Graco Nautilus SnugLock LX Review

Car Seat Techs have a certain lingo that may be incomprehensible to the non-tech crowd, and this incudes nicknames for different car seats.

The Graco Nautilus is a staple of tech-recommended lists in its category, and we affectionately refer to it as the “Nauti.” Cue the joke here about how I’m a Nauti girl. Because I am. I loved this car seat even before I had one of my own.

And what, exactly, is the Nauti’s category?

Officially, it falls into the “combination seat” category, but many caregivers may know it as a “harness-to-booster” seat (sometimes called a “harnessed booster,” which is a bit of a misnomer that I discourage).

In plain terms, the Graco Nautilus SnugLock LX is a forward-facing, harnessed car seat that can be converted into a high-back booster and then into a backless booster. You will sometimes see it referred to as a “3-in-1” seat, with that “3” representing the aforementioned trio of modes.

And who, exactly, might use a Nauti?

You might be wondering if every kid will at some point need to use a combination seat like the Graco Nautilus. The answer is … it depends on the kid and the family.

As you know, children begin their car seat journey rear-facing. The Graco Nautilus does not rear face, and it is therefore not suitable for infants or young toddlers. The Nautilus is not the next seat following the bucket seat; it’s going to come into play either when a child’s convertible car seat is no longer meeting their needs or when a younger sibling needs to be moved into the convertible seat.

Remember that car seating best practice is to rear-face children as long as possible, until they hit the rear-facing maximum for their convertible car seat. While no provincial law stipulates this, as a strict minimum, children should not be switched to forward-facing mode until age 2.

You may be interested in the Graco Nautilus because you have an older child whose convertible car seat can now be passed onto a younger sibling, and it makes financial sense to get the older child a harnessed seat that will convert into a booster seat down the road.

Another reason you might be in the market for the Nautilus is that your child is already forward-facing, or ready to forward-face, but their current seat isn’t suitable. For example, some convertible seats on the market have a very low harness height, meaning a child outgrows their harness long before they’re mature enough or heavy enough to move to the booster stage. The Graco Nautilus could be a solution for this scenario since it has an 18″ (45 cm) top harness height which is typically plenty to keep a child harnessed until they are booster ready.

Alternatively, some convertible seats don’t install well in forward-facing mode once children reach the weight requiring a seat belt installation, and many caregivers don’t know this prior to purchase. Being a very versatile seat with an exceptionally easy seat belt install, the Nauti could be a great replacement seat in this scenario.

What I will say is, if your child still fits their convertible car seat in forward-facing mode, you don’t need to upgrade them to the Nautilus; it makes more sense to move them into a dedicated booster when they’re ready.

And why, exactly, is the Nauti SnugLock on my Nice List?

1. It performs well in all 3 modes

When it comes to recommending a combination seat for a family, there are very few that are even worth considering, in my humble opinion. This is because a family looking to buy a combination seat is typically looking to buy the last seat their child will ever need. Therefore, not only does the seat need to perform well in harness mode, it also needs to work effectively as a booster, and the Nauti delivers in all three modes:

  • High enough top harness height (18″/45 cm) to keep the majority of children harnessed until booster readiness.
  • High enough shoulder belt guide to keep the majority of children in high-back mode until ready for backless mode.
  • Good belt fit in both high back and backless booster mode.
  • 10-year expiry to get the most usage out of all modes.

Unfortunately many seats that convert into booster seats do not make great booster seats, either from an ease-of-use standpoint (parents want boosters that their kids can buckle themselves into without help) or from a safety standpoint (once converted to a booster, the seat doesn’t provide a reliably safe belt fit). Fortunately, that’s not the case with the Nauti.

2. It is exceptionally easy to install

The SnugLock panel makes seat belt installation a breeze.

The Graco Nautilus SnugLock LX is an upgrade from the regular (non-SnugLock) Nautilus in that it features a super easy seat belt installation thanks to the SnugLock Panel.

Remember that at some point, almost every car seat requires a seat belt installation. The majority of auto manufacturers stipulate a maximum weight of 65 lb (29.5 kg) for their vehicles’ lower anchors (total weight of the car seat and the child), so by the time a child weighs anywhere from about 35–45 lb (16–20 kg), depending on the weight of the car seat they are using, they will need their seat installed with the vehicle seat belt and not the lower anchors.

A seat belt installation is, of course, an equally safe car seat installation method when done properly. Doing a seat belt installation properly can, however, be tricky given the sheer variety of seat belt and buckle positions and how they interact with a car seat.

A secure seat belt installation requires tightening the seat belt and locking it, making sure that the car seat does not move more than an inch from side to side or front to back once the installation is complete. Properly tightening and locking the vehicle seat belt can require a great deal of sweat, and the SnugLock panel eliminates this entirely.

Overview of forward-facing, harnessed mode

Fit to child:

  • Child height range: 27″–49″ (69–125 cm)
  • Child weight range: 22–65 lb (10–30 kg)
  • Harness height: 12″–18″ (30.5–46 cm)

The Nautilus SnugLock comes with a bum cushion, crotch buckle cover and harness pads. The bum cushion must be used if the child’s shoulders are below the lowest harness setting (which would only be the case if the child has a torso less than 12″ or 30 cm). The crotch pad and harness pads are optional