The album of Ariel #422

[ebb]

Howard...Well now, That's interesting....GFRC!
What sort of material is that???

With oil prices never coming down and advances made in fiber and concrete technology I would guess many one-off builders are thinking ferro-cement again!

Remember the glory days of concrete boat building in this area. And still have mental snapshots of one boat being finished over in Alameda at Svendsen's yard where literally everything, the whole super-structure, was being done in 'crete. It was a sculptural masterpiece, with a beautiful fair hull and fine details.

Nice Brit ferro sailboats as small as 24' were professionally being built in the '50's. Some of them are still around. There is a French concrete dinghy from the turn of the century that's still around. And crete has successfully been used to sheath tired wooden boats. www.ferroboats.com

The boats I saw had huge iron rebar and chicken wire or hardware cloth armatures that took forever to set up and tie and required a crew of professional plasterers to finesse the hull. I wonder if techniques and concrete and armature material has progressed to where the problems of 30 years ago have been solved. Ofcourse the main problem with the boats of the '70's was with the lack of knowledge of the armatures building them.

Anyway, my thought is that an Ariel hull and top could now be done with glass or other fiber reinforced waterproof complex concrete with epoxy coated rebar and plastic mesh. Producing a monoque hull equal to fiberglass, equal in displacement, no 'electrolysis' problems, and a lot cheaper.
GFRC and other modern materials might make it possible to think outside the ferroconcrete box to develop new, quicker, better ways of construction.
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Thinking of Kurt's interest in poly foams maybe vermiculite could be introduced into the concrete GFRC shell mix.

[Howard]

Howard...Well now, That's interesting....GFRC!
What sort of material is that???

With oil prices never coming down and advances made in fiber and concrete technology I would guess many one-off builders are thinking ferro-cement again!

Remember the glory days of concrete boat building in this area. And still have mental snapshots of one boat being finished over in Alameda at Svendsen's yard where literally everything, the whole super-structure, was being done in 'crete. It was a sculptural masterpiece, with a beautiful fair hull and fine details.

Nice Brit ferro sailboats as small as 24' were professionally being built in the '50's. Some of them are still around. There is a French concrete dinghy from the turn of the century that's still around. And crete has successfully been used to sheath tired wooden boats. www.ferroboats.com

The boats I saw had huge iron rebar and chicken wire or hardware cloth armatures that took forever to set up and tie and required a crew of professional plasterers to finesse the hull. I wonder if techniques and concrete and armature material has progressed to where the problems of 30 years ago have been solved. Ofcourse the main problem with the boats of the '70's was with the lack of knowledge of the armatures building them.

Anyway, my thought is that an Ariel hull and top could now be done with glass or other fiber reinforced waterproof complex concrete with epoxy coated rebar and plastic mesh. Producing a monoque hull equal to fiberglass, equal in displacement, no 'electrolysis' problems, and a lot cheaper.
GFRC and other modern materials might make it possible to think outside the ferroconcrete box to develop new, quicker, better ways of construction.
__________________________________________________ _______________________________________________
Thinking of Kurt's interest in poly foams maybe vermiculite could be introduced into the concrete GFRC shell mix.

It is indeed Glass Fibre Reinforced Concrete. The glass must be Alkali resistant or it gets broken down. (Cement is nasty stuff, though nothing compared to the cesspool that is resin.)
Crazy strong and can be made to look very pretty. We do alot of big signs as well as surface work for municipalities, Golf, Parks and Rec, restaurant, etc...mostly to make rocklike structures, or countertops.

I also spray it through a big pump into forms/molds. It is a very interesting development in strength/weight tradeoff. Theoretically you could take any glass mold (though I use latex or silicone for 3D stuff and melamine for flat) and spray staight into it, no gel coat required. I seal with a penetrating polymer. Pretty tough stuff. You can use anything from slag to styrofoam peanuts to fill volume.

[CapnK]

Wow, neat replies, good stuff. I am headed out of town for a few days, if I can reply while gone I will, if not, then when I return...

Did some work on the "WC" the other day, cut the berth up/out some to make a level-surfaced small foot platform, and lowered the part that the porta potti sits on. It's working well. I'll get some pics when I get it looking a little better.

