How To Know How Deep To Set Your Float – 2 Easy Ways

An angler fighting a big fish - knowing how deep to set your float is a critical part of good float fishing
This pool starts out at 4 feet deep for 30 feet, then has a 2 foot deep high spot and then drops into 6 feet of water, but it also has a trench on the far side that is close to 8 feet deep where this client hooked his fish. Without knowing how deep to set his hook he would have never caught this fish.

Knowing how deep to set your float is a critical part of good float fishing, and if you do this well you will catch a lot more trout, steelhead, and salmon in the rivers that you fish. But how do you know how deep to set your float? In this article, I will answer this important question so you will know how deep to set your float in any river that you fish.

You want to set the depth of your float so that the bait is 8 to 16 inches off the bottom of the river because that puts the bait right in the fish’s face. The closer the bait is to the fish the more likely it will eat it. You can use your float and bait to detect the bottom.

As a guide, I set or adjust my client’s floats for them because I know exactly how deep each spot is. But many anglers don’t know how deep the spot they are fishing actually is and they often fish too high or too low and they don’t make the necessary adjustments to their float to get it down to the fish. This means they are missing fish.

Setting your float too deep from the start might mean you will be snagging on the bottom and you may lose your hook and bait on the first cast. The other problem is that few fish will feed down.

A recent study indicated that fish in a river tend to only feed downwards 13% of the time. The other 87% of the time those fish are feeding on food that is straight at eye level or above and beside them. This is another reason why you need to set your float at about 6 to 12 inches off the bottom.

Know How Deep To Set Your Float By Finding The Bottom

I tell my clients that when they get to a new spot and they can’t see the bottom or can’t visually determine the depth of the spot, their first or primary goal is to find the bottom, then start focusing on catching a fish.

If they are lucky, they will catch fish while they are trying to find the bottom.

Finding the bottom is a great way to set your float for the right depth of the spot or the line that you are about to drift your float down. Once your find the bottom you simply make your leader below the float shorter.

I use a few methods for finding the bottom because finding the bottom is actually harder than you think for a few reasons which I will discuss below.

I will also discuss exactly how I find the bottom below.

The River Bottom Is Not Always Flat

One of the reasons that finding the bottom is difficult is that the bottom of a spot that you are fishing might not be the same depth everywhere through the entire spot.

The top of the pool could be deeper than the bottom, or the far bank could be deeper than the close bank or maybe there are some high spots or some deep spots. I will discuss how to figure all of this out.

If you are in a spot that is mostly 5 feet deep and you set your float so your bait is 1 foot off the bottom, you will catch some fish, but there could be a spot in the middle, or near the back of the pool that has a 6 foot wide by 10 foot long deep trench that is 9 feet deep and that could be where 80% of the fish in that pool are holding.

This means that if you set your float 1 foot off the bottom in 5 feet of water, your bait could be 4 feet out of the strike zone for 80% of the fish in that pool.

One side of the river could also be shallower than the other side of the river so where you set your float for halfway across the river might not be good for the other half of the river closer to the far bank, or vice versa.

I map out the bottom of all the spots that I guide so that my clients don’t miss any fish and this is one of the reasons why some years I will hook over 500 steelhead in the fall.

My clients will often see me set the float depth 2 or 3 times in the same spot and I do this because I want to make sure I get their bait in the strike zone of fish that are sitting in holes or trenches that I know are deeper.

Use The Right Bait For Finding The Bottom

Some baits are more buoyant than others, and baits like a plastic worm that floats are not good baits for finding the bottom.

Using a heavier bait like a tungsten weight fly, or a glass bead which are both very heavy are the best baits to start with to help you find the bottom. Your goal is to simply find out how deep your float needs to be before those heavy baits start dragging the bottom or hooking fish.

If I start hooking fish before I hit the bottom I will keep fishing that depth because chances are it’s just above the bottom anyways. If the fish stop bitting, I will often continue making my leader deeper to be sure I’m not way over their heads in other parts of the pool.

If my float starts catching bottom or tilting hard downriver I will make it 12 inches shorter.

