Why are Cement Hulls, Bad ? or Are they ?

[Stillraining]

When I think of ferrocement built boats I think of your avatar.......right or wrong that's the general perception I have.....there are always exceptions to the rule....I would not however take the risk with my luck.

[Omatako]

As fstbttms said, many ferro boats were built in backyards to very tight budgets so the re-bar frame would be constructed in stages, left to rust, bound with wire, left to rust, plastered with random-composition mixes by unprofessional people to random thicknesses, etc, etc.

There were a lot of ferro boats built in factories by professionals using exacting standards, state-of-the-art anti corrosion processes and the result was a number of excellent boats.

How do you tell the difference? I don't know except to say that badly built ferro boats are mostly obvious. If you see a really good-looking one, that's where the problem starts. You will have to do a decent amount of research to convince yourself that it isn't just a stroke of luck that a bad boat looks great.

It's a risky business but that is why they are sooooo "affordable". they're really hard to sell.

[Superpickle]

Originally Posted by danjarch

First, I'll second what faster said. If this is a good deal for you because it lets you buy more boat then you can afford then it's going to bite you in the rump since it will still need all the usual stuff that goes along with owning a 40 foot boat.

Second, one more thing to consider is that the reason the price is so good is that ferro boats take a long time to sale and even then sale for a lot less then fiberglass or wooden boats of the same size. So just be aware that once you go to sale the boat, your going to have to keep paying slip fees until it sales and it will sale for less then comparable boats built in fiberglass or wood.

Thank you, thats the kind of advice i wanted in my other post.. INFO, not Geers and snotty remarks..
And, I think you are getting your Sail, Sales, and Sell , mixed up and im having trouble deciphering
But, your right, i was seeing a Lot of boat for less.
Still, I DO love the inside.. Drat..

[JomsViking]

26 tons! That boat will never sail, but motor most of the time. It also means that longer passages will be slow, maybe even so slow that it is unsafe - say you need to get through a canal, pass or similar with a deadline (tide turning, or whatever).
So you really need to consider if you want a sailboat, or a sail-assisted motorboat. (and as Faster touched on, it's actually underpowered engine-wise also).
EDIT: The HR40, which is a heavy 40 footer, weighs 10 tons

[bubb2]

I agree with Faster and Joms. 26 tons on a 40 water line. Thats a barge not a boat.

[Jeff_H]

It is not so much that Ferrocement is bad per se, but that it has its limitations. Properly done and used on big enough boats where it actually makes sense then it is a reasonable method to build a boat but never an ideal method to build a boat.

The boat in your link, has much bigger issues than the fact that it is ferrocememt. It is a terrible design in terms of its likely sailing ability and general layout. No matter what material this boat was constructed in, it would be a really poor choice for anything other than a live aboard that you did not plan to sail.

But more to the point, it will cost you as much to buy and upgrade and maintain that boat as to buy and as it would to buy, upgrade and a maintain a reasonably high quality fiberglass boat with a more universally appealing design. In most marketplaces ferrocement boats are simply worth a lot less to a fiberglass or aluminum boat of an equal design and build quality, so on a boat to boat comparason so it will be much harder to get the money back that you invested in the purchase and restoration. It is for that reason, if none other that people are suggesting that you walk away from that particular ferrocement boat.

I did want to touch on Seabreeze 97's point about the durability of concrete buildings and transportation structures. Unlike boats, within reason weight is not as critical factor so in buildings, we can tollerate much thicker concrete as steel protection. Typically in a concrete building any element that in contact with the ground is required by code to have a minumum of 3 inches of concrete over the top of any structural steel reinforcing, and even concrete that is in the air, requires a minimum of 1 1/2" of concreteprotection over the steel. That 3" or even 1 1/2" is a much thicker cover than the typical 1/4" to 3/8" concrete cover over the steel in a ferrocement boat, and that 1/4" to 3/8" cover is for a material that is nearly constantly exposed to high moisture.

But also, because concrete building designs are less concerned about weight than ferrocement boat designs, the margins of safety, on buildings can be and typically are many times higher than those used in designing Ferrocement.


Anyway the following is an article on Ferrocement that I wrote for another venue but which summarizes Ferrocement, albiet a viewpoint that represents a North American point of view. (You might also want to look at the rather long and very detailed discussion on ferrocement boats over at the Cruisers Forum.com. Ferro Cement Hulls? - Cruisers & Sailing Forums Its a good thread with people weighing in on both sides, including a number of people who actually own ferrocement boats. and it includes much of the engineering data that backs up the claim that on a pound for pound basis, ferrocement is the weakest boat buillding material.)



To begin with, simply taken on a pound for pound basis, ferro cement is the weakest of all of the commonly used boat building materials. Ferro-cement operates by the same principle as fiberglass, in other words, a high tensile strength reinforcing held in shape by a high compressive strength, low tensile strength cement. The cement in ferro-cement ideally is a very high strength Portland cement with a very fine sand aggregate. (The cement in fiberglass is polyester, vinylester or epoxy resin.) The tensile reinforcing material in ferrocement is steel (sometimes with glass fiber added). (In fiberglass it is glass fibers or other hig tensile strength materials in a variety of forms, kevlar, carbon and all kinds of new variations on these materials).

