Ferro Cement Cat

I would like embark on building a ferro cement catamaran houseboat of between 80-100 feet in length

This cat will be used in fresh water lake and will have to be constructed on site due to the access to the site.

Speed is no consideration and as it will be used leisurely. No shore power available so would require gen sets.

If anyone can provide plans and building instructions for the hull, please reply to me here.

TQ

 

WOW ferro boats !! anyone else lived long enough to remember concrete boats of the early years ?
Fantastic boats and increadable to sail and to be on .A friend i went to school with sail and lived aboard for years on a ferro yacht !
Ended up on a reef once near Hawai so when the tide went out it was into the dammaged area with a hammer to break all the damaged concrete out of the wire ,a bucket or two fast setting cement and it floated off on the next tide and sailed back to a place where it could be repaired properly .
As a cat !! i have not doubt about the hulls but the bit in the middle , not sure you'll have to find some old ferro boat nut to chat to !!.
Italy is the place where ferro was used exstensivly in the building industry for free formed load baring shapes .
I even belonged to the ferro maine association for about 5 years in the early 70's . Fantastic

 

These are not boats but should be interesting.

www.marinahousing.fi/en

I'd build a flat bottom barge (pontoon) with an eye pleasing top view (boat shape). Then stick a superstructure on top.

Just an idea.

 

Check out the Scow designs !! flat bottomed , pointy bow ,carry lots of weight and completely sailable in coastal conditions . Here in New zealand they were the pack mules of the past ,could go any where in any conditions and helped with the forming of some of our country towns and of shore island communities . The Auckland maritime museumn have a working scow that a designer friend of mine drew up and built for them .He has all the plans and info on how it was made and what it was made of and the sail plans etc etc . Hes in the usa at the momment and wont be back for a couple of months .

.

 

Concrete cat does not make sense... The flat-bottomed-scow seems an excellent idea a simple hullform that would be ideal as a ferro-cement construction prospect... Do you know the construction techniques and constraints? build inverted and complete the in-the-water section at ONE DAY - use a team to ensure this is done as "dry joins" are a weak/leak point You need considerable skill at the ancient art of "solid plastering" and to be able to work the inside and outside simultaneously to ensure the 20 odd layers of chicken wire and the internal form-work of lots of quarter inch reo-bar are completely covered and there are NO airgaps...

I came upon one build during the plastering phase and the guy on the mixer was collapsing with the unaccustomed effort and I was roped in for a while... Man it was an intense effort and a 45ft took well into the night from a dawn start and 12 volunteer helpers building similar boats... I do not like your chances... especially on a 80-100 footer?

I suggest you do some serious research... and practice making a couple of 12 ft models of the hull only rowing boats...

 

I think by memory the first ferro boat was a small row boat was built in 1848 in Italy , its in the museum . its really a simple easy way to build boats but there is a cut off point where its impractical . Saw a little 22 foot single masted yacht and it was built like a concrete loo , heavy as and did about 4 knots down hill with a tail wind and the motor full out with all its sails up . A guy i worked with lived on it for a year or more in a tidal greek so it was stuck in the mud twice a day but didnt worry the boat at all .
In a scow form it would be quite practical because some of the internal frames in the hull could be water tanks for fresh water and for gray water and be a integral part of the whole stucture . being a scow it could sit on the bottom in shallow places and yet could be sailed or motored . In the early day there were even scow racing on the Auckland harbour here in NZ .Some were really big boats as i recall .

 

Tunnels: check page three of the attached document for a picture of the ferro row boat you mentioned. It is an interesting story. Your memory is pretty good too: the year was ~1887.

 

http://www.ferrocement.org/forum0.html

1848 !! MY MEMORY HASENT FAILED ME !!CHECK THE HISTORY PAGE !

 

I stand corrected!

 

It can be done

Having designed and built Ferro Cement boats back in the 70's I can tell you that what you are proposing is quite feasible. However, if you want a structure that will last and have minimum problems you need to be aware of the realities of such and undertaking. If anyone even suggests using chicken wire and rebar steer away from their advice. Concrete is strong in compression, steel is strong in tension, ferro cement structures need to make the best use of those strengths in order to build a strong structure. I’d be glad to go into further detail if you contact me.

 

bruce46- gotta agree with everything you said...use mesh not chicken wire.
or for your application you might use plasterers lath 1/4 inch openings.
either way - FC is a great way to do you hull type..it will last forever if done properly- for your type use a closed mold. i.e set up frames- try using radiused bottoms on your hulls as in half moon shapes for strength, then strip plank it with cheap spruce, then staple your rods on then the mesh then plaster. its not hard and in a hull you suggest make the pontoons large with lots of reserve bouyancy.
you yourself could draw up the plans..just get a pencil and start sketching.
buy some graph paper and rulers and a flexible stick for curves. your most likely wont have many curves but just in case...

this is ther best boat building material and it gets a bad name only because its not conventional and its less forgiving than other materials on plastering day...just research it well then do it...yeah maybe do a couple small models to get a feel for it...btw i agree a barge hull is much better for a houseboat. more floatation and stronger and easier to build a scow type hull.
you can do it!

