ferro cement..is that a good building material???

[reginaldvanacker]

Hi looking for a boat I came up with a possible choice, only it is ferro cement, can anybody ex[lain me what kind of material it is and if it has disadvantages? ( boat is built in 1980) thanks

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[Ric]

Don't buy it!! They suffer badly from "concrete cancer" whereby the iron reinforcing embedded in the concrete rusts. Has it been "freshly repainted"? If so, definitely don't go near it.

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[CharlesM]

hmm... Ric - That seems like a rather sweeping statement.

I am busy negotiating for a ferro boat, and would like to know what you base your statement on. (am I doing the wrong thing?)

Anyone else in the know perhaps have a comment on Ric's comment?

Cheers
Charles

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[Trevethan]

Ferro cement is basically a steel armature plaster in cement. For larger boats (40 foot plus) it can be a very good building material.

Good ferro boats are great, but there are a lot that were knocked up in people's back gardens that weren't -- look for a yard built boat, and get a survey.

As an example I saw what was supposed to be a Hartley Tahitian, but was modified to a junk rig. Spoke with teh designer and he said that according to his plans, the hull was not suitable.. too many forces too far forwards.

He also looked at her lines and said by thge waterline she was at 10 tonnes too heavy, probably due to poor plastering.

Ferro boats generally sell at a considerab;lle discount to steel and grp boats of similar size in the UK, partly becasue the hulls are cheaper to build, but it also reflect a prejudice that many have against ferro.

In Australia and New Zealand there are many more ferro boats and there are viewed with less disdain.

Try www.ferro-boats.com for some hints.



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[Trevethan]

Ric, by the same token one shouldn't buy steel boats because they rust, GRP boats because of osmosis, rotting cores, wood boats because they rot and aluminium because of the galvanic corrosionris...

I think your post prrobably typifies the view that many have of ferro boats, which is why they are much cheaper.

A crap boat is a crap boat is a crap boat, not matter what it is made from.

One issue about ferro boats is insurance -- it can be tough to find.

Companies view them as a bad risk becuase of the homebuild factor and also becuase when a number of owners tried to seel their boat they didn't get what they expected and some then sank in rather odd circumstances.




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[Chris_Robb]

Charles - I was following your earlier post (I Think)

I have seen a number of ferro boats where ther are rust weeps down the side of the hull. This is often coming from the armeture - which is rusting, probably because of poor layup or damage. When iron rusts it increase hugely in volume - so if this starts in a big way, you have a real problem.

Other problems are (from a friends experiance) getting insurance. - It took him nearly 3 months, and only got 3rd party in the end plus total loss.

As a result of these prejiduces they are a real problem to sell, even when cheap.

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[boatless]

Windboats had an excellent reputation too.

<hr width=100% size=1>my opinion is complete rubbish, probably.

 

[AndrewB]

<blockquote><font size=1>In reply to:</font><hr>

Ric, by the same token one shouldn't buy steel boats because they rust, GRP boats because of osmosis, rotting cores, wood boats because they rot and aluminium because of the galvanic corrosionris...

I think your post prrobably typifies the view that many have of ferro boats, which is why they are much cheaper.

A crap boat is a crap boat is a crap boat, not matter what it is made from.

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Isn't the problem that ferro repairs are a lot harder to fix than GRP, steel, and wood? And that while GRP, steel and wood problems are evident on the surface, and can generally be dealt with early and without major reconstruction, ferro might lead to finding rot throughout the armature, to the point that the hull simply crumbles away. Does this ever happen?

I too have thought about ferro, but been put off by its reputation.


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[Trevethan]

Ferro repairs are generally easy. I had a couple of rust spots on mine. I ground back until I had bright metal maybe 3/8" below the surface, painted with with a rust inhibitor and filled with an epoxy based filler "repair stone for good" very easy. and not had a problem since,



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[jeanne]

I have a ferro boat, which I built in my backyard twenty years ago. I have sailed it many miles, [two atlantic crossings] and repaired collision damage holes in it from an inch or so across to about four feet across. It is still seaworthy, and insured, and IMHO, the prettiest boat on our river.
There was this investment guru, was the name Warren Buffet?, who said that the secret of his success was never buying anything he did not understand, so I guess the short answer is don't buy it.
But if you really want to go sailing, and are prepared to learn about the material, then it is a fine way to go. They are strong, with a comfortable motion at sea, due to their weight, and usually to a traditional , sea-kindly design. It is hard to insure a ferro boat, but it is hard to insure any boat for long distance cruising, so why not buy a cheap concrete boat, and go sailing, insured for third party risks, in the knowledge that you could lose the boat without losing all your money? My mate Jimmy Harris refloated and repaired one which had hit a reef in the Chagos Archipelago, with a sack of cement and some chicken wire, and I would like to hear from any steel, GRP, wood or aluminium boat owner who can say the same.

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[CharlesM]

Hi Jeanne

Who insures you? Is it full insurance or 3'rd party?

Is it heavily loaded because its ferro?

Cheers
Charles

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[richardandtracy]

One thing that's not been mentioned about the ferro boat is that, while it is called concrete, it's usually made from a 1:1 sand/portland cement powder mix. This is usually very alkaline which prevents the steel mesh core from rusting. It is also very impermeable to water and chloride ions.
The material is usually very poor in tension - so you need a good thickness to the hull to be able to withstand bending forces induced by waves [or rocks!]. Some ferro is made very well and can be very flexible - but take that as the exception. The material is one of those few materials where is gets stronger with age, so a 20 year old boat is likely to be stronger than a 5 year old one (all other factors being equal).
The impact resistance mechanism of concrete is microfractures rather than much elastic or plastic bending - so repeated pounding can seriously damage the material.

