On Fri, 05 Mar 2004 20:47:21 +0000, beryl george
wrote:



To what do you propose to tie the other ends of the ropes?

snip

To the cradles of surrounding boats.

Definitely don't do that. There should be nothing tied to the cradles.

Steve

Definitely don't do that. There should be nothing tied to the cradles.

Why? I can understand why you wouldn't want anything tied to single
props, but what would be wrong with tying a boat to it's cradle
Must admit though, the idea of supporting a boat using guy ropes from the
top of mast, scares the hell out of me, don't know the maths and stuff, but
it doesn't seem right to me.

On Sat, 6 Mar 2004 08:47:36 -0000, "Nigel"
wrote:


Definitely don't do that. There should be nothing tied to the cradles.

Why? I can understand why you wouldn't want anything tied to single
props, but what would be wrong with tying a boat to it's cradle

Because it can pull the cradle out. Even tying to your own cradle is a
bad idea. If a wind kicks up it can start the boat rocking and
vibrating. That's the worst time you'd want a rope that might be
flapping around in the wind putting tension on the cradle trying to pull
it out.

If you HAVE to tie something off to the cradle (like tying off a tarp)
take the line under the boat and tie it to the one on the other side.
That way, at least the line is pulling the cradle in instead of out..

Must admit though, the idea of supporting a boat using guy ropes from the
top of mast, scares the hell out of me, don't know the maths and stuff, but
it doesn't seem right to me.

Actually, as long as the ropes are strong enough and they are secured
well at ground level and you have a big enough angle at the mast
(probably at *least* 45 degrees), it doesn't seem so bad to me. You're
not supporting the boat, you're only preventing it from tipping over
(same thing cradles do btw.) The rig should be able to take the stress.
Afterall, what do you think is pushing the boat over when you heel.

You may want to have multiple sets of ropes, one set at the top and one
set at the spreaders, kind of like the way radio towers are supported at
multiple levels.

If it's well balanced and you keep an eye on the tension so it doesn't
try and start to tip over, no big deal. Not something for long term
unattended storage though.

Steve

On Sat, 6 Mar 2004 08:47:36 -0000, "Nigel"
wrote:


Definitely don't do that. There should be nothing tied to the cradles.

Why? I can understand why you wouldn't want anything tied to single
props, but what would be wrong with tying a boat to it's cradle

Because it can pull the cradle out. Even tying to your own cradle is a
bad idea. If a wind kicks up it can start the boat rocking and
vibrating. That's the worst time you'd want a rope that might be
flapping around in the wind putting tension on the cradle trying to pull
it out.

If you HAVE to tie something off to the cradle (like tying off a tarp)
take the line under the boat and tie it to the one on the other side.
That way, at least the line is pulling the cradle in instead of out..

Must admit though, the idea of supporting a boat using guy ropes from the
top of mast, scares the hell out of me, don't know the maths and stuff, but
it doesn't seem right to me.

Actually, as long as the ropes are strong enough and they are secured
well at ground level and you have a big enough angle at the mast
(probably at *least* 45 degrees), it doesn't seem so bad to me. You're
not supporting the boat, you're only preventing it from tipping over
(same thing cradles do btw.) The rig should be able to take the stress.
Afterall, what do you think is pushing the boat over when you heel.

You may want to have multiple sets of ropes, one set at the top and one
set at the spreaders, kind of like the way radio towers are supported at
multiple levels.

If it's well balanced and you keep an eye on the tension so it doesn't
try and start to tip over, no big deal. Not something for long term
unattended storage though.

Steve

Definitely don't do that. There should be nothing tied to the cradles.

Why? I can understand why you wouldn't want anything tied to single
props, but what would be wrong with tying a boat to it's cradle
Must admit though, the idea of supporting a boat using guy ropes from the
top of mast, scares the hell out of me, don't know the maths and stuff, but
it doesn't seem right to me.

beryl george wrote:

To what do you propose to tie the other ends of the ropes?

To the cradles of surrounding boats.

I would not be happy to have you as a neighbor in this instance. Aside from
the fact that I am just being a grump, this is very poor practice. In the
second (or third, or whatever) place, you must somehow assure your
neighbors, the yard, and the insurance companies that this is a good idea.

Which it definitely is not.

--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://kerrydeare.home.comcast.net/

beryl george wrote:

Wouldn't it be simpler just to run ropes from the bottom
corners of the cradle frame to strong points on deck?

Would not rope stretch be a possible potential problem with
such a heavy boat.

Not really, but you could use chain instead if it worries you.

Just roughly: Suppose your mast ropes are at 45 degrees, the
deck is 10ft above ground, the mast is 50ft tall, then the
mast ropes will be 85ft long.

Suppose a lateral force is applied (by wind, say) which is enough
to tilt the boat by 5 degrees against the tension of the mast
rope. That would cause the mast rope to stretch by 3.5 feet, or
about 4% of its length.

If your half-beam is 7ft, and the cradle bottom half-beam is
the same, I calculate the cradle rope would need to stretch from
10ft to 10.6 ft, or 6% of its length, in order to permit the
same 5 degree angle of heel.

Now if you were using the same type of rope for cradle-to-deck
as for elsewhere-to-mast, and if both ropes may be presumed to
be operating within their linear stretch/tension range, then it
takes 1.5 times as much force to stretch it by 6% as by 4%. The
lever arm advantage follows from the stretch distance ratios,
3.5:0.6, or about 5.8:1. This means that a heeling moment which
exerts 1 unit of tension on the mast rope would exert 5.8 units on
a cradle rope. Divide this by the force ratio of 1.5 to get a
number a little less than 4. I reckon that means you're as OK
if you use 4 cradle ropes each side as you would be if using one
mast rope of the same calibre and stretchiness each side.

Better still if you use heavier and/or less stretchy rope.

On Fri, 05 Mar 2004 20:47:21 +0000, beryl george
wrote:



To what do you propose to tie the other ends of the ropes?

snip

To the cradles of surrounding boats.

Definitely don't do that. There should be nothing tied to the cradles.

Steve

To what do you propose to tie the other ends of the ropes?

snip

To the cradles of surrounding boats.

Or has anyone any other suggestions of a better
way to support the boat whilst it is epoxied.


Wouldn't it be simpler just to run ropes from the bottom
corners of the cradle frame to strong points on deck?


Would not rope stretch be a possible potential problem with
such a heavy boat.

beryl george wrote:

From other members of the news group thoughts and
experience am I missing something or is this something
that can be carried out providing there is care with
a reasonable degree of ease and safety.

The plan is to block of the foot of the keel and
secure ropes from the top of the mast out to the
sides at about 45 degrees to hold the boat upright
so the support pads on the wintering cradle can be
lowered

Well, provided you have something very secure to anchor the far end of
the ropes to, that would work fine.

But you could shortcut the procedure and not take up nearly so much room
by using some "legs" which could be simple stout poles, or something a
bit more complex, secured to the boat's chainplates. That's what holds
the mast up, so you'd be using the same part of the hull which is built
ver very strongly... but you'd be saving all the stress on the rig.

Fresh Breezes- Doug King