Open mesh on ferro hull

[Kiwi.]

Originally Posted by Scout 30

Telling Sven his boat is not worth repairing based on this limited information is irresponsible IMHO. People love to generalize on forums and generally ferrocement boats are not a good investment but if you already own the boat & it's in good shape otherwise scrapping it because of this defect is silly. There are some ferrocement boats out there that are really amazing. Now if this is just the tip of the iceberg & you need to repower, rerig or get new sails then you might want to rethink moving forward. How about some more detail about the boat & some pictures.

Well said Scout. The hull of a yacht is typically less than 20% of the total cost of the ship. Rebuilding a ferro hull under a well found yacht can be an excellent idea. Here in NZ we have many old Hartley ferros still floating and performing well. The "ferro revolution" in the 60s and 70s was all about amateur boat-building and the repair of ferro boats is, likewise, well within the average DIYer. However, as with the original building philosophy of ferro boats, it just takes time.
I like the dentistry analogy; you have to chip and grind back to clean metal then rebuild from there. Find a copy of Jackson's book
https://www.amazon.com/Concrete-Boat.../dp/004623005X but read up on the latest epoxy techniques.

[Scout 30]

Originally Posted by redhead

Hi FC owner here. I would be very concerned at the extent of rust as well. Just like a dentist remove the cement and rusted wire until you no longer see rust. Retie new screening in (we call it chicken wire) and epoxy just as if you were building it. Also examine the stringers under heads and galley. We found rust there but nothing mortal. We did blast the bottom, but we had done this before on other boats, it takes a very light hand.

This looks like a huge job. Good luck

Wow! It's a good thing you're holding this boat up because the apparent adequate lack of bracing is scary.

[upston]

Hi Seven,

Just completed a haul out on a 55ft ferro boat. I had some damaged armature as well. Dig out the crud till you have firm ,tight material. Surface rust is fine but if the wire is rusted through chase it back till it is intact. If it is compromised all the way through to the other side then you may want to move on but I don't think this is the case from the picture.

Hit all the exposed wire with rust converter several times till it turns nice and black. Do the hammer test all over the hull to be sure you have a solid structure. Now you have two ways to go.

Cement or epoxy. Cement is cheap and easy enough if you know your way arroung a mixer and keep your water content very low BUT bonding thin layers of morter to old salty hull is not a sure thing even with all the high tech additavies avaiable today.

I went epoxy over the whole hull below the water.

1. two peneterating epoxy layers to get a good bond to the old hull.
2. patch large damaged areas with paste epoxy , I used fiber reinforced stuff that was like peanut butter.
3 Optional step if you have the time skim coat all the unfair spots with sandable microballon epoxy. I skipped this step as I had limited time in yard.
4. Barrier coat two or three coats. Medium thick epoxy but rollable.
5 Bottom paint of your choice.

PM me if you have questions, lots of ferro haters out there and with some justification because of bad home built junk but a well done hull makes a fine boat.

GRP blisters, steel rusts, aluminum dissolves, wood rots, we all have our issues but some ferro boats are older than the owners and still going strong.

Good luck Upston

Never try to teach a pig to sing, it will frustrate you and ANNOY the pig. RH

[redhead]

Originally Posted by Scout 30

Wow! It's a good thing you're holding this boat up because the apparent adequate lack of bracing is scary.

We were on a 100 year old marine railway - they haul heavier than us (about 60 tons) on a regular basis. There are four enormous pilings squeezed up against the boat holding us tight, those blocks are just in case something shifts. Trust me we were secure

[Lepke]

There are etches made to pretreat steel by most makers of quality paints. The etch removes the rust and leaves a rust free surface, ready for an epoxy primer. The real problem is the rest of the mesh and framework. Mesh open to the outside allows pathways for water to travel to the interior. Cement is permeable. Even rocks absorb some water.

Just because a FC hull floats in a marina doesn't make it safe or reliable in the ocean. I know of several still young FC hulls that came apart enough to sink at sea. Quickly.

