to reduce density I find interesting. When I was in Portugal, they were busting up old fishing boats to reduce the fleet size. Chainsaw and back hoe were the standard tools. I noticed the concrete ballast had a lot of pine cones in it,must be the same idea. Puzzled me at the time.
Andrew

[Bob Triggs]

A fellow whom I know who is restoring a classic and quite important vintage sailing schooner, recently spoke about using "limber cement" in the work. He explained that sometimes builders used portland cement to improve the flow of water toward the bilge. They would shape the cement into the timbers as needed. Kind of like a gutter system. So it would make sense that someone could have used cement for this purpose but may not have wanted the extra weight of a solid mass of cement, so thay used lighter or more bouyant objects and materiels entrained into the mix to reduce overall weight. From what this man says this was a common practise in the older days and quite effective. He also says there is no rot issues with this method. (I am protecting his privacy by not mentioning his name.)