Ok, How typical, ask a question and get a different answer from all who respond... lol... Gut and belly strapping is the same, the strap is just going in-between layers. On this particular load in the picture if you have winches on both sides of the trailer I would use both so that its pulling from both sides. Thats just me, some guys do and some don't.
I'll have to look tomorrow, or when I have more time but, I recall reading on here a guy was put OOS by Texas DOT for a load being over 3 tiers high with no straps in between. Can't remember if it was lumber or not... @WadeH how did the shipper load this? Did they load 4 stacks high at one time where you weren't able to toss straps in between or was it say 2 at a time giving you or the driver an opportunity to toss some belly straps on?
The shipper loaded 2 tiers at a time all the way around, then put in the middle row of 2x4 spacers, and then loaded the next 2 tiers on top all the way around. I think the lift operator would have let me throw belly straps on if I had thought to ask. I watched what the other flatbedders were doing and followed their lead. The other 3 loads that went out also had no belly straps. Two other drivers used 3 straps over the top on just the front stack, and two on both the middle rear stacks. One other driver used 3 straps over the top on both the front and back stacks, with just two straps on the middle stack.
Just because "they" do it.....I hauled lumber for a number of yrs on the Oregon/Washington coast pulling maxis & b trains. It was company policy to gut strap our loads. Seen more than one load of lumber scattered in the ditch because there was no gut straps. Like Jon Jon said, cross strapping also secures the load better.
For whatever it's worth, here's a load of lumber that my dad hauled from the Cloverdale, Ca area in 1952 to Camarillo, Ca. Not sure what the rules were then, but he made it. I'm thinkin they used cable with winches. And I dont think they went 70 mph either, note the butane tank (Hall-Scott power) and 3 spare tires.
Way old school! Cables were pretty well replaced with straps when I started except for fruit bins with corner irons and I think they still use cables there. Not long ago I was talking about the old days with a friend and I commented that I probably couldn't remember the right way to put a cable on a winch. I'm not sure that looks like Cloverdale. The profile of the hills in the background remind me of Ridgewood summit. I'm unloading in Eureka right now, I'll try to remember to pull in and look on my way south. @truckdad you should have an online photo museum. Thanks, I love this stuff!