Ferrocement

I know how much many hate ferrocement but everyone agrees its cheap so beat it. i want to use ferrocement to make bricks which allow me lower the cost of labor and time . i know its possible to build a boat with everything i want to know how much this design lower my time and cost.

 

If you are talking about boat construction prefabricated panels will increase cost significantly over conventional techniques. The hull itself takes more material to make and needs additional mechanical and chemical fasteners. You need a full set of steel molds for each model, big vibrating tables, mobile heavy lifting equipment, steam curing equipment. Automating armature shaping and placing is possible but not economically viable.
The reasons it works well for land based structures are the simple shapes and uncomplicated armature placing allowing for modular molds, and the high production output demanded by the construction industry.

Ferro is a labor intensive method, choosing between spraying (with or without a mold) and hand plastering is dictated by the local market economy.

 

Not everyone agrees it is the cheapest. I don't for sure. In general only inexperienced persons think that the cost of building is low. You need to first calculate the percentage of the total cost between the hull and the whole finished boat. Then, calculate the cost of fitting the interior. Wood is the easiest since parts and reinforcements can be glued/screwed anywhere. Fiberglass is second as parts can be tabbed or wooden blocks added for securing fasteners. Metal is third as welding tabs or other sections is possible, but has to be planned ahead as the heat will be an issue. Wood and fiberglass are easy to retrofit or add during construction as there is no heat. Ferrocement needs a lot more planning. This is a major issue for amateurs. It is possible to add on, but the methods are more complex. Also, ferrocement is not conducive to build in small stages like wood or metal. Using bricks (small sections) will require some kind of structural attachment and sealer for the seams. Those materials will cost more than building the whole hull in a different material. What is the size boat you are planning on?

 

Rumars thanks for replying; gonzo in my country cement and sand is so cheap - the best cement for building in water is only 0.02 per kilo.

 

Cement may be cheap, but the hull is only a small part of the cost, if its anything more than an open rowing boat. They ARE time consuming in the hull construction, though the plastering has to be done in a single session for best results. What size boat and for what purpose?

 

How cheap or expensive ferro is depends entirely on the local market. From a strict raw materials point ferro uses between 30 and 70% less steel, needs no paint and only minimal welding. Cement is cheap but its installation costs are high because of the amount of labor (skilled and unskilled) involved. Determining what's cheaper can only be done for a specific place at a specific time. Even if ferro is determined to be cheaper then steel this doesn't mean it's the cheapest in that particular market, wood or fiberglass can still be competitive, especially when it comes to initial cost as opposed to total lifetime cost. Many wooden fleets survive because it's cheaper to buy and maintain a less expensive boat every 10 years instead of something that lasts 25 years but is more expensive up front.

 

Cement and sand are not all the same. You need high quality Portland cement and well graded sand from a quarry, not beach sand. Also, there are a number of adittives to modify the grout mix for the purpose. The water quality also affects the mix. There are a lot of manuals for concrete and grout mixes. I work a lot with concrete inspecting and supervising construction of highways and bridges. Random mixes are not a good idea. Air entrainment is another critical issue. Too little makes the mix brittle Too much makes it porous. You may find that consulting a civil engineer is the best option.

 

If you just want a barge go for it.
If you want to build a "real boat", something with an engine, and a useable/outfitted interior,
then your "savings" will be close to nil.
The general consensus is that a hull represents only ~10>12% of a finished operable boat.
Being as the cost of a Ferro hull, (proper materials/knowledgeable competent labor,) is still not cheap, the overall savings might only be perhaps 3>5% at most.
And when you go to sell it, you'll realize that you lost way more than you "saved".
Ferro had its "day in the sun" about 50 years ago and as the realities of building a boat from it sank-in it just faded away.
Build a Ferro boat with prefabricated "bricks"?
You're going to need more than enthusiasm and imagination.

 

Compared to what?
Maybe it's cheaper compared to other construction methods in Iran, I don't know.
It won't save you any time however.
Are others in your area building boats this way?
Is it working?