Skip Gundlach wrote:
Of the several power folks I've spoken with, there was unanimity that I
should wait (varying from a week to a month, with a couple of weeks
being a consensus of adequacy) for the hull to stabilize before trying
to realign the propshaft.

I guess more boats are more poorly built than I realize.
Most of the boats I have experience with, including our 22yo
36' Taiwan-built trawler, have very little or no deflection
when set up on jackstands, and no need whatever to
"settle." In a boat that has more than a tiny fraction of an
inch deflection, I'd think they need some structure re-tabbing.

Fiberglass is wonderful structural material, and most of the
people designing boats know how to spec a girder or panel.
Must be the builders!



-----

Lots of great info there, and likewise very helpful links. Thanks so
much to all for those.

You're very welcome. Most of what I wrote was cribbed from
earlier posts I wrote to answer similar questions.

.... Given the purely cruising nature of our boat,
we don't have adjusters nor running backs - though, given the added
inner forestay, it might have been a good idea. So, the rig will
remain tensioned and static, other than the occasional times we might
pull the inner off to the side (removable fitting), which I presume
would change the shape of the mast slightly.


If you're going to fly a sail from that inner stay, you'll
want to set it up pretty tight, and of course it should be
opposed by increased tension on the aft lowers.

Remember, anything less than 10% of the wire's working load
will let the wire stretch, and will not pre-load the toggles
& pins... you will then have shock loading on the rig and
that can produce rather bad results.


One minor question, which seems counter-intuitive to me: Pulling the
lowers to as to bow the mast AFT. Why is that? If any curve, I would
think it should be forward...


You're right. I was assuming that either your spreaders rake
aft, thus inducing bend in the mast, or that you have double
lowers.

Coincidentally, I was talking yesterday with one of the yard guys who
previously was the head rigger at Catalina.

He essentially echoed the above comments about alignment, but said that
once snug and firm, a couple of full turns on each of the turnbuckles
would be about right.


That could produce either dangerous under tension or a rig
that gets progressively out of column under more loads....
bad advice IMHO. Maybe he's the reason why Catalinas are not
Baltics




As we sailed it over, in mostly very heavy weather, it balanced very
nicely, so I presume the rake is about right. Until we played with it
in nearly 30k, pinching tighter and tighter, making it heel
substantially, we had no weather helm nor lee helm we could discern.

So, I'm pretty comfortable about the angle of the mast.

Sounds good, although you might want to add a little bit of
rake. Some weather helm is good. I would recommend taking a
tape measure to the main halyard and measuring the rake in
some way that is clear & repeatable, and writing this in
your maintenance log. That way you don't have to start from
scratch if you ever take the mast down.



Once we get to sailing, we'll check out the lee cables. If they are
slack under any but very substantial loads, we'll take up some more on
the tension, duplicating the turns on each side, but still checking for
straight line in column.


Right. Get the boat heeling about 20 degrees and the shrouds
on the lee side should not be noticably slack... the tension
will definitely drop, but they shouldn't be slatting around!

One funny thing I have noticed, many boats do not have the
same tension on opposite shrouds when the mast is set up
straight & proper. Can't explain it, but it's that way on at
least a dozen boats I've played at tuning up. Oh well, if it
was an exact science, it wouldn't be fun.

Fresh Breezes- Doug King

"DSK" wrote
I guess more boats are more poorly built than I realize.
Most of the boats I have experience with, including our 22yo
36' Taiwan-built trawler, have very little or no deflection
when set up on jackstands, and no need whatever to
"settle."

A Trawler? I thought this discussion was about sailboats!

Sailboat rigging does bend the boat and when stored, the hull tends to
revert to it's original shape.

It is impossible to put 1000+ lbs of force on the forestay and backstay and
not have the hull deflect. Fibreglass laminates are elastic, so do bend and
the bend releases when the forces are removed.

Wooden sailboats (especially those with long overhangs) when stored with
mast down, used to settle unless the bow and stern were supported. If this
was not done, the rig tension would open up the seams, especially around the
keel. Fibreglass boats may settle a bit further due to gravity if stored for
very long periods but not much. Important though to have weight on keel and
not on supports which may deflect the hull under pads.

One other thing. The temperature has an affect on rig tension - both on
thermal expansion and on elasticity of metals and hull. Aluminum expands
about 30% more than S/S does. In addition, these metals and the hull become
LESS elastic as temperature rises. It's a complex mix of affects! If the
rig is set up in cold weather, by mid summer the tensions will be different.
Just keep watching the leeward shrouds and tighten up when need be.

"DSK" wrote in message
. ..
Skip Gundlach wrote:
Of the several power folks I've spoken with, there was unanimity that I
should wait (varying from a week to a month, with a couple of weeks
being a consensus of adequacy) for the hull to stabilize before trying
to realign the propshaft.

I guess more boats are more poorly built than I realize. Most of the boats
I have experience with, including our 22yo 36' Taiwan-built trawler, have
very little or no deflection when set up on jackstands, and no need
whatever to "settle." In a boat that has more than a tiny fraction of an
inch deflection, I'd think they need some structure re-tabbing.

