Calculating weight of lying timber

[MikeM]

I have been asked to make an offer on some recently felled Scots Pine currently lying in the wood. The timber will be extracted by the vendor so my offer will be based on a roadside price. I know how much I want to offer per ton, but need to be able to estimate the weight of the wood in its current position.

 

The logs are between 10cm and 30 cm diameter and most are cut to approx 2.9m lengths. At a rough guess from a brief initial inspection there is about an artic load.

 

Any advice on how to come up with a reasonably accurate calculation of the weight gratefully received.

[Alycidon]

Agree a price per ton then put the trailer over a weigh bridge. Some trailers have self weigh systems on them, talk to your local timber hauliers.

 

A

[roseyweb]

Forest Mensuration, I spent years studying it, have three books on my shelf full of numbers for working it out, its quite a dull process.

Do it by volume as weights a bit dodgy, only do by weight if your selling fresh stuff do it by volume if your buying.

Volume is Length x height x width, minus 30% for air depending on how well stacked

[muldonach]

I have been asked to make an offer on some recently felled Scots Pine currently lying in the wood. The timber will be extracted by the vendor so my offer will be based on a roadside price. I know how much I want to offer per ton, but need to be able to estimate the weight of the wood in its current position.

 

The logs are between 10cm and 30 cm diameter and most are cut to approx 2.9m lengths. At a rough guess from a brief initial inspection there is about an artic load.

 

Any advice on how to come up with a reasonably accurate calculation of the weight gratefully received.

 

 

I am assumming you do not intend to take it over a weighbridge or handle it with a crane fitted with a load-cell?

 

((L1+L2)/2)x H x 2.9 where

 

L1 = length of bottom of stack

L2 = length of top of stack

H = height of stack (assumes level stack, if there is much variation then measure the height at fixed intervals, add them together and divide by the number of measurements taken)

 

You then need a stowage factor which I think is available from the FC mensuration tables - do not have a copy available at moment but will be about 0.6/ 0.65 at a guess - if the timber is straight- that will give you an estimate of the volume of actual timber in the stack.

 

You then need a density for the timeber to get the tonnage - google green timber density and you will get a figure.

 

It is not an exact science, in particular bendy timber or poor stacking will result in an overestimate of weight.

 

Cheers

mac

[roseyweb]

I am assumming you do not intend to take it over a weighbridge or handle it with a crane fitted with a load-cell?

 

((L1+L2)/2)x H x 2.9 where

 

L1 = length of bottom of stack

L2 = length of top of stack

H = height of stack (assumes level stack, if there is much variation then measure the height at fixed intervals, add them together and divide by the number of measurements taken)

 

You then need a stowage factor which I think is available from the FC mensuration tables - do not have a copy available at moment but will be about 0.6/ 0.65 at a guess - if the timber is straight- that will give you an estimate of the volume of actual timber in the stack.

 

 

You then need a density for the timeber to get the tonnage - google green timber density and you will get a figure.

 

It is not an exact science, in particular bendy timber or poor stacking will result in an overestimate of weight.

 

Cheers

mac

 

Thats better than my answer, its been a while

[MikeM]

Thanks for the responses so far. The problem is it’s not stacked, just lying where it as been felled. The vendor wants to know the price I’ll offer before extracting and stacking on the roadside, so the deal has to be done before it can be accurately weighed.

 

I know what I’ll offer per ton, I was hoping there was a simple way of estimating total weight with the wood lying where its been felled. I’m assuming it’s a 2 stage process of a) work out the volume and b) convert volume to weight. One advantage is that the timber is all fairly straight.

 

I know a more experienced eye could probably get close enough just by looking. Neither the vendorn or I have that experience. I just want to try and come up with a figure that leaves us both feeling the deal is a fair

[treequip]

Thanks for the responses so far. The problem is it’s not stacked, just lying where it as been felled. The vendor wants to know the price I’ll offer before extracting and stacking on the roadside, so the deal has to be done before it can be accurately weighed.

 

I know what I’ll offer per ton, I was hoping there was a simple way of estimating total weight with the wood lying where its been felled. I’m assuming it’s a 2 stage process of a) work out the volume and b) convert volume to weight. One advantage is that the timber is all fairly straight.

 

I know a more experienced eye could probably get close enough just by looking. Neither the vendorn or I have that experience. I just want to try and come up with a figure that leaves us both feeling the deal is a fair

 

Why ?

 

He is going to have to extract it at some point.

 

I would offer the price per tonne and let him worry about the rest.

[firewood]

Given that the timber is not yet stacked it will be very easy to screw yourself on the price. (been there, got the t-shirt). If i were you i would insist on a timber truck with scales or you put it over a weighbridge to get a definitive weight and pay accordingly.

 

If stacked then macs post above covers it.

 

http://www.kinnoirwoodfuel.co.uk

[Dean O]

if he doesnt extract and stack surely its worth nothing as it will rot where it lies.

or does he not need to sell it? and will only extract if its worth it to him?

[MikeM]

They are small woodland owners only just starting to manage their woods and I guess taking a cautious approach and wanting to know the value of their product before committing to the cost of extraction.

 

Things are further complicated by the fact that wood of less than 20cm diameter commands a lower price due to local market factors, so I am actually being asked to make 2 separate offers, one for the timber under 20 cm and another for over.

 

They are good people and I am hoping to develop a long term relationship with them. That’s why I am trying to accommodate their requests. I realise it would be much easier to stick it on a truck and take it over a weigh bridge, but that’s not the deal currently on offer.

 

Incidentally how is the value / price of standing timber calculated? Could I not use a similar approach?