Ferro Cement Hulls ?

[BillAU]

Originally Posted by awab

this message is for bill,
I been reading this post you link to some time ago.
It is right not to build cement tanks for diesel. But this is not my case. I have steal tanks and this tanks have a leak.
In this post they not recomanding to take the oel penetrated parts of the hull out. Only cleaning and sealing new so far I understand.

I have no problem to take the old tanks out. I am looking only for the for the best action to deal with the penetrated parts.

thanks for your effort,
peter

Hello Peter,

Ferro Cement is completly "water" proof. i.e. It will not permit "water" to pass-through it. Dieseel "is" a different kettle of fish all together.

I have contacted Colin Brooks seeking his advice on your problems, I have pasted his reply below...Some good news and some not so good but as you are the one on-site, then only you can decide on the next step/s.
Below is Colin Brookes reply to my query, I also provided links to your boat pictures for Colin to view.
Quote:

Hi Bill,
I see no reason why not to use the punched plate as a filter for the keel cooler (however an external keel cooler in tropical waters is not a sensible option).
It really is the only way to fix the bad deisel soaked area by breaking out the old and putting in a new cement plaster mix.
It would be adviseable to break away a larger area to ascertain what the hull is made up of.
Re Stan Huntingford, he is likely a very competant Naval Architect, but that does not necessarily mean he has any experience or knowledge of ferro-cement construction. He is not known as having any expertise in this field, the same as I have very little in the field of aluminium construction, yet I am a world recognised Naval Architect with more boats built sucessfully to my designs than almost any other designer. You may also find the Huntingford may have actually designed the vessel to be constructed in a different medium, and the builders have adapted it. The builders may also have cut corners from the original specifications, these are all possibilities.
I note the hull is also showing signs of a depleted coat of red material. If this is a copper based antifouling it is not good. If it isd the remains of a red-oxide paint is no problem.
regards
Colin Brookes.m.SNAME.
Hartley & Brookes Associates
End Quote.

Hope the above is of help to you Peter,

Bill
Australia

[BillAU]

Originally Posted by awab

this message is for bill,

In this post they not recomanding to take the oel penetrated parts of the hull out. Only cleaning and sealing new so far I understand.

I am looking only for the for the best action to deal with the penetrated parts.

thanks for your effort,
peter

G'day Peter,

IMHO the most important section, for me, from the link I provided is:
Quote:
The plaster mix of a ferro-cement hull will absorb carbon fuels and especially diesel fuel. And if the plaster mix is not absolutely spot on, diesel will break it down.
End Quote:
As you, nor anyone else not involved with building your boat from scratch, have no-way of knowing if the mud (FC) was "absolutely spot on" when mixed and applied. For me, the safest route would be to remove all the diesel damaged area, clean and replaster with FC...That's just my personal choice, I like to play it as safe as possible when dealing with the Sea or any waters.

Cheers Peter and good luck with things.

Bill
Australia

[awab]

hello bill

thanks for your effort. I am very impressd. Even taking out the penetrated spots and replace with new cement would not be the worst thing. I will see what I am doing.

There is the also the repair of the front damage. By building the new armature was the question to weld the new rebar to to old one.
now I found this side.
The Home Machinist! • View topic - Welding Rebar
The welding of rebar does not seams that easy.

What is the word on this by the group.

Another idea to repair the mast:

After stepping down the mast I could cut it before the bend and after. The bend lets say is about approx. 6 feet. This 6 feet get replaced with a new piece and spliced together like done with a lot of masts. This should make a straight mast again.

Bending back would be much more difficult if not impossible.
Buying a used one has a lot of other very expensive problems.
Buying a new one is would cost more then the boat.

It was clear to me to face a lot of challenges. Its getting very interesting to find solution.
thanks
peter

[awab]

hello

so more I read about the different solutions so more confusing it gets.
Here is another link to the welding of rebar.

Fluxcore & rebar? [Archive] - WeldingWeb™ - Welding forum for pros and enthusiasts

In my case I dont even know the rebar used is weldible. I can imagine also the heat to the existing cement is not really good.

It seams now it is better to build the armature without welding.

Hope there are more ideas out there.
thanks
peter

[BillAU]

Originally Posted by awab

hello

so more I read about the different solutions so more confusing it gets.
Here is another link to the welding of rebar.

Fluxcore & rebar? [Archive] - WeldingWeb™ - Welding forum for pros and enthusiasts

In my case I dont even know the rebar used is weldible. I can imagine also the heat to the existing cement is not really good.

It seams now it is better to build the armature without welding.