Fiberglass is wonderful structural material, and most of the people
designing boats know how to spec a girder or panel. Must be the builders!


Doug, Essie takes serious exception to the slanderous allegation that she
was "poorly built." I told her that you really didn't mean it, but I think
it'll be a while before she forgives you.

KLC Lewis wrote:
Doug, Essie takes serious exception to the slanderous allegation that she
was "poorly built." I told her that you really didn't mean it, but I think
it'll be a while before she forgives you.



OK, re-phrase that statement so as not to be pejorative.

However, there is really no reason for a fiberglass boat to
have any measurable flex in it's hull, other than rigidity
(and the strength that is a commensurate by-product) not
being high on the list of builder's priorities. For example,
many years ago a buddy of mine & I went in shares on a fancy
racing boat, a 1-Tonner. Several years past it's prime, of
course, or we would not have been able to afford it.

This boat had been built to be driven *hard* under sail, and
stiffness means speed to a racing boat. The tuning guide
said that at times, it was possible and desirable to place a
tension of 10,000 lbs on the backstay. I spoke to the
builder and asked if the boat would really take this, and he
laughed and said "Heck yes, when we trialed that boat, we
put 20,000 on the backstay and measured a little less than
1/4" deflection along the deck."

In years before and since I've worked on and sailed a number
of boats, and have found some that flex more, some that flex
very little or not at all. Perhaps it's just idle prejudice
on my part, but the ones that flex less seem to me to be
more desirable.

Fresh Breezes- Doug King

"DSK" wrote in message
.. .
KLC Lewis wrote:
Doug, Essie takes serious exception to the slanderous allegation that she
was "poorly built." I told her that you really didn't mean it, but I
think it'll be a while before she forgives you.


OK, re-phrase that statement so as not to be pejorative.

However, there is really no reason for a fiberglass boat to have any
measurable flex in it's hull, other than rigidity (and the strength that
is a commensurate by-product) not being high on the list of builder's
priorities. For example, many years ago a buddy of mine & I went in shares
on a fancy racing boat, a 1-Tonner. Several years past it's prime, of
course, or we would not have been able to afford it.

This boat had been built to be driven *hard* under sail, and stiffness
means speed to a racing boat. The tuning guide said that at times, it was
possible and desirable to place a tension of 10,000 lbs on the backstay. I
spoke to the builder and asked if the boat would really take this, and he
laughed and said "Heck yes, when we trialed that boat, we put 20,000 on
the backstay and measured a little less than 1/4" deflection along the
deck."

In years before and since I've worked on and sailed a number of boats, and
have found some that flex more, some that flex very little or not at all.
Perhaps it's just idle prejudice on my part, but the ones that flex less
seem to me to be more desirable.

Fresh Breezes- Doug King



Well, there's flexing and there's flexing. Essie is built exceptionally
stout for a boat of her size, having been built back in '63 before
scantlings for fiberglass boats had been developed. In those days they
really didn't know how thick things like hulls should be, so they erred on
the side of, "I dunno, Frank. Better lay up another quarter inch or so."

But a boat on the hard is unlikely to be supported the same way as the water
holds her. Essie's cradle supports the keel (full) for a good portion of its
length, then there are two supports foreward and two aft (P&S) -- for a
total of four. Over the length of a winter, with the hull alternately
heating up and cooling off (there are times even in winter when the hull can
be hot to the touch during a particularly bright day, only to drop below 20
degrees f at night), this "support" cannot help but put some unusual
stresses into the boat. When launched again in the spring, it takes a while
for the boat to relax into the water.

Again, with Essie we're talking fractions of fractions, but it's still
noticable. And she is WAY stronger-built than she needs to be. The flexing
we are talking about isn't "oilcanning" from scantlings that push the lower
limit.

KLC Lewis wrote:
Well, there's flexing and there's flexing.

Agreed.


.... Essie is built exceptionally
stout for a boat of her size, having been built back in '63 before
scantlings for fiberglass boats had been developed.

I've heard this a lot, but it's not 100% accurate. The Navy
was very interested in fiberglass for it's small boats
(gigs, whaleboats, utility boats, etc etc, which had been
previously built out of wood). In the early 1950s they paid
for, and published, a large scale engineering study of
fiberglass including how well it stood up to UV. Lots of
early boat builders used this reference.


But a boat on the hard is unlikely to be supported the same way as the water
holds her.

Agreed again. The cradle or jackstands should be positioned
to support the internal structural members, like bulkheads,
directly. And fiberglass will exhibit 'creep' under
consistent heavy load for a long time. But it won't creep if
it's not loaded past the point of measurable deflection.



.... The flexing
we are talking about isn't "oilcanning" from scantlings that push the lower
limit.


Actually, oilcanning is annoying but not particularly bad
for fiberglass. FG can withstand at least an order of
magnitude more cycles of flexing than steel before
fatiguing, in this respect it's far superior to metal.

If given a choice between a hull that had oilcanning in some
panels (for example, the big almost-flat section in the bows
of many boats) and one that flexed over it's whole length
from rig loads, I'd pick oilcanning. But it would be a lot
better to have neither.

Fresh Breezes- Doug King