Visit our Popular Forums

MickB · 29-09-2019, 14:02

Youtube Sailing Catapala Ep. #146. Sorry I couldn't copy paste the link on my phone. These guys are a young couple with two kids that have documented their sail from when they purchased the ferro boat from Magnetic Island, sailed it to the Gold Coast, particularly refitted it and have since ( over the last few years) sailed up and through Asia. The episode I quoted is a repair job on the hull. I've sailed on a few ferro boats but not recently, they are heavy and slow to react and can be shattered if they hit a wharf or a bomby but so can a fiber glass hull. Would I have one; probably not, but if you've got a week to watch all 170+ episodes of the above YouTube channel which spans about a 3 year period I don't think the hull gave them any problems and I believe they only paid 30-50K AUD so pretty cheap cruising.

Simi 60 · 29-09-2019, 14:57

Quote:

Originally Posted by Maclir

In civil engineering construction projects the recommended minimum cover to steel reinforcement is 50 mm. In ferrocement hulls a cover to steel is maybe 1 mm. Otherwise the hull it too heavy, therefore ferrocement reinforcement rusts and spalls the cement. Unless it is protected by some magic coating.

I seriously doubt that

RaymondR · 29-09-2019, 15:14

The bigger ones seem to be more successful than the smaller.

I know of one which has been tied up for about 20 years without any hull maintenance at all other than the repairs to damage caused by a pontoon driving down onto it during a flood. The repairs were carried out with it in the water. Other than the paint mostly peeling off it appears as sound as the day it was built. A steely would have sunk by now and FG be in very ragged condition due to UV damage.

I also observed another one which had been damaged when it was run onto rocks at high tide and, having been left to stand up until low tide, toppled over and stove in the turn of the bilge. They put some pumps in and it re-floated and then the leak was fothered with a tarp until it was put on the slip and the hole repaired, which took about three days.

Where the impact occurred the concrete shattered but the steel mesh kept a lot of it trapped much reducing the inflow of water. I suspect that had they flowed in some rice or other grain which swell when soaked in water the leaking would have stopped. It was a good illustration of them basically being a steel boat with the holes sealed by concrete and without the constant corrosion protection problems.

Many of them were well fitted out but have poor resale value and if one wants or needs a largish boat at low cost they are a good option.

SVTatia · 29-09-2019, 15:45

Quote:

Originally Posted by captlloyd

If negativity had any value some of you folks would be wealthy. You’ve never even seen the boat.

What negativity? This is reality, and we are commenting on Ferro boats in general. Have you seen the boat? What is your opinion Cap?

gbowen · 29-09-2019, 18:32

i must comment on the cover requirement Simi60 mentions. It is true that the ACI code requires a minimum of several inches of concrete. The ACI Committee on Ferrocement waived this requirement and the cover now recommended is a sand grain size or two (maybe 2 mm). The reason being the mixes are so much richer than normal concrete. The Det Norske Veritas Requirements for Ferrocement Vessels state that the cover is not to be greater that 3 mm nor less than the netting layer diameter closest to the surface.

I put my first boat in the water in 1977 and it was a family home for 15 years. It had not a speck of corrosion when I sold it in 2011. I religously sealed it with epoxy paint and prior to the sale re-sealed it again in the presence of the buyer.

It has long been argued what the minimum size can be for a ferrocement boat. The Hartley Tasman was 27 ft. The Donovan Nulgarra and Bingham Flicka were 19 feet. Kan Walker in Melbourne built some light all mesh boats. My last boat is 23 ft with a 1/2 inch thick skin.

If the boat in question was built in Australia or NZ, I expect it to be of good quality because of the reservoir of collective experience in these areas. We had user groups and shared equipment such as grout pumps and mortar mixers.

TassieBloke · 30-09-2019, 00:30

In terms of Concrete Technology, it has little to do with cover over reinforcement, and everything to do with the permiability of the concrete. One of the only ways to adjust that, is cement content as a function of the water cement ratio. Compaction is also necessary.
In any concrete pour, this is absolutely critical wrt the longevity of the concrete. If you see a concrete agitator driver being directed to add water to increase slump, reject the load. There are additives for that. The addition of water adjusts the water cement ratio, and thus the strength amongst other things.

As a graduate engineer, my first project was supervision of driving piles at a Zinc Smelter in Hobart, Tasmania. It was a new wharf, and we drove hundreds of piles into one of the most aggressive ground conditions I have ever seen. It was not that long before, that they had stopped pumping sulphuric acid directly into the Derwent river. The leaching of acids into the ground was something from last century.
Our pile design was so extreme, that we had precast piles of 90MPa, with a normal house slab being maybe 30MPa. To deal with the hydration heat produced from curing, they were constantly watered to cool. The wharf still stands today.

My point, is that concrete can be used successfully in very very agressive environments. To do that, the mix design has to be very carefully put together, and QC at the batching plant spot on. Cover to reinforcement can be calculated, so 50mm as is usually specified, can be changed as necessary.

Back to Ferrocement hulls. I have never built one, but from an engineering perspective, absolutely possible provided the quality of the concrete be very closely supervised. I guess this is where the homebuilt hulls will ultimately fail, because unless the guy on the mixer was pedantic about each mix, there will large variations to the mix quality, and thus eventual failure from salt water ingress and resultant spalling.

