Ferro Cement hulls

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
So if built properly, a FC hull is better than other material? Fiberglass blisters, steel rusts, aluminum can suffer from electrolysis and wood rots. What are the negatives of a well built FC hull?


Water soluble chloride intrusion corroding the reinforcing steel mesh. Steel expands, and cracks or spalls off concrete layer. Concrete is strong in compressive strength, but not tensile strength.

Impact damage often has a 7:1 damage ratio. 3" impact on hull equates to a 21" area or repair on the inside of hull. Generally cracking. Modern polyurethanes can seal the crack but structural weakness may still be present.
 
So if built properly, a FC hull is better than other material? Fiberglass blisters, steel rusts, aluminum can suffer from electrolysis and wood rots. What are the negatives of a well built FC hull?

Wowwww. I found the U.S. Navy Ferro-Cement Boat Building Manuals to build a 2 engine 65 ft Powerboat.

Volume 1. is about the Frame Building.
Volume 2. is about the Plastering and Steam Curing

Ferro Cement Boat Building
 

Attachments

  • Ferro-Cement.JPG
    Ferro-Cement.JPG
    106.3 KB · Views: 357
Last edited:
I watched a ferro sail boat being built. The core or armature is composed of many layers of what looked like chicken wire mesh. That gave the hull its shape but was difficult to achieve a fair and symmetrical hull. The cement was all done in one day by professional plasters.
As others have observed the cost of a hull is a small part of a boat and not worth the effort IMO unless you are building in a very primitive area and will add minimal other stuff to the boat..
 
It's always risky to generalize (a generalization!), but a good FC hull is amazingly stable. Not in terms of rolling, but for temperature, sound, flexing, as an epoxy and paint base, etc.

Lots of public info on FC construction but it's all old by today's standards. There are FC boats over 100 years old. There are some that have been salvaged off reefs, patched, and refloated. As a current method it's essentially been abandoned - perhaps because there are so many fiberglass hulls still around that can be had almost for free.

The challenges come at the edges and intrusions - a major PITA to drill and cut requiring specialized equipment. And keeping the armature from corroding. A well built hull, once cured, will generally not have an issue with rusting and spalling - the problems here are evident even before launch. There is a concern about electrolysis - they are, after all, "metal" hulls.

Yes they are generally heavy, in part because it's hard to control thickness. Take a look at the cross-section of my cockpit in the photo in the link above and note the change in thickness.

And, yes, they are difficult to survey and thus hard to insure (and, by extension, hard to finance).

I'm quite satisfied with mine, but I've owned wood, fiberglass, and steel cruising boats for more than 30 years and knew what I was getting into.


Keith
 
Copied from: https://en.wikipedia.org/wiki/Ferrocement


The inventors of ferrocement are Frenchmen Joseph Monier who dubbed it "ciment armé" (armored cement) and Joseph-Louis Lambot who constructed a batteau with the system in 1848.[6] Lambot exhibited the vessel at the Exposition Universelle in 1855 and his name for the material "ferciment" stuck. Lambot patented his batteau in 1855 but the patent was granted in Belgium and only applied to that country. At the time of Monier's first patent, July 1867, he planned to use his material to create urns, planters, and cisterns. These implements were traditionally made from ceramics, but large-scale, kiln-fired projects were expensive and prone to failure. In 1875, Monier expanded his patents to include bridges and designed his first steel-and-concrete bridge. The outer layer was sculpted to mimic rustic logs and timbers, thereby also ushering Faux Bois (wood grain) concrete. In the first half of the twentieth century Italian Pier Luigi Nervi was noted for his use of ferro-cement, in Italian called ferro-cemento.
"ferrocement" being referred to as ferro-concrete or reinforced concrete to better describe the end product instead of its components.
Ferro concrete has relatively good strength and resistance to impact. When used in house construction in developing countries, it can provide better resistance to fire, earthquake, and corrosion than traditional materials, such as wood, adobe and stone masonry. It has been popular in developed countries for yacht building because the technique can be learned relatively quickly, allowing people to cut costs by supplying their own labor. In the 1930s through 1950's, it became popular in the United States as a construction and sculpting method for novelty architecture, examples of which created "dinosaurs in the desert".


First build Ferro-Cement boat by Joseph-Luis Lambot in 1848..
 

Attachments

  • Bateau_en_ciment_armé_de_Lambot.jpg
    Bateau_en_ciment_armé_de_Lambot.jpg
    134.9 KB · Views: 96
Last edited:
Hi all, my first post here.

My mom and her husband have lived aboard a Ferro Cement Trawler for near 20 years cruising between the Ottawa area and Green Turtle Key in the Bahamas. The hull on the Sheena II is near 40 years old and completely trouble free and seemingly as strong as the day she was commissioned. She gets attention wherever she goes and many people are curious about her. She's VERY heavy for her size of course.