Setting your float by usingg this drop shot rig
This drop shot float rig is a great rig for helping you find the bottom so you know how deep to set your float.

You can also use a weight closer to your bait to make it heavier and to help you locate the bottom, or you can use my drop-shotting rig like the one in this diagram which puts your weights below the bait.

Drop Shot Rig For Bottom Detection

The drop shot rig is my number one rig for finding and mapping out the bottom.

With the Drop shot rig, your weight is placed at the very bottom below your bait or fly. You will only add as much weight as you need to get the weight down fast without sinking your float or constantly hanging up.

The weights will gab the bottom which lets you know that you hit the bottom. Often you will lose some weights if it gets snagged up badly, but you also lose almost no hooks, flies, or baits, and weights are usually cheaper and easier to replace.

With some lighter baits and traditional leader setups, the baits will simply drift or lightly drag across the bottom making it very hard to detect the bottom with your float.

But with this drop shot leader method, the weights will stick and grab the bottom making it easier to detect the bottom. Your float will often twitch, bounce, or keep tilting hard down river which indicates that the weight is hitting the bottom or is hanging up, then releases and the float straightens.

Once you detect the bottom and determined the depth, you can continue to fish with this rig by simply shortening the leader.

However, I mostly use this method just to map out the river bottom and to determine depths throughout the entire spot, and then switch to a more productive leader setup. I discuss mapping out the bottom below.

If you are fishing with this method, the length of line between your bottom weights and where your tag line or fly attaches can be anywhere from 6 to 24 inches.

If the fish are hugging the bottom, I will often go with an 8 to 10 -inch shot line/weight line, and a 4-inch tag line for the bait. This should keep the bait about 6 inches off the bottom and right in their face.

In winter or colder conditions or when fish are inactive, I tend to fish closer to the bottom, with the belief that the closer you can get a bait the more likely they will eat it.

In warmer or ideal water temps or when fish are moving and are active, I will try to fish my bait higher. I will also most often (if legal to do so) I will use a two bait rig with the baits spread out 12 to 30 inches apart.

If the fish are active and willing to move farther, I will use a longer 12 to 16-inch shot/weight line, and a 4 to 6-inch tag bait line.

The bait tag line, also known as the dropper line, that I have found to work the best is about 4 to 6 inches long and made from 8lb to 10lb fluorocarbon leader. Any longer than 6 inch and it may tangle or drag bottom.

Mapping Out The Bottom – Why It’s Important

I would not be as good as a guide if I didn’t know my spots. So one day i diced not to fish and to just go out with a bunch of heavy weight under a float and find the bottom in all the regular spots I fished and guided. This was eye opening for me.

By doing this, I was able to detect deep spots that I didn’t know were there, high spots that I just thought were the normal depth of the entire bottom, and what I call trenches.

Finding these holes, trecnhed and high spots enable me to set my depth far more accurately and that accounted for almost double the fish I would normally catch out of a spot. It made me realize that I, and likely most other anglers were missing fish!

An added bonus to mapping out the bottom and knowing where these shallow and deep spots are is that there are times of the year or even times of the day when fish will hold in these deeper spots. During high sun and in the winter these holes where I would catch 90% of the fish, but only after I figured out where the holes where.

This is an exact bottom map of one of my favorite steelhead pools.
This is an exact river bottom map of one of my favorite steelhead pools. During low light hours or when the fish are moving I catch all the fish at the top of the pool near the rapids but at other times there are no fish there.

What I discovered is that most guys make a drift, hit a 3 foot high spot, set their float accordingly, and fish the rest of the pool based on that high spot. The miss fish sitting in a 8 or 9 foot hole or trench.

And sometimes that high spot is a giant 4 foot by 4 foot bolder sitting in 7 feet of water. They tap the top of that bolder and adjust their float according, and them miss all the fish sitting on the bottom. It’s important to map out the entire pool, especially if you can’t see the bottom.

If all the fish are holding in the part of the pool that is very deep because it’s cold, or because the sun is high and bright and they don’t want to be in the shallow water, if you don’t know where that deep spot is you will end up missing a lot of fish.

