So a while back I got the idea to make my own Tropical Rucksack since the reproductions looks discontinued and originals were going for $400. The frame is almost identical in style to the ARVN rucksacks frame so I used the ARVN I have and this picture to extrapolate some measurements.
I took those and overlaid them on the Medium ALICE ruck that I was planning to use as the host for this project and came up with theses
The Tropical Rucksack is slightly smaller than a Medium ALICE (LC-2) and has a few differences visually on the sides.
The tropical has a row of web hanger area around the very top and two lash points on each side.
The ALICE had the web hanger area a little lower from the top and only one lash point per side
Besides the integral frame and shoulder straps the hardware on the Tropical was made out of aluminum and plastic and the nylon tape on the pockets was smaller and thinner. Check out the Gear Illustration post on it for some more.
So with all this info in hand it was time to build the frame and get to work! Well not quite, finding the right thickness of metal proved elusive. The local Home Depot never seemed to have it, or it would be a sheet rather that strips. 20 gauge is probably your best bet. 22 is way too thin and 18 is a bit overkill. So the project sat on the back burner for a while. Then I lucked into an original Tropical Rucksack and suddenly I wasn’t as interested in making one. Go figure.
You are probably thinking “Wait, the title said “Making a Tropical Rucksack” and you didn’t actually make anything?” Au contraire, while I was figuring out the details for the retro style frame I was also experimenting with a modern take. I had seen some people use the frame from the new MOLLE medium rucksack with an ALICE bag.
The components I used are;
* ALICE medium bag,
* MOLLE 1609 frame,
* MOLLE Medium/4000 waist/hip belt
* ALICE shoulder straps.
* Aluminum bar
Pictured below are the most commonly seen LC-2 shoulder straps but I ended up using the “Enhanced” or late style LC-2 straps.
Now one of my initial qualms with the 1609 frame was it’s flexibility. Take a look at the video below. I was concerned that it would be too floppy and not support the weight and shoulder straps properly. I had seen some others use a metal bar across the top to reinforce it so I did the same.
I took a strip of aluminum that I had left over form another hairbrained idea of mine but I think it was a 1″ wide by 1/8″ thick piece. I just bent it by hand and knee to match the curvature of the frame. Then once it matched just cut and radiused the ends. I also dilled a 1/4″ hole on each end to bolt it to the frame.
I attached it to the frame at the uppermost holes with some 1/4″ screws and nuts I had laying around. The waist strap/hip belt/kidney pad belongs to this frame so it attaches normally. The pack bag itself slides over the frame and attaches much the same as it would on an ALICE frame. Just instead of the circular holes that the bottom straps go through it’s the vertical slots.
Now the shoulder straps have a few different ways to go about them. The common LC-2 strap’s (short green rectangle pad) attachment straps are on the short side so if you attach them to the bar they don’t reach to the front of your shoulders and you end up with the adjustment buckle digging into your armpit. You could just attack them to the little D rings on the pack bag an that will solve the length issue but then that some what defeats the purpose of having a frame as now its essentially just hanging from the bag not supporting it. It took me a while to find a pair that weren’t being sold for an excessive price but the “Enhanced” or final version of the LC-2 shoulder straps are what I went with. I’m not a fan of the attachment straps being separate and the durability seems suspect to me but they are long enough to easily reach either the bar or frame itself. Also with the longer padding you wont end up with the adjustment buckle digging into your arm pit.
Quick side note:
There are aftermarket straps that are much nicer and I was very close to ordering some but you are looking to spend $40 and up. Since I was trying to keep this inexpensive I opted not to; for one because I’m cheap but also if you aren’t careful you will have spent as much on a project as you would if you had just bought a new pack. Right now I think I’m only into it for $50 since the pack bag was left over and something I had bough years ago already.
I like to run the shoulder straps through the D rings on the bag as a way to ensure they don’t slide around or wear on the edges of the opening. I have tried attaching them to both the bar and frame and there doesn’t seem to be any difference. Although running them through the frame is likely stronger.
I really like this set up for a lightweight medium sized rucksack. It stays off you back and sits nice and high so if you wanted to use belt kit it won’t interfere. Additionally it is very light and was cheap. The only other thing that I would recommend is changing out the metal buckles for some fastex ones, they are so much more convenient. Hopefully you found this useful.
Here is a video explanation of the set up.