TiggerToo
Well-Known Member
Just seen what looks like a very nice Colin Archer lookalike with a ferrocement hull (made in 1975). Are there any donwsides to this material for hull construction?
Ferrocement: why not?
- Thread starter TiggerToo
- Start date
AntarcticPilot
Well-Known Member
It's like the little girl who had a little curl! When it is good, it is very, very good - but when it is bad it's horrid!
I understand that the problem is that the vast majority of ferro boats were home builds. Nothing wrong with that - but it means that there are no consistent measures for quality of construction. And the difference between "very very good" and "horrid" is build quality. Has the concrete been properly consolidated, with no voids? Is the reinforcing wire of the proper quality? Is the concrete made with the correct additives and so on? I am not an expert, but I understand all these things can cause problems.
Anyway, the point is that there is no generalization anyone can make. On the good side, if it is still in one piece and looking good 35 years on from being built, then it is probably a good one! On the down side, it is very difficult to assess the quality of a ferro hull - but no doubt someone here will come along with some tips.
photodog
Lord High Commander of Upper Broughton and Gunthor
Difficult to Insure.
Difficult to Sell.
You need a Brickie to fix it.
Difficult to Sell.
You need a Brickie to fix it.
VicS
Well-Known Member
Here's a nice one
I don't know what the downsides are apart from the fact that the owner started building it at least 25 years ago ( but he did build it from the ground up) He must have launched it 7 or 8 years ago and he is still working on it. Not yet left the yard jetty as far as I know.
I don't know what the downsides are apart from the fact that the owner started building it at least 25 years ago ( but he did build it from the ground up) He must have launched it 7 or 8 years ago and he is still working on it. Not yet left the yard jetty as far as I know.
r_h
Well-Known Member
Agree with both, although third party insurance should not be a problem.
This means that even if it's one of the good ones the price needs to be really, really good.
If the price is right it can be a bargain way of getting a very heavy displacement traditional yacht.
Bajansailor
Well-Known Member
They are lovely boats - I sailed on a friend's 39' ferro-cement Colin Archer gaff ketch from the Hamble down to Lisbon one summer, and she sailed well and was supremely comfortable (19 tonnes displacement!).
And they should last pretty much forever - so long as you dont allow them to come into heavy contact with anything that is hard. Or soft for that matter.
Another pal (who is a Builder, of high repute) built his own 40' ferrocement yacht to an extremely high standard and she was beautiful. However she washed ashore here a few years ago in the aftermath of a hurricane and was pounding on a soft sandy beach (no rocks) for a while.
They carted her away in bits in a skip.
Another yacht came ashore on the same beach the following year in similar weather conditions. She lost her rudder, and had one very small hole punctured in the hull.
She was built of plywood.
My friend's Colin Archer was laid up here for a while, and they asked me to organise some repairs, including some plastering that needed to be re-done (the boat was approx 30 years old then). I found that repetitive gentle tapping with a small chipping hammer would fracture the cement quite easily. Extrapolate this up to the yacht aground with the turn of the bilge pounding on a coral reef, and what happens?
Some other pals had an encounter with a fibreglass jet-ski in Tobago last year - and the jet-ski managed to fracture the cement, which turned out to be quite a major repair job.
More about it here - http://www.el-lobo.co.uk/html/april_2009.html
And here is a photo of the damage - http://www.el-lobo.co.uk/html/april_09_photos_18.html
TT, stay with those lovely steel boats you are drooling over!
And they should last pretty much forever - so long as you dont allow them to come into heavy contact with anything that is hard. Or soft for that matter.
Another pal (who is a Builder, of high repute) built his own 40' ferrocement yacht to an extremely high standard and she was beautiful. However she washed ashore here a few years ago in the aftermath of a hurricane and was pounding on a soft sandy beach (no rocks) for a while.
They carted her away in bits in a skip.
Another yacht came ashore on the same beach the following year in similar weather conditions. She lost her rudder, and had one very small hole punctured in the hull.
She was built of plywood.
My friend's Colin Archer was laid up here for a while, and they asked me to organise some repairs, including some plastering that needed to be re-done (the boat was approx 30 years old then). I found that repetitive gentle tapping with a small chipping hammer would fracture the cement quite easily. Extrapolate this up to the yacht aground with the turn of the bilge pounding on a coral reef, and what happens?
Some other pals had an encounter with a fibreglass jet-ski in Tobago last year - and the jet-ski managed to fracture the cement, which turned out to be quite a major repair job.
