Shimano Thunnus 4000 ci4 Review

Shimano Thunnus 4000 ci4 Review

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If you are on the hunt for a high-performance spinning reel for saltwater fishing, you will probably come across the Shimano 4000 Ci4 but how good is it really? And how does it measure up against the competition? This is our detailed and honest Shimano Thunnus 4000 ci4 review (you can check the current price and more info on Amazon here).

While it is not the number one most powerful spinning reel on the market, nor does it have the highest retrieve ratio or strongest drag system, it definitely holds its own when compared to the competition.

Besides that, it does have a few really useful features which makes it ideal for all kinds of saltwater fishing, maybe not for the absolute largest of fish, but for some pretty decent size prey none the less. Let’s take a deeper look into what this reel has to offer;

Features & Specs

This is quite the powerful, strong, durable, and high performance spinning reel. Sure, it does have a couple of drawbacks that we will talk about throughout this review, but generally speaking, it is a decent spinning reel with a lot of good features.

The Drag System

The 4000 Ci4 does come with quite a nice drag system. It features 15 pounds of drag, which is alright, although admittedly not that high. We do need to say that the components used for the drag system here are of a very high quality. The brakes and other components are not going to break down anytime soon. No, 15 pounds of drag is not all that much, but still more than ideal to catch some decent size fish with.

It’s enough to ensure that smaller and medium size fish can’t pull out your line very much, but it’s probably not ideal for very large and heavy fish that are going to put up a massive fight.

If any fish applies more than 15 pounds of force opposing the line, the drag system here will not do too much, so don’t use this reel for very large fish, as it probably won’t be able to hold the line without having it shoot back out into the water along with the fish.

Gear Ratio & Line Retrieval

Now, we do have to say that it is pretty average. The gear ratio here, at 4.8:1, is not huge, but also not small. It is pretty average for this kind of spinning reel, but more than good enough for slow and medium retrieval, and to reel in some pretty decent sized fish with ok speed.

With this kind of gear ratio, you can reel in 30 inches of line per handle crank. Not, it won’t reel your line in super-fast, at least not as fast as reels with a 7:1 or 6:1 line ratio, but it will do just fine for medium and slow retrievals.

It’s a good choice for medium size fighting fish that need to be worn out a bit before you can finally net them. Just so you know, this reel features a 6 BB + 1 RB system to ensure steady and reliable line retrieval.

Varispeed Technology & Dyna-Balance

One of the best aspects of the Shimano 4000 ci4 is that it comes with Varispeed technology. This Varispeed tech helps to ensure consistent spool speeds both during casting and retrieval. This makes for easy casting without too much tangling and kickback, plus it allows for smooth reeling too.

At the same time, the Dyna-Balance system included here is very useful for counteracting any wobble in the crank and reel when you are retrieving your line. In other words, this helps to counter-balance the rotor in order to enhance smoothness both during casting and retrieval. We do have to say that we absolutely love both of these features.

Line Capacity

This reel does have fairly high line capacity, although not insanely high. It should be more than good enough for most basic fishing needs, especially when it comes to offshore saltwater fishing. The 4000 ci4 can handle 240 yards of 8 pound test monofilament line, 200 yards of 10 pound mono line, or 160 yards of 12 pound test mono line.

In terms of using PowerPro line, it can handle 270 yards of 15 pound line, 190 yards of 20 pound line, or 145 yards of 40 pound line. As you can see, this thing does have a fairly decent fishing line capacity. What is also neat here is that this saltwater spinning reel comes with a nice outer rim in order to ensure that your line stays exactly where it is supposed to be.

A PLM System

A really nice feature that we need to mention is the propulsion line management (PLM) system. We are not going to get into exactly how this feature functions, as it is a little complicated.

However, what you need to know here is that this propulsion line management system helps to prevent backlash and it helps stop wind knots from forming in the line too. This is quite important when it comes to sea fishing, as strong winds can definitely cause your fishing line to tangle.

Durability & Saltwater Use

This reel has a very high level of durability. All of the components used in the construction are of a high quality. The reel itself is made of C14 carbon fiber, which is excellent as far as we are concerned. This stuff is about as tough and durable as can be.

It is rated as being up to 20% stronger than graphite. In terms of sea fishing and going for some large fish, this is undoubtedly very important.

On that same note, this carbon fiber is totally impervious to rusting and corrosion, another very important factor for anything to do with saltwater fishing. We do have to say that we are quite impressed at how durable this saltwater spinning reel manages to be.


The final aspect of the Shimano 4000 ci4 that we want to mention has to do with its weight. Yes, the carbon fiber used here is very durable, as are the other components.

However, just because this thing is tough does not mean that it has to be heavy. This thing weighs barely more than 1 pound, making it quite a lightweight spinning reel. Having a lightweight reel is beneficial because it helps stop fatigue.


  • Superior durability.
  • Very lightweight.
  • Helps prevent line knotting and backlash.
  • Special system to stop wobble.
  • Decent gear ratio and retrieval rate for slow and medium retrievals.
  • Drag system that is ideal for small and medium fish.
  • Great for saltwater purposes.


  • Should still be washed with fresh water after use.
  • Not ideal for very high speed retrievals.
  • Not great for catching super large fish.

You can check the current price on Amazon here

An Alternative

If you are looking for some alternatives to the 4000 Ci4 then we would probably suggest the Shimano Ultegra CI4+ spinning reel.

The 4000 Ci4 is good for medium fish, medium line, and medium retrieval rates, so really just an all-around average, yet highly functional spinning reel. The Shimano Ultegra CI4+ spinning reel is basically its older cousin.

Now, one thing to note right off the bat is that the Ultegra actually has a lower gear ratio than the Thunnus, but it actually retrieves more line per crank, over 40 inches of it to be exact.

Although this spinning reel is not quite as adept for saltwater fishing as the Thunnus, it does have the advantage of having a much rated drag system, 44 pounds of drag, so close to 3 times that of the Thunnus.

In terms of line capacity, the Ultegra can hold on average 3 times more line than the Thunnis, making it ideal for super deep water fishing and really long casts.
With that being said, the Ultegra does not appear to be as rugged or durable as the Thunnus, but at the end of the day, both are nice options to keep in mind.

Related: Shimano spinning reel maintenance guide.


Overall we like the himano Thunnus 4000 ci4. It may have a couple of minor drawbacks, ones that we really don’t take too seriously mind you, but all in all, it appears to be a very nice saltwater spinning reel. It’s good for slow and medium retrieval speeds, it has an OK drag system, it prevents wobbling and backlash, it’s lightweight, and features superior durability too.