Listening for decay

[David Humphries]

Hi David, to add my ten penneth..

 

Whilst delivering the Basic Tree Surevy Course I explain about the 'nylon mallet' as a basic sounding device to detect decay / dysfunction but suggest it should be used in a targeted manner, rather than just randomnly 'knocking around', as it could still cause injury to lightly barked trees. That said I do acknowledge that not all examples of decay / dysfucntion exhibit visual signs.

 

Not sure what the guys in the vid were trying to establish, other than obvioulsy decay of course, but was that part of a safety inspection or pre-climb...wudda liked to have seen the ladders secured too...once a H&S nurdy always...

 

I have used the boot technique before too, but raised too many clients eyebrows so bought myself a mallet...much more impressive.

 

Hope you're well.

 

Cheers..

Paul

 

Howdee Paul,

 

thanks for taking the time to input

a very valid point in terms of working at height from a ladder.

 

I remember fondly, whilst on Guys' PTI at Merrist wood some years back, that one of the candidates was a little 'over enthusiastic' with a sounding hammer during a trial pre-assessment inspection.

This is what was in my head when I chose the apt soundtrack by Mr Bonham, in the video footage

 

The trees (a pair of lapsed oak pollards) were both assessed pre-climb to determine the extent of decay in the bollings.

 

As a result of the sounding inspection, the obvious one with advanced decay (both Laetiporus sulphureus & Fistulina hepatica) issues, has been deemed not structurally stable enough to be climbed & has been taken off the schedule for climbing reduction. It will instead be tackled with a tracked mewp when I have the oportunity to fit this one in with others.

 

 

Going back to the ladder issue, they were footed at the beggining of the ascent & deemed as stable enough on the ground & trunk to carry out the sounding without having to over-reach & then moved twice more to gain access to different parts of pollard head (possibly not clear on the video?)

They would have (as per our site specific R/A) additionally have been secured at the top if the work required exiting the top of the ladder or for any form of cutting. See last image.

 

But as you rightly point out, additional securing would lessen any perceived risk further.

 

Thanks again for the input

 

 

 

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[daltontrees]

Have you tried the soft faced/nylon type hammer as opposed to rubber mallet Jules ?

 

Is choice of 'hitting implement' about preference or availability for you?

 

Do you think you can ascertain different types of decay via sounding?

 

 

 

Do you inform the watching client that the tip of said boot has been specifically developed as a sounding implement for tree inspection?

 

 

 

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My techniques were described a little roughly, in practice I am not going round whacking trees like the guy in the Rank Films gong advert.

 

By small trees I mean young ones that I suspect through strimming damage or frost splits are developoing decay from within. In a previous life I studied geology in some depth; in rock mechanics there is a tool which I think was called a Schmitt Hammer which delivered a fixed amount of energy to the hammer blow, the recoil could be used to assess the approximatee dgree of weathering of the rock. I have been trying to get a similar approach with sounding for tree decay. The boot technique involves putting a knee on the stem and swinging the boot from the same distance back. The contact is with the flat vibram front of the boot. Sometimes the reverberation through the knee is as telling as the sound from the contact. The client understands when I explain.

 

I should get a nylon faced mallet for bigger trees. The choice of mallet is intuitive rather than of availability. The rubber one is quite hefty and I don't use it on thin barked trees. But I am fairly confident of the indication it gives of the relative extent of decay on big old Ash, Oak and Pine for example. I am curious now to know what nylon does that rubber doesn't.

 

As a slight aside, I recently surveyed all the trees on a golf course. The stems facinmg the tee-offs were pockmarked, the result certainly of golf ball impact. I imagine a hammer improperly used could do something similar.

[daltontrees]

I see Sorbus sells the nylon ones for £27, they weigh just 1 lb. They also seem to be available elsewhere in 1/2 lb., 1 1/2 lb, 2 lb etc. Any recommendations on what size is best? My existing rubber mallet is about 2 1/2 lb. and anything less will not bring out the boom on a big tree.

[Matthew Corran]

I bought one from buybrandtools for £12 I think!

[treeseer]

The earliest reference I could find.......

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I first saw it presented in 1996 by the legendary John Britton in California. He was a handson man; no drilling.

 

first saw drilling by bartlett guys in 2002. they quickly set the hammer down and started drilling; have not slowed down since.

 

saw mike in 2005? ISA Nashville. tony the radar guy was there as well no contest that i recall or noted but mike's sounding was eerily accurate and very inspiring.

 

isa 2007 Dan Marion led a session using a plain old metal clawhammer. the bartlett guys said forfend but that seems ironic given their penchant for destructive sampling/barrier breaking. I still like the clawhammer on the flare of thickbarked trees, as when flipped it is a good digging implement.

 

i dont fancy the nylon heads; they don't give a thunk like other heavier hammers. I typically use the rubber mallet but have been switching to the below Thor-like wood mallet, as it resembles the tool on my fambly's coat of arms.

 

I don't imagine myself a sounder of Ellisonian dimensions but can hear hollows. As years go by (where's Marianne Faithful come from?) it seems less clear; has anyone used a stethoscope for this task?

[Tony Croft aka hamadryad]

 

i dont fancy the nylon heads; they don't give a thunk like other heavier hammers. I typically use the rubber mallet but have been switching to the below Thor-like wood mallet, as it resembles the tool on my fambly's coat of arms.

 

 

a tiny nylon hammer is as effective as a large mallet, and less likely to be used "vigorously"!

[David Humphries]

I see Sorbus sells the nylon ones for £27, they weigh just 1 lb. They also seem to be available elsewhere in 1/2 lb., 1 1/2 lb, 2 lb etc. Any recommendations on what size is best? My existing rubber mallet is about 2 1/2 lb. and anything less will not bring out the boom on a big tree.

 

 

This is the Thor we have at work (having originally used a rubber mallet).

 

Thor 710R Soft & Hard Faced Hammer 32mm 385g | Nylon & Plastic Hammers

 

Although this has a small head it does have the option of a hard & soft 32mm face.

It weighs 385g roughly 3/4 of a pound

 

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[daltontrees]

TA, I shall get myself a couple of different weights and try them out. They can indeed be bought for little over a tenner.

[treeseer]

"a tiny nylon hammer is as effective as a large mallet, "

 

Not for my ear it isn't.

 

"and less likely to be used "vigorously"!

 

Perhaps the opposite could occur, if the little hammer does not make a big enough sound.

 

There are others over here who favor a broader striking surface, in part i suspect to lessen impact per square unit of area?

[ScottF]

Surprised there's no research to support hammerology seeing as it's so widely promoted. Having read the UKTC thread I agree witrh Julian Dunster that a destructive test with a live tree (destined for removal anyway) would be most telling.

 

I'd happily supply the PiCUS and Resistograph for comparison. Perhaps we could do an accurate measure of the stem as a template and allow a number of hammerers to draw out where they think the cavitation is and then use various other means (PiCUS,drills,Thermal etc) and compare the findings.

 

Could be mighty interesting.