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Old 14-09-2011, 14:07   #61
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Re: Intelligent Discussion on Ferro

Barnakiel, regardless of the build material there are early signs of problems, wood boats rot, grp boats get osmosis and many other issues,steel boats rust,damage can lead to water intrusion with ferro,aluminum boats have their issues too but what is common to ALL is that there are early warning signs that need to be heeded. The problem is that very often they are not until the molehill has turned into a mountain.
Almost all Ferro boats are 30 or so years old and also all 30 year old production GRP boats are built with polyester resin, not epoxy, yes more and more newer boats are built with some form of epoxy but not the ones built in the heyday of ferro.
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Old 14-09-2011, 14:36   #62
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Re: Intelligent Discussion on Ferro

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Originally Posted by clockwork orange View Post
Barnakiel, regardless of the build material there are early signs of problems(...)
No doubt.

But you did not tell me what the 'early signs' of the metal grid corroding under the cement are!

Again, I would love to hear someone share on how heavy, say a 1 sq ft, of 20 mm piece of ferro-cement hull is and how this weight compares to other building materials at comparative strength.

I think if f-c were such a thing, the world would be full of f-c boats. Somehow, it is not. And there must be a good explanation.

?

b.
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Old 14-09-2011, 15:28   #63
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Re: Intelligent Discussion on Ferro

If you want to get your feet wet with F-C and get familiarity with the material, just build a wood dinghy, a GRP dinghy, a steel dinghy and a F-C dinghy. Row each of them around the bay. Leave them on a rocky beach during a storm, pick each one up and pack to an inland lake. Leave them tied to a dock for 12 months and check for any signs of deterioration. Assume no matter how good the paint job some paint will get scraped off or chip allowing salt water intrusion, so no paint.

Let me know how it turns out.
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Old 14-09-2011, 23:59   #64
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Re: Intelligent Discussion on Ferro

Quote:
Originally Posted by barnakiel View Post
No doubt.

But you did not tell me what the 'early signs' of the metal grid corroding under the cement are!

Again, I would love to hear someone share on how heavy, say a 1 sq ft, of 20 mm piece of ferro-cement hull is and how this weight compares to other building materials at comparative strength.

I think if f-c were such a thing, the world would be full of f-c boats. Somehow, it is not. And there must be a good explanation.

?

b.
First, I am no expert in FC boats but I imagine the first signs of a problem with the steel frame in any FC boats would be rust stains. Now, from my research and understanding of FC boats, rust stains "should" never appear because the steel frame is in-closed with the FC but nothing last forever, so if the FC coating, say on the gunwale's, has become worn or is damaged, and water can get to the steel framework, then that would show-up as rust stains. Rightly or wrongly, I believe if the damage is not severe, the damaged/worn area of FC could be cleaned-up and repaired using the proper FC mix, the specifications being:


1 part Portland cement
2 parts aggregate (1/3 sand; 2/3 gravel)
1 part water


Also gained from reading articles of building FC boats, I don't believe "lightly" rusted steel in the framework would be dangerous or disastrous for the boat. From what I've read, during building, rusting of the steel is preferable/stronger than clean steel, I've read, “Due to a chemical reaction between the lightly rusted steel framework and the FC, the FC bonds better and stronger”


As for why all boats/yachts are not built using the FC system? Not everyone can work with cement or mortar and get a good end result, nor can a lot of people get the steel framework right. On top of that, “if” a builder does get the framework right and true, he/she must then find a “team” of “good” plasters to get the hull plastered in one go! (I don't believe one man, or woman, could plaster a 35' and bigger yacht frame in one go on their own, never mind getting the hull fair) I guess companies building steel, alloy and fibreglass boats can get their boats out the door much quicker and cheaper than they could if they were building FC boats, that means more money in “their” pockets but that's only my views.


One more thing, during my search I have found a lot of FC built yachts and...They are all over the world...So I'm guessing they must have got from their build site to the foreign ports where they now are offered for sale by being sailed their by their owners/skippers.


