ferro-cement

You are absolutely right Andy, a good ferro boat is as good as a good boat built out of any material, your boat looks very nice btw. They get a bad rap unfairly imho. Interestingly, I am always reading how they don't have any value but whenever I see a nice ferro boat for sale the asking price is in line with a like grp boat of the same vintage, by default, all ferro boats are 30 to 50 years old and grp boats of that age are a dime a dozen too as are old wood boats, factor in that custom or home built boats of any material don't fetch as much as production boats and im just not seeing the low value. We only have one ferro boat in my area, an Endurance 35, you can sure tell its ferro, but it has been in the water every summer as long as ive lived here which is over 30 years, the hull is reasonably fair, its just that they have never tried to make it look like anything else and that's ok. Maybe ill talk to the owners sometime and get the story.

Steve.

 

I'm not sure of your experience level Andy, but you surely don't have to xray 'glass boats to know what's going on with the laminate and fastener condition is a very simple thing to inspect as well. On the other hand you do have to xray a ferro boat and surmising the wire condition is a guess at best, without a core sample.

In the USA ferro got a bad rap back in the early 70's, when lots of plans where sold and children only mothers could love resulted. There were also a few less than scrupulous ferro builders, that put as lot of crap on the market, just before the "dark years" when a general production glut, all but killed the market. In Europe and Australia, this is much less the case.

 

i had a 29 ft ferro sloop built by khan walker, he was a guru of ferro here in aus. he built his hulls by pulling the mesh over a mould and putting it under tension with hydraulics. after the hulls were finished he gave them a layer of cloth and epoxy. my boat weighed 3.5 tons and the hull thickness was 3/8 of an inch. was bone dry in the bilge for all its 50 year life of sailing. khan walker proved ferro could be equal or better than most materials when built well. his boats sold well but were labour intensive and he had to change to grp to be competitive in the end.

 

Windboast UK

Hi guys I,m new on here and have to say what a fascinating thread, I own a 50 year old Windboats Southwind 26ft ferrocement by Graham Bunn, she,s been on the Norfolk Broads in the UK all her life, most of her early life was as a hire craft so was probably not treated very gently, but not exactly had much in the way of the elements thrown at her either... I have to say her hull is still pretty sound and never seems to have more than the odd inch or so in her bilge, Ive not had to do repairs myself (yet) but the previous owner tells me he used epoxy cement inside and out and found (with a good roughen up and clean) them to be easy and straightforward, superstructure is FG, I will try to post a photo taken a couple of years ago when the hull was repainted,
best regards,
Geoff
...or maybe not its asking for a url to post an image... I will try again when Ive worked it out..

 

Finger Trouble

Windboast ????????????? lets try Windboats.......
think Ive worked out how to post an image...
regards,
GeoffB

 

At Drexel University a senior class project was development of technical data for this type of marine construction. Boards were made up with various reinforcing material, steam cured, and tested to failure using the university's stress testing machines.

We produced boards 3/4 inch thick x 8 inches wide x 4 ft long, and boards 1-1/2 thick x 12 inches wide x 4 ft long. For testing the boards were supported at the ends, and pressed down in the middle, giving a bending moment across the smallest section. The 3/4 thickness was considered appropriate for boats to about 45 feet, and the 1-1/2 inch material considered proper for working boats to about 100 feet length.

More than 50 combinations of reinforcing materials were tested, and the best structural properties were found as follows:

1. Cement Mix, 1 part Portland cement, two parts sharp No1 sandblast sand
2. The best reinforcing mesh was found to be galvanized expanded metal lath, much more stable than woven or welded chicken wire, or other types of hardware cloth. The lath would fail predictably, with a stress-strain curve similar to ductile materials (yielding with considerable additional strain to failure). Other reinforcing mesh types would reach yield point, then the board would typically break catastrophically.
3. For maximum strength, 4% to 5% of the cross section should be steel. This makes a boat skin with excellent strength, and cement can still be troweled thru the mesh.

Shooting a standard 30-06 thru the 3/4 board produced a hole about 2 inches diameter, with lath forced out from both sides of the board surface. No damage beyond the immediate vicinity of the hole.

A couple of years later a fellow engineer made a 30 ft sailboat this way, with frames welded up in 1/2 inch reinforcing bar trusses. Longitudinal stringers of 1/4 inch diameter rods. 3 inches on centers, and three layers of wire lath on each side of the hull. The hull had large bilge keels, so it could be beached and still stand upright.

That was in 1972, and the boat has given excellent service. It has since been sold, but it is still in service

 

Epoxy Cements

thats really interesting.. so no epoxy used in the mixes? Ive seen so many different thoughts and suggestions on repair methods it can get a bit confusing, even with epoxy cements Ive seen 2 pack types, cement and sand but mixed with an epoxy no water, types for structural work, types for cracks even types claimed to be waterproof for repairs to docks and jetty,s, Im tempted to use the 2 pack type myself (if and when required) as 1. I cant get the mix wrong and 2. they are claimed to cure no matter the weather/temperature, I saw a post on another forum where an ex worker at Windboats reckoned they repaired using a 1 part Portland cement to 2 parts sharp sand mixed with river water, time will tell I suppose...
regards,
Geoff