Hope there are more ideas out there.
thanks
peter

G'day Peter,

If this were my boat, I would first remove the pulpit, furler and all other fittings from the bow of your boat, then I would break-out "all" the damaged FC, all the way back to "sound" FC. Breaking out the damaged FC is best done by two men, one inside the hull holding a heavy hammer against the section being worked and a man outside the hull doing the breaking- out of the damaged FC. Doing that would expose the mild steel mesh and the galvanised bird-wire and you could see what size mesh and bird-wire has been used in the armature.
I would then purchase the same size mild steel mesh and galvanised bird-wire as that used in the build, then "tie-in" the mild steel mesh using galvanised or plain mild steel wire ties before arc welding it in places for extra strength. You can then cut the mesh to shape before tieing the bird-wire to the mesh using the wire ties.
For welding, I would use 1.5mm diameter General Purpose electrodes, these should be about right for welding the mild steel mesh BUT...As I'm NOT the best welder around...Please check with a welding shop or someone who knows more about welding the mesh. You can then tie-on the galvanised bird-wire using galvanised or mild steel wire-ties before plastering with new FC and don't forget to apply a good dose of PVC (wood glue) to the sound FC just before applying the new FC.
Peter, if your welding is as good as my own it may pay you to employ a pro' welder to weld the new mesh to the old, I believe a pro' welder could do the job in an hour or two.

Good luck with the project Peter and keep us informed of your progress.

Bill
Australiah

[BillAU]

Hello Peter,

Here is a link I found on the forum, it opens a PDF file on FC Hull Repairs (it was posted by wolfaroo, another member who had similar problems) and it could help you with your hull repairs

Bill
Australia

[BillAU]

Do any AU or NZ members have any knowledge on a Mr Willacott as a FC boat designer

[awab]

hello bill
thanks again

It show very well that the repair in the end is not very complicated. wolfaroo is using not
quicken wire for his repair. Is the reason that the rest of the boat is also constructed different or is the this kind of wire easier to use.

also why is he using so much epoxy on his patch.

still the question is open what kind of primer should I use after cleaning the hull.
Does somebody has info about the pool paint.

thanks
peter

[awab]

hello

Just another idea for the oel penetration problem came up.

Lets say after a good cleaning in and out. Inside I could leave a good amount of degreaser. Now from outside - now comes the tricky part - ccould be a kind of suction.
Lets say vacuum. This would suck the degreaser trough the cement after a while.

I came up with this idea after seeing a german company cleaning streets after heavy oel spills with this suction prozess. They have only heavy and expensive equipment to do this.
But in fiberglas work there is also a lot of vacuum packing so far I know.
Any idea to use this for my problem.
I have a vacuum pump for my refigeration repairs.

thanks for thinking with me
peter

[DumnMad]

Which sand to use? Someone asked this question. Quartz or Basalt or other hard sands are fine but the grain size must be graded as in normal concrete sand. i.e. not all the same size like you get in wind blown beach sand. Well graded means the gaps between grains are smaller and more easily filled by the much smaller sized cement particles and this leads to water-tightness.

[BillAU]

Originally Posted by awab

hello bill
thanks again

It show very well that the repair in the end is not very complicated. wolfaroo is using not quicken wire for his repair. Is the reason that the rest of the boat is also constructed different or is the this kind of wire easier to use.

also why is he using so much epoxy on his patch.

still the question is open what kind of primer should I use after cleaning the hull.
Does somebody has info about the pool paint.

thanks
peter

Hello Peter,

Everything I have read on FC boats state, Quote: "Square Mesh" was used on the earliest built boats, the "Advance" to the use of "Twisted Wire Netting" was made many years later. End Quote.
It also states, "the damage on hulls built using square welded mesh was/is much worse than damage to a hull built using Twisted Bird Netting".

So I'm guessing the change away from Square Mesh to Twisted Wire Netting was a safety issue BUT some people/builders stuck with Square Welded Mesh because the Square Welded Mesh is cheaper to buy than Twisted Wire Netting.

As for: also why is he using so much epoxy on his patch.
I have no idea Peter, perhaps wolfaroo will drop-by and answer that question.

In every book I've read on the subject of repairing holes in FC hulls, it states. Plaster Mix for large repairs/holes is 2 to 1 by bulk of sand and cement to a dryish mix. The higher the water content in the mix, the greater the shrinkage. Keep the level of plaster in the repair slightly lower, then use filler (Epoxy Filler can be ordinary car body repair filler) to level for the final finish after curing.
For bonding the new plaster to the old plaster, use ordinary white water soluable PVA...Sold as Wood Glue.

Perhaps other members who have carried-out similar repairs to the hull of their boats will drop-by and give us their opinions.

Originally Posted by awab

hello

Just another idea for the oel penetration problem came up.

Lets say after a good cleaning in and out. Inside I could leave a good amount of degreaser. Now from outside - now comes the tricky part - ccould be a kind of suction.
Lets say vacuum. This would suck the degreaser trough the cement after a while.