[commanderpete]

Interesting explanation why there are problems with 2 part "pour foam"

see reply #6

http://boatdesign.net/forums/showthread.php?t=13679

[ebb]

Foam at the mouth.*
Yeah, it's been known for decades that 2-part urethane foam is lethal stuff. I have known and known about guys who've died using and installing urethane foam. By direct inhalation and by cancer. It's lethal when you are pouring it, when it off-gases after it cures, and when it catches fire. It's not true closed cell, it's unstable and can disintegrate if liquids get in to the space where it lurks. And the liquids WILL get in. Even if it supposedly is completely isolated from the accomodation you wouldn't trust it. It should never be installed in a closed living space. Like a boat.

As pointed out by the guys on the above forum, the DIY pour-in-place market is miniscule. Maybe that's why we never have had an alternative. Not enough dead bodies. You never trust who it is that's making this stuff. Or their MSDS. Though to be fair to them: if they told you how evil their product was, you probably wouldn't buy it, and profit is really what it's all about.

Those unsinkable ETAP boats bother me on this score.

Probably should research the synthetic foam rubbers and readymade poly foams we are intending to use for their 'blowing agents'.
CFC's are still screwing up the planet. Dow and Dupont just dance around creating new ones not covered by legislation. Ozone and Hypoallergenic and Planet are words too pussy for these guys. Some foams are beginning to be made using inert gases like CO2.
Sweet Styrene is a carcinogen and toxin.
Hot wiring styrofoam can produce toxic fumes. So can sanding. And the sanding dust is also hazardous. Burning this highly inflamable stuff creates bad fumes too. The jury will always be out on these products: It's worth while considering the possible migration of nasty chemicals out of these foams.

Seems to me there should be a foam-in-place EPOXY by now.
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*Kurt, sorry for the rant in your space here! In the last year 3 people I've known have died from cancer. At this moment three more connected with the estate here are fighting cancer also: one shrinking visibly is being fitted today with a chemo bag to wear. Another is battling leukemia, another prostate.

[mrgnstrn]

Kurt

Your flotation project got me thinking...

As I recall, you are planning on putting in just enough extra flotation to basically float the boat at it's gunwales. Basically, this is mostly a submerged body. So you may want to consider a few things:

VCG, VCB: Vertical center of bouyancy and V.C. of gavity. You will want to make sure that the VCB is above the VCG, otherwise your boat will be more stable upside down than right side up. (note, this is necessary only because you are now a submerged body, like a submarine. Once you are not a submerged body, you can rely on form stability to help keep you upright)

LCG, LCB: Longitudinal center of bouyancy and L.C. of gavity. This one would be a bigger concern to me. If these two don't line up on top of each other, your boat will float with the bow skyward and stern 26' below the surface. (or vice versa). How are you going to recover from that, even after you fix the hole? It's not like you can bail out the stern....it's totally submerged.

Lateral CG and CB may also be a concern, but if you put approximately equal flotation on port as starboard, you might be able to deem yourself OK.


Also, you might want to think through the repair and recovery process. OK, you have hit a submerged container, put a 10" gash in the leading edge of the keel, quickly taken on enough water to sink the boat, but the flotation has kept the boat from becoming a coral reef project.
Now what?
How do I repair the problem? Do I need to careen the boat way over to reach the hole to repair/patch it? Can I do it all underwater? After I have repaired the hull, how do I get the water out? Are all the gunwales above the water, can I bail, can I shut the cockpit scuppers to keep from filling back up the cockpit? is water draining into the cabin, cockpit lockers from the cockpit? if the lockers are sealed, how do I drain them?

What this led me to believe is that you need to have some temporary flotation bags to enhance the flotation for recovery.

Don't get me wrong, your passive flotation solution is very elegant. Always there, don't have to worry about it not working, no moving parts to fail at the wrong time. And these inflatable bags may be unsuitable for permantent installation and use in an emergency.

