Advice on repairing this ferro?

Discussion in 'Boatbuilding' started by PacificJim, Jun 11, 2016.

  1. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    All chickenwire is not the same. We bought some and within 2 years it is heavily rusted and falling apart, it's actually just disintegrating to the point where you can rip it apart by hand.
  2. PacificJim
    Joined: Mar 2016
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    PacificJim Junior Member

    Thank you all for more input. The owner said it was "Aviary Wire" -it is a hex pattern but nothing else is known.

    Thanks for that info SamSam -bonding agent. I'm concerned about adding more bulk. It's a big boat so it could probably handle a few gallons on one side... would that be the common way to deal with the fairness here? Blast and then add a bonding agent and fair it out with some kind of agent or an epoxy...??? It would be nice to get it smooth, unless it's because of rusted wire.

    I'd be interested in the whole sounding work you suggested Ray. It’s not my boat yet but I think now that you mentioned it, before I’d make a serious offer, it would be VERY prudent to sound the whole hull for voids and issues! I’ve gone centimeter by centimeter over every boat I’ve owned -ever square inch or centimeter gets scrutinized, especially before I think about serious sailing in them. However, I’ve no experience with ferro (all the more reason to on this then eh?) ...! I’m guessing tapping with a small hammer for voids and then fine-drilling and filling with epoxy is the plan if they’re small, or demo and uncover if large…?

    I’ve been trying to decide
    (a) the engine room hull discoloration is dangerous or just more cosmetic
    (b) the aviary wire swelling is common/can be repaired easily enough or the sign of hull-death, and
    (c) As such, if this project is worth our time and money -vs- a boat of less size and ability but that needs less work. We like the design, and LOVE the big, flush decks... but...

    In the test I did do, I tried to scrape some of the hull to expose the aviary wire- was unable to do so with the chisel and hammer I had on hand -(I wasn't willing to hammer hard, just enough to try and flake off the top). I think it would take a mallet and cold chisel I to expose the wire even where the cement is thin-that cement is HARD! I wasn’t even able to scrape much of the paint off either- it’s become almost part of the hull (epoxy coating maybe?)… So I wasn’t able to tell if there was rust leashing out to the concrete over that aviary wire you see- until we sand blast it, what it is is what we see. It will need to be sandblasted to clean, or a grinder to the whole thing!!! I do not remember having such a hard time EVER to get some bottom paint or material to peel off.

    Here’s some pictures of the engine room-
    I tried to fuse them together, so there’s some weird overlaps -it’s 4-5x pictures together. Owner told me he’s since cleaned it up a bit, so maybe I’ll drive over and look at it again.

    ENGINE: That’s a Chinese-built Air-Cooled Deutz F2L912 Diesel Engine. I believe more commonly used in trucks over there, but not sure. Owner said the oil was from bad seals. However, look at the fuel filters- that could also explain it! I can imagine 2 years of fuel slowly mixing with rain water from the missing aft-hatch causing those dark stains in the hull and the diesel smelling drips on the hard. Hmmm… Oh, under the tanks themselves it’s dry -just FYI. I didn't take pictures up close- despite it being rather large in the engine room (8' x8 or so with about 5' headroom) it's crowded.

    Attached Files:

  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Aviary wire comes welded and woven, with woven being most common and cheaper. It's a very light wire, typically 22 gauge and I've never seen ferro scantlings for a woven wire just welded. This is commonly referred to as chicken coop wire, which would scare the crap out of me.
  4. SamSam
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    SamSam Senior Member


    After looking at it and realizing the scale is larger than I thought, I believe that is what we call chicken wire. Here it's being used for stucco. If I was to use it for ferro, I would use the stuff made for stucco, or a kind/brand that stucco people use for stucco.


    I thought it was this expanded metal stucco lath, but the mesh is a lot smaller than chicken wire.


    Googling 'aviary wire' shows regular chicken wire and this welded or soldered square mesh. Around here it's called hardware cloth and is pretty expensive but a lot tougher than normal chicken wire. We use it on openings to keep rats and squirrels out. Whatever you decided to use, I would at the least use only hot dipped galvanized wire.

  5. JakubT
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    JakubT Junior Member

    Are you sure galvanized ferrous material will merge well with cement?
  6. PacificJim
    Joined: Mar 2016
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    PacificJim Junior Member

    That section right there in the picture of the starboard bottom sides, is about 5' high or so, top of picture to bottom. It does look like standard "chicken" wire size to me, in person, BUT SMALL -they're about 1" hexes at most I think. If it was bare wire I'm not sure I could put the end of my thumb or anything but a pinky through one of the holes...

    No one knows if it's galvanized, but I DO see some rust around where it's swelling, looking over some of my detail pictures...

    The boat was made in the early 1970's so whatever was available and known then. It's 3/8" rebar on 3" centers in a double diagonal, with 3 layers of this wire mesh either side, and reportedly 1-1/8" thick. Tapping around the hull it sounds to be about that thick.

    Note, this boat has been cruising for 40 years, and for a few in some heavy ocean weather. It's been on the hard the last 3 and prior to that just casual sailing in the San Juans for 8-10 years I think. The only bad sounds I heard was where that diesel is leaking out and up a bit (it's about 3'~4' min. of "dead" wood -vertical keel).

    The builder was a senior Marine officer from WWII who served in the Solomon Islands/S.Pacific. He was reportedly quite a perfectionist and a yacht/boatyard guy after he got out of the service, and it was to be his personal retirement vessel (were not they all?). He saw heavy seas and wanted to go back cruising there with his family, and wasn't going to have his boat fall apart on him I'd guess. From my research it wasn't that he couldn't have made it in steel or even FRP there at the yard -he was a yard worker and had money enough and a good pension as a senior officer in the Marines. Maybe while on tour he saw a lot of boats like these in the S. E. Asian islands there and decided ferrro was best? I don't know if he intended it to last 50 years though -when he built it he was already around 70. My understanding is that if it wasn't a GOOD ferro, being that's it's cruised for 40 years, we'd have known by now.

