Best way to judge weight of what we lower

[Marc Lewis]

I can't see how a chart is going to help. You would need to measure the log for the chart to be accurate. You only need to know roughly the weight of the section of wood to be lowered because you will/should be working well within SWL.

[agrimog]

if you cant do quick mental volume calcs and estimates of weights, you shouldnt be cutting up the tree, you need to know that every bit you cut off isnt going to put an undue stress on your rigging setup, or be too heavy for your lowering system. this can be taught in various courses, but once again it comes down to experience and a good working knowledge of what different trees weigh in there green state. ie if your chogging down a standing dead wood, your "bits" can be a lot larger than the same tree in full leaf. thats why the guy with the time on the "tools" can comand a higher wage than the newby, 99% of the time!!

[Stubby]

My mate up the tree looks at me and moves the saw up and down along the limb until I say stop . he cuts it I lower it . Never had one run away with me . Been lifted a bit on the initial; snatch on occasion but thats all .

[Grass hopper]

When the capstan breaks in half, the log comes flying down and goes through the garage roof and the groundie runs about screaming because of serious rope burns to his hands, you need to cut em a bit smaller

:lol::lol::lol::lol: Best ever..

[Amelanchier]

...I have always went with the thought 1 metre cubed of water is a ton, wood floats so must be lighter...

 

Be careful with that - some woods sink (though you're unlikely to be rigging Ebony or Persian Ironwood) and the principle of buoyancy ensures that things that are heavier than water can float provided they displace a greater weight of the fluid.

 

There is a table here that might be applicable (but note that its dry wood that was sampled - live timber will be much much heavier in most cases);

 

Mass, Weight, Density or Specific Gravity of Wood

[Le Sanglier]

The obvious answer is common sense and experience as previously stated.

Another factor can be if in leaf or not, some species like maples and some pops in full leaf can "float" down onto the strain point considerably reducing shock loads.

I guess the load is never heavier than the point where the rope initially takes the strain and this can make a big difference.

Not strictly relevant I know but it's raining all day and I'm fed up painting the hallway.

[timtree81]

When the capstan breaks in half, the log comes flying down and goes through the garage roof and the groundie runs about screaming because of serious rope burns to his hands, you need to cut em a bit smaller

 

Fantastic

[Ms2004life]

Theres also a chart in the book the art and science of practical rigging which may be of help..

[Pete Bannister]

This simple chart might be useful, Sorry but I cant remember where its from.

It gives green 'oak' a s.g. of 1 and you can see it allows for heavier timber.

Keeping things like this simple is valuable and what this chart shows nicely is the effect of diameter on volume/mass. ie

if d1 = 10 then d2 = 40 (and not 20 which is a mistake Ive seen happen)

Log mass charts.pdf

[Shane]

While youre building up experience - a very rough guide is to imagine the branch/trunk is a cylinder FULL of water. So if it is 4ft long and 2ft diameter you have an oil barrel's worth of weight.

 

As stated previously the small branches and stems are more difficult -

If the leafy branch is 10 ft long and its 6 inch diameter at the butt end just assume a 10ft pipe 6 inches diameter full of water - if that doesn't equate to anything you can imagine then double the diameter and divide the length by 4.

This roughly gives you two 20 ltr tubs stacked on top of each other (2ft 6 x 12 inches).

 

This is not dead accurate but its a start till you get the hang of it.

 

And don't worry about the quarter length/double diameter thing - just do it.