Oil Leaks into Ferro Hull

[popeyecrew]

hi all
we have a ferro boat and due to family commitments we had to store it for about 9 months. it now has a leak in the bilge area which is sealed with paint but the paint has come off in some spots and oil and diesel has leaked into the hull. has anyone an idea how to fix this problem?
if you are a passionate ferro hater don't worry commenting, any sincere advice appreciated.

[Boracay]

Fixing ferro is something of a black art, but having built (and fixed) a ferro yacht I'd suggest the following (Verify this with a naval architect before proceeding. Make sure they sign off on anything that affects the structural integrity of the hull.) :-

1) Make sure the boat is out of the water and supported so the area on which you are working is not loaded. Read the safety data sheets for all material that you will be using and take the appropriate precautions, especially proper ventilation. Wear disposable overalls, gloves, goggles and hearing protection.
2) Totally degrease and clean the entire area. Remove paint back to bare cement or epoxy primer over surrounding area. This includes the entire bottom of the bilge. Try to get good access.
3) Chip back any oil contaminated areas as far as practicable. Your guess is as good as mine as to how far this is. Don't do this while the boat is in the water. Oil and seawater will damage ferro.
4) Allow the entire area to dry totally.
5) If the amount of concrete removed is very substantial degrease any contaminated reinforcement and replace any damaged reinforcement. Replace any damaged cement with good quality portland cement, sand and pozzolan (Check for correct mixing ratio). Use a bonding agent to join new cement to old cement.
6) If the chipped back area is small fill with epoxy filler.
7) Reprime the entire area with thin epoxy primer.
8) As the epoxy primer goes "cheesy" topcoat with good thick gooey (technical term - look it up) tar epoxy. If you're clean and happy after this you did it wrong - read the instructions and take care.
9) Get clean as best you can and reassemble boat. The tar epoxy wears off with your skin...

[wolfaroo]

Originally Posted by Boracay

... 8) As the epoxy primer goes "cheesy" topcoat with good thick gooey (technical term - look it up) tar epoxy. ...

Hi Boracay,

I'm trying to learn as much as possible about the maintenance & repair of ferro cement hulls and have been gathering info from numerous sources. In his book 'Ferro-cement Boats' (2008), Colin Brookes makes a strong argument against using tar epoxy on a ferro hull, due mainly to problems encountered applying future coats of paint and/or repair work/rubbing down the hull. I'm curious to know your perspective if you have time. (I have some major repair work ahead on my own FC hull and would like to undertand as much as I possibly can about ferro cement).

Thanks,
Neal

[Boracay]

When doing the inside of my Hartley 32 I used tar epoxy on the inside to well up above the waterline.

I'm aware of the subsequent recoat issue but at the time (1970's) I thought it would just about last forever, and the real worry was an oil and water mix getting into the ferro. Straight epoxy resin was not generally available.

These days with so much acceptable quality resin available there's probably nothing wrong with going that way. If I were doing it again I'd try to start with a nice warm thin resin (working in small batches!) and add a couple of coats as it became cheesy/tacky.