murphy4trees
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The industry standard for height of cables is 2/3 distance from branch union to tips. I will usually go even higher, as high can be done, without going to extraordinary climbing efforts. The worse the structure of the tree, the higher the cable goes.
I have seen that most of my peers usually cable below the 2/3 level, sometimes much lower. One issue could be that is is difficult to judge exactly where the 2/3 level is. However, I think that most put their cables in low because it is just easier climbing to go lower, or that is only as high as their bucket reaches. Or perhaps they mistakenly think that the cables need to be in big wood to hold.
I heard a talk by Bruce Fraederick of Bartlett resaerch labs that J lags are acceptable in wood up to 10" diameter. The old standard was 8". Does anyone know when the standard changed? Around here, almost every cable I put in is in wood under 10". It is only where cables are put in low that the wood diameter exceeds 10", on all but the biggest trees.
I cabled a 85-90' ash yesterday. The wood on one side was 6" and the wood on the other was probably 8-9". I was over 2/3 the distance but not by much. I'll see about posting a photo.
Think about it... On a 100' tree, with co-dominant stems at 25', the height of the cable should be 75' to make the 2/3 ditance standard... There is no way the wood at 75' is going to be over 10".... The smaller the tree, the smaller the diameter of wood at standard height. SO the VAST MAJORITY of cabling jobs, if done properly will be in wood under 10", and therefore can be done with J lags....
So I question the need for through bolts.... And I think that vast majority of cable failures with J lags are due to improper instalation... either too low, or lag not set in line with cable .... or both. This is due to improper training and lack of climbing skills.
It is often difficult to make the swing at 2/3 the height, especially on wide trees. The TIP needs to be way up there, and even then it can be difficult. I recently bought a sidekick which is very useful for grabbing a line set in the opposite lead, for those of us that don't use a pole saw in the tree very often. It is a small and light telescoping pole with a small hook on the end.
I recommend it highly even though it doesn't see everyday use. Having this tool can make installing cables at the proper height a lot easier, and thus may save a few trees along the way.
I have seen that most of my peers usually cable below the 2/3 level, sometimes much lower. One issue could be that is is difficult to judge exactly where the 2/3 level is. However, I think that most put their cables in low because it is just easier climbing to go lower, or that is only as high as their bucket reaches. Or perhaps they mistakenly think that the cables need to be in big wood to hold.
I heard a talk by Bruce Fraederick of Bartlett resaerch labs that J lags are acceptable in wood up to 10" diameter. The old standard was 8". Does anyone know when the standard changed? Around here, almost every cable I put in is in wood under 10". It is only where cables are put in low that the wood diameter exceeds 10", on all but the biggest trees.
I cabled a 85-90' ash yesterday. The wood on one side was 6" and the wood on the other was probably 8-9". I was over 2/3 the distance but not by much. I'll see about posting a photo.
Think about it... On a 100' tree, with co-dominant stems at 25', the height of the cable should be 75' to make the 2/3 ditance standard... There is no way the wood at 75' is going to be over 10".... The smaller the tree, the smaller the diameter of wood at standard height. SO the VAST MAJORITY of cabling jobs, if done properly will be in wood under 10", and therefore can be done with J lags....
So I question the need for through bolts.... And I think that vast majority of cable failures with J lags are due to improper instalation... either too low, or lag not set in line with cable .... or both. This is due to improper training and lack of climbing skills.
It is often difficult to make the swing at 2/3 the height, especially on wide trees. The TIP needs to be way up there, and even then it can be difficult. I recently bought a sidekick which is very useful for grabbing a line set in the opposite lead, for those of us that don't use a pole saw in the tree very often. It is a small and light telescoping pole with a small hook on the end.
I recommend it highly even though it doesn't see everyday use. Having this tool can make installing cables at the proper height a lot easier, and thus may save a few trees along the way.
