ferro cement

[kim r]

i am getting ready to haul my ferro cement hulled Ingrid Ketch- it is showing some bubbling under the paint and when the bubbles burst there is a rusty run- - i anticipate having to sand it and treat it - any ideas on what to treat it with ??? ferro cement is a composite you know full of all kinds of goodies - the runs - i am hoping this is superficial - the hull i so thick - but i know it has a metal frame

[boatman61]

Steel rod frame with chicken mesh... sounds like the wires rusting away... biggest problem is water seeping under the toe rail and getting into the internal layup through the voids..

[barnakiel]

Not sure but perhaps once you cured the spots, you can cover the whole thing with epoxy (?) "osmosis style".

I would try phosphoric acid, rust lock, etc. to seal the steel matrix.

b.

[Crimea Cruiser]

Pretty sure it is equivalent to a soaked core on a fiberglass boat. Except the metal mesh and rebar is rusting as opposed to the core on a fiberglass rotting. Either equals a lessening of structural strength levels.

Check this prior thread for some other opinions. http://www.cruisersforum.com/forums/...ats-27043.html

[DumnMad]

You could enquire about Aquron. It looks like water, soaks into the concrete and forms a gel inside and prevent chloride attack on the steel. They use it on salt soaked concrete bridges. Not sure how well it would work with less porous 2:1 cement mix.

[Crimea Cruiser]

This is the thread I meant to attach. http://www.cruisersforum.com/forums/...hulls-397.html Sorry. Best of luck with haul and repairs.

[BillAU]

Have a look on this site, they do concrete treatment, I know FC is not concrete but if you contact the site, they may be able to better advise you.
This epoxy site is linked to that first site, this may be a better choice for you,

Good luck with things, remember what Colin Brooks says on FC boats,
Quote from Ferro Cement.Org:

One of the great advantages of a ferroboat hull is....if it was built reasonably well in the first place, almost any damage is repairable.

End Quote

Bill
Australia

[pent4ngle]

I am the owner and slave to a tough girl another Hartley Tahition stretched in the run .
There are many successfully maintained FC yachts out there and a wealth of experience for advice .
It is re commended that concrete degradation and bingles on FC yachts
be either sandblasted and air chiseled to remove damaged material .
Blast will reveal concrete and steel condition . Weld in new bars and wire gal mesh.
Expose repair on both sides of hull .
Thoroughly paint the repair with epoxy resin/ epoxy metal primer to aid adhesion later .
Form up outside of hull repair with light plywood and tom to slip cradle
From the inside pour / trowell a mix of 1/2 Ltr epoxy resin 1/2 Ltr fine cut sand and 1/4 Ltr cement . Adjust viscosity to suit . Do in multiple pours if necessary - really ugly bog .
THIS STUFF IS STICKY AND AFTER CURE VERY HARD
Ramset Epoxy Grout is also good and easy to handle .
Strip form - Grind - Epoxy/Sand bog to low spots - Grind - Voila
Old heads - owners of multiple FC yachts recommend 3 coats of epoxy to the
blasted hull - followed by either a key coat and antifoul or antifoul direct within 24 Hrs of epoxy cure. Same for inside if possible .
Note that FC yachts dont like water on both sides of uncoated hull for any period or reason -electrolysis is also a problem here . Earth anodes and
fittings underwater .
Cheers

[psk125]

The "Rust spots" that you describe bubbling up under the paint make me think of a Beneteau (cast iron keel) I saw that had bubbles on one side of the keel under the paint when it was hauled. Popping the bubbles uncovered a fine dust of red powder that dribbled away as the hull drained off. Electrolysis caused by stray currents from a boat in a neighboring slip (known to have had issues with its electric wiring) apparently pulled the iron out of the keel of their neighbors. If there's iron in your hull matrix (I hope there is!) beware of electrolysis as well as rust.

[NorthPacific]

Some great advice positive pent4ngle and from others, what makes this site special at times.