Intelligent Discussion on Ferro

[Tnflakbait]

I think the best thing about FC boats is that they are cheap. Thats always cool. If you like a heavy boat they are good as well. Like others have said amateur builders have given them a bad name. I have seen very few FC boats with fair hulls, but they do exist. If they sink in the harbor they make a great mooring for the next boat!

[Weyalan]

Back in the 70's ferro yacht won line honours in probably the msot prestigous blue water yacht race int he world; the Sydney to Hobart. Helsal II was a fine example of a "good" ferro boat - well built and quick. She won a lot of races and broke a lot of records (even thoughshe had the nickname "The floating footpath").

Ferro boats have got themselves a bad name (rightly or wrongly) because of horrible build quality by backyard builders. One of the most important things about a ferro hull is that it should be poured in a single shot so that you are never trying to bond new wet material onto older material that has already dried. ood ferro boat hulls are made in a single day, utilising lots of builders at once. Too many ferro boats were built by one or teo builders over days, weeks, months & even years in back yards. Backyard builders also seemed to have a mentality that more was better, which, with ferro, is not the case.

So, well built ferro boats are absolutely fine. Badly built ones are a disaster wating to happen. Unfortuantely, the bad ones have given the good ones a bad name. How many bad ones are out there and what is the ratio of good ones to bad are questions that merit further consideration.

Unfortuantely, one result of the "bad" ferro boats is that it is hard to get insurance on ferro boats, even if you have got a "good" one.

[dana-tenacity]

If you find a good one you can get it at less than the replacement cost of the other gear onboard, use it as a mould and build another.

[coot]

Originally Posted by Alan Wheeler

It's hard to repair!. No it's not actually. It is one of the simplest medieums and certainly the cheapest of all to repair.

Originally Posted by Weyalan

One of the most important things about a ferro hull is that it should be poured in a single shot so that you are never trying to bond new wet material onto older material that has already dried.

These two statements have me wondering how you would repair it. Would you use cement to patch a hole, like you would use epoxy with fiberglass? If so, how would you make the new cement stick to the old material?

[Alan Wheeler]

Sean said...I wasn't implying ferro would be lost more easily.

And no implication taken Sean. I know exactly what you meant.

Mark, thats a good question. Firstly let me address the one shot and two shot methods. It's a little confusing to some and slightly a misconception.
There are two accepatable methods. A one shot, that means that the inside and outside is plastered in one hit. This technique is fine for smaller hulls, but a little too much for large hulls. So.....
The other method is the two shot. This is done by the outer side of the hull being laid up first and allowed to harden enough that you can safely walk around the internals of the boat. Then the inside is plastered. This method is quite acceptable and is a very good way to build a boat. A lot more care can be taken to get plaster into tricky areas. All in all, it means the plaster team are not compleatly tuckered out trying to get the entire boat done in one hit.
Now where the issue comes in is if either the outer plaster and the inner plaster are done in several hits. The outer especially MUST be done in one go.
Now to answer you question on repair Mark. There are two ways of repairing the hull. Small damage can easily be done with Epoxy mortar. In fact, some hulls were attempted to be built entirely from Sand and Epoxy. But it became too expensive and unneccessary to build the entire hull that way.
For larger areas, the cement plaster is used. But an application of a bonding agent is used at the join of old and new plaster. This is simply PVA glue. PVA glue can also be used as an additive to a cement mix to make it more "plasticised". It helps with smoothing and shaping cement.
The biggest problem that occurs with repair is truing to get the old cement broken away fromt eh hull. I watch a guy swing a sledge hammer at the side of his hull and the thing bounced of and nearly took him off the scaffold with it. It took him a great deal of time and sweat to break away the area of damage.

[cooper]

As wheels has said...for small repairs epoxy is the easiest way. You break away any "broken " bits of cement that are still attached to the wire so you have a clean hole and exposed mesh. It is best to chip a little more away any where that you dont have an edge with exposed mesh. You then lace across between the mesh with similar size wire or lace in another piece of mesh. l then throw rust converter at the mesh but this is not always nessesary. Mix up a suitable quantity of slow cure resin (epoxy) and brush some of this over the whole hole and wire. Add your choice of filler to the rest of the mix to make a stiff paste. If the area is larger than 25mm it is best to have a "back up" plate on the in side of the hull. This can be any bit of stiff board stuck to the hull with a good strong tape. This board should be covered in packaging tape (the thin brown stuff) on the side that is going to have the epoxy against it because epoxy dosent stick to it. Trowel the paste in and try to remove any air voids. Trowel off slightly proud of the hull in an upwards direction. (No matter what you will get a little bit of slump and this helps). Let cure and then sand and paint. NEVER use car bog.........cheersMartin

[cooper]

Hey Mud nut l have put up some pics of christmas just for you !! Its under life on board and headed "bush fires" We got a blast of 85 knot SW, caused much crazy stuff, and a ridiculous 46 degree top temp (caused big headache) The most memorable new year thus far.........cheers Martin

[fragile]

hi all, i've gotta tell you a friend with a ferro boat who is the builder says ferro boats are cheap because the hull value should be considered to be nill, then some

[Alan Wheeler]

I don't quite understand your comment nor your point. The hull is labour intensive and there is a lot of steel in them. Cement and sand maybe cheap, but not free. So the hull costs money to build.

Speaking of the steel content. It is a better discription to say that an FC hull is actually a steel hull. The cement plaster just waterproofs it. The steel matrix is made of a husge quantity of steel rod and is layered with a lot of mesh.