But after things have calmed down, you may need to pull these bags out to lift up the bow to fix the hole, or stern to fix a rudder problem, or to lift the gunwales well clear of the waterline for bailing. And if you are crafty, you could make them blow up with those handy sized CO2 cartridges they use on lifevests. Or the similar sized cartridges they use for air-guns. And you can store a lot of them for a long time, until needed. That way if you need to inflate and deflate it a couple of times for all the necessary recovery operations, you can.

food for thought.

________________

oh, and just thought about this.....Don't you also own "Nemisis" up on Maryland? Why not trial sink that boat instead of you beloved Katie Marie......?
Then give the hull to Tim Lackey and have him do something amazing out of it....Like make it fly or something!
(clarification, Lackey is a true genius and artist with a boat hull. Nothing else implied herein)
________________

[CapnK]

Thanks for the input Keith - I can tell you have put plenty of thought into it. I hope that I can address your thoughts succinctly here. Any failure to do so can be attributed to the fact that I am 3 beers into a Friday night at this point.

I am shooting for a better than "decks awash" scenario. Ideally, she'll float at or above the same level as the cabin-side shelves/the stringer against the hull. All, or at least 95%+, of my flotation - discounting sealed cockpit lockers and lazarette - will be below this level. (Cockpit/lazzy will be slightly above that, it's upper few inches.) My thinking there is that as soon as the flotation goes under, it's pushing *up*. Hopefully, the push up will counteract the 'pull down' enough to stop the boat with the decks *above* being awash. I am seeking to put enough foam in to counter sinking, if barely; any extra flotation over and beyond that from sealed lockers will supplant that bare minimum, ideally keeping the deck at least 10" above the water surface.

BUT... (there's always one of those, right? ) -

Sinking that deep is an absolute worst case survival situation, pure and simple, something that should only happen if 'disaster-with-a-capital-D' strikes, and is wearing a t-shirt with my name on it in bold letters. At that point, I'll be glad to just not be swimming to the nearest continent or other landmass.

if it comes to that, I will have to wait until conditions calm enough to deal with pumping out a very flooded boat, but I *will* be able to wait _and_ have all my stores available for survival and repair, both of which seem important.

Would that be fun? Not at all, no way, no how. But to my mind it beats worrying about, say, the liferaft tubes popping for {pick a reason}.

Basically the entire front half of the boat (everywhere ahead of the midships taper), anywhere a penetration can be affected, will be inside of one locker or another. The ideal there is to contain any flooding to just one or two lockers, the same as crash bulkheads do on a ship. This would mean that although the hull was breached, it won't flood - just those lockers will. Also, at the same time, I have *significantly* reduced the amount of interior space which could be flooded if that Disaster were to happen. Less water inside means less water available to be sinking the boat, and also less water to be sloshing around and upsetting the CG/CB balance.

As far as CG/CB - not being a N.A., and not owning one , I _am_ having to kind of eyeball-engineer some of this. You are correct that I am seeking to balance the amount of flotation side-to-side. I am also doing the same fore-and-aft, with the cockpit lockers and lazzy all being independent from each other and seal-able, just like the forward lockers. Under the cockpit sole will also be another area sealed from air/water, providing flotation.

So my strategery is first and most importantly prevention of the possibility of flooding, and second, staying afloat however long it takes to survive and repair if flooding does happen.

Repair strategy is something which will be under active consideration up until I leave shore. I do plan to carry a bit-n-brace, lots of appropriately long fasteners, and plenty of underwater-setting epoxy. There will be some pieces of wood aboard which will serve a secondary purpose as large-hole-patchers if need be.

It would be *really nice* to have a bag or two to provide extra lift where/when needed. I will take that idea into serious consideration. If the boat is capable of floating on its own, then the bags could be pumped up manually, when needed. A bag that could be used that way wouldn't need a bottle reservoir, valves, etc etc...

I sold "Nemesis" a long time ago, and sadly, am unsure of her fate. I do hope she is being fixed up, or has been already, and is under sail during the warm months up on the Chessy. Even if that means she doesn't get to feel the tender ministrations of the Plastic Classic Wizard, aka Mr. Lackey.

Thanks again, I really appreciate the discussion. As always, feel free to poke holes in my thinking - I'd much rather find out I was wrong or off in my thinking before I find out 'out there'.