What's a rock weigh?

[Ragnor]

So I have been doing a little looking into pulley systems, for moving boulders. My question is what does the boulder actually weigh?
Obviously that depends on the size and the specific material the boulder is made from. But does anyone have an idea in general what the weight is for a 3'x3',4'x4',5'x5' boulder. Just a ballpark figure? I know from past experience it took two strong guys yarding on a 15' log to roll a 4x4 boulder out the way. Them things are real heavy. The material is mostly granodiorite and quartz diorite.

links and suggestions on pulley setups are welcome also

 

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[et1955]

Have you looked at Come-Alongs, I have several hidden down on the sultan river, great for moving those big rocks and they are not that expensive.

 

[Tuberale]

The come-a-long is a great tool for moving boulders. It helps to have lots of big trees nearby. In a pinch, you can use a longer boulder to move a smaller boulder.

 

[Oddjob]

In water, on land half and half?

If its in water then you want to use float bags. If it is on land and you just want to flip it over, then dig you a small channel out on one side and the dig out a little on the other side and use some rig innertubes folded. Cheap and safer than cables.

 

[kcm]

There was another thread not too long ago - covered this same question about moving rocks. Had virtually every idea under the sun as replies. ...Can't find the thread, though.

 

[Ragnor]

Have you looked at Come-Alongs, I have several hidden down on the sultan river, great for moving those big rocks and they are not that expensive.

we talking just a standard come-along cable winch? will they pull large boulders?

 

[Ragnor]

Easy to calculate an estimation. You've got the size of the boulder, get the cubic size calculated, then go find a rock of the same material of a fairly calculable shape. Measure, calculate cubic size, weigh that sucker.

Then find out what proportion of a cubic yard that thing is, and you've got a good estimator for calculating the boulder. Then add 42 and multiply times Michal Jordan's shoe-size. (OK, kidding on that last part, but the point being you need to add a bit for possible density differences). You'll find a big boulder probably weighs more than you think it does...

And if that is daunting, here's a few sites that give estimates:
Sandstone:
Boulder Sizing and Weight Estimation

Granite:
www.graniteexpress.com/wp-content/uploads/2010/05/boulder-coverage-charts.pdf

"Natural Stone"
Free material calculater for boulder weights and coverage

All are estimates only, of course, given that your boulder will be of a different material/density. But this could help. Cheers!

Skippy

Well that's far too practical! lol. Thanks that's actually king of genius.

 

[Ragnor]

Here is a video

The actual scale is hard to realize in this image. The water looks shallower and the rocks look smaller then they actually are. That is a very large whitefish also. I think I'll eat him.



This is one of the areas I need to move rocks. I have areas above water that they are just as big also. The large black boulder near the bank underwater is probably 6' long or so.

 

[et1955]

we talking just a standard come-along cable winch? will they pull large boulders?

Up to 8000lbs. Depends on what version you buy, I have moved many 3ft. boulders with the 2000lb version out of a hole 8ft. down with sloped sides but my problem is when I get them out I run into 6ft boulders, the Sultan is famous for that. You will need a rock net, I made my own but you must find a way to attach to the rock, not easy. There is a 8000lb version being sold. On your other thread you posted you talked about landslides, well tomorrow I will be hitting one, it happened before the 1990 and 1996 floods, so much gold was trapped in it, Mother's Nature natural riffle.

 

[winners58]

how about specific gravity. water is 62.427 lb per cu.ft, SG of granite is 2.73, basalt SG=3.00
1'x1' = 1cu.ft 62.427 x 3.00 = 187.261 lb's
2'x2' = 8cu.ft = 1498.248 lb's
3'x3' = 27cu.ft = 5056 lb's
4'x4' = a lot...

the weight of a rock in water is minus the SG of the water, if you use the example of basalt its 2/3rd's the weight. (hint x by .66)
if the rock weigh's 100 lb in the water lifting it out of the water it suddenly weighs 150 lb's

Boulders & Winching - Dave Mack

 

[Jeff95531]

There was another thread not too long ago - covered this same question about moving rocks. Had virtually every idea under the sun as replies. ...Can't find the thread, though.

I think it was this one kcm...

http://www.treasurenet.com/forums/g...big-rocks-boulders-making-bouldering-kit.html

 

[kcm]

That's the one. Thanks Jeff!!

 

[goldog]

That 4x4 number. 64cu/ft. = 12k. We better get a bigger boat. Good thing they aren't all cubes.