Remember also...Many people fall in love with the “idea/dream” of living on their own boats, living a life of luxury while cruising calm tropical seas but, after buying/building and living aboard their boats for a time, sometimes quite a short amount of time, they find their dream is far from the reality of owning and living aboard their own boat, so they sell their dream and return to a life more familiar. i.e. living ashore, hiring a boat for a holiday afloat and handing the boat back after they get their sea fix.
Any and all boats needs work to keep them up to scratch, sometimes that means lots of hard work and, far from cruising calm tropical seas all the time, the sea can be a fearful place to be at times. I know from my experience at sea, there were quite a few times when I found myself wishing I was safely tucked-up in my cot ashore but...We had no choice but to ride-out the storm and thankfully make landfall safely. By the way, when I experienced those storms, I was aboard a 40,000 + ton, 14,000HP diesel engine steel ship but it was still frighting for me and...I believe anyone who says “I wasn't frightened in that hurricane” Well...I just don't believe them. It must have been pure hell for anyone on a small yacht, (any boat smaller than our ship) to have been caught in any of those storms and I hope they all made it safely ashore.


Cheers,


Bill
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Old 15-09-2011, 08:15   #65
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Re: Intelligent Discussion on Ferro

Quote:
Originally Posted by barnakiel View Post
No doubt.

But you did not tell me what the 'early signs' of the metal grid corroding under the cement are!

Again, I would love to hear someone share on how heavy, say a 1 sq ft, of 20 mm piece of ferro-cement hull is and how this weight compares to other building materials at comparative strength.

I think if f-c were such a thing, the world would be full of f-c boats. Somehow, it is not. And there must be a good explanation.

?

b.
The reason why you the world is not full of FC boats is obvious, like steel, wood, aluminum etc it does not lend itself well to mass production, plain and simple. So far only GRP does.
With any hull constriction you need to watch for early signs of problems and fix them immediatly, if you do this you will get a long life from any of the common materials, it really comes down just as much to the quality of the owner than the quality of the material. I have built a FC boat, many cold molded boats and GRP boats and done repairs on hundreds of boats of many materials and i can confidently say i would be happy with a well built,well maintained example of any of them. What may supprise some is that while FC was pushed as a home build material it is in fact one of the least suitable materials along with one off solid GRP because the skill level to turn out a hull that is indistinguishable from a pro build needed is extremly high, Why? because none of the materials that go into the build are self fairing, so and extreme amount of care needs to go into every step of the build to end up eith a beautiful hull, even metal hulls utilize self fairing materials which of course are nullified by a poor welding sequence but thats another story.
The early signs of problems with FC are as bill pointed out, rust bleeding thru, and spalled areas of cement from impact which are very easily repaired as soon as they are discovered, really it is just like with steel boats where you are constantly vigilant, touching up paint to protect the steel. Just in case anyone thinks that GRP is immune to maintainance i once had to recore a large area of the topside of a balsa cored boat (J35) where the damaged area was a hole about the size of of the end of my finger right on the edge where the hull meets the deck,something with a sharp edge had apparently been dropped on it so as a quick fix someone had googeed a blob of silicone in it and then never fixed it properly, over the years water got by it and travelled down the balsa (which baltek will tell you wont happen) and turned a very minor repair into a very expensive major repair, Of course poor build practice played into this also as the core should have been tapered out before it got to the top edge anyway but poor build practices are very common with GRP production boats in pursuit of the $$$.
Steve.
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Old 15-09-2011, 13:22   #66
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Re: Intelligent Discussion on Ferro

Quote:
Originally Posted by capn_billl View Post
If you want to get your feet wet with F-C and get familiarity with the material, just build a wood dinghy, a GRP dinghy, a steel dinghy and a F-C dinghy. Row each of them around the bay. (...)
I agree, and I modify: build a sailing dinghy, do all the tests you mentioned and sail them against each other!

I have seen GRP vs. F-C boats, same for same (e.g. Endurance).

b.
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Old 15-09-2011, 15:04   #67
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Re: Intelligent Discussion on Ferro

The steel in an FC boat will not rust unless exposed to oxygen. If the steel in question, and I have no idea what they used, either wire, (as in fence for hogs and such), or rebar. Oxygen with moisture are both required for rust. That is one reason it is called Oxidation. So, seeing as how there are no cracks for moisture and oxygen to get to the steel, it is not a problem. Every high rise building I ever worked on, with a concrete floor, first has a rebar or "hog wire" frame work, then wet concrete poured over it. Most elevator shafts are built the same way. Rust is not even figured into the equation.