More about it here - http://www.el-lobo.co.uk/html/april_2009.html
And here is a photo of the damage - http://www.el-lobo.co.uk/html/april_09_photos_18.html
TT, stay with those lovely steel boats you are drooling over!
Spuddy
Well-Known Member
There were two on the hard near me. One had hairline cracks vertically in the hull which were toshed over with paint before selling.....ooer. Other was OK and a lot of boat for the money. Inevitably ferro boats are great big lumps so everything needs to be substantial : rigging, sail area and a big engine and probably not many economies to be made there if fixing required.
MrCramp
Well-Known Member
I have always fancied a ferro cement boat. This is the link to the main source of information in the world!!
http://www.ferroboats.com/
http://www.ferroboats.com/
LittleSister
Well-Known Member
I sailed a friend's ferro boat for many years, and agree with most of what's been said above.
A good one is brilliant. Many are really rough, but they don't have to be. Many are grossly over-built, with the consequent effect on performance.
If you find it's got cracks or crumbling concrete, walk away - it hasn't been built properly. Tap test the hull all over for consistency of sound.
Small repairs are often very simple - much easier than wood or GRP. Setting off in a group for a ferro-cement boat rally in the Netherlands many years ago, one of the boats got swept by the tide onto a scaffold pole projecting from some works to a jetty, holing the hull just above the waterline. It would have holed any GRP or wooden boat, too, I'm sure. The rest of us continued after passing them some epoxy cement. The hole was repaired with this by the skipper and his mate the same day, and the holed boat caught up with us (IIRC) the next day.
I've seen them taking some serious bumps (including a collision between two ferro heavyweights) without any harm, so I suspect that the ones mentioned above that sustained inordinate damage were faulty in some way.
Note also that 'ferro' boats are that - ferro=iron. They are steel framed, and the cement 'just' keeps the water out and strengthens the frame. They should be immensly strong, but if the cement is faulty, that frame will be rusting away inside.
A good one is brilliant. Many are really rough, but they don't have to be. Many are grossly over-built, with the consequent effect on performance.
If you find it's got cracks or crumbling concrete, walk away - it hasn't been built properly. Tap test the hull all over for consistency of sound.
Small repairs are often very simple - much easier than wood or GRP. Setting off in a group for a ferro-cement boat rally in the Netherlands many years ago, one of the boats got swept by the tide onto a scaffold pole projecting from some works to a jetty, holing the hull just above the waterline. It would have holed any GRP or wooden boat, too, I'm sure. The rest of us continued after passing them some epoxy cement. The hole was repaired with this by the skipper and his mate the same day, and the holed boat caught up with us (IIRC) the next day.
I've seen them taking some serious bumps (including a collision between two ferro heavyweights) without any harm, so I suspect that the ones mentioned above that sustained inordinate damage were faulty in some way.
Note also that 'ferro' boats are that - ferro=iron. They are steel framed, and the cement 'just' keeps the water out and strengthens the frame. They should be immensly strong, but if the cement is faulty, that frame will be rusting away inside.
25931
Well-Known Member
I admit that the Snowgoose was built like a battleship but I was rather surprised when my port bow penetrated a ferro boat without sustaining a scratch. The repair was complicated by the need to weld as well as plaster. That happened a couple of years ago and isn't the reason why Equinoxe is for sale now.
snowleopard
Well-Known Member
Th biggest problem with ferro is that during the 70s the idea got round that you could build a huge boat for pence. Many were amateur built and they saved money in inappropriate places. Chief among those was the plastering. When faced with quotes for plastering equal to everything they had spent so far on materials, some oped to DIY resulting in poor quality, uneven thickness, improper curing and so on.
The really bad ones are obvious: mesh patterns showing on the surface, dents and flat spots, wavy sheerlines etc. The merely amateur are harder to spot.
One thing is certain - if you want to sell you'll have a hell of a job. The good ones are very good but the poor ones have given them all a terrible reputation.
Another point is that it's a heavy method of construction and anything under 35 ft is going to be very heavy displacement. Above 40 ft it starts to be competitive with other methods for strength: weight ratio.
Don't worry about hidden rusting of the reinforcement - as long as the armature is covered the cement will inhibit rusting.
The really bad ones are obvious: mesh patterns showing on the surface, dents and flat spots, wavy sheerlines etc. The merely amateur are harder to spot.
One thing is certain - if you want to sell you'll have a hell of a job. The good ones are very good but the poor ones have given them all a terrible reputation.
