Should I put concrete in the bilges?

[lesweeks]

Either side of the keelson in my restoration project there was a fillet of cement/concrete filling the 'v' shaped space, surrounding the ends of the frames and, I guess, preventing 'stuff 'n' muck' from falling down and lying there. The survey completed a few years back suggests that this is original from when the boat was built - 100 years ago next year. But it was all loose and broken and so I've removed it.

The question is, should I replace it, or just try to keep the bilges clean? It certainly wasn't waterproof and so moisture must have been kept down there rather than being able to evaporate away, but new cement may be more successful.

Does anyone have any experience or views on this? Advice gratefully received.

 

[Ludd]

That was standard practice in wooden fishing boats,but it was something that I never felt was a good idea----seemed to me it would be acidic,and damage the wood,apart from as you say ,trapping moisture . BUT having removed it after the thick end of 100years,if you've seen no ill effects,it would seem to be OK!

 

[petehitch]

I had an old Danish fishing boat that had concrete in the fish hold. On the insistence of the surveyor we removed it. The timbers were as new after 50 yrs. We replaced it after spraying with Cuprinol to be sure.

 

[oldfrank]

You need advice more expert than my memory - As I recall modern concrete attacks the wood and I think that lime based mortar is correct. If you can't find the answer PM me and I'll ask the orifice.

 

[BlueLancer]

Don't know for sure but isn't the concrete for ballast purposes as well.

 

[AntarcticPilot]

I'd be worried about concrete (as in Portland Cement types) - it is definitely BAD for organic material, and continues to leach for a long time. It is a no-no in sensitive areas of Antarctica.

 

[stuhaynes]

SEnsible answer, I think NO.

 

[old_salt]

If it was a small fillet of cement/concrete filling the 'v' shaped space, surrounding the ends of the frames and not sufficient to add any ballasting effect. Then it may have been there to prevent 'stuff 'n' muck' from falling down and lying there as you say.
One of the problems is the 'stuff 'n' muck' gets in builds up then packs in and forces the planks away from the keelson or hog and the same can happen along the horn timber in a counter also the rise of the stem where the ribs are tenoned into them.
A solution other than cement/concrete is Tar.
It is water proof and will not have any adverse affect on the wood and will stick to the wood even after a good soaking of wood preservative.
Get a chunk from a builders merchant heat it in an old cast iron pan and a good long handled ladle and pore in the V till you have just enough to allow any water to flow over the rib ends and though the limber holes.

 

[westernman]

Pilot cutters used to all have cement in the bilges over the top of the lead ballast. In the ends, they used to put less ballast and put in wine bottles and put the cement over that to give a flat surface down the length of the boat.

Owners of the original cutters, all seem to say that the wood under the concrete is generally very sound compared to the rest. As some one else pointed out, it might not me the same concrete you get today.

 

[lesweeks]

Thanks for all the opinions. I was at the boat today and it's not concrete but certainly a cementy type substance.

A solution other than cement/concrete is Tar.

What was interesting was that towards the bow the space was (is) filled with pitch which has not come away and still acts as a good seal. In light of that, I might take Old Salt's advice and use it instead - unless, of course, someone knows a good reason why I shouldn't.

 

[alan006]

As someone has already suggested, how about a compromise. If you line the woodwork with a thick layer of bitumin based paint then pour the concrete onto this. The bitumin will act as a natural barrier and protect the timber from any adverse chemicals in the concrete.

I've got a timber boat that was built in 1946 and someone had put a false deck above the saloon. I had to remove this as it was rotton and found that fortunately someone had put a thick layer of bitumin ontop of the saloon before building ontop of it. The result was none of the rot had damaged the original timbers below it. You can imagine my silent thanks to that person.

 

[Woodlouse]

Pilot cutters used to all have cement in the bilges over the top of the lead ballast. In the ends, they used to put less ballast and put in wine bottles and put the cement over that to give a flat surface down the length of the boat.

Owners of the original cutters, all seem to say that the wood under the concrete is generally very sound compared to the rest. As some one else pointed out, it might not me the same concrete you get today.

The ballast in the pilot cutters was very rarely lead. Mostly scrap metal and iron pigs. It's remarkable what you'd find digging out the concrete, in one boat when it was being broken up they found an artillery shell.

It is true though that the concrete in the bilge preserved the wood remarkably well. Any original material in the restored boats is more than likely to be underneath the ballast. As far as I know there's nothing special about the cement used either. Just a standard readymix truckload. Certainly acidity shouldn't be an issue as most woods are slightly acidic anyway.

On a different note, Hiscock writes about using cement as a filler for wood. I've come across it before in topsides and frames.

 

[alan006]

I wonder if the acidity in modern concrete could leach through the hull timbers and start attacking the hull fastenings?
As the previous poster has noted, older pilot boats can use alternatives to lead for ballast. I've seen granite blocks used for this purpose.

 

[Csail]

No idea where you get it now but try and source incanol.

 

[Bobobolinsky]

Why are you talking about acidity in cement/concrete, it's alkali, that's why it protects steel reinforcement from the seawater attack and does not corrode it. Ever tried to get cement off a plank, it sticks like sh!t. A friend has concrete ballast in the bows of his 60 year old boat. Unfortunately he had some corroded iron floors. We had to jackhammer the concrete out. Beneath the concrete was as if laid down yesterday. We replaced the floors, recast the concrete and then after it was cured floated it with hot roofing tar. One of the local boatyards took 40 ft out of the middle of a barge, and found that the concrete ballast was filled with artillery shells, so it was quite common after the war to use any scrap for ballast

 

[H/V Vega]

Oldsalt has the right idea mate

I would follow old salts advice on this one and go with the tar. Pitch would be even better if you can find it. I have seen that done in many a boat and with no bad results ever. Cement on the other hand has caused the death of more than one good boat where the owner was too cheap - or dumb - to get proper ballast in. I always figure we are responsible for making sure these old girls can live another 100 years and sometimes that is not easy to do. Then again that's why old wooden boat nuts like us were born.

