Peter Wiley wrote:

It'd depend on the boat really. Rerigging a racing boat could get
really expensive I'd assume, but it's likely the winches are a lot
bigger than most cruisers would have.

It could get hairy trying to simplify the running rigging for 2 handed-sailing; but
then some race boats have a workable deck layout already.

Hull construction would be my
first concern.

Agreed, with some attention definitely on the rig.


I was just chatting to one of my staff who sailed in the
1998 Sydney-Hobart race and had a carbon fibre hull start to delaminate
in Bass Strait. They also lost nearly everything on the foredeck
including pulpit etc when they dived into a wave. Repairs were very
expensive.

I'm somewhat lukewarm on carbon fiber. It's great stuff, but it's yield to failure
curve is almost straight... which means that you get very little flex, and no
cracking or gradual failure... one second it's whole & hearty, the next second
you've got a loose bundle of carbon splinters. Carbon fiber also requires an order
of magnitude (or thereabouts) greater skill & preparation & tooling to make good
secondary bonds.

If you (or some careless bugger in a steel boat ) punch a
hole in the hull in some flyspeck harbour in the Pacific, how is it
going to be effectively repaired? Do you need 8' plus of water to sail
it? How many crew do you need with the existing rig? What's the
accommodation like?

Yep... a functional approach. Always best IMHO. These are issues for any cruising
boat shopper. No such thing as a perfect boat, but one can try and maximize
utility.




My approach would be the same as for anything else - decide what the
aims are first, then see if what you're looking at is fit for your
intended purpose, or can be made so at an acceptable time/money cost.
If so, go for it. If not, think of the scrap value to you then offer
less.

I think what's happening is that a lot of these boats are on the market because of
the economy, and the owner can't reconcile himself to scrap them, yet their sale
value seems to be hovering right around scrap value.

Fresh Breezes- Doug King

DSK wrote:

I'm somewhat lukewarm on carbon fiber. It's great stuff, but it's yield to failure
curve is almost straight... which means that you get very little flex, and no
cracking or gradual failure... one second it's whole & hearty, the next second
you've got a loose bundle of carbon splinters.

So you are saying it's Hookian until failure ?
If you look at a mast, CFRP has far more flex than Al before failure.

Carbon fiber also requires an order
of magnitude (or thereabouts) greater skill & preparation & tooling to make good
secondary bonds.

The bond in all FRP is plastic to plastic. There is no difference
whatsoever in that regarrd for CFRP. The "tooling" is in fact simpler as
it is less hard than glass fibres. If the CFRP carries a greater load
then more attention needs to be paid to scarf length and surface prep
but otherwise it is is the same.

Where do you get these ideas Doug?

Cheers MC

The navigator© wrote:


So you are saying it's Hookian until failure ?
If you look at a mast, CFRP has far more flex than Al before failure.

Nope, sorry, wrong again. Aluminum can bend & stretch a lot further before breaking than
carbon fiber can. You either must be thinking of load cycles to fatigue, or else you're
just making up malarkey to sound impressive.




Carbon fiber also requires an order
of magnitude (or thereabouts) greater skill & preparation & tooling to make good
secondary bonds.

The bond in all FRP is plastic to plastic. There is no difference
whatsoever in that regarrd for CFRP.

You're saying that one can wet out and lay up carbon fiber just like fiberglass?

Try it and see.



Where do you get these ideas Doug?

Well, I don't just make them up out of thin air like you apparently do.

Fresh Breezes- Doug King

DSK wrote:

The navigator© wrote:


So you are saying it's Hookian until failure ?
If you look at a mast, CFRP has far more flex than Al before failure.

Nope, sorry, wrong again. Aluminum can bend & stretch a lot further before breaking than
carbon fiber can. You either must be thinking of load cycles to fatigue, or else you're
just making up malarkey to sound impressive.



Carbon fiber also requires an order
of magnitude (or thereabouts) greater skill & preparation & tooling to make good
secondary bonds.

The bond in all FRP is plastic to plastic. There is no difference
whatsoever in that regarrd for CFRP.

