On multi-use items, do you give the item a weight credit for the extra item left at home? Let me explain…
I always hike with trekking poles. When considering the weight of t poles, I categorize them as "Clothing-Worn," much like my hat or my gloves (I don't have them on all the time, but I still carry them).
Sometimes I use a tent, sometimes I use a tarp. The tarp uses the t poles for support. When using a tent, on the gear list the poles _add_ weight since they don't contribute to the shelter. When using a tarp, on the gear list the poles _don't_ add weight to the shelter since I'm carrying them anyway.
The weight of the total tent is only 25% heavier total tarp (tarp + ground cloth + bug protection), but if I account for the reuse of the t poles for the tarp (14.5 oz.), i.e., subtract their weight from the total weight of the tarp shelter system, the tent is about 90% heavier.
I hope I've explained it clearly; this "weight credit" issue when using a tarp has been nagging me.
Regards,
Simon