 

[Nealo]

On the inland waterways many steel boats use concrete as ballast, and many a boat has had its life extended by pouring concrete into the bilges - it is certainly a very effective way of preventing corrosion. (How would reinforced concrete work otherwise?)

It's a shame concrete has an image problem. Many of the prejudices are based on ignorance, as demonstrated by those who refer to its "acidity". In fact concrete, as has been mentioned, in its wet state is highly caustic ie alkaline, it is well up the ph scale and will burn the skin as anyone who has been exposed to it for any length of time will testify. When set, however, it is practically neutral/inert so can't react with wood or any other organic material.

As the romans discovered, concrete is almost the perfect building material. Apart from its high compressive strength and ease of moulding, it is probably the most environmentally friendly of all building materials, more so than wood as there is very little CO2 involved in manufacture. Most of the problems associated with concrete are to do with poor design and sloppy building practices, eg Spaghetti Junction. You might say that it has been a victim of its own success - cheapness and ease of use leading to carelessness.

I think the same applies to the use of concrete as a boat building material. Used correctly it should be an ideal substance but there are too many horror stories of boat that were not properly built. But I remember in my home town a coal miner built a concrete yacht in his garden and eventually set off around the world in it.

All you can say as regards ballasting is concrete is probably inferior to lead or iron because it is less dense ie you would need more of it. On a yacht where you are trying, usually, to minimise the wetted surface area you need lead ideally & I'd suggest cost is the main reason why iron keels predominate. If space underwater isn't a priority you might as well use whatever's cheapest & you don't get much cheaper than concrete!

 

[sailorman]

On the inland waterways many steel boats use concrete as ballast, and many a boat has had its life extended by pouring concrete into the bilges - it is certainly a very effective way of preventing corrosion. (How would reinforced concrete work otherwise?)

It's a shame concrete has an image problem. Many of the prejudices are based on ignorance, as demonstrated by those who refer to its "acidity". In fact concrete, as has been mentioned, in its wet state is highly caustic ie alkaline, it is well up the ph scale and will burn the skin as anyone who has been exposed to it for any length of time will testify. When set, however, it is practically neutral/inert so can't react with wood or any other organic material.

As the romans discovered, concrete is almost the perfect building material. Apart from its high compressive strength and ease of moulding, it is probably the most environmentally friendly of all building materials, more so than wood as there is very little CO2 involved in manufacture. Most of the problems associated with concrete are to do with poor design and sloppy building practices, eg Spaghetti Junction. You might say that it has been a victim of its own success - cheapness and ease of use leading to carelessness.

I think the same applies to the use of concrete as a boat building material. Used correctly it should be an ideal substance but there are too many horror stories of boat that were not properly built. But I remember in my home town a coal miner built a concrete yacht in his garden and eventually set off around the world in it.

All you can say as regards ballasting is concrete is probably inferior to lead or iron because it is less dense ie you would need more of it. On a yacht where you are trying, usually, to minimise the wetted surface area you need lead ideally & I'd suggest cost is the main reason why iron keels predominate. If space underwater isn't a priority you might as well use whatever's cheapest & you don't get much cheaper than concrete!

(How would reinforced concrete work otherwise?)

The steel is in this case Enclosed no air/water can get to the steel

 

[H/V Vega]

Cement in wooden boats

Please do not do it mate. I have seen so many wooden boats killed by this cheap way out. It works for a few years then you can kiss the boat good bye. Several things happen none of which have to do with the cement itself. One is that no matter what you do fresh water gets between the cement and the wood and starts rot - rot that you cannot then get to to repair. When you need to make repairs - and that ability to change bits is why so many wooden boats have lasted over 100 years - it becomes a nightmare. There are many easy and better ways of ballasting your boat. I grew up in a boat yard and have had wooden boats for most of my life, I have seen first hand what cement in a wooden boats bilge can do. Please think long and hard about this before you do it. Sure its cheap, but it WILL kill your boat as sure as fiber glassing it would.

 

[Woodlouse]

Please do not do it mate. I have seen so many wooden boats killed by this cheap way out. It works for a few years then you can kiss the boat good bye. Several things happen none of which have to do with the cement itself. One is that no matter what you do fresh water gets between the cement and the wood and starts rot - rot that you cannot then get to to repair. When you need to make repairs - and that ability to change bits is why so many wooden boats have lasted over 100 years - it becomes a nightmare. There are many easy and better ways of ballasting your boat. I grew up in a boat yard and have had wooden boats for most of my life, I have seen first hand what cement in a wooden boats bilge can do. Please think long and hard about this before you do it. Sure its cheap, but it WILL kill your boat as sure as fiber glassing it would.

Sorry, but what you say flies straight in the face of all the evidence provided by the Bristol Channel Pilot Cutters where the concrete in the bilges is the only thing that has preserved most of them. Most of the original material on the rebuilt boats will be wood that was buried in the concrete below the waterline.

Providing it's done well then you have nothing to worry about concrete in your bilges. You have to quite carefully shape it so that water cannot get trapped anywhere, and instead runs off into a sump to be pumped out as any water left standing can start to cause rot in the frames as they exit the concrete. Other than this you have very little to worry about.