Another point is that it's a heavy method of construction and anything under 35 ft is going to be very heavy displacement. Above 40 ft it starts to be competitive with other methods for strength: weight ratio.
Don't worry about hidden rusting of the reinforcement - as long as the armature is covered the cement will inhibit rusting.
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Drifting off thread a bit, but how many people know about ferrocement aircraft?
The French built some pilotless target drones in the 50's out of ferrocement. Very thin cement, obviously, and they claimed only around 10% heavier than standard construction.
However one thing they were not designed for was a long working life!
The French built some pilotless target drones in the 50's out of ferrocement. Very thin cement, obviously, and they claimed only around 10% heavier than standard construction.
However one thing they were not designed for was a long working life!
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Following on from Snowleopard, I would be more hesitant about pronouncing no corrosion problems. I was once involved with the refurbishment of 1950's Unity prefab houses, which had precast concrete frames , lintols, and cladding. Many were exhibiting severe corrosion of the reinforcement bars, even with 15-20mm cover. In civil engineering, the recommendations were a minimum of 50mm cover to prevent corrosion; you are unlikely to have that in a boat hull.
xxyyzz
Well-Known Member
They generally weigh the same as the equivalent non-ferro boat, it's just that the weight that would be added as ballast at the bottom of the keel is instead in the construction of the hull. Making them a little slower and maybe less stable, but not significantly, and they're not racing boats anyway.
DownWest
Well-Known Member
Jay Benford in the US designed in Ferro and built a nice little 14ft. So it can be done. But he does not recommend it now, mainly as a result of another designer or two that pushed ferro as a cheap and easy way to build, resulting in the bad rep. A mate built a 34ft pinkey ketch from his design. Professionally plastered, it is difficult to spot it is not GRP.
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dukes4monny
Well-Known Member
I've often wondered......what happens to a ferrocement hull if it's struck by lightning? Does it act like a Faraday cage and protect everything inside, or, does it act like a large electric heater element and explode the concrete off the wire cage?
davidfox
Well-Known Member
There are some fab looking boats in there and some dont appear all that cheap either!!
Baggywrinkle
Well-Known Member
The latter ....
When struck by lightning it blows a hole in the hull where the resistance from the metal frame to the water is lowest (relative to the rest of the hull) - Depending on the guage of the wire frame, the frame shouldn't heat up much (check out the guage of a lightning conductor), but it will conduct the charge very effectively to its chosen exit point where localised heating causes the damage. It's down to luck really. My brother knows someone hit by lightning in South America on a ferro boat ... it went down like a stone, literally. Ended up stuck on the bottom bolt upright with a bit of mast and sail still visible.
Having said that, even plastic boats get holes blown in them by lightning - just depends where the exit point to earth (sea) is, and how powerful the strike.
Metal is best, faraday cage effect and large surface area with even resistance path to earth. Carbon fibre just goes bang and de-laminates as all the carbon fibres try to get away from each other while conducting the strike to earth.
Here's the after effects on a tree where the sap is vapourised blowing the tree apart ... (2 mins onwards)
http://www.youtube.com/watch?v=h0NOmFHByUc&feature=fvsr
When struck by lightning it blows a hole in the hull where the resistance from the metal frame to the water is lowest (relative to the rest of the hull) - Depending on the guage of the wire frame, the frame shouldn't heat up much (check out the guage of a lightning conductor), but it will conduct the charge very effectively to its chosen exit point where localised heating causes the damage. It's down to luck really. My brother knows someone hit by lightning in South America on a ferro boat ... it went down like a stone, literally. Ended up stuck on the bottom bolt upright with a bit of mast and sail still visible.
Having said that, even plastic boats get holes blown in them by lightning - just depends where the exit point to earth (sea) is, and how powerful the strike.
Metal is best, faraday cage effect and large surface area with even resistance path to earth. Carbon fibre just goes bang and de-laminates as all the carbon fibres try to get away from each other while conducting the strike to earth.
Here's the after effects on a tree where the sap is vapourised blowing the tree apart ... (2 mins onwards)
http://www.youtube.com/watch?v=h0NOmFHByUc&feature=fvsr
Bobobolinsky
Well-Known Member
Saw a ferro motor boat hull that the yard had tried to cut up. After trying a 9" grinder, they tried a sledge hammer. Neither method did much damage. Know a boat that was dropped by the crane, totally egg shelled down one side. Another was abandoned in the yard and cut up by a concrete busting company with big diamond saws and diamond cutting rope.