[fragile]

thanks alan, i think the point is that without breaking into the hull and seeing whats in there and what its doing , unless you know its history you consider it a gamble. your comments were valid and even make sense

[mudnut]

Cooper,it sure has been a hard year allover.Pic's were cool man.From the Errie to Priceless,1st to last in that order.So in keeping with the thread,How is the interia of ya FC done,Iv'e seen a lot of minimalistic approaches and some rather lavish one's at that,I love the different concepts that people arrive at when designing there boat.Good ta see ya standing.Mudnut.

[muskoka]

I'm not sure about ferro-concrete as a hull material. Concrete is a great material but it takes a lot of skill to set up as the thicknesses decrease. And, basic concrete does allow water infiltration which would make me worry about the steel reinforcing. Architectural concrete frequently suffers from spalling when the thickness of concrete over steel reinforcing is too thin (less that 50mm) and that's just in rainwater infiltration. That would make your average hull 100mm + the diameter of the armature bars. Seems very heavy.

On the other hand, glass reinforced concrete (GFRC) can be cast very thin and is very strong. And it can be cast much thinner than it would with steel bars. That would seem a better pairing for a salt water environment.

But concrete is also very sensitive to the mixture (gotta do that slump test) and needs to be mechanically vibrated to fill in any air pockets. Not to mention the various admixtures, sequential pouring etc. I'd think a professional quality hull would cost the same as a fibreglass hull due to the labour required to do it properly. So I'm not sure where the advantage would lie.

That's my view as an architect with a basic understanding of concrete engineering - I'd like to hear from any engineers or FC boat builders about their views. Very interested actually, as it would be good cross-discipline knowledge in respect of some of my projects!

[Alan Wheeler]

And, basic concrete does allow water infiltration which would make me worry about the steel reinforcing.

Arrrr, now ya see, this is the biggest misconception out there. The cement plaster IS NOT CONCRETE! The plaster is a very different product. As different as Epoxy vs Ester. They may both have many similar characteristics, but they are very different products.

i think the point is that without breaking into the hull and seeing whats in there and what its doing ,

Now this is the other miconception that tags onto the first. There is no need to know what is going on inside the hull. The fact that it is Cement ensures that the steel is being kept safe. The very high concentration of lime in the plaster and along with a few other chimicals in there, ensure that the steel is very well protected. At the time of build, the best thing to do is actually allow the steel armature to rust slightly before the plaster is applied. This is because a chemical reaction takes place and the rust is converted to a stable iron product that stops rust form conitinuing. This allows the plaster to also get a "grip" of the steel rod better.
One of the major advantages of the cement plaster is that it is subject to reverse Osmosis.
I have now seen repairs done, that when the concrete was broken away, the steel rods inside looked possibley better than the day it was first placed. Certainly it was in great shape anyway.

But there is defintaly some valid concerns as well. How DO you know if the hull is OK or not. This concerned me when I first came into contact with FC, but I have scince seen a few hulls and now understand a lot more. Firstly, the biggest mistake made was the cement mix. Mainly in the sand medium used. It is important..no, Imperitive that the correct sand is used. I have scince found that it is very easy to spot the "bad" mixes. The sand needs to be clean, washed "sharp" river sand. Big mistakes were made by using beach sand. I have seen one hull that there were more shells in it than sand. Salt is the biggest killer. It dissolves in the wet plaster, but as it dries out, the salt crystillises and fills spaces that the sand should be. Then when it gets wet from rain,t eh salt washes out and the hull is left porouse. Very easy to spot as the hull literaly eats away and gets a white powdery stuff all over it, which is salt.
Apart from that, the other areas of concern is in the construction itself. How thick is the plaster? and how have deck fittings been held down. And how much as the builder used his own creative licence to go beyound the original design. If the orginal cabin top was sugested it should be ply, then IS it ply or cement. If the use of cement up high was not designed inthe original concept, the boat will behave something terrible.
Oh while I remember, another misconception is the keel Ballast. Steel punchings are often used for one very simple reason. Lead and Cemement do not like each other. Once again because of the chemical properties of the cement mix, placing lead into it results in a product called Lead Plumbate. The cement will NEVER set. It stays this mushy mess. So steel was the simplest thing to add to the Keel. It doesn't matter what goes down there, just as long as it meets the designed weight once again.

[Brent Swain]

My first boat was ferro. Minimal maintenance o the hull . I never heard of a ferro boat having structural problems at sea, but when mine hit a Fijian coral reef it broke up in very moderate conditions , like a pumpkin dropped on a sidewalk. Ive seen similar failures . They don't mind the sea, but hate hard objects. One newly launched one in Auckland was moored over a cut off piling. When the tide went out the piling went thru the hull and thru the foredeck, first night afloat.none of this could happen to a steel hull. My first boat wouldn't evern have been dammaged in those conditions had she been steel.
For the price, if they are cheap enough , one can very easily get more value out of them than one has ut into them. Live aboard for a few years and it owes you nothing. If you build another hull later, all that gear you get off them is probably worth more than the boat cost you initially.
After losing mine in Fiji I switched to steel and have lived happily ever after. The gear I salvaged made the next boat real cheap to build.I got many years of cruising out of her so she owed me nothing.
Brent

[ssullivan]

Brent, were you able to salvage the rig and everything? How much were you able to salvage to then fit to the new steel hull? Very interesting story.