BoatBanter.com - Hull Flexing

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Yes, thanks.

In article ,
The_navigator© wrote:

Well?

Cheers MC

The_navigator© wrote:

But the boat is not solid steel is it?

Cheers MC

Peter Wiley wrote:

Actually quite a few sailboats *are* much more rigid than you seem to
know. You're taking your experience on plastic boats and assuming it is
generally applicable. The flex in a steel or ferrocement hull is
certainly there (everything flexes to some degree), but it's a fraction
of what is common in lightweight toy racing boats which are built to
minimal standards of seaworthiness and do, indeed, flex. In fact, the
toy boats often break when coming off a fairly moderate wave, as recent
Sydney-Hobart races have shown so well.

The remark about water being much less compressible than the boat is
pure & utter bull****. Even frozen water is a lot more compressible
than steel. Also has lower shear strength, tensile strength etc.

As to measurement of a boat to 0.005", I can easily believe that this
is possible. It's not even all that difficult. Whether there's any
point and whether the measurement is repeatable are different issues.

Peter Wiley

In article ,
The_navigator© wrote:

That boats are built differently has nothing to do with it. Sail
boats are not rigid nor even near it. To be as rigid as you suggest
would probably mean they would not float. If you had ever been in a
real boat beating to windward your would know they are *not* rigid.
Put your hand on the forstay and look at it unloading when she buries
her bow and look at it going tight on the crest (that's revealed by
the luff bending). It's loading up/unloading because the boat is
flexing. If you ever get the chance (assuming that any boat owner
could put up with your big mouth and BS) have a good hard look at the
hull of a boat pounding hard to windward and look and feel hull
panels flexing. The boat needs has to flex to reduce impact loadings
because water is much less compressable than the boat. Once again you
reveal your lack of experience with big boats by suggesting
otherwise. This typifies your inability to grasp even simple ideas.

As for measurent of a boat to 5 thou, look at the coefficent of
expansion of say GRP or even Al (which expands muchg less) and then
tell me how much a boat moves during a typical day/night temperature
cycle. Now you want to tell me it's easy to measure a 5 thou
deflection over a 40' boat? Even if the boat builder had access to
interferometric equipment (which I'm sure they did not use -as there
would be no point in such an accurate measurement) it would still be
hard. If you think it's so easy how come you need a 'crew'. Lets face
it this is yet more Doug Kig (I'm a ****ing hero) BS. Have'nt you
ever wonder why you don't make more money -after all, you are such an
expert...

My point is that Ella is not a large racing boat and yet still has
more than 1 ton rig tension.

Cheers MC

DSK wrote:

The navigator© wrote:

I'd say It's BS because boats are simply not that rigid

Oh yeah, and all boats are built to the same structural standard,
aren't
they.

and it's hard to
measure to an accuracy of 4 thou on big objects.

Now that is total BS. It costs, but if you're willing to pay, I'll
bring a
crew and and gear, and show you how to measure movement in any axis on
objects of any size & orientation down to 5 ten thousands +/- 1

It's part of what I do for a living, thanks very much. The NIST has
occasionally asked me for advice on this type of thing.

.... Even Ella has a backstay
tension of 2,500 lbs when beating.

Gee, and there's no difference between "2500#" and 15,000# is there?

Why do I bother answering your posts?

DSK

Just what I remebered. It could be something to do with an interaction
with the oxide layer couldn't it?

Cheers MC

Capetanios Oz wrote:

On Thu, 13 Nov 2003 13:48:50 +1300, The_navigator©
wrote:

I thought 552 was recommended for Al.

Cheers MC

Looked it up,
Can't see any specific reference to ally
http://www.sikaindustry.com/tds-ipd-sf552-us.pdf

and 292 looks pretty much the same
http://www.sikaindustry.com/tds-ipd-SF292-oem-us.pdf

Oz1...of the 3 twins.

I welcome you to crackerbox palace,We've been expecting you.

Peter Wiley wrote:

snip

Be nice to see a light schooner on the Derwent.

Be nice to see one full stop. I think I'll bring Flying Tadpole
II home from Pt Augusta, where she's not getting used, clean her
up and see if I can flog her off. ALl my sailing gets done now
in Lady Kate, and I'd love to see some youthful 40 y.o. campaign
Flying Tadpole II again and set the picnic race scene quivering
in horror once more. It's a whole new generation. Even the
skiffie skippers I once knew have grown huge rumguts and
inhabitat ancient trailer sailers now...

