Looking For Some Feedback.....

[ProgressiveRescue]

Guys....This is a anchor I came up with and I'd love some feedback on it. As you can see it's a pressure treated 4x4 with a one foot piece of 4x4 acting as a riser on either end. Its held together with 3/4 inch gussets. I drilled four holes in the 4x4 allowing rebar or pickets to be driven through it if this is used on soft ground. I've played around with it in doorways and elevators and it seems to work well. The overall length of the unit is 6'. Being I'm the one that made it I may unintentionally blind to any foreseen problems.
Thanks for the thoughts,
Mike Donahue

[IMG]

ImageShack.us[/IMG]

[FiremanLyman]

Mike, would you tie back with a tensioned picket system? Pickets with webbing tied in a windlass hitch using a piece of re-bar to tighten them like a tourniquet (for those uninitiated into picket systems).

Using 1 inch rolled steel pickets three feet long, a one to one is rated to support 1400 lbs. A one to one to one (three in a row) rates at 1800 lbs, and a three to two to one (load sharing) will support 4000 lbs.

I like it. I would feel very confident using your lumber with a tension picket system. (edited it from "using your wood")

[TRT24]

with your standard beveled pickets, you are going to have problems driving four of them into the lumber, unless you do them all at the same time. As they go deeper into the ground their angles change. This would torque the lumber more with each picket. You would be better off using pickets as anchors.

[jdcalamia]

If we're driving all these pickets, why not just use them instead of "Mike's wood"? If everything is tied together with spanish windlasses (sp), it's pretty much the same thing without the added difficulty of getting pickets to fit in the holes, etc...I like the risers for use on the floor in doorways, etc as a deadman.

[ProgressiveRescue]

I had thought about the use of a picket system however the purpose of this is to allow you better organization of your rope systems. With a picket you're rigging from the same point, granted you can use a rigging plate to better organize your operation however in my eyes that's like putting all your eggs in one basket.
I'm thinking if you drive all the pickets (4) to a depth where only a foot is sticking out of the 4x4 that should give you enough strength for a one or two person load. I guess soil conditions wold ultimately dictate that statement though.
Once this damn snow melts I'm going to do some load testing with it. Being I'm in Jersey that could be some time.
Mike

[stickboy42]

on a different note, let's mention the wood used. Pressure treated wood tends to be some of the lowest quality stuff out there (might be the right species (southern yellow pine but look at the knot size & check slopes and you'll find it to grade out very poorly) but yet seems to be used regularly in shoring/rescue operations. I would swap the 4x4 with a good quality 4x4 (doug fir select or #1 if possible). IIRC most of the data in the FOG for wood usually refers to doug fir/southern pine so the data presented is based on those species.

another point would be that treated wood is preserved with either CCA and ACQ and I'm skeptical about that and it's effects on webbing/rope/etc... eliminating treated might be the prudent thing at least for a long term creation such as the anchor you built.

just my .02.

[ProgressiveRescue]

on a different note, let's mention the wood used. Pressure treated wood tends to be some of the lowest quality stuff out there (might be the right species (southern yellow pine but look at the knot size & check slopes and you'll find it to grade out very poorly) but yet seems to be used regularly in shoring/rescue operations. I would swap the 4x4 with a good quality 4x4 (doug fir select or #1 if possible). IIRC most of the data in the FOG for wood usually refers to doug fir/southern pine so the data presented is based on those species.

another point would be that treated wood is preserved with either CCA and ACQ and I'm skeptical about that and it's effects on webbing/rope/etc... eliminating treated might be the prudent thing at least for a long term creation such as the anchor you built.

just my .02.

Two great thoughts. I'm not so concerned about the effects of the pressure treated wood on the software because that can be easily remedied by some old hose or canvas. However changing the wood species is an easy change. On the other hand.... the load this anchor (lumber) will see should be well within its load rating. Even under a shock load the four pickets will absorb some of that load force decreasing what the lumber actually sees. But the idea is always to make the best system possible so why not go with better lumber.
Mike Donahue

[servantleader]

an improvement?

I don't have experience with pickets in dirt, but I do in snow. For snow anchors (in something we call the "Sierra configuration"), the snow pickets are angled slightly away (maybe 15 degrees) from the direction of pull.

Would drilling those holes so they go through the wood slightly diagonally, thus allowing each picket to be angled slightly away from the direction of pull, improve the strength of the anchor?

Would that unacceptably weaken the wood? Is there some other technical or practical issue I'm overlooking?

[FiremanLyman]

I don't have experience with pickets in dirt, but I do in snow. For snow anchors (in something we call the "Sierra configuration"), the snow pickets are angled slightly away (maybe 15 degrees) from the direction of pull.

Same idea, Picket systems are angled at 15 degrees away from load. 3 foot long pickets are driven 2 feet down.

Would drilling those holes so they go through the wood slightly diagonally, thus allowing each picket to be angled slightly away from the direction of pull, improve the strength of the anchor?

Would that unacceptably weaken the wood? Is there some other technical or practical issue I'm overlooking?

I think drilling the holes at the same angle would benifit, it would allow the base plates to rest on the ground, otherwise it would risk splitting the wood under load.

For the hassle, using a picket system on its own would be better. This wood anchor gives you mutiple attachment points, but you are adding weight to whatever you are securing the anchor with. Still would use it.