Hammocks and Stress on Standing Rigging

[rhumbunctious]

I see alot of hammocks strung up on decks, attached to the standing rigging (e.g. forestay and shrouds, etc.) and while it's clear that this works, I've been wondering what kind of stress and possible reduction in lifespan this may cause to the rigging. Since the stresses on standing rigging are expected to be vertical along the length of the wire, and the hammock places a bending stress horizontally, what is that doing to the wire? Is it causing or increasing work hardening at the point of stress/bend?

I'm wanting to string a hammock up myself, but am concerned about the long term affects/damage to the rigging.

Any experts care to comment?

[avb3]

Originally Posted by rhumbunctious

I see alot of hammocks strung up on decks, attached to the standing rigging (e.g. forestay and shrouds, etc.) and while it's clear that this works, I've been wondering what kind of stress and possible reduction in lifespan this may cause to the rigging. Since the stresses on standing rigging are expected to be vertical along the length of the wire, and the hammock places a bending stress horizontally, what is that doing to the wire? Is it causing or increasing work hardening at the point of stress/bend?

I'm wanting to string a hammock up myself, but am concerned about the long term affects/damage to the rigging.

Any experts care to comment?

I am NOT an expert, but I would suspect the stresses on the rigging inflicted in the normal course of sailing would be much higher then a static stress that a hammock produces.

Again, not an expert, but common sense tells me the loads from sails are significant higher then a 180 Lb or a 220 lb person just lounging.

I would be more concerned that whatever attachment mechanism I used doesn't the impact integrity of the wire.

[rhumbunctious]

Originally Posted by avb3

I am NOT an expert, but I would suspect the stresses on the rigging inflicted in the normal course of sailing would be much higher then a static stress that a hammock produces.

Again, not an expert, but common sense tells me the loads from sails are significant higher then a 180 Lb or a 220 lb person just lounging.

I would be more concerned that whatever attachment mechanism I used doesn't the impact integrity of the wire.

The stresses along the direction of the rigging are certainly much more when sailing, but when sailing there aren't stresses across the rigging, perpendicular to the wire. You're quite right about how the hammock is attached is the concern.

[waterdancer]

Although the force is probably more than 200 lbs because of the angle, I tend to agree that on any boat 25 ft or larger the stress jnduced through the use of a hammock is minimal.On a smaller boat that has loose rigging, it may indice some kinks.

[dockbumdan]

I have a hammack rigged between my roller furler and my mast, boat's a 37, I use the same ATN crusing spinnaker "Tacker" that I use for flying my crusing spinaker, I can't imagine that the stress induced by my weight onto the furler is more than the stress caused by the spinnaker.

[Jim Cate]

Consider the loads imposed on your forestay by a partly furled genoa... the hammock will not overstress the shrouds unless an elephant should have a nap in it.... on a trailer sailor!

Cheers,

Jim

[Unicorn Dreams]

I don't think that 100 lbs. or so side load on 1/4" cable is going to be much, toggles should eliminate some of the stress.
I swing my hammocks under the booms of my boat.
Admiral has a tendency when I'm sleeping and don't answer her, to loosen the main sheet and let the boom swing over the side of the boat. Just glad I don't tie slip knots when rigging it. She hust might untie and dump me in the drink..

[daddle]

A quick estimate with pencil...a 100kg person is probably not a problem. An elephant, no way. The sideways pull on the forestay is maybe 100kg...depends on the sag in the hammock (more sag, less force). The tension in the stay will be from 10 to 40 times that (up to 4000kg or 8800# on a really tight rig) depending on the amount of forestay sag (more sag, less tension).

So it's not insignificant in some cases. And I could imagine the wire or foil getting a kink in it from the sharp bend if the rig was really loose or the napper was a big fan of cheeseburgers.

[Acedude]

Use multiple lines attaching the hammock to the forestay to spread the load. That or a couple sheets of stiff leather around the forestay as well.

That would help to prevent kinks.

Still doesnt prevent the overall total stress on the forestay though....