Hopes this sheds some light on concrete [emoji846]

NevilleCat · 30-09-2019, 05:18

I'm not sure that you should try to compare Ferrocement construction to traditional reinforced concrete.
There used to be a couple of great old specialist ferrocement boatbuilding books at my local library but they have since disappeared, probably in the annual sell-off of old books which is a shame for a lost resource. They contained the details of the mortar mix and specific slump rates etc. And the desirability of having a team of plasterers do the hull in one hit.
Experiments in ferrocement have shown it can be laid up quite thin successfully, even to make canoes and kayaks(!) and when laid up correctly in a plank it apparently could be remarkably flexible and resilient.
I don't know about that but there were a number of yards or teams that specialised in building or plastering ferro boats up until the 90's around Australia and New Zealand so I presume similar in other parts of the world. It would actually be interesting to have some of the best regarded ones listed for future reference. Although some of the amateur built boats were often plastered by the same teams from the professional yards.
Off-hand I can think of Sayers in NZ...there must be others; I remember so many ferro projects being built in backyards in NZ when I was a kid.
In Aus there was Wilf O'Kell designing so presumably building at the time?
Kan Walker in Geelong; plenty of his boats still around, quite a few were epoxied from new it seems, and at least one sold recently that had been glassed from new as well.
Other names I have picked up were Ken Cock in South Australia and I've seen a number of Hartley RORC designs in Tassie built by the same guy but can't remember his name.

Talbot · 04-10-2019, 07:03

IMHO ferro got its bad name from failures due to lack of knowledge and inexperience of a lot of home builds.
Long distance ferro cruisers are available for not much more money than the cost of the equipment and if that boat was professionally built by a good experienced boatyard, it represents extraordinary value for money.

Siberian Sea · 04-10-2019, 07:05

I have several friends whom own commercial fishing boats in Alaska made from cement and these vessels are tough as hell. Up to 40 feet a cement boat and wooden boat weigh about the same larger wooden boats are the more heavy. Now all this weight shows in two ways, first yes it’s not a light wind vessel but in heavy seas it rides like a champ. A properly built and well maintained cement boat has perhaps the longest hull life of any materials.
Folks who balk at these boats for the most part have never been at sea on one. I’m not saying this particular vessel in the add is good or not but..... cement boats can be built with wonderful lines, true blue water stability, long hull life and yes can be repaired if damaged, fire resistant.
I like them and and if in the market for a boat would be willing to look at one. We all have our own opinions and ways of doing things just a stroll down the local marina docks and you can see the vast selection and styles. I’m always attracted to the boats that step out of the generics, the ones that don’t look like a clone from a Clorox bottle, salty boats who’s owners speak humbleness in foreign accents having just arrived from fare away islands.
So I hope someone gets this boat and shows the negative talkers how to step out of the line of uniformity putting together their own dream and this dream takes them to distant harbors so folks like me can be reminded what is was like to make your dreams reality.

BenBowSirocco · 04-10-2019, 07:23

Hey guys- anyone ever heard of a roof being done in the same method as ferro-cement boats?
If so, what would you call the process?

Anyone know the title of a really good book on how to build a top notch ferro boat? Not personally interested in building one, but the ability to make a curvaceous and beautiful long lasting watertight structure interests me.

captlloyd · 04-10-2019, 07:26

Quote:

Originally Posted by Maclir

In civil engineering construction projects the recommended minimum cover to steel reinforcement is 50 mm. In ferrocement hulls a cover to steel is maybe 1 mm. Otherwise the hull it too heavy, therefore ferrocement reinforcement rusts and spalls the cement. Unless it is protected by some magic coating.

So You are thinking when you are ready to plaster up a ferro cement hull you just call up the concrete company and have them send out a truck. Perfect. You couldn’t be more misinformed. The concrete is a blend of specific agregates and mixtures that you compound yourself, it is not your run of the mill concrete. As previously stated, the weight of the hull becomes as light or lighter than other types of construction. I would think around 40 feet. Also as previously stated, the oldest floating hull is a cement hull. And some of you question the seaworthiness of 35 year old boats built of other materials. Geesh !

BobMc · 04-10-2019, 08:34

Knew a Navy officer who built a ferro-cement boat while stationed at Gitmo in the late 60s or early 70s. Last time I saw him/it was in the early 1980s in Newport. He had sailed it around the Caribbean and up the East Coast. It was a nice looking boat, but have no idea about the hull integrity.

Cadence · 04-10-2019, 10:32

The bad rap taken by Ferocement boats is primarily deo to uninformed builders. Never the less it exists, so even a well done boat is going to carry the stigma.

NevilleCat · 04-10-2019, 14:37

Quote:

Originally Posted by BenBowSirocco

Hey guys- anyone ever heard of a roof being done in the same method as ferro-cement boats?
If so, what would you call the process?

Anyone know the title of a really good book on how to build a top notch ferro boat? Not personally interested in building one, but the ability to make a curvaceous and beautiful long lasting watertight structure interests me.

Ferro cement houses were a bit of a passing fad around the same era. Some quite stunning places built but definitely "outside the box" (think Hobbitown).
As ferrocement gains its strength from the curves then this led to curvey designs. I have seen a doco on a famous place in the hills in California and right down to home built off the grid construction in an isolated area in Asia. Try searching on youtube etc.
Anyway just giving the thread a bump...I know it's a drift, but hoping someone might be able to point you in the direction of books or other resources.