Ping:... Joe
 

Joe wrote:
Heat Treating???

Well back in the old days there was this ol man who buildt many a 62
fter in his back yard on the Chesepeake Bay. All his hulls are fair and
hand nibbed using a rose torch and nibbing bars.

Hmm, I don't think a cutting torch qualifies as heat
treating... but if you want I'll check with SAE...

... Most sleek steel hulls
you have ever seen.

Sleeker than Navy destroyers?


I used truckbed liner as non-skid. When exposed to hard traffic and UV
it becomes polished and slippery and needs re-coating in 3 yrs. I like
the stuff but it's expensive Like 400 for me do do a small path and
spot near the masts. I used Duraback(sp??) brand name. MIL Spec
approved non-skid now.

Sounds expensive. I spent far less than that on the whole of
our new deck, which is fiberglass cloth & LPU.

... On a new build inside any good epoxy is great if
properly applied! I do not like epoxy that is exposed to UV. It is
stronger and more chip resistant but fades , streaks and needs to be
re-coated more often than a good oil base.

Yes you're right, epoxy does not stand up to UV very well.
OTOH you can paint over it with almost everything.


... If I had a new bare hull Id met-coat the whole
thing inside and out. Thats spraying a molten hot zinc on. Thats how
they coat the offshore platforms before painting. It's the very best
for steel.


Sounds like hot galvanizing. Why not just electroplate it
with zinc, or build it out of zinc in the first place? I bet
you will say "Zinc is not as strong as steel" but it would
be if you made it thicker... it would be heavier but so
what, if you wanted a light weight boat you wouldn't have it
made of steel in the first place.

DSK
Joe

Ping:... Joe
 

Sounds like hot galvanizing. Why not just electroplate it
with zinc, or build it out of zinc in the first place? I bet
you will say "Zinc is not as strong as steel" but it would
be if you made it thicker... it would be heavier but so
what, if you wanted a light weight boat you wouldn't have it
made of steel in the first place.

DSK


Doug,

I'm not an engineer, I just saw what people who could afford to do it
right did. And I saw it endure harsh abuse in an extreme salt water
application. Many steel shrimpers now met coat.
You can beat the snot out of met coat with a 10lb sledge and never
cause a rust streak.

Joe

Ping:... Joe
 

In article , DSK
wrote:

Peter Wiley wrote:

High carbon steel has somewhat greater tensile strength, but so what.

IIRC the biggest difference is a straighter yield curve,
maybe slightly stronger too. If high carbon steel were
really stronger in tension, they'd make cable from it.

Bad argument. Yachties use s/steel cables and structurally they're
inferior to galv steel cables. Instrument packages often use synthetic
cable, in fact I'm looking at buying 4000m of 12.7 OD with fibre optic
cores for underwater video work.

Steel yacht hulls are massively overstrength anyway, the plate
thickness is set by the need for min thickness for corrosion allowance
over the life of the hull.


It's the best stuff if somebody is going to be shooting at
you,

Only with a peashooter. I can pop a 7x57 or 7.62 NATO round clean thru
1/4" 1020 carbon steel plate at 200m. Done it plenty of times.

or you plan to bounce over a lot of rocks. Other than
that, the only reason I can think of to build a boat of less
than 20 tons (or so) out of steel is because you are already
a skilled metal worker and have a lot of supplies, and
really really like the concept of a bulletproof boat
(although it should be recognized that fiberglass can also
be bulletproof).

I disagree but we've done this argument to death. My personal tradeoff
point is about the 8 tonne mark for a steel boat.

The other bit you missed is that steel lends itself well to 'one off'
builds pretty readily. Fibreglass, at current prices, is better for
mass production from moulds.

I wonder how well a boat would hold up if sprayed both sides
with that plastic pick-up truck bed liner material?

Wondered that myself for the bilge areas where it's hard to inspect and
hard to repaint.

High carbon steel does *not* slow rust appreciably. Some steel alloys
have greater corrosion resistance but this is due to the alloying
elements, not the carbon. In fact, very *low* carbon steel resists
corrosion better than high carbon steel.


IIRC most stainless steels are very very low carbon.

Stainless steels may be low carbon, but that's irrelevant. They're
alloy steels containing a heap of chrome & nickel.


OTOH there is a lot of truth in Joe's statements if you take
them to their logical conclusion and use the highest
carbon material... carbon fiber!

Yep. And the difference in tensile strength between yield point and
ultimate failure point is...... ? Personally I don't like the idea that
what I'm sailing on might crack in half like an eggshell.

PDW

Ping:... Joe
 

Joe wrote:

Stronger, harder, stronger.. Steel with sufficient carbon compositions
can be heat-treated, allowing
parts to be fabricated in an easily-formable soft state then made
harder for structural applications.
High Carbon steel rolls and holds it's shape nicely, and I suppose high
carbon slows rust too!
I've never seen a carbon anything rust.

Joe

It is unfortunatley very dificult to heat treat large pieces, such as
boat hulls. As for forming, untreated high carbon steels and low carbon
steels, as 1005 behave simalarly at the onset, but with repeated forming
the high carbon will likely work harden and become brittle.

Rust? Just leave a file out in the rain for a day or two, it'll rust
like hell and I assure you that files are made from very high carbon
steels.

Cheers
Marty

Ping:... Joe
 

I suggest you dip your files in paint if you don't want them to rust.

Just my 2 cents.

Joe