Ultrasonic Testing can tell you where the steel is and what type used, as long as there are no voids in the cement. It can also be used to determine the thickness of the hull/deck.
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Old 15-09-2011, 15:16   #68
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Re: Intelligent Discussion on Ferro

Quote:
Originally Posted by barnakiel View Post
No doubt.

But you did not tell me what the 'early signs' of the metal grid corroding under the cement are!

Again, I would love to hear someone share on how heavy, say a 1 sq ft, of 20 mm piece of ferro-cement hull is and how this weight compares to other building materials at comparative strength.

I think if f-c were such a thing, the world would be full of f-c boats. Somehow, it is not. And there must be a good explanation.

?

b.
.6 cubic feet of quickcrete weigs 80 lbs. Steel weighs .2833 lbs per cubic inch, aluminum weighs about .10323 per cubic inch. That is just off the top of my head, but represents accurate weights. You can divide or multiply that from there.
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Old 15-09-2011, 22:02   #69
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Re: Intelligent Discussion on Ferro

For those seeking to learn more about Ferro Cement boats, you can get more information on Ferro Cement boats, straight from the horses-mouth at: The World Of Ferro-cement Boats
Once there, click on the link: Buying A Ferroboat and while you're visiting Ferroboats.com, check the other links. The page, Buying A Ferroboat, explains why FC yachts sell for less than a same size GRP, Aluminium, wood or whatever. (The images and content of the website are copyright and may not be reproduced without written consent. That's why I'm not posting the information here)

Bill
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Old 16-09-2011, 09:47   #70
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Re: Intelligent Discussion on Ferro

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Originally Posted by NeptunesTrident View Post
.6 cubic feet of quickcrete weigs 80 lbs. Steel weighs .2833 lbs per cubic inch, aluminum weighs about .10323 per cubic inch. That is just off the top of my head, but represents accurate weights. You can divide or multiply that from there.
Hmmmm. This makes:

concrete: 150 lbs / cft
steel: 490 lps / cft

vs.

resin: 35 lbs / cft
glass: 160 lbs / cft

What do you think the corresponding (strength for strength) panels will be?

I know that GRP is supposed to sit at about 50/50 ratio. How much steel do we need inside the ferro then?

???

b.
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Old 16-09-2011, 10:04   #71
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Re: Intelligent Discussion on Ferro

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Originally Posted by barnakiel View Post
Hmmmm. This makes:

concrete: 150 lbs / cft
steel: 490 lps / cft

vs.

resin: 35 lbs / cft
glass: 160 lbs / cft

What do you think the corresponding (strength for strength) panels will be?

I know that GRP is supposed to sit at about 50/50 ratio. How much steel do we need inside the ferro then?

???

b.
That is an excellent question. To me, and this is just my opinion, and I am not a ferro cement guru here, but twisted steel wire, fairly heavy gage, or a heavy gage welded wire. Cement, regardless of its composition, gets its strength from the reinforcing material. So it would depend on the hull thickness and I would go with the heaviest steel I could use, in the tightest configuration and still get positive flow of the cement. But, then, thats just me. I read the ferro cement boat link and it has some good information. And having read this thread, it has got me looking at fc boats. But I would never attempt to build one.
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Old 16-09-2011, 10:08   #72
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Re: Intelligent Discussion on Ferro

But in any case, a 20 ton boat still weighs 20 tons. No matter what material is used to construct the vessel. And I am not looking at sailboats for speed racing. I have a bass boat for such things.
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Old 16-09-2011, 11:55   #73
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Re: Intelligent Discussion on Ferro

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But in any case, a 20 ton boat still weighs 20 tons. No matter what material is used to construct the vessel. And I am not looking at sailboats for speed racing. I have a bass boat for such things.
You are wrong.

Off course, x=x, no matter what material was used, but this is not the point.

The point is that the same design boat, built to the same strength, may end up:

1. heavier,
2. with the 'wrong' weight distribution.

By wrong I mean: in a sailing boat it is a common thing to have a light hull and heavy ballast - and the ballast is placed lowest.

You may build the boats to the same weight, but perhaps you will end up with a boat which has no ballast (?) - all weight would be in the hull. Maybe this is a less than perfect solution?

Etc.

If you look at the materials weight data above, you will clearly see that both components in f-c are way heavier than in, say, grp construction, may be that the resulting f-c is actually, say, 3 times heavier than grp.

(Now: say a 3000 kg boat, where ballast is e.g. 50%, will have hull weight at 1500 kg. The same hull executed in material 3 times heavier will be at ... 4500 kg PLUS 50% ballast = ...