If I could figure out how to post a picture I would.
 
Last edited:
My mom and her husband have lived aboard a Ferro Cement Trawler for near 20 years cruising between the Ottawa area and Green Turtle Key in the Bahamas. The hull on the Sheena II is near 40 years old and completely trouble free and seemingly as strong as the day she was commissioned.

Perhaps stronger - cement never stops curing and increasing in strength (though it really slows down after about a year).

Would love to see a picture!


Keith
 
A famous FC racing sailboat here named Ragamuffin was also known as "The Flying Footpath(sidewalk to our friends across the Pacific).
 
A famous FC racing sailboat here named Ragamuffin was also known as "The Flying Footpath(sidewalk to our friends across the Pacific).

It was Tony Fisher's original Helsal, the ferrocement boat that won the 1973 Sydney Hobart.

Screen%252520Shot%2525202015-09-29%252520at%2525203.33.02%252520AM.png


5914854-3x4-700x933.jpg
 
Hi all, my first post here.

My mom and her husband have lived aboard a Ferro Cement Trawler for near 20 years cruising between the Ottawa area and Green Turtle Key in the Bahamas. The hull on the Sheena II is near 40 years old and completely trouble free and seemingly as strong as the day she was commissioned. She gets attention wherever she goes and many people are curious about her. She's VERY heavy for her size of course.

If I could figure out how to post a picture I would.

I met Mike and Sue several times between the Bahamas and Dry Tortugas. I'm glad to hear they are still out there. Please tell them Wallace says hello and will see them in the Abacos next winter.
 
I met Mike and Sue several times between the Bahamas and Dry Tortugas. I'm glad to hear they are still out there. Please tell them Wallace says hello and will see them in the Abacos next winter.

Hi Wallace...I'll pass on your message for sure. They now leave the Sheena in Florida for the Summer as mom was finding the journey up and down the ICW a bit too much. They travel back and forth between Ont and Florida by car...they will be headed down later this month to get the Shenna provisioned and ready for the crossing.
 
Once I made an extended cruise on a well-built FC sailing ketch. Whether motoring or under sail, her handling characteristics were identical to what you'd expect from an equivalent boat made of any other material. Visually, she could have been wood or glass - you wouldn't know 'til you thumped your fist against the full or deck.

All hulls work and flex a bit at sea, but as far as I could sense, not that one! She was stiff and solid, and eerily quiet below. I felt secure aboard in all conditions.

My reservations about FC began to recede - then we hauled-out. A small rust stain here and there highlighted very tiny stress cracks in the hull, which the builder said was normal and maintainable. Maybe so, but I couldn't help wondering just what was going on behind the surface where (obviously) water and oxygen were getting at the steel armature.
 
Maybe so, but I couldn't help wondering just what was going on behind the surface where (obviously) water and oxygen were getting at the steel armature.

That' FC in a nutshell. You can know that if there is rust it will expand and spall off the cement but you still wonder about what you can't see. Of course you can grind down a small bit and verify (and patch with epoxy even) but owners don't bother.

There's a surveyor in Seattle who has an old dentist X-Ray machine (2 separate pieces) who's mentioned to me a couple of times about trying it for a hull survey. I don't feel the need myself but could see doing it if I ever wanted to sell.


Keith
 
Have not been keeping up on this thread however, came across this Seattle Craiglist post and wanted to share:
A few years older than mine - a lot to like there for the money. Couldn't figure out what those bars were across the forward companionway.

Builder listed as Tacoma Marine. There was a Samson yard in Tacoma in that era, maybe that was it?

There was also Tacoma Boat Building Company. Not sure the year it was founded, but chairman was Frank Lynott from 1974 into the 80s. He was a member of my YC - his boat was named "6 foot 6" - but I didn't really know him. He died a few months ago.


Keith
 
Greetings,
Seems like a LOT of boat for $7.5K. I see those "bars" across the fwd companionway and I can't figure out what they are either. Guesses? Wouldn't be bracing of any sort would it? If so, maybe $7.5K makes sense...
 
Greetings,
Seems like a LOT of boat for $7.5K. I see those "bars" across the fwd companionway and I can't figure out what they are either. Guesses? Wouldn't be bracing of any sort would it? If so, maybe $7.5K makes sense...

Chart rollers?
 
Well just sayin when I went through SAMS surveyor Education in Stuart years ago ... Watchword was stay away from ferro hull surveys ... Issues are significant. That said never surveyed one.
 
Well just sayin when I went through SAMS surveyor Education in Stuart years ago ... Watchword was stay away from ferro hull surveys ... Issues are significant. That said never surveyed one.
Heaven forbid they taught you enough to tell the good from the bad.....
 

Latest posts

Back
Top Bottom