You're saying that one can wet out and lay up carbon fiber just like fiberglass?

Try it and see.



I was under the impression that CFRP parts had to be baked in a kiln. I am
curious
as to why you can't just wet it out and let the resin/epoxy cure like we do with
glass?

Cheers
Marty (everybody is ignorant, just about different subjects)

Martin Baxter wrote:


I was under the impression that CFRP parts had to be baked in a kiln. I am
curious
as to why you can't just wet it out and let the resin/epoxy cure like we do with
glass?

There are a couple of issues, one is that because of the surface properties of the carbon,
resins don't like to adhere to it and will not penetrate the weave unless forced through by
pressure. Some resins will not work at all with carbon fiber.

Another is that the relative density of the resin and the cloth is out of whack, and the cloth
will "float" itself right out of the resin if allowed to.

I think that baking in a kiln is desirable for some types of resin that work well with carbon
fiber, and the overpressure helps ensure good penetration.



Cheers
Marty (everybody is ignorant, just about different subjects)

I'm sure no expert on the subject, but earlier this year started corresponding with a builder
of boats who does great work in carbon fiber, in the hopes that we will some day soon have a
great looking super light tender.

http://community.webshots.com/album/82561569ZSrzNA

BTW I might be wrong about carbon fiber masts, thinking about carbon fiber vaulting poles...
they don't make those out of aluminum. However the issue of low yield before failure *is* a
well known factor in carbon fiber structures, I'm not sure how they get around this with pole
vault poles.

Fresh Breezes- Doug King

DSK wrote:



BTW I might be wrong about carbon fiber masts, thinking about carbon fiber vaulting poles...
they don't make those out of aluminum. However the issue of low yield before failure *is* a
well known factor in carbon fiber structures, I'm not sure how they get around this with pole
vault poles.



Doug, I believe that so called "Carbon Fiber" pole vault poles are actualy
a mixture of carbon and traditional glass.

Cheers
Marty

DSK wrote:

Martin Baxter wrote:


I was under the impression that CFRP parts had to be baked in a kiln. I am
curious
as to why you can't just wet it out and let the resin/epoxy cure like we do with
glass?


There are a couple of issues, one is that because of the surface properties of the carbon,
resins don't like to adhere to it and will not penetrate the weave unless forced through by
pressure. Some resins will not work at all with carbon fiber.

More BS. The key is that you really should use epoxy for it's superior
adhesion peoperties to the fiber so that it will transfer more load to
the fibers before bond failure but polyester type resins will work and
are used. The result will be a lower ultimate strength FRP but with a
greater deformation before failure. The failure mode is then cracking
between fibers and bonding rather than fiber breakage. Thgis allows more
slippage and energy dissipation before complete failuree. Given the
expense of carbon over glass, it makes sense to exploit it's strength
fully by using epoxy.


Another is that the relative density of the resin and the cloth is out of whack, and the cloth
will "float" itself right out of the resin if allowed to.

Good lord.


Cheers MC

DSK wrote:

The navigator© wrote:


So you are saying it's Hookian until failure ?
If you look at a mast, CFRP has far more flex than Al before failure.


Nope, sorry, wrong again. Aluminum can bend & stretch a lot further before breaking than
carbon fiber can. You either must be thinking of load cycles to fatigue, or else you're
just making up malarkey to sound impressive.

Must I rub your nose in your ignorance? Why do you think windsufer masts
are made of carbon (before that GRP) and not Al? Have a look at the flex
of some unstayed carbon masts!



Carbon fiber also requires an order
of magnitude (or thereabouts) greater skill & preparation & tooling to make good
secondary bonds.

The bond in all FRP is plastic to plastic. There is no difference
whatsoever in that regarrd for CFRP.


You're saying that one can wet out and lay up carbon fiber just like fiberglass?

You can (and I have for some special local reinforcing) but most use
prepreg these days for big jobs.

Cheers MC

The navigator© wrote:

Must I rub your nose in your ignorance?

You can try, but you better check your upper lip first.

DSK