I came up with this idea after seeing a german company cleaning streets after heavy oel spills with this suction prozess. They have only heavy and expensive equipment to do this.
But in fiberglas work there is also a lot of vacuum packing so far I know.
Any idea to use this for my problem.
I have a vacuum pump for my refigeration repairs.

thanks for thinking with me
peter

Oil spilt on roads would not be left to soak into the roadway for years, for safety it would be cleaned-up quick-smart.
In your case, the diesel has been damaging your boat hull for years, it has soaked through the hull from inside to outside so, if it were my boat, I would do as Colin Brookes recomends in his email, I would chip-out/break-out the diesel damaged FC and replace with fresh/new FC. I know it would be a big job Peter but better safe than sorry.

Cheers Peter,

Bill
Australia

[Yachts66]

I dunno, it just seems to me that given the ease of removing the affected cement and replacing it, all other options seem....well....iffy at best. I think the consensus here is diesel oil saturated cement is a bad thing, no matter how it happened. I guess you could play with leaching and vacuuming and all those other ideas that might or might not work, but they are probably just as difficult and more expensive than just removing the affected cement and replacing it! Seems so to me anyways. There's no doubt in my mind that this is exactly what I would do if I had a FC boat with this problem.

[clockwork orange]

Bill,are you sure you are reading correctly? as i recall the choice of chicken mesh vs welded sqare mesh was largely designer driven with designers such as Hartley prefering chicken wire and Benford and others being proponents of square mesh, i believe chicken wire came first and was also cheaper not more expensive, at least thats the way i remember it from back when i built my boat. Also auto body filler is polyester based,not epoxy and should not be used in ferro repairs.
You asked about a particular kiwi designer, i believe the name is Woolacott, i think there was a Bert and a John, they designed wood boats but i think some were built in ferro,but not neccesarily designed for the medium.

[BillAU]

Originally Posted by clockwork orange

Bill,are you sure you are reading correctly? as i recall the choice of chicken mesh vs welded sqare mesh was largely designer driven with designers such as Hartley prefering chicken wire and Benford and others being proponents of square mesh, i believe chicken wire came first and was also cheaper not more expensive, at least thats the way i remember it from back when i built my boat. Also auto body filler is polyester based,not epoxy and should not be used in ferro repairs.
You asked about a particular kiwi designer, i believe the name is Woolacott, i think there was a Bert and a John, they designed wood boats but i think some were built in ferro,but not neccesarily designed for the medium.

G'day mate,

I'm taking the info' I published from Colin Brookes latesst book, Ferro-Cement Boats, 3rd addition, page 29, Tittled...Mesh Or Netting...It's choice and application. In the article Colin states, Twisted Wire Mesh is the biggist cost in building a FC hull. The article provides further info' on why Hartley and other FC designers moved from square welded wire to twisted wire mesh. Twisted Wire Mesh IS more exspensive so cost was/is not the main factor for the change.

As for the car body repair gear, that info' I found on page 127 under Repairs
Quote: Epoxy Filler for levelling and finishing purposes can be ordinery car body repair/filler. End Quote.

As I know nothing about repairing car bodies I go with the recommended product.

Thanks for the info' on Woolacott...I wonder how well were his FC boats designed and built by others

Bill
Australia

[clockwork orange]

Hi Bill, that suprises me, when i built my RORC 39 begining in 1971 i of course was deep into the "scene" and never heard of any Hartley ever being built with welded square mesh,i agree that the mesh, regardless of type would be one of the biggest costs in building a FC hull, although i would think that the plastering on mine would have been the biggest single expense due to the fact that i, like most of the builders i knew, used pre mixed plaster mix rather than starting with the raw ingredients as well as hiring Ev Sayers team to come down from Whangarei on 3 seperate occasions to do the plastering while me and a few other builder friends did the laboring of mixing and delivering up to the plasterers, well worth the money imho as as long as you have done a good job of fairing the armature you end up with a nice fair, light hull. I am not aware of any designer who moved from welded to twisted mesh. Welded mesh was more expensive when i built my boat. I dont know where mr Brookes buys his EPOXY auto body filler, maybe such a thing exists in NZ but certainly not in the US, car body work requires the quick curing time of polyester, you would never get the job done if you had to wait around for epoxy to cure.
Woolacott is a very well known name in kiwi boating,all heavy displacement designs that would probably have lent themselves well for conversion to FC. There were quite a few Herreschoff designs built in FC even though he never designed for the medium. When i was building a my boat there was a Herreschoff 58ft Bounty being built in Auckland that was an absolutly first class job,beautiful, i dont know who worked out the FC scantlings,probably the builders.

Steve.