What Size Pipe for a Raft Frame? Start With 1-1/4″ Schedule 40 Aluminum
Short answer first. Most DIY raft frames are built from 1-1/4″ IPS schedule 40 aluminum pipe, which measures 1.660 inches on the outside and 1.380 inches on the inside. Side rails, cross bars, uprights, all of it is the same pipe. You buy one spec and cut it to whatever lengths your build calls for.
That is what I built my own frame out of here in Central Oregon, and it is what most of the frames you see on the water are running. The rest of this page is why, what happens if you go a different direction, and how to check what you already have.
Two Different Pipes Get Sold as “1 1/4 Inch”
This is the single most common reason a fitting shows up at somebody’s house and does not fit, so it is worth two minutes.
Pipe is sold by nominal size, and nominal size is not a measurement. True 1-1/4″ IPS schedule 40 is 1.660″ on the outside. There is also a lighter wall tubing circulating in this market that measures 1.625″ on the outside, and it gets called 1-1/4 inch too.
Thirty-five thousandths of an inch does not sound like much. It is the difference between a saddle that clamps evenly around the pipe and one that sits on a gap.
So before you order fittings, put calipers on your rail and write down the outside diameter. Not the label, not what the guy behind the counter said, the actual number. If you are buying pipe new, ask for 1-1/4″ IPS schedule 40 and confirm 1.660″ OD on the order before it ships.
Is 1″ Pipe Big Enough for a Raft Frame?
You will see 1″ frames out there in both aluminum and steel, but steel frames are most common. These are welded frames that are generally a single piece not able to be broken down or a 2 pieces that slot together when installed in the raft. They work great but lack adaptability and are not compatible with a lot of other standard raft frame parts.
1-1/4″ Aluminum Is the Platform Everything Else Bolts To
Here is the practical argument, and honestly it matters more than the pipe itself.
Once your frame is built you are going to start hanging things on it. A foot bar. A bimini mount. Rod holders. Drop bag straps, cooler tie-downs, an anchor system, a seat mount, a dry box cradle. Almost all manufacturers of aftermarket hardware offer a 1-1/4″ mounting optoin, because that is the most common frame pipe size.
Build on 1-1/4″ and the whole accessory ecosystem is open to you. Bolt on whatever you want, whenever you want, from whoever makes it. Build on something else and every add-on turns into a shim, an adapter, or a trip to a welder.
This is the thing people do not think about on their first frame and then think about constantly on their second one.
Aluminum, Steel, or PVC
Quick version, and there is a fuller breakdown over on our guide to choosing raft frame materials.
Aluminum is the default and it is the default for good reasons. 6061 schedule 40 is strong, light, does not rust, and any metal supply house has it on the rack.
Steel is strong and cheap and heavy, and it rusts. Galvanized helps. You will feel the weight every time you carry the frame down a ramp or lift a loaded boat off a trailer.
PVC might even be an option for some. A flat water fishing platform, a pond boat, a kid’s first build, or a mock-up to test your bay spacing before you cut metal. Building a PVC version to figure out where you actually want things is a smart move. But it flexes under load, it goes brittle in UV and cold, and it lets go without much warning. Anything with current in it, anything with rock in it, anything you are loading with a week of gear, build it out of metal.
Anodized, Waxed, or Bare
Bare aluminum oxidizes, and the oxide comes off on whatever touches it. Black marks on your tubes, on your dry bags, on your hands. Every boater who has run an aluminum frame knows the look.
Three ways to deal with it.
Some suppliers stock fully anodized 6061 pipe, and that mostly solves it. It costs more and it can be harder to get in the length you want, so call ahead.
A coating knocks it down for a season. A hot wax coat is the common one, and there are spray coatings people use. Cheap, easy, and you reapply it in the spring.
Or you roll with it. Plenty of people do. The marks come off the rubber with some effort and the frame does not care.
For most builds I would buy the cheap local pipe and wax it. The difference between mill finish and anodized buys a lot of other gear.
Build It So It Comes Apart
This is the part people wish they had thought about a year in.
A welded frame is one shape forever. It is rigid and it is clean, and if you know exactly what you want and your gear is never changing, it is a fine answer. Most of us are not that person. Your cooler changes size. You go from a drop stitch bag to a dry box. You add a passenger, or a dog, or a rod. You run a different river with a different load.
A frame built on connectors comes apart with a wrench. You move a cross bar four inches, you add a bay, you pull the whole thing down and stack it in a corner of the garage instead of hanging it from the rafters all winter.
It also travels. Some of the trips worth building toward want a frame that breaks down, whether that is fitting in a truck bed with the rest of a multi-day load or getting flown in to a put-in. The Middle Fork of the Salmon sits on a lot of bucket lists for exactly this reason and it is worth building with that day in mind even if it is three seasons out.
You do not have to decide today what your frame looks like in five years. That is the point. Just do not build something that makes the decision for you.
Where to Buy Raft Frame Pipe
Call a local metal supplier rather than a big box store. They stock 1-1/4″ schedule 40 aluminum, they sell it by the foot or the stick, and most of them will cut it to your lengths for free or close to it. That saves you hauling twenty foot sticks home and fighting them with a chop saw in the driveway.
Bring your cut list. Measure twice, because a bar cut short is a bar you buy again.
If you would rather have it show up at the door, we sell 6061 aluminum pipe in 1-1/4″ IPS schedule 40 in the exact spec our fittings are cut for.
What You Need to Actually Build It
Pipe and connectors. A standard four-bay frame takes ten connectors and whatever pipe your dimensions call for.
Our SRC raft frame fittings are forged 6061 T6 aluminum, sized for 1-1/4″ schedule 40, and every one ships with the stainless U-bolt and hardware to mount it. If you are still working out dimensions, start with the frame building guide.
And if you measure your pipe and get a number you are not sure about, email it to me. I will tell you straight whether our fittings work on it. I would rather lose a sale than have you eat return shipping on a part that was never going to fit.
Common Questions
What size pipe is used for raft frames?
1-1/4″ IPS schedule 40 aluminum is the standard, measuring 1.660″ outside diameter and 1.380″ inside diameter. The same pipe is used for side rails and cross bars.
Can I use 1 inch pipe for a raft frame?
You can, and people do. It is lighter and cheaper but it flexes more on longer spans, and most aftermarket frame accessories are built for 1-1/4″ pipe, so you limit what you can add later.
How do I know what size pipe my existing frame is?
Measure the outside diameter with calipers. 1.660″ is 1-1/4″ schedule 40. 1.625″ is a lighter wall tubing sold under the same nominal name and it is not interchangeable. 1.315″ is 1″ schedule 40.
Is aluminum or steel better for a raft frame?
Aluminum for almost every build. It is lighter, it does not rust, and 6061 schedule 40 is easy to source. Steel is stronger for the money but the weight shows up every time you move the boat.
How much pipe do I need for a raft frame?
It depends on your boat and your bay layout. A common four-bay frame on a 14 foot raft runs somewhere around 40 to 50 feet of pipe. Lay out your dimensions first, build a cut list, then order.