View Full Version : ferro sheathing of wooden boats

10-09-2001, 04:59 PM
Is anyone in a position to give me information on the ferro sheathing of wooden boats? I have a general idea of the technique, but need precise details. I want to sheath a 28ft yacht, oak frames with strip ply skin. Do you know of any books or publications which provide this information?

10-09-2001, 05:14 PM
I can't help with the idea of ferrocement sheathing (in fact, I've never even heard of it until now), but Allan Vaitses wrote a useful and detailed book on fiberglass sheathing for wood boats: "Covering Wooden Boats with Fiberglass".

John B
10-09-2001, 07:02 PM
The only time I've ever heard of it is when it's been used as a last measure, cost effective way of making a boat float when no other method would do. They did it to one of our old harbour ferries here so that it could continue it's duties as a static floating restaurant.( after it had sank at the wharf).

personally, I hate the idea. But that's just me.

Bob Cleek
10-09-2001, 07:42 PM
Fuggedaboudit! Really dumb idea. To begin with, think about the weight factor. Totally out there. Shows you are thinking, though. Keep at it. For openers, why do you want to do this? Could it be that a strip ply skin proved to be also a dumb idea?

10-09-2001, 10:01 PM
These days you could jus' call up the local pool builder and get him to bring in some of that Shot-crete, have'er done in an hour or two, fair'er up with a cold chisel and voila!

Seriously, I think this is something that has not come up here(I didn't search), so post pics if you can, I'd love to see the process. I'm sure by now anything besides 'more epoxy q's' would be a welcomed segue for most of us.

10-09-2001, 10:07 PM
to start with....it ain't the ferrocement you normally think of.....and also it wasn't engineered for normal boats but as a last ditch way to save a barge......and the cement mixture is a combination of cement, graded fines, a latex binder, chromium trioxide and an epoxy sealer.........wood am more better...

10-10-2001, 02:53 AM
Here (in Finland) I have heard of one about 30-35 footer that was sheathed so; also a 3-masted schooner that I've seen myself (a long story cut short: a group of eager people wanted to save that ship, got it on a shipyard, was too expensive to repair all rotten etc stuff, got it sheathed, couldn't probably pay the fellow who did the work, so now this man has the ship and tries to get it seaworthy - I do not know the current situation, saw it a couple of years ago). No pics AFAIK. I found some info in finnish - if somebody is really intersted, I can translate parts of it...

Well, to the question: it seems to be possible - but you would probably need somebody who is familiar with the technique and also able to estimate if the work is worth it, considering the changes in displacement and the center of gravity and possible other issues.

There are some ferro boat pages in the web - perhaps they have some useful information.


10-10-2001, 06:52 AM
I seem to remember back during the "ferro craze" in the early to mid 1970's reading about sheathing tired boats to 'add life' to them. Probably in "National Fisherman" or something similar where someone wanted to save a rust sick old Novi. I never thought much of the practice but I know it has been done, and there is published information out there.

Frank Wentzel
10-10-2001, 07:25 AM
If Paladin is correct and chromium trioxide is used in the process, I wouldn't touch it with a ten foot Lithuanian. Cr2O3 is a potent carcinogen, extremely corrosive, very toxic, and very high on the EPA hit list. All waste generated during the project would require disposal as hazardous waste (very expensive). The boat itself might require disposal as hazardous waste if and when.

From what has been described so far this sounds like a process suited to a last ditch effort on a commercial vessel that is ready to be scuttled. It does not sound like a process suitable to a small recreational-use vessel.

/// Frank ///

10-10-2001, 03:18 PM

Have you looked at:

Then select "Ferro-Sheathing".

They have written a book.


10-10-2001, 04:15 PM
The amount of Chromium trioxide used is minimal and is used very sparingly. It is purchased as a powder and used in diluted concentrations of 100 to 300 parts per million (by weight to that of water) which equates to 5 to 13 grams or about a level teaspoon of powder for every 100 pounds of water. The moisture content of the sand and aggregates used in the mixture must be taken into account. This amount of Chromium trioxide will turn the water green but will not otherwise stain the hull.
Additionally, Pozzolan is a very fine powdered aggregate used to also increase the density of the concrete mixture. It does add slightly to the strength of the mixture but the main intent is to reduce water absorbtion into the hull. The most common Pozzolan used is diatomateous earth because a 1 to 2 percent mixture to weight of the dry cement has the same effect as a 15 percent addition of other Pozzolans.....
Vinsol Resin Air is an entrainment agent that may also be used..about one heaping teaspoon to about a pound and a half of diatomaceaous earth........
been there, done that...got the "t" shirt... built a 29 foot catboat that weighed 2/3rds that of a similar wooden one and it's still sailing........

10-10-2001, 05:38 PM
When I was a teenager, I had a 24-ft Grady White runabout with a 100 hp outboard. The hull had been glassed below the water line. Turned the boat into a tank that plowed into waves. Great boat for bluefishing and beer drinking!

I can't imagine encasing that boat in cement! Unless I wanted to scuttle it!

[This message has been edited by PatCassidy (edited 10-10-2001).]

10-10-2001, 10:25 PM
well, iron boats float don't they.....it's a matter of proper engineering and displacement...unfortunately 98.5 percent of the stuff that's been done hasn't been properly engineered. Sorta like the 99.5 percent of lawyers giving the other .5 percent bad karma.

10-11-2001, 07:26 AM
Leaving aside the ethics/purist aspect of it and just answering the question.
Several smacks have been ferro sheathed with varying success, the cockler Alice and Florrie was one of the success stories. The bawley, Band of Hope is still around but Priscilla was ferroed and is now up for a re-build.
More info is linked from my smack site and the smack list in particular at:- http://www.alberta-ck318.freeserve.co.uk/smacklist/smacks.htm
The experience of some is that the smack floats heigher after cladding as the old wood dries out.
My thoughts are that if it is a cheap way of keeping and old girl in use then that is preferable to loosing the boat all together. Ferro sheathing a 40' smack is about 10k whereas a re-build is 60k and the original hull is still there under the ferro for re-building later.

10-11-2001, 12:03 PM
Or they could Bronze it, like people used to do with baby shoes, and use it for a decoration.
This sounds mickey mouse ethically, aesthetically and financially.
Yuck http://media5.hypernet.com/~dick/ubb/frown.gif
Can you say, "Good money after bad" children?

[This message has been edited by TomRobb (edited 10-11-2001).]

[This message has been edited by TomRobb (edited 10-12-2001).]

ken mcclure
10-11-2001, 12:09 PM
Originally posted by TomRobb:
Or they could Bronze it

Bronze sheathing. Hmmmmmmmmmmmmmm........

10-11-2001, 02:17 PM
or cupro-nickel.