 

Keep it coming

Hey mateys..

Keep your comments coming.

I appreciate your feedback.. good or bad.. it is a learning process. I am looking at this project with great interest.

The house boat will be used in a lake and since it is fresh water, it should last forever! Barge bottoms are another option since buoyancy maybe much better.

Will barge bottoms take more power to get it up to the required speed ? since there will be little or no waves and no currents at all, flat bottom is preferred!

I am looking into diesel electrics with a bunch of batteries that call also be charged using solar panels. Trying to be green!

The reasons for ferro cement are logistics and cost.

Keep your comments coming, please.

thanks

 

LT Marine--im not a naval architect but i have designed and built six boats- all worked great and floated at thier lines. I built a barge back in 08. it wasnt fC(althought i almost did use that barge as a mold) i built if for about 700.00US. 20 x 10 x 18 inches for a calm river. it was wonderful and modest hp-about 5hp pushed it to displacement speed easily even in wind.

im guessing about 30 hp diesel could push that barge no probs even in a good blow.. btw the barge will feel like your standing on land itll be so stable!!
as for de's i have dealt with DE systems for my sub project ..also of ferro-cement.
the thing with DE's is they get complex. not saying dont try it...
- in my system i dont need large motors to power a sub as under water the sub is almost weightless, and no weather issues...very little torque and hp is required..on your vessel you will need at least in my estimate about 20 hp electric in a storm to not have all that windage push you into a grounding or into rocks. you want to be confident in that- trust me i have lived on houseboats for many years in all seasons..the higher your cabin is and the wider and longer- the more its going to act like a giant sail. think a 70 ft sail if you house structure is that long...and that boat - cat or barge type- is going to be as agile as a tree....you want to use your electric engines only in calm weather and the diesel in windy. But my advice is just go for a single diesel, its easier and if your not motoring too much the carbon footprint wont be a problem. a 50 hp perkins diesel 4108 uses about 3/4 gallon an hour!! very inexpensive to run. and easily would push that barge. your not going to win any races but you will be fine...
if you go with DE use a couple golf cart motors...have you thought about how to charge your batts??...the batts practically will take a long time to charge unless you are using mega sized arrays of solar panels. and then it gets both expensive and complicated...best to run a couple truck alternators off the shaft of your diesel and use 24-48 volt ev motors. then your charge time with heavy duty truck alternators is about 20 mins max for about 6-8 batts. this results in huge savings in fuel. and less complicated. even when those batts are full from solar they are going to run out in about 1- 2 hours. faster under bigger loads. batteries cannot be drained out if they are deep cycle and deep cycles MUST be slow charged--- use ordinary car batts cheap..but you will have to buy new ones about every year or two, unless you maintain about 1/2 the charge at all times.
good luck..tell me how it progresses

 

From experience with concrete in building construction, I have a hard time believing chicken wire would keep together a 80-100 ft boat. My experience (yes, it's still a bit limited, I'm young) is that anything under 6mm (1/4'') rebar is of no use.

I'd use something like 6mm rebar net, 150mm x 150mm (6''x6'') eyes, doubled to get 3'' eyes. And at least one layer near outside and an other near inside surface. In addition to the net I'd use maybe 20mm (3/4'') rebar for longitudal tension, inside the outer net layer spaced something like 500mm (20'') on the bottom and all top surfaces (see the sketch).

It would be a damn lot earier to do this kind of hull upside down, the mold being open at the top, so you could be sure there wouldn't be any voids. After flipping the work can be continued on the above water parts. The problem is your hull is probably gonna be to big to flip. Not structurally, but getting big enough crane on site might be a headache.

Yes it's gonna be heavy, maybe has something to do with the saying 'better safe than sorry'.

Here's the sketch. It might be a bit more than strong enough, I'm no engineer so the measures are by what feels good. The stats, lenght 24,6 meters, beam about 8 meters, hull height 2 meters. Bottom 300mm(12''), sides 250mm(10'') and the grid inside 200mm(8'') wide and 300mm(12'') high, spaced 2 meter center to center.

Again, just an idea, something I'd feel safe in.

Lurvio

 

nice lurvio- yep--thats close to what i would have designed..i would use 10 mm rebar spaced every 6 inches. yes build it upside down ...you wil get better results..and btw- ferro is very strong. once cured it is like steel.- but dont use chicken wire..even though baout 70% od builders use it...there are pros and cons for it but i believe that 1/2 inch wire mesh can wrok well ans is stronger---or you could hybridize the layers. but for sure your gonna need minimum eight layers - four inside the hull then your stringers and rebar then your four outside layers...id do a integral framed design..because the mold is going to set you back...also keep in mind turning ther hull will be no cost picnic. and with all due respect to Lurvio--you could get away with a square hull not radiused toa point at the bow. just a rake on the ends is all youll need. make sure your draught is going to give you room for your prop to have enough water not to cavitate. i.e. you may need ballast...hope this helps...
Doug
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