Fiberglass pole advice

[harbor-tech]

I have a portable antenna, tripod and telescoping mast, made up of (3) 8 foot sections of fiberglass tubing, with a 70 cm dipole topping it. The mast diameters are 1.75, 1.5, and 1.25 inches. I currently use 1 foot 'overlap' between sections, for 22 feet effective height. I chose 1 foot overlap because it seems 'safe', but with no hard data to back that up.

My question is: Should I keep the 1 foot overlap, or is 6 inches enough? Or maybe, I am dangerously over-extended, and should go for 18 inches overlap. Does anybody have any experience / advice to share on this subject?

 

[prcguy]

Depends on the pole mfr, material thickness, etc. 22ft is not that tall and I would think a 6" overlap or maybe even 4" is fine. I've had several telescoping fiberglass masts up to 33ft that had tapered sections and they only had about 4 to 6" of overlap. I have a 50ft MFJ mast that can be put up with about 6" of overlap but the mast is not sturdy enough for anything more than holding up a vertical wire at that height. If I use about 2ft of overlap on each section it will hold up various VHF/UHF antennas but that has more to do with bowing over the entire length vs strength at the overlap points.

I have a portable antenna, tripod and telescoping mast, made up of (3) 8 foot sections of fiberglass tubing, with a 70 cm dipole topping it. The mast diameters are 1.75, 1.5, and 1.25 inches. I currently use 1 foot 'overlap' between sections, for 22 feet effective height. I chose 1 foot overlap because it seems 'safe', but with no hard data to back that up.

My question is: Should I keep the 1 foot overlap, or is 6 inches enough? Or maybe, I am dangerously over-extended, and should go for 18 inches overlap. Does anybody have any experience / advice to share on this subject?

 

[harbor-tech]

Thank you prcguy! That 4 to 6 inch sounds great! I got the poles from dxengineering, 1/4 inch walls. I've done Ok at 22 feet, and though another foot doesn't sound like much to many, when you're out in the boondocks it matters.

 

[iMONITOR]

That 4 to 6 inch sounds great! I got the poles from dxengineering,

Which one did you buy?

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[WB9YBM]

My question is: Should I keep the 1 foot overlap, or is 6 inches enough? Or maybe, I am dangerously over-extended, and should go for 18 inches overlap. Does anybody have any experience / advice to share on this subject?

You didn't mention wall thickness, which probably plays a role in that (at least to a point). I'm not sure if there are mathematical formulae or manufacturer spec's that would mention tensile strength or some such...

It would depend also on wind loading--how much force is applied at a given point and how much leverage is created by a given pole length & wind strength.