[nautitrix]

First off you must understand what has happened to this boat. The wire you see, has rusted enough to blow the concrete off the side of the of the hull to at least the first outside layer of the armerature (re-enforcing wire cage). In order to stop the rust in the rest of the wire you need to expose it down to the point where you can see there is no rust. Go to an industrial tool rental supplying tell them you need to rent an electric needle-gun. When you see it you will understand how to use it immediately. Do not cut, grind, or sandblast, until you have exposed all of the rusty steel with the needle-gun. You will be able to chip off the concrete around the wire armature and with a deft touch have the original steel to sister to (set along-side). Then you can coat the exposed wire with Ospho, or some other rust converting product. Then you can make repairs. To get the damage exposed you do not need to cut out the existing armerature, you can sister in the same type and size of wire and tie it together with wire tie. Then go to your concrete products people and tell them you need to cover the existing wire and concrete with a concrete bonding epoxy. You want a sticky slow set epoxy that you can paint on as you put on new cement over the damage. You then can epoxy coat with a waterproof epoxy over the whole hull.
People will tell you it cannot be repaired but the liberty ships were ferro boats and they would be towed back in pieces and make one good boat out of three. The advice about hammer sounding the rest of the hull will let you know how far into this project you really want to go.
good luck and smooth waters
BobV

[UNCIVILIZED]

I don't know FC but know that bonding over rust is a real bad idea, given how much it expands in volume as the rust progresses. Here are a couple of resources on FC, the blog is by some folks who've sailed quite a lot of miles in theirs, & more info on it & them can be found over on attainable adventure cruising. Not all who wander....are lost
http://www.ferrocement.org/

[Scout 30]

Originally Posted by redhead

We were on a 100 year old marine railway - they haul heavier than us (about 60 tons) on a regular basis. There are four enormous pilings squeezed up against the boat holding us tight, those blocks are just in case something shifts. Trust me we were secure

I figured there was more to this than meets the eye. Looks scary though.

[DumnMad]

Looks an easy fix to me provided the only corosion is where cover was sandblasted off.

Good high cement ferro doesn't let the corrosion sneak down the wires as happens with concrete. I would ignore the naysayers because they're talking about concrete instead of ferrocement. Totally different behaviour. (Most poorly constructed "ferro" boats were actually constructed with the builders thinking they were concrete.)

[Deltasailor]

Originally Posted by TeddyDiver

Sorry to say but that is beyond reasonable repair IMHO

Sorry to say but it is FxxxD. Cut your losses and find a similar GRP hull and move all the fittings.
A friend of mine bought a abandoned hull which was rusting for about 10 years plastered it with ferro and fitted it out.
Sailed it out to Madira. On his way back home 5 miles off the Azors it went down like the stone it was. A week in a life raft almost killed him and his wife. Once rust has got into the wire all the integrity/strength in the hull has gone! Chuck it!

[captlloyd]

Originally Posted by Scout 30

Telling Sven his boat is not worth repairing based on this limited information is irresponsible IMHO. People love to generalize on forums and generally ferrocement boats are not a good investment but if you already own the boat & it's in good shape otherwise scrapping it because of this defect is silly. There are some ferrocement boats out there that are really amazing. Now if this is just the tip of the iceberg & you need to repower, rerig or get new sails then you might want to rethink moving forward. How about some more detail about the boat & some pictures.

So right Scout. I am sick of people spouting off about subjects they know nothing of. One of the bonuses of ferro cement is its ease of repair and immense strength. On a properly built hull the water will not transverse through the hull any more than a fiberglass hull. I would look into the plastic/cement patching products available these days, I have used it and I really like it. It goes on very smoothly. Also as stated use a rust encapsulating/converting product to treat any rust. Good luck and avoid all negative talk.

[bigman1]

I don't think ferro hulls will last like grp because the mesh is made from mild steel, once the salt gets at it corrosion corrosion corrosion. .The best that can be done is to patch, but what about the unseen parts.

[captlloyd]

Originally Posted by bigman1

I don't think ferro hulls will last like grp because the mesh is made from mild steel, once the salt gets at it corrosion corrosion corrosion. .The best that can be done is to patch, but what about the unseen parts.

The steel if properly encapsulated it will never rust. Water doesn't penetrate ferro cement. There are 60-70 year old ferro cement boats and barges floating about.

[jimbunyard]

The first ferrocement boat was built in 1848, the first 'composite' construction (unless one counts sealskin and whalebone or birchbark and cedar I guess), preceding fiberglass by about 90 years...

This one was built in 1942, and purposely run aground in the early fifties off the north coast of Lanai. Though she looks pretty bad, I suppose that says something about the potential of the construction method...

[GordMay]

Greetings and welcome aboard the CF, upston.