Time to resurrect the Ferrocement yacht? - SailNet Community
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post #1 of 25 Old 2 Weeks Ago Thread Starter
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Time to resurrect the Ferrocement yacht?

Since the 1970s, which seems to have been the heyday of ferrocement yachts for the leisure boat industry, concrete technology has made some significant advances. Specifically, glass fibers and superplasticizers have improved the workability and strength of concrete.

Glass fibers provide more anchor points for the cement, much as rebar does but on a more localized scale. Superplasticizers have been described as the equivalent of a dryer sheet for cement. It breaks the electrostatic bond of cement molecules which lets the concrete spread much more evenly and consistently.

This makes me wonder if it's time to look at the ferrocement yacht again, at least for the DIY boat builder?

First, what is a ferrocement boat? Short version, ferrocement boats are wood (or whatever, I guess) framed boats covered in wire mesh on which a cement mixture is placed. Done right, weight was about the same as a steel boat.

Superplasticizers application could improve ferrocement boat building in three ways: 1, the cement mix spreads much more evenly, leaving less voids for the sea to get in; 2, it increases the compressive strength significantly; 3, it can remove the need for a "steam hut" used to cure the mixture on the boat hull. (Concrete cures stronger when it's water evaporation is slowed while curing.)

New glass fibre technology, although it doesn't add much normal (compressive) strength, does address two of concrete's "weaknesses:" 1, it's normally weak(er) in tension than other materials, and more importantly to our discussion; 2, it's brittle. The glass fibres of today address that and a lower brittleness of a hull could be of high interest to someone with the misfortune to run aground.

sid.ir/en/VEWSSID/J_pdf/103820080504.pdf

How to Build a Boat Out of Ferrocement - DIY - MOTHER EARTH NEWS
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post #2 of 25 Old 2 Weeks Ago
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Re: Time to resurrect the Ferrocement yacht?

Interesting.

Since the target market is the home builder, how difficult are these new techniques to implement? How about inspection and QC?

I salute anyone who actually completes a home boat build of any kind. I built a 14ft boat out of Bolger's "Instant boats" and it took much more time (and money) than I expected. I can't even imagine a real backyard build.

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Re: Time to resurrect the Ferrocement yacht?

Let us not forget the advances being made in self healing concrete. Having a material for a boat hull that heals itself would definitely raise it above those current construction materials.

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Re: Time to resurrect the Ferrocement yacht?

It may be that ferro-cement boats now make more sense than in the past, but the problem with any home-build is the total cost. You can get such good bargains on the used market that building your own makes little or no sense financially.
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Re: Time to resurrect the Ferrocement yacht?

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You can get such good bargains on the used market that building your own makes little or no sense financially.
a boat is hardly a wise financial decision.

It's still not going to stop anyone from building wooden boats, bare hulls, restorations, etc.
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Re: Time to resurrect the Ferrocement yacht?

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a boat is hardly a wise financial decision.

It's still not going to stop anyone from building wooden boats, bare hulls, restorations, etc.
Bah, whatever. If boats make you happy, then it's wise to spend money on them, and wise to consider various approaches to acquiring them.
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Re: Time to resurrect the Ferrocement yacht?

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Bah, whatever. If boats make you happy, then it's wise to spend money on them, and wise to consider various approaches to acquiring them.
While it's true that boats rarely yield a monetary return on investment, they pay back in massive quantities of "utility".

Utility Definition | Investopedia
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Re: Time to resurrect the Ferrocement yacht?

I don't think the materials would be any more difficult to use than the original in most ways. The "pourability" of the concrete mix is easier with the plasticizer and the builder would just need to measure carefully and mix thoroughly.

There is one thing I've not quite worked out in my head. As the pourabilty goes up I'm not sure how well it would stick to the upside down hull and in the mess. This stuff flows really well. Which is good in that the need to vibrate goes way down as do the voids. But it won't do much good if it runs off onto the ground.

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Re: Time to resurrect the Ferrocement yacht?

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I don't think the materials would be any more difficult to use than the original in most ways. The "pourability" of the concrete mix is easier with the plasticizer and the builder would just need to measure carefully and mix thoroughly.

There is one thing I've not quite worked out in my head. As the pourabilty goes up I'm not sure how well it would stick to the upside down hull and in the mess. This stuff flows really well. Which is good in that the need to vibrate goes way down as do the voids. But it won't do much good if it runs off onto the ground.
if it was a DIY job, would it help to consult the guys who spray concrete pools? They tend to spray on vertical surfaces and could give some insight to the issue.
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Re: Time to resurrect the Ferrocement yacht?

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if it was a DIY job, would it help to consult the guys who spray concrete pools? They tend to spray on vertical surfaces and could give some insight to the issue.
That would definitely be worth checking into.

Sailing "Horizons," a Hunter 31, from the Middle Chesapeake around Solomons Island.
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