I have been dreamily eyeballing what appears to be a very nice sailboat for sale on Craigslist that is ferro-cement. There are MANY questions that need to be answered about this boat so I will start here with the first one: Is ferro cement construction any good? How does is compare to fiberglass? What should one look for when judging the quality of the construction of a ferro-cement boat? Should I just move on?
Ferro-Cement Anyone?
- Thread starter markwbird
- Start date
Too weird for me 
The World of Ferroboats
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The more steel in the construction of a ferro cement boat the stronger, so you would do well to consider a steel boat.
-Will (Dragonfly)
-Will (Dragonfly)
How much are they willing to pay you to take it?
I’d want to know a little about the construction. Some have the rebar frame welded together, some just wired. I’ve seen wired ones poke holes in themselves. On the plus side , concrete is available everywhere for repairs and there are lots of concrete boats and ships out there.
Ferrocement boats can be nice. But there are several caveats. Who built it? There was a time period where it was quite the rage to make your own boat from this material. A serious difficulty with ferrocement is that there is no way to inspect the hull for defects. You can't check for moisture, cracks or any other defect that could be catastrophic, as far as I'm aware. Where is the hull from? When was it built? Where has it been? Has it has a significant impact? All are important questions to know the answers to. There are apparently some good ferrocement boats that were made in New Zealand and possibly Australia. I haven't followed that hull type with a lot of interest so I'm not totally up-to-date - primarily because I would never buy one. If the hull is homemade. I would very strongly discourage buying it. Was the boat built down under? If so, it might be a good one...
The main difficulty from my perspective is you can't know the condition of the hull. For me that's a deal breaker. There are internal degradation processes in cement you can't detect. I'm sure you know that cement does not float at all...
dj
The main difficulty from my perspective is you can't know the condition of the hull. For me that's a deal breaker. There are internal degradation processes in cement you can't detect. I'm sure you know that cement does not float at all...
dj
Are there? There was a small surge in construction in the 60s and early 70s, are any of those boats still around?
How old is the boat in question? I don't have experience with ferro cement boats outside of what I was told growing up as a sailor and my previous post outlines the major points there. However, I worked as a mold builder for an architectural concrete company in Sarasota and have done some work of my own in concrete
A concrete bridge I built, about ten years ago, over our pond. Concrete is cheap and easy to work with, but it is not strong in tension and is pretty inflexible. There are bonding additives that improve on that, somewhat. With poly and glass fiber reinforcing mixed into the concrete, it can be much stronger in tension. My concern would be about the weathering and the stress of use a sailboat is subject to. Ocean waves, wind and rocking on the rigging anchor points, Winter ice, ... all work to undermine the cement bond on the aggregate material. Tiny stress cracks in the gel-coat of fiberglass doen't mean the underlying glass is weak, but with a concrete boat, any surface cracking could mean there is no more tensile strength left clear down to the armature. It requires an enormous amount of rigidity and strength of materials to keep a 40 foot hull from flexing in a stormy sea. I don't think concrete is up to the task for more than a few storms.I would want to see the bare concrete, no paint, especially around the keel, inside and out. Look for loosened chain plates, rudder post, deck to hull connections. Anywhere the weather beats on her and wherever she might be inclined to flex when coming down off a big wave with the mast whipping about.
Cement boats are heavy and tend to be slow, not that that is a deal breaker for a sailboat. I'm just not a fan of the whole concept, but, like I said, no real personal experience.
Good luck on you're quest.
-Will (Dragonfly)
Will,
There are a series of highly specialized filler and additives that are needed to produce "marine grade" concrete. I don't remember the details. One of the problems is not surface cracks, that are visible, but rather cracks initiating on the inside of the concrete. These cracks can grow so that the entire structure is compromised and you can't see it at all. And there are no NDE techniques that will detect them either. An external visual examination is insufficient for this structure.
dj
It is, in fact, home built by a delivery skipper. He did an exceptional job by the photos. Here’s the funny part: it’s listed on Craigslist and on a broker’s site.
Craigslist ad: “designed and built in backyard in Sausalito by owner over 15
years”
Broker ad: “built in Sausalito in private yard to designers specs with designer
overseeing construction”
Both technically true.
Craigslist ad: “designed and built in backyard in Sausalito by owner over 15
years”
Broker ad: “built in Sausalito in private yard to designers specs with designer
overseeing construction”
Both technically true.
I'm with DjL on this one. A properly built stone boat (cement) could last a hundred years without a problem. I saw one dig such a deep hole in the coral reef it ran onto in 5 days that it had to be craned out of it, yet it only put a 1' X 1' hole in the boat.
It's all about the construction. Keeping the steel re-bar dry and rust free before concreting is paramount.
