Trantra construction, steel & glass

[sailboy21]

I don't want to start a 1000 days thread... but this post is regarding the construction of the 70' schooner Anne, previously known as "Tantra." On the 1000 days website, there is a section detailing the construction. It is interesting and quite impressive. Amazing they could pull together and build a 70' 60 ton schooner like this in someones front yard. Quite impressive.

http://1000days.net/home/media/boatb...atbuilding.htm

But, It seems like they were building a ferro-cement boat. The steel framework, chicken wire, rebar etc.. that is a ferro-cement construction.
Then the story takes a turn and they apply a resin to the whole thing. No glass anywhere I can see. Seems like it would be strong, but has anyone heard of ferralite? Resin, being brittle, seems like a poor match to steel. They don't bond well, different thermal expansion coefficients, and with rust.. don't want to think of that. The thermal expansion coefficiant of steel and cement are very close, that is why they are used together.
Never seen anything like this before? Anyone else?

[sailingdog]

If you think that is impressive, you should read the story about the building of That... a 62' LOA 40' beam Trimaran. Granted, the boat is made of cold-molded plywood, but the plywood was cut by the builder, using a saw setup he built himself... The boat is actually a gorgeous boat... with incredible woodwork.

[camaraderie]

Sailboy...it is not plain cement that is generally used, but a mix...my guess is that it is semantics in terms of the construction material.
See here: http://www.sailnet.com/forums/showpo...5&postcount=44

BTW...they have not been heard from since Saturday. I am wondering if something is wrong as this is most unusual and they are finally into some large seas and heavier weather.

[sailboy21]

Thats a really good post. I am quite familiar with cement, concrete etc as I have been employed in the construction materials quality control business. This, is not an issue about ferro cement. It is stated that Anne is:

"...likened the hull to a sealed steel and fiberglass bottle."

However, according to the construction series there is NO fiberglass involved. Anne is:

Welded-rebar frame, chicken wire mesh, and a mixture of POLYESTER RESIN and something called Ferralite. No more, no less, no fiberglass, no ferrocement.

Here is the exact quote from 1000days site:
"We mix a white powdered product called ferra-lite with polyester resin, and push it through the mesh and steel until every gap is filled"






Ferrocement is a mixture of cement, sand, and water... When you add crushed rock you get concrete. My boat is concrete actually.. well the keel is, 5000lbs of concrete and iron.

In the blog Capt. Stowe states the boat is leaking... not so much like a sealed bottle. They did make a report as of today. I just hope they make it safely 1000 days out or not.

I also noticed I spelled Tantra wrong.. I apologize.

[camaraderie]

SB...glad to see they are still alive out there. Guess Sonja is just sick...but that is dangerous too.
Anyway...here's a blurb on construction mixes. My guess is that Ferralite is just an old brand name of one of these mixes:

Ferro-cement and epoxy/grp combinations
Either cement on it's own or sand and cement, are mixed with epoxy to create an 'epoxy mortar', is marketed by many manufacturers around the world under various brand names. There are also manufacturers who market it with added shredded glass, carbon fibre and various other stranded materials, used mainly for bridge and building repairs. The mixing of resins and concrete has to be very carefully considered for two main reasons. First their expansion rates are very different. (Steel and a concrete/plaster mix, expand at virtually the same rate). Secondly resin mixes and concrete mixes have reversed osmosis conditions.

There have been many attempts and experiments to improve 'Steel reinforced plaster' (ferro-cement), and 'glass reinforced plastic' (fibreglass), by mixing the two in various combinations. Basically trying to combine the long life and high impact resistance of ferro-cement, with the weight advantage but rapid deterioration of fibreglass. Most of the experiments were done during the 1950's and 60's. The experiments were usually in the vein of either looking for reduction in weight, increased flexibility or increased strength/impact resistance. In the marine world, time proved that there were major drawbacks with resultant osmosis and expansion problems. The former a major obstacle to the use of resins. It is interesting to note that many Scandinavians seem to have taken on the subject almost as a crusade, and some to this day are still experimenting. Although I have to say in general, it still seems to be just covering old ground.
I must point out however that with regard to small areas of repairs the use of epoxy as a compound (not mixed with the plaster), but as an entity attached. Has a place and is acceptable under certain circumstances.

It would certainly be a breakthrough if you could resolve either the heavier weight of ferro-cement, or the rapid deterioration and osmosis problems of fibreglass.

http://www.ferrocement.org/combi.html

[smallyachts]

The Schooner Anne is constructed of Fer-A-Lite mortar mix over a standard steel "ferro" armature. Fer-A-Lite is a unique mixture of various polyester and glass short fibers and is mixed with standard polyester boat yard resin.

There is no concrete in the mixture.

When properly constructed these hulls are virtually impervious to moisture and very resistant to impact damage.

The Schooner Anne did not receive a final barrier skin when she was constructed over 30 years ago, but is holding up extremely well regardless.

More information on Fer-A-Lite mortar mix can be found at www.fer-a-lite.com

For those interested in the finer points, it was invented by Platt Montfort who is also credited with developing "git-rot" as well as several ultra light canoe and dinghy designs.

[camaraderie]

Smallyahts..thank you or the information and the link. I note that you are a representative for Fer-A-Lite. Policy here requires that you disclose that fact in your signature so that others may beaware of your personal and commercial interest. Full rules for commercial posters are here:
http://www.sailnet.com/forums/showthread.php?t=39218

Thanks again and welcome!

[chucklesR]

Cam,
I love the way you follow up on things like this. Kudo's to you.

[sailingdog]

I was wondering how he knew so much about a boat that he doesn't own.