    However, then I hear that well, it wasn't a professional layup, so run away!....
    It's had it's time-that rust and those stains... not worth the time or effort, not with what your money could buy in a FRP or other material.

    Yeah, but I can't find a boat big enough for us in this size with our budget in any of the other materials (besides dry-rot wood) that doesn't need an additional $10k-$30k in work -!!!!

    Those little nodules -is that rusting chicken wire then? Kind of looks like someone might have sandblasted too aggressively a few decades ago and then not sealed it proper.

    I just ordered Colin's book.
  7. PacificJim
    Joined: Mar 2016
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    PacificJim Junior Member

    Here's what I found that seems to fit the owner's description
    Farm Supply

    Chicken (Poultry) wire would be 1" -that's MUCH bigger than this stuff. I'd hesitate to even call it "Gopher Wire" (3/4").
    What the boat has does look like their "Aviary Wire" (1/2" hexagon).
    It's a slightly lighter gauge than the hardware cloth (which I'm familiar with from years of working with it), and it has more room in the holes as they're hexagons vs squares.

    I'll take pics at some point with a tape measure for the repair people here, but here's a close up (about 6"-8" away from the hull)
    ...By the way, from the pictures I have, it MOST resembles the 2nd hex-mesh image you put up- that welded stuff. Where the wires meet they are on top of each other, rather than twisted like modern chicken wire is. So I'm guessing it's the 1/2" welded galvanized aviary wire, 6 layers total, with 3/8" rebar between on double diagonals on 3" centers. Once we demo a chunk we'll know for sure eh?

    Attached Files:

  8. PacificJim
    Joined: Mar 2016
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    PacificJim Junior Member

    Forgive any typos -Im all thumbs on little touch screens.
    Got the definitive= small hole (1/2") galvanized aviary wire.

    According to Collins Brookes repairs would be as follows:
    Pressure clean all bilges and outside of hull with strong detergent
    Let dry and remove any remaining dark stained areas after confirming any voids or diesel penetration and diesel leakage... Demo to dry areas all diesel/oil soaked remaining that couldn't be cleaned up with pressure washing and strong detergent. Repair armature and aviary with same. Treat all exposed metal. Use white PVA (wood) water soluable glue to bond old cement to new... 2-to1 parts sand/cement to patch keeping a dryish mix and use filler to level for the final finish after curing... Epoxy for other leveling (auto body filler is fine). Epoxy mortar for larger holes (West or similar) w/cement and fine silicon sand added to mortar slump consistency.
    The showing aviary wire is sandblasting damage from the past most likely - use the auto epoxy to level and fair after cleaning bare.
    Paint formulated for road markings will stick to ferro just fine as well as pool finishes.

    So SamSam you were right on the money there.

    It was a well built boat but not maintained well or treated right...
    So just needs about as much work to fix the neglected diesel damage as it took in cost originally to build the rest of the hull almost... Not a difficult job but time & labor intensive.
    What a shame it was neglected so long -bad sandblasting (Brookes says never NEVER sandblast except to destroy bad plaster layups and to demo)...and essentially some bad filter fitting and fuel leaks and all that damage ...almost has destroyed the vessel, or it has if no one winds up taking it on...

    I wish I was younger I'd take it on. But at almost $300/month yard fees...
    Anyone know good repair persons looking for a job like this, Pacific NW of USA?
    Last edited: Jul 13, 2016
  9. FloodyBloody
    Joined: Jun 2017
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    Location: New York

    FloodyBloody New Member

    Are you sure it is not woven wire mesh? Is this opening definitely hex and not squares? By the way you are describing the smaller openings - it sounds to me like it could be a welded or even a woven wire cloth ( something like this: ) - If so - you should be able to grab a local hardware store, and I think the standard width on a lot of these rolls is in fact the 60" or 5 Feet that you are looking for.

    Unfortunate that this job sounds like it will be too large to handle for an individual, but if you find the right small repair man or company, I believe you can get back to good shape in no time...

  10. ckent323
    Joined: Aug 2015
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    Location: California

    ckent323 New Member


    Did you ever repair the boat? It is unfortunate that I did not see your post and this thread when originally posted.

    My father, now deceased, owned for over 35 years, a commercially built Ferro-Cement sailboat built by Romack Marine in Long Beach , Ca in 1974 that was based on a Samson C-Breeze or C-Baron design. Similar to the boat you discussed, it originally had steel diesel tanks which degraded over the years and leaked. The diesel fuel softened the concrete hull immediately behind the tanks where the diesel had been in long term contact with the concrete. Dad moved the boat to the boat yard in Port San Luis and hauled the boat in the early 2000's. Over a period of about a year (not full time work as he lived 3 hours away) he chiseled and ground out all of the damaged areas, rewove in new wire and replastered in accordance with the advice Colin Brookes provided which was the same as above.

    The boat is still on its mooring in Morro Bay and the bilges are still bone dry. The repairs worked well and have held up for over 16 years. Inspections during periodic hull cleaning in-situ over the years have revealed no signs the repairs to the hull have any issues, however, there are numerous rusty "bleeders" and rust spots in the hull above the water line that are largely smaller than my thumb and a couple as large as my hand. Unfortunately, Dad was not able to maintain it for several years before he passed and it is long overdue for haul out again.

    Bottom line, repairing ferro-cement can be done readily by an owner and while tedious and requires use of the proper materials and attention to details, is something pretty much anyone can do.

    Hopefully anyone else out there with a ferro-cement boat that needs repairing can find this thread.


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