In the picture above I show you an exact river bottom map of a favorite steelhead pool on my guiding run.

During low light hours or when the fish are moving in early fall, I will catch almost all my steelhead at the top of the pool near the rapids which is where they will stop for a couple minutes to rest before they shoot up through the rapids to the next pool. This is a great spot early morning and just before dark when they are ready to start moving up the river.

During mid-day when the sun is high and the fish stop moving and they are less active I stop catching fish at the top of the pool and I will catch them all in the middle of the pool where the current is slower.

In late fall or wintertime when the water is ice cold, I only catch fish in the deepest part of the pool where they are holding. This is why mapping this one particular pool has put hundreds of steelhead on the line for my clients. On that same stretch of river, I have many other pools that go from shallow to deep or have trenched that the fish tuck into.

An angler that doesn’t have this pool mapped out and doesn’t know there are shallow and deep spots will hit bottom in the middle of the pool where it is shallowest and then set their float at 3 to 4 feet deep and that means they will miss all those fish sitting 9 feet down.

I see this happen all the time, anglers bump or locate the bottom, set their float to that level, and then never touch it again, and they miss a lot of fish because of this.

Fish during the winter or fish holding in very deep water are often less active and won’t move very far for a bait which is why you need to find these deep spots and map out the bottom of the pool.

Mapping the bottom has allowed me to catch 10 times more fish, and allows me to stay on fish under all conditions and at all times of the year.

How Do You Set Your Float

The first thing to do when setting your float is to look at the spot you are about to fish and try to determine how deep it is by what you can see.

If you can’t see the bottom just guess based on what you can see.

At the edge of the bank, you might be able to see the bottom out into the river until it looks to be about 3 feet deep and then you lose sight of the bottom. Maybe you can see the bottom at 4 or 5 feet deep before you lose sight of the bottom. This is the depth that I would start with.

If I lose sight of the bottom at 3 feet deep I set my float to 3 feet deep and make a cast in close and see if I either hook a fish or a hook bottom. If nothing happens I make it 1 foot deeper and cast into the same spot and see what happens.

I also use just the angle of my float to help detect the bottom because sometimes you will be on the bottom but the float won’t pull under. When searching for the bottom I will hold the float back just enough so that it stands perfectly straight up, if it keeps hard tilting downriver I’m hitting or dragging the bottom.

If I don’t hit bottom on my first couple of drifts, I will keep making my float deeper until I start hitting the bottom. Once I hit bottom I will make my leader 6 to 12 inches shallower or shorter because I know fish feed up and I will make a couple of casts and hope for a fish.

Then I will move my float out 1-foot further and see what happens in that line. If I don’t hit the bottom there, I will make it 1 foot deeper and I will repeat until I hit the bottom there and then move it one foot further again and repeat the process.

I will repeat this method all the way across the entire spot because it might be 4 feet deep at 10 feet out from the edge of the bank that you are standing on, but it might be 8 feet deep 15 feet further out.

Cross Section of a river
One side of the river could be deeper than the other side. If you are standing on the left bank and set your float based on the 4 foot depth you will be too shallow once you get closer to the other side.

I fish or drift my float in lines from the top of the pool to the bottom of the pool and I find the bottom with every line until I know where the bottom is. This is how I map out the bottom of the pool.

Once I have mapped out the bottom of the river, I memorize it so I know how deep I need to be each and every time I fish that same spot.

The key is, once you start hitting the bottom, shorten up your leader by 12 inches so you are not dragging the bottom.

When I move to the next spot I repeat the process.

If you want to know how I teach my clients to fish in lines or how to cover the water effectively, I suggest reading my article Effectively Covering The Water When Float Fishing.

How Do You Find The Holes?

How to find deep spot in the river
Finding the deep spots and fish in what I call the trenches can be the key to catching more fish.

Finding the holes can be difficult but it’s not impossible.

I talked about dragging a heavy bait or some weights across the bottom to locate the bottom. Once I find the bottom I will make my leader 12 inches shallower and make a couple of good clean drifts at the right depth. Good clean drift means having the proper angle and speed.