Ferro-cement's weight comes from a number of sources. First of all, no matter how small the boat, there is a practical limit to how thin ferro-cement can be. Ferro-cement needs to have a minimum thickness in order to have sufficient depth of cement material over the steel to protect the reinforcement from moisture (the typically quoted thickness of cement protecting the steel varies between Ľ” and 3/8”, depending on the source and the cement being advocated). Because of this boats below 40 to 45 feet are generally considered too small to use ferro-cement efficiently. (i.e. their hulls, and deck structures weigh a lot more than they an equal strength structure would in some other material.)

The implication of the weight issue is not readily obvious. At the risk of sounding like a broken record, Weight in and of itself does nothing good for a boat. It does not make it stronger, or more comfortable or more stabile. Weight does increase the stress on the various parts of a boat. It increases the size of a sail plan required to achieve a particular speed. It increases drag and typically means that for a given draft a boat will have a less efficient keel (i.e trading off greater drag for the same amount of leeway.)


In order to carry more sail area the heavier boat with equal or less ballast stability needs greater form stability, which comes at the price or a choppier motion and greater drag, or greater ballast or deeper ballast which adds more weight and drag and perhaps depth.


Similar to steel, to keep the weight down, many ferro-cement cement boats have reduced ballast ratios when compared to other construction techniques. This means that they need more sail area because of their weight but they can't carry more sail area because of reduced ballast ratios, at least not without using lower aspect rigs which are by their very nature much less efficient on almost all points of sail.


This is further complicated by the fact a higher proportion of the weight in a ferro-cement boat is carried in the in the topsides (and sometimes decks). This means a high center of gravity which has a variety of implications; reduced stability, wider roll angles, smaller angles of ultimate stability, and more prone to excitation rolling (which may be slightly offset by the greater inertial moments due to weight).

This added hull and deck weight, larger sail plan, and perhaps greater ballast requirement to carry the sail plan make these boats a less than ideal choice for distance voyaging for a variety of reasons. Any given design can only safely carry so much weight before it begins losing safety, stability and sailing ability. If excess weight weight is required for the hull, deck, rig and ballasting, there is less weight available to carry food, stores and gear. For a given payload, a bigger more capacious boat is required. And since displacement is a major component in determinging the amount of anticipated maintenance costs (affecting sails and deck hardware size, ground tackle and dock lines, engine size and fuel consumption, down to even simple things like the amount of bottom paint required), these boats that can become expensive to maintain as well.


Which then brings us to maintenance costs. In a study performed some years back looking at the life costs of various materials, ferro-cement-cement came out as the second highest maintenance cost material (if I remember worst to best was steel, ferro-cement, conventional wood, aluminum, fiberglass, cold molded wood) Of course as with any generalized study there will be case by case exceptions and given the comparatively small sampling of non-FRP boats the results could easily been skewed by a few bad apples.


Other problems with ferro-cement are the difficulty of connecting things to it, and prevention of rot in wood in contact with ferro-cement. The difficulty in bolting to ferro-cement is that ferro-cement hates localized loadings. It’s hard to glue things to ferro-cement; secondary bonds are greatly greatly weaker than primary bonds.


Then there is the market value issue. ferro-cement does have a reputation in the States that does not match the comparatively high regard that it is held in other countries. Some of this is just plain unfair prejudice but some of this comes from real shortcomings in the materials as noted above. A well-built ferro-cement boat can be a reasonably good cruising boat. But the image of the crudely finished ‘hippie’ built cement and rust buckets still clouds the perception of ferro-cement for many North Americans.

The other problem is telling whether the boat that you are looking at is a good boat. It is very hard with non- destructive survey techniques to tell whether the original work was done well and is in good condition. While sounding will reveal any major separations in the cement to reinforcing bond, it does little to determine the affects of fatigue, poor curing practices or cold joints. With Ferro-cement it is particularly important to maintain the ferro-cement parts in good condtion. That can be very significant. People who buy boats because they are priced well below the market, often are overly frugal or just plain do not have the money that it takes to properly maintain a boat. An otherwise good Ferro-cement boat left to poor maintenance and miss-handling can quickly become a poster child for why North American’s don’t trust Ferro-cement.


To me the real cost of owning a boat is the difference between what you paid for the boat, the cost of upgrades and maintenance and the price that you can get when you sell the boat. The problem with a lot of low value boats is that the sales price is always limited no matter how much you put into the boat. This works against ferro cement boats big time.


I guess my conclusion is if you are strictly looking for a low initial up front cost boat and don't mind putting some sweat equity in, and you can look past the sailing shortcomings, and you actually find one that was well built and well maintained, a ferro-cement boat might work out fine for you. For most of us, they do not.


Respectfully


Jeff

[TQA]

That boat is at the bottom end of what I reckon is the ferro comfort zone re length. It would make a good liveaboard and would motor around OK.

But I would have my doubts about its sailing ability with that rig.