If you see rust weeps from the boat it'll usually be due to small cracks in the cement allowing water to get to the steel core. This must be dealt with as the steel reinforcing expands and spalls off the concrete, and there will be zero strength in the hull material perpendicular to the crack.

Concrete cancer is possible, but not very likely in a hull as it's usually caused by chloride ions being introduced into the mix at the plastering stage (something that's fairly difficult to do if you are not using ballast dredged from the sea floor). The cancer occurs when the cement component reacts with the chloride ions to create a high volume jelly that can burst the concrete.

Whether you buy the boat is up to you.. If it's home made, I'd suggest you look at the build quality of the rest of the boat. If it's good, [and by the same person as plastered the hull!] it's likely the hull will be well founded. If the workmanship elsewhere is not good - make you own conclusions as to whether it's good enough.

Personally I prefer ferro to glass - I'm more comfortable with the repair processes and initial manufacture processes involved. However, I prefer steel even more, and made my hull out of it.

Regards

Richard.


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[Peppermint]

Re: Worth considering

I'd prefer one to a wooden boat if I was going Bluewater on the grounds that my woodwork is shabby but I can plaster and weld.

You need to find out a lot about the boat though. Some were built by people who hadn't a clue. The problem is excessive rusting of the structural steelwork and inconsistant plaster quality or thickness. If it was built by a sensible team these matters will have been sorted. If there's no rust anywhere that will be a remarkable piece of structural steel.

I'd have thought you could find a surveyor who knows a bit about this construction if you try the professional bodies.

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[CharlesM]

wow

talking about ferro-fement (FC) boats certainly gives me some serious mood swings.

I have just heard today my offer (happens to be the maximum I gave myself before entering negotiations) for a FC boat has been accepted.

Given I am spending close on my lifes savings (which is not that much!) I am of course very nervous about it, and then when getting the negative comments about FC I of course wonder if I am doing the wrong thing.

It is always nice to see informative posts (like Richards) and of course like to hear from those that have FC boats and are happy with them. Any pointers to competent or good surveyors would be appreciated.

For my 2p - I would never be able to afford as nice a boat as I am in the process of purchasing if it was not FC. You get a lot of boat for your money. I am of course afraid that should it (living on board) turn out to not to be my (or Felicity's) cup of tea, that I may find it difficult to sell, given there is such a small FC market. (It swings both ways I guess) I did read somewhere that when it comes to selling, FC owners find it really hard to shift their boats. Millstone was a word the writer used!

Anyway - hopefully soon I will be telling you nice people I am taking delivery. I am not getting too excited yet, since it can still fall through (and did on a previous attempt-different boat) but... well - I am reaching for my dream

Charles

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[seaesta]

Yep its a good building material - especially for buildings. Not sure about suitability for home/ameteur boat building though!

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[Trevethan]

What is the name of the vessel? PM if you like. It's just that dodgy fijian I mentioned earlier was heading south when last I checked...

We saw her in Bristol and could have had her for £20k or so... and she was originally up for £70k, but I chatted to a surveyor who looked at her for another buyer and he was rather concerned about the weight and rig , as was the designer

Try www.ferro-boats.com for some ideas about surveyors.

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[northener]

I don't know all that much about ferro-cement - but in a discussion I did hear once that you should have a good look inside at the primary "ribs". If these are quite pronounced then there is a possibility that they might be steel tube which is not so good as they can rust from the inside out - solid bar is better which will still be evident but not as much - someone else will have to suggest possible sizes though.
I also heard that if you take a solid bar and sweep it along the hull you should hear a "ring" if all is well - that dull sounding areas could suggest problems with cement not being fully adhered to the reinforcement.
A good surveyor will be invaluable (enter Nigel?

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[jeanne]

Hi Charles,
I am insured with St. Margerets, and I am satisfied with them, even though they charge about 2% of insured value, twice the usual rate.But they tell me that they only cover me because I first insured with them twenty years ago, when they accepted all types of constuction, and that now they will not take FC, so that information is not much use to you.
The best book to explain the different techniques of FC construction is 'The First Ferro Boat Book' by Pete Greenfield, which is probably out of print. Other books are usually only about the writers own system, [Hartley etc.]which is fine if that applies to your boat, and the builder stuck to it, but there are feuds within the FC world ond no- one has the 'Best' system. Windboats have their own system, are highly regarded and probably the only ones to be correctly called 'professionally built'.
There is a site called 'the world of ferro boats' where the answers to some questions may be found.

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[aroma]

don't get me started
I put a hole in my yacht a month a go startes to repair it at approx 10 oclock and was all fixed except painting by 2 oclock try that with any other medium,
During our blow in 2000 sinking 34 ish vessels most were scraped the 2 ferro yachts were repaired with a nother on 2001 its is sailing very well as said before a good ferro is a good yacht find a survayer that has ferro experiance or somebody that has owned a ferro vessel
you could try www.hartley-boats.com
or hartleys ferro cement boat building published in 1979 might find it in the libarary Warren

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