Speed control is the most critical fundamental of good float fishing and you can see more about that on my page Controlling Your Speed For More Fish When Float Fishing.

To find out if there is a hole or trench, after a couple of good drifts and before I move my cast 1 foot further out I will make it deeper by 1 or 2 feet and purposely try to drag the bottom while trying to hold my float as straight up and vertical as possible.

What I’m looking for is, if the float keeps wanting to hard tilt downriver but them all of a sudden stands straight up and doesn’t want to hard tilt down, it likely means it just got deeper there and I found a hole.

Sometimes a hole or trench on the bottom might only be a small 8-foot by 3-foot trench that is 3 or 4 feet deeper than the rest of the pool and many fish will hold there.

Sometimes, the pool could be shallow at the top but then deeper near the back of the pool. If you are hitting lots of bottom in the first 30 feet and set your float at 3 feet to fish that first 30 feet but the back half of the pool is 9 feet deep you will miss a lot of fish at the back of the pool.

Once I find a hole I will remember exactly where my float went from tilted downriver to standing up because that is the start of the hole and I will make repeated casts right where the hole starts and will make it deeper and deeper until I hit the bottom of that hole.

I will also remember where the float starts to drag again because that is the end of the hole. The hole might be 5 feet long or 35 feet long.

I repeat all these steps and drag the bottom from one bank to the other and from the top of the pool to the bottom of the pool until I have completely mapped out this pool, and then I move to the next one and do it again.

Controlling your depth during the presentation is one of the 4 fundamentals of float fishing that I teach when guiding. It’s important to know and do all 4 fundamentals well if you really want to catch more fish when float fishing.

If you are not sure what these 4 fundamentals are check out my page Centerpin Fishing For Beginners: 20 Steps From A Top Guide.

If you know someone that struggles to catch fish when float fishing, be a good friend and share this website with them too.

The Right Float And Right Size Float

Using the right float and knowing what size of float to use is important when both finding the bottom and when fishing.

A reader just asked about what size float to use and using the right float and the right size of float is important for finding the bottom. I discuss my favorite floats on my page 5 Best Centerpin Floats For 2022.

The size of float that I use for steelhead depends on the depth and the velocity of the river at the spot I’m fishing.

On a slower section of the river, a smaller float is often all that is needed to keep your leader in the verticle angle that I show on my diagrams. The exception is if you need to cast very far and need to add more weight, then a bigger float might be required.

If the current is too fast and it drags the leader and changes the angle from say a 90-degree straight down to an angle of 45 degrees or shallower, in which case you will require more weights and a bigger float that can handle those weights.

Too many weights will sink a float, too few weights and the float will sit too high on the water.

It’s the same with the depth, shallow water requires fewer weights to get your bait down fast so a smaller float is usually good, whereas deep water or deep and fast water will need a lot more weights and a much bigger float will be needed.

As a rule of thumb, I try to use the smallest float possible, as long as it can handle all the weights that I need to use for that spot, and it will cast far enough, and that I or my clients can still see it when it’s 200 feet down the river.

I might change float sizes if needed based on the depth and velocity of each spot so it’s a good idea to use a float that can be easily changed.

If you are not sure if you have too much weight, try this.

If you are in a very clear river, put on a bright bait, cast it upriver but close into your bank so when it drifts by you can see it. You want to try to see how deep your bait is and at what angle your leader is at.

If the bait is almost directly below your float and it’s deep, you are good.

But if the bait is 6 feet up the river or 6 feet down the river from your float and on a sideways angle you probably need more weights, or you need to control the float speed so that it puts the bait back under the float and close to the bottom again.

If you are controlling your float speed well and you still have a more sideways angle then you need more weights and maybe a bigger float that can handle the extra weight.

Every float is different and not all of them are right for float fishing in rivers.

Whatever float you decide to use, you should know how much weight each size of that float is required to make the float sit perfectly in the water. Sitting perfectly usually means only an inch or two is sticking up out of the water.