Good buy if you are looking for a floating home. Bad buy is you want to sail ANYWHERE,

[GeorgeB]

So Pickle, got to ask: Have you ever been sailing on anything larger than a dinghy before? And, are you looking for advice or just validation? Seems to me that you ask for the collective wisdom of the board and then get a little defensive when it doesn’t go your way. I’m surprised that the boat in Florida that you are so enamored with was built by a professional builder at all. The topsides photos have the look of a backyard build. I’d hate to see what it is below the waterline. The interior looks cute in a pirate ship sort of way. Is that what you are going for? A pirate ship? Sorry for being blunt but my narrow mindedness was formed over many years and many, many miles of sailing experience. Don’t take my word for it, call a couple of insurance companies and see if you can even get insurance. Seriously doubt if you could get a liability policy for it either.

But if it is validation you-re going for: Do it, do it now! Just because us guys own sail boats made out of dead dinosaurs doesn’t mean you have to! We probably overspent for our Tupperware boats! Don’t fall into our trap! We make boating expensive – it doesn’t have to be that way! In fact, done properly, sailing is cheaper than living under a bridge! Besides, being constrained by our experience, we have become narrow minded and need you to come over to our side and drink the kool-aide too. Be an outlaw! Live the dream – not somebody else’s reality!

[Superpickle]

Originally Posted by GeorgeB

So Pickle, got to ask: Have you ever been sailing on anything larger than a dinghy before? And, are you looking for advice or just validation? Seems to me that you ask for the collective wisdom of the board and then get a little defensive when it doesn’t go your way. I’m surprised that the boat in Florida that you are so enamored with was built by a professional builder at all. The topsides photos have the look of a backyard build. I’d hate to see what it is below the waterline. The interior looks cute in a pirate ship sort of way. Is that what you are going for? A pirate ship? Sorry for being blunt but my narrow mindedness was formed over many years and many, many miles of sailing experience. Don’t take my word for it, call a couple of insurance companies and see if you can even get insurance. Seriously doubt if you could get a liability policy for it either.

But if it is validation you-re going for: Do it, do it now! Just because us guys own sail boats made out of dead dinosaurs doesn’t mean you have to! We probably overspent for our Tupperware boats! Don’t fall into our trap! We make boating expensive – it doesn’t have to be that way! In fact, done properly, sailing is cheaper than living under a bridge! Besides, being constrained by our experience, we have become narrow minded and need you to come over to our side and drink the kool-aide too. Be an outlaw! Live the dream – not somebody else’s reality!

No no no. I do Appologise, if i came across in a Flippent manor..
Sailing in an Inner tube doun the Clackamas river in oregon,, or mabee that was Coasting

I was wanting some advice, not just Attitudes.. Sorry if i was Un appriciative ( i know, Spelling )
Do like the Piraty look though

I havnt a clue what to look for or whats good and bad.. Just want to learn to sail and move to Samoa. mabee

[GeorgeB]

Pickle,
The comment about the 42,000 pound displacement got me to thinking. This thing is north of a thousand pounds per foot LOA. Your typical 40+ footer FRP cruiseris going to weigh in somewhere under 600# per foot. I thought, “hey, this would be fun to run the numbers through my ratio calculator”. I googled “Windboats” and got a hit from a builder in England. They currently build for Oyster. Their history made no mention of Ferro-Cement, but they used to build “custom yacht builds”. I had better luck with “Endurance”. Seems that the designer was one Peter Ibold, a civil engineering professor and self taught yacht designer. He won a “best amateur yacht designer contest” in Norwich England with his Endurance 35. He was pretty prolific, ultimately designing 60 different boats that were built by over twenty different boatyards. However, He never gave up his day job in civil so i don't think he was that successful. I eventually found a 1978 brochure from Windboats for the Endurance 40+ (a.k.a. “41”?). At the time they billed themselves as a leading builder in Ferro (the picture depicted hull #2). The 40+/41 was built by various builders in wood, steel, and fiberglass in addition to the cement. The Endurance boats ceased being built in the early ‘90’s

Herein lies one of the big problems in Ferro, there are no molds or single builder so there is no consistency. Each boat is a one off construction. The Ft Meyers boat for example, is five tons heavier than the original design weight. You can only imagine the differences in construction quality. This boat in particular is a little weird, having a junk rig, unstayed masts and an 800 sq ft sail plan. This sailplan is not much bigger than my 34 footer with a large genoa up. To manage two halyards and two sheets, you get exactly two winches. But hey, one of them is self tailing! Do you need any additional information as to why this isn’t a good deal?

The used boat marketplace is pretty efficient. Both buyers and sellers tend to be equally knowledgeable and have access to the same information. And the selling prices reflect the boat’s true, relative value. You are not very likely to find a “diamond in the rough”, the market is way too efficient. If you buy a boat on the bottom part of the scale, you will often spend more out of pocket money to bring that boat up to “mid range” standards than what you would have spent if you bought the mid range boat in the first place. Boats are expensive, cruising boats more so. Think house expensive, not Kia Sportage expensive. Don’t be seduced by your dreams and pictures of pirate ships. Get knowledgeable, or better yet, find someone who is. There are consultants that can help you in this arena. Cruising Concepts in Alameda is one, for example.