Not fixed opinions, just thoughts.

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Old 16-09-2011, 13:57   #74
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Re: Intelligent Discussion on Ferro

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Originally Posted by barnakiel View Post
You are wrong.

Off course, x=x, no matter what material was used, but this is not the point.

The point is that the same design boat, built to the same strength, may end up:

1. heavier,
2. with the 'wrong' weight distribution.

By wrong I mean: in a sailing boat it is a common thing to have a light hull and heavy ballast - and the ballast is placed lowest.

You may build the boats to the same weight, but perhaps you will end up with a boat which has no ballast (?) - all weight would be in the hull. Maybe this is a less than perfect solution?

Etc.

If you look at the materials weight data above, you will clearly see that both components in f-c are way heavier than in, say, grp construction, may be that the resulting f-c is actually, say, 3 times heavier than grp.

(Now: say a 3000 kg boat, where ballast is e.g. 50%, will have hull weight at 1500 kg. The same hull executed in material 3 times heavier will be at ... 4500 kg PLUS 50% ballast = ...

Not fixed opinions, just thoughts.

b.
You must keep in mind that the weight of the material is directly proportional to the static strength ratio of material. So, with this in mind, a boat built of fiberglass may have a hull thickness of 3/4 to 1", where as in steel it may by only 3/16" thick. Strength to weight will still be roughly the same. So the 20 ton boat still weighs 20 tons.
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Old 17-09-2011, 01:05   #75
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Re: Intelligent Discussion on Ferro

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I know that GRP is supposed to sit at about 50/50 ratio. How much steel do we need inside the ferro then?

???

b.
G'day b,

I would only be interested in "How much steel do we need inside the ferro" if I were planning to build a FC boat but, I would not be asking that question on any fourm, I'm 100% sure "all" that information would be provided to me in the boat plans...Besides, I would "never" spend good money buying boat plans from expert designers, like Hatley, then "not" follow the build instructions to the letter. Hartley have being doing their thing for many years, (since 1938, Hell! They were selling boat plans before I was borne...Only just ) and I'm pretty sure, they do know what they're talking about when it comes to boat design and building FC boats. Heck, Hartley reckon "over 95,000" Hartley boats have been built world wide. So they must be good at what they do. i.e. Design and build boats, FC and all other types.

As I plan on buying my "Pro" built FC boat, or a well built amateur built boat, I'm not really interested in "How much steel is needed inside the FC"
The buyer/builder would have got "all" the required information for building a safe sea going boat when he bought the plans from the boat designer and, if that boat got to 10, 20 or 30 years of age, I believe the builder would have followed the build instructions...To the letter.

All the FC boats I'm looking at are around the 30 to 40 years old, they are still looking good sitting on the water and, from what I'm told, they sail just fine. That being so, they must have been built to speck, had the builders not followed the build instructions to the letter, I'm guessing boats built by someone "not" following the build instructions, would be on the seabed...Or close to being so.

The FC boats I'm looking at are scattered all around the world, from Aus' to Ireland...In every direction and most of them were not built where they are today being offered for sale...They were sailed to their present day locations.
To get a boat built in the UK or Europe to America or South America, (East Coast) the boat must have sailed the Atlantic Ocean, not always an easy voyage to safely complete. If the FC boat was built in NZ or Aus' and was being offered for sale on the East Coast of the USA, or the East Coast of South America, the boat would have to have been sailed over the Pacific, through the Panama Canal then through the Caribbean, into the Atlantic and on to it's final destination. If the Aus' built boat was to visit the West coast of America, Canada, Central or South America...Hell! They only need to cross the Pacific

What I'm trying to get through to you is this...For a boat, "ANY BOAT THAT HAS TRAVELLED THE WORLDS OCEANS" to arrive at it's 30 or 40 year birthday, that boat must have been well built in the first place i.e. The builder must have followed the build instructions to the letter...And had a good crew to sail her safely over the worlds oceans.


Off course, the boat may have been built on the cheap by builders ignoring the build instructions provided and...believing "they" (the builder) could do a better job than the designer, and/or the boat may always have been lucky enough to have sailed the worlds oceans only on calm days...to get accross the oceans and to get to be 30 plus years of age, yep, I suppose they could have been real lucky but...I doubt that very much

Bill
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