Many floats have lines on the floats or color separations. So an orange top float should probably be sunk to where the float goes from orange to black or brown, or whatever the lower float color is. To sink it to that level you need to have enough weight.

There are advantages to sinking the float enough, which include the float tracking straight in the water better.

How to know how much weight to use for each float size? An example, a 6.2-gram float might be able to handle up to about 9 AB-sized shots, however, not all weights are classified as AB, or AA, or BB, so it will depend on your brand of float, but you can figure it out manually.

Take float, add 10 inches of line to the bottom of it (no hook), put it in flat slow water, keep adding weights to that 10 inches of line below the float until the float sits perfectly or sinks to the perfect depth in the water. Then remember how many of that size weights you need for that float to be perfect.

If you use more than one size of float, you should start with your smallest float add enough weights until it’s perfect, then go up one size of float and add more weight until that float size is perfect, then go to a bigger one, and add more weights again until it’s perfect.

Record or remember all that information so you will know it for future trips.

I also try to use the same type of floats and the same brand of weights all the time. changing floats and weights might mean you need to figure it all out again.

The right types of weights are important and it does make a difference for many reasons. I use the same type of weights when float fishing, when bottom bouncing, and when fly fishing. See my page Weights For Fly Fishing: Everything You Need To Know if you want to know more about the weights that I use and recommend.

When you fish, use the right amount of weights based on the velocity and the depth of each spot and then change floats according to your weights.

Also keep in mind that when using stuff like weighted jigs for steelhead, the jig itself can add a lot of extra weight, therefore, you may need to go to a bigger float to accommodate for the extra weight, or use fewer weights knowing that your jig will add the weight you need to get down to the fish or give you a great leader angle.

I would usually go with fewer weights and a smaller float, over more weights and a bigger float unless I need that extra weight to cast a mile out.

Got A Question About How Deep To Set Your Float

The two best methods for finding the bottom are to use the drop shot rig or use the drag method with a heavy bait or fly. But if you have a question, comment, or tip regarding how deep to set your float let me and other readers know in the comments section below.

Tight Lines

Graham

6 Comments

  1. I’m already assuming that you have your full set up already when float fishing. Float, swivel, shot line, swivel, leader then bait. I’m reading your article about when you’re trying to find the bottom and you said once you find the bottom you shorten your “leader”? So you cut off your leader line and retie it with your new baits shorter? Or do You just mean shortening it by pulling your float down lower? I’m confused. I’m fresh to the float fishing and your information has opened my eyes to ALL of my mistakes.

  2. HI Graham, I use West Coast Floats primarily and fish the big and small river of Southern Oregon (Elk, Sixes, Rogue, and Chetco).

    The one aspect of float fishing I struggle with, at least using West Coast Floats, is to know what size to use on a given stretch of river. The floats range from 1/8 – 1oz for steelhead. I’m familiar with shortening or lengthening the leader, but it still leaves me wondering if I’m using the correct size float.

    Let’s say I choose to fish a 1/8oz jig and a 1/4oz inline weight with a 3/8oz float. Lengthening or shortening the leader aside, how do I know whether to stick with the same set-up, go down (i.e. 1/8oz jig + 1/8oz inline weight and a 1/4oz float), or go up (1/8oz jig + 3/8oz inline weight with a 1/2oz float)?

  3. Hi Graham, I’ve got four questions for your drop shot rig. #1 How much line do you usually have between your bait and your bottom weights?
    #2 How much weights do you recommend at the bottom of the drop shot rig?
    #3 Is this a rig that you can fish with or more so just to find bottom?
    #4 If you can fish this rig, once you found bottom, how far off the bottom do you keep your weights for your next drifts?
    Thanks

    1. Hey Chris,

      Good questions, thanks.

      I updated that portion and other portions of this article to answer these questions and be more clear, but in a nutshell, add as much weight as you need to get the weight down fast without sinking your float or constantly hanging up.

      Yes, you can fish it, but I mostly use this rig for mapping out the bottom and then change to a more effective leader.

      If I were to fish it, once I locate the bottom, I’d shorten the leader by 6 to 12 inches.

      Best of luck
      Graham

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