--
Flying Tadpole

-------------------------
Learn what lies below the waves of cyberspace!
http://www.internetopera.netfirms.com

In article , Flying Tadpole
wrote:

Peter Wiley wrote:

snip

Be nice to see a light schooner on the Derwent.

Be nice to see one full stop. I think I'll bring Flying Tadpole
II home from Pt Augusta, where she's not getting used, clean her
up and see if I can flog her off. ALl my sailing gets done now
in Lady Kate, and I'd love to see some youthful 40 y.o. campaign
Flying Tadpole II again and set the picnic race scene quivering
in horror once more. It's a whole new generation. Even the
skiffie skippers I once knew have grown huge rumguts and
inhabitat ancient trailer sailers now...

Ah well, you get that with age & lack of maintenance. I've been
shovelling sand & gravel for my slab base - get fit campaign after 8
weeks doing nothing except work/eat/sleep/eat/eat/work etc during which
time I put on 2 kg. I'm getting hassled about putting my daysailer in
the water, just been pricing a new 2-3HP o/board for it. The Honda 4
stroke is only (IIRC) 13kg so it might get the nod. I'll happily leave
my boat on the foreshore but leaving the motor as well is pushing my
luck, even if I can see it from my window.

Peter Wiley wrote:

Ah well, you get that with age & lack of maintenance. I've been
shovelling sand & gravel for my slab base - get fit campaign after 8
weeks doing nothing except work/eat/sleep/eat/eat/work etc during which
time I put on 2 kg. I'm getting hassled about putting my daysailer in
the water, just been pricing a new 2-3HP o/board for it. The Honda 4
stroke is only (IIRC) 13kg so it might get the nod. I'll happily leave
my boat on the foreshore but leaving the motor as well is pushing my
luck, even if I can see it from my window.

Pair of cheapie wheels, a wooden strongback, a step and a couple
of occy straps and trundle the motor hom. You could put the
wheels on the boat too...

--
Flying Tadpole

-------------------------
Learn what lies below the waves of cyberspace!
http://www.internetopera.netfirms.com

Hey Peter! Welcome back! My penguin still has not arrived by UPS...did =
you pack enough ice and fish with it?

--=20
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Peter Wiley wrote:

... I don't have any problems with people owning lightweight plastic boats
- they do go fast and point high, plus you get lots of exercise
changing headsails with each 5 knot wind change. Just that nobody
should think they're good for much else.

Agreed, but with reservations. You mention a friend who just bought a
ferrocement cruiser on the cheap, what would you think if instead, he'd
bought a newer former racing of the same capacity, for half the price he paid
for the FC job? DOn't know about over there, but in the US there is no market
at all for retired racers and they are going begging. Some are cheesy junk,
true, but some have great potential as cruisers IMHO. It just requires some
knowledge & judgement to pick among them, as with anything else (cars, women,
power tools, etc etc).

Fresh Breezes- Doug King

The navigator© wrote:

Bwhhahahahahhahaa.

What an intelligent reply. No wonder it's one of your favorites, did you teach it to
Boobsprit?

But you don't know anything as you've not posted a single fact.

Actually, I've posted lots of facts.

Not even
heresay really. I say again, all 40' racing boats deflect more than 5
thou with a 10,000 kg backstay tension.

And I say again, all boats are built the same, aren't they?

.....I just said you were BSing as usual -and you still
are. So now you know about yacht structural design?

I know what I've read, and what I've seen.

Did you do a course
in Naval Architecture in your imagination too?

No, did you?

DSK

Hull Flexing... dammit Tadpole!

I just ruined a keyboard

Flying Tadpole wrote:

You mean, you want a heroic ode, based on the poor elephant seal,
cumbersome and easily attacked by vicious sealers on land, speedy
and graceful on/in the water, but nevertheless doomed by its
liberal outlook and engineering limitations?

"More than" is not a single number dummy. I though you said you'd studied?

Cheers MC

DSK wrote:

Not even
heresay really. I say again, all 40' racing boats deflect more than 5
thou with a 10,000 kg backstay tension.

And I say again, all boats are built the same, aren't they?