Hi. I'm looking for recommendations for a repairer for a ferro hull on a sailboat based in Sydney please. Any help or guidance much appreciated.

You probably will have to do it yourself.
look online, I think there are some good blogs etc about ferro repairs.

Depends what the problem is. The most difficult is going to be if the concrete is "spalling" ie rust has got to the reo and it is expanding. Could be terminal, but maybe do a search for concrete repairers and see what comes up.

Ferro boats are interesting things

it seems that most people who don't own them are sceptical whereas most owners seem to say they are a good thing

I was surprised to read in a article about the how thick the hull needs to be ( I can't remember what it was but it wasn't very thick) and how anything thicker than that was just added weight

Regards Don

The trick was and I say was because I don't think a ferro has been done in say 20 years, was / is to keep the reo bar & wire net in the middle of the render. For tradies whom rendered / hard plastered buildings all day everyday, not such a hard trick to get hold of, and those vessels will be around for a long time. Repairs might consist of chipping out the old damaged render from say a hole punched from a collision with a wharf and re rendering , or instead of using cement an sand to effect that sort of repair epoxy & thickener and maybe some fibre glass. But as Yarra pointed out if the reo is turning to rust it's not good

Select to expand quote

Donk107 said..
Ferro boats are interesting things

it seems that most people who don't own them are sceptical whereas most owners seem to say they are a good thing

I was surprised to read in a article about the how thick the hull needs to be ( I can't remember what it was but it wasn't very thick) and how anything thicker than that was just added weight

Regards Don

There were quarter tonners built in Victoria in the seventies where the ferro hull was 1/4 inch thick!

I know very little about ferro boat repairs . But because this is the interweb thingo ,i will put my two bobs worth in the mix .
If the chicken wire and or reo bars are rusted ? you would need to cut that out and replace with new overlapped at least 300mm back over good existing reo and tied with tie wire . re render with sand and cement 50 /50 mix wit bondcrete added . epoxy coat until you are sick of doing so . Good luck . Remember i know nothing about ferro boat repairs.

Ferro cement would be a great idea if it were not for the ferro. I'm a civil engineer that knows about concrete, reinforcement and corrosion, but I have no experience with ferro cement boats.

Some engeeringy-geekery ... The calcium and magnesium carbonates and sulphates in the cement set up an alkali environment, which protects the ferrous reinforcement. Over time, carbon dioxide in the air, and seawater get through the barrier, reduce the pH and attack the iron, causing rusting and spalling. Rusted iron takes up about 19 times the volume of the parent metal. The expansion forces the cement barrier out with spalling and cracking, which improves the pathways and accelerates corrosion. The reason the reinforcement is there is because cement (hence concrete) has little tensile strength, which means that thin elements (such as boat hulls) would be brittle, and easy to break. The reinforcement also controls cracking as the cement/concrete shrinks after placement. The setting reaction is exothermic, causing the mass of cement/concrete to expand initially when mixed with water and placed. Although the Hoover Dam is still cooling down from the reactions from when it was first built, thin-hulled boats are probably well past the reaction-cooling stage.

So, a useful development would be to replace the iron reinforcement with some other, non-corrosive fibre to provide the necessary tensile strength without the vulnerability of iron. However, there are few commercially viable options, or it would be used more widely. One of the problems is effectively mixing the non-iron fibres with the cement/aggregate mix - lightweight fibres tend to float to the top. Another is cost. Alternative technologies include cathodic protection, but it can't be applied effectively in retrospect - it has to be designed and built into the thing One of the conditions for cathodic protection to work is a continuous electrical circuit throughout the reinforcement, which is probably hit-and-miss with the dry-jointed reinforcement in a ferro boat. You also need an earth ... and this is the point when I get fuzzy and hand over to the electrical engineers.

None of this helps the OP much, except to say that steel-reinforced concrete (and hence ferro boats) have a limited life. And when it starts to rot, there is not much you can do about it, except major surgery, such as replacing large panels of the hull and hoping that the relative stiffnesses of the original and replacement panels are close enough not to cause the whole to work apart under sail.

Interesting fact about the Hoover dam. I saw a reo product advertised last year that was made from spun basalt,( it may have been mentioned on seabreeze, ) it would be a way to avoid rusting reo in a new build, most all of the long lived vessels where glass epoxy sheathed. I know of one that is discribed as glass composite for insurance purposes. I don't think anyone in this era would consider a ferro build, new boats are popped out of moulds and 2nd hand boats are cheap and numerous.

Select to expand quote

Achernar said..
Ferro cement would be a great idea if it were not for the ferro. I'm a civil engineer that knows about concrete, reinforcement and corrosion, but I have no experience with ferro cement boats.

Some engeeringy-geekery ... The calcium and magnesium carbonates and sulphates in the cement set up an alkali environment, which protects the ferrous reinforcement. Over time, carbon dioxide in the air, and seawater get through the barrier, reduce the pH and attack the iron, causing rusting and spalling. Rusted iron takes up about 19 times the volume of the parent metal. The expansion forces the cement barrier out with spalling and cracking, which improves the pathways and accelerates corrosion. The reason the reinforcement is there is because cement (hence concrete) has little tensile strength, which means that thin elements (such as boat hulls) would be brittle, and easy to break. The reinforcement also controls cracking as the cement/concrete shrinks after placement. The setting reaction is exothermic, causing the mass of cement/concrete to expand initially when mixed with water and placed. Although the Hoover Dam is still cooling down from the reactions from when it was first built, thin-hulled boats are probably well past the reaction-cooling stage.

So, a useful development would be to replace the iron reinforcement with some other, non-corrosive fibre to provide the necessary tensile strength without the vulnerability of iron. However, there are few commercially viable options, or it would be used more widely. One of the problems is effectively mixing the non-iron fibres with the cement/aggregate mix - lightweight fibres tend to float to the top. Another is cost. Alternative technologies include cathodic protection, but it can't be applied effectively in retrospect - it has to be designed and built into the thing One of the conditions for cathodic protection to work is a continuous electrical circuit throughout the reinforcement, which is probably hit-and-miss with the dry-jointed reinforcement in a ferro boat. You also need an earth ... and this is the point when I get fuzzy and hand over to the electrical engineers.

None of this helps the OP much, except to say that steel-reinforced concrete (and hence ferro boats) have a limited life. And when it starts to rot, there is not much you can do about it, except major surgery, such as replacing large panels of the hull and hoping that the relative stiffnesses of the original and replacement panels are close enough not to cause the whole to work apart under sail.

The ferro work boats are probably the longest lasting boats out there. Dutch barges must be well over a hundred years old now.

This is the 54 foot American built ferro schooner that used to be parked next to my boat. My boat is visible just behind. She came off the mooring and ended up on the bank down the river. Mooring chain failed. She had full insurance and the boat was recovered. About 3 days later after a shipwright inspected her she sank at the mooring. She was refloated and this photo was just after, mud all down the sides. The insurance company tried to sell her and I even tried to give her away on this forum. She eventually was towed away and destroyed. Masts and new furler cut up and sent to the scrap merchant. 50 years old at the time. Hull was immaculate.

Hi Ramona

Do you know the reason why she sank

Regards Don

Select to expand quote

Donk107 said..
Hi Ramona

Do you know the reason why she sank

Regards Don

I think the key words were shipwright and insurance.

Thank you all for your feedback - much appreciated.