If you could trace her lineage and be sure she was built by a reputable yard, then you could be getting the deal of a lifetime. If not you'll take your chances. If the boat is a goodly number of years old, it should be possible to visually sight the topsides for lumps and bumps that would indicate some rusting of the re-bar under the concrete. I doubt anybody would spend the money necessary to fair out an old stone boat just to sell it for under 10k.
However, do not buy a Sampson designed stone boat. They are terrible designs that sail poorly and are extremely uncomfortable at sea.
Good luck.
It's all about the construction. Keeping the steel re-bar dry and rust free before concreting is paramount.
If you could trace her lineage and be sure she was built by a reputable yard, then you could be getting the deal of a lifetime. If not you'll take your chances. If the boat is a goodly number of years old, it should be possible to visually sight the topsides for lumps and bumps that would indicate some rusting of the re-bar under the concrete. I doubt anybody would spend the money necessary to fair out an old stone boat just to sell it for under 10k.
However, do not buy a Sampson designed stone boat. They are terrible designs that sail poorly and are extremely uncomfortable at sea.
Good luck.
There are so many good yachts without risky building techniques out there that can be found for a reasonable dollar, I can't understand how any ferro-cement yacht owner can find a buyer. The heavier the boat, the more sail necessary to drive the hull, the more momentum to overcome when docking, the larger the engine and fuel burn to run compared to a similar length yacht built in glass, wood, composite, aluminum or even steel.
Trying to insure a ferro will be very difficult. That's fine if you don't mind losing your yacht in an accident, but if involved in an accident with another yacht, having no insurance could mean complete bankruptcy when the lawsuits start. In terms of weighted risks/rewards, the ferro yachts come up way short, even if the actual boat is lovely inside.
Trying to insure a ferro will be very difficult. That's fine if you don't mind losing your yacht in an accident, but if involved in an accident with another yacht, having no insurance could mean complete bankruptcy when the lawsuits start. In terms of weighted risks/rewards, the ferro yachts come up way short, even if the actual boat is lovely inside.
I would always worry that when, not if, the hull gets hairline cracks, and water reaches the steel, the repairs will be difficult, or the hull will eventually become unusable. With fiberglass boats so readily available and so proven to last, why bother messing with ferrocement? If it seems too good a deal to be true...
While some of us are cautious or skeptical of ferro-cement hulls, it is worth remembering that ALL hull materials can have fatal flaws if not constructed properly.
When considering aluminum, steel, cold molded wood, plank-on-frame, and fiberglass, it *always* depends on materials and labor skill.
Moving up a (marketing) level, there are well known commercial boat builders at the "low end" of the market whose products have proved to be worse than many home-builts. (sigh...)
So, before finalizing that purchase, get a survey.
Your insurer is gonna insist on one anyhow.
When considering aluminum, steel, cold molded wood, plank-on-frame, and fiberglass, it *always* depends on materials and labor skill.
Moving up a (marketing) level, there are well known commercial boat builders at the "low end" of the market whose products have proved to be worse than many home-builts. (sigh...)
So, before finalizing that purchase, get a survey.
Your insurer is gonna insist on one anyhow.
Going with a boat built out of a fad product verse a more popular proven product is a choice. A good or a bad choice depending on your perspective. A ferroCement boat would require the owner to have some good DIY skills as there are few builders or yards with experience using the material.
I knew a fellow in the early 70’s that built a 34 foot FerroCement boat in his back yard. He was all into the project. Had dinner with him and all he could talk about was the strength of the material and the ease of construction. The hull sat for over a year and a half. Then we lost touch with him. Not sure if it ever floated.
Let us know what you decide. It is your money and your boat you get to wrestle with the decision.
I knew a fellow in the early 70’s that built a 34 foot FerroCement boat in his back yard. He was all into the project. Had dinner with him and all he could talk about was the strength of the material and the ease of construction. The hull sat for over a year and a half. Then we lost touch with him. Not sure if it ever floated.
Let us know what you decide. It is your money and your boat you get to wrestle with the decision.
You should certainly have insurance. Talking to an insurance company, in preparation for buying, might be revealing
-Will (Dragonfly)
The US has been building built concrete ships since at least 1917. They were cheaper than their steel counterparts and they weighed less.
However, this is not a new technology or untested. "The oldest known ferrocement watercraft was a dinghy built by Joseph-Louis Lambot in Southern France in 1848."
I have seen some absolutely beautiful and very well built ferro boats and I can say for certain that very few people could identify them as ferro boats from more than a few feet away.
However, this is not a new technology or untested. "The oldest known ferrocement watercraft was a dinghy built by Joseph-Louis Lambot in Southern France in 1848."
I have seen some absolutely beautiful and very well built ferro boats and I can say for certain that very few people could identify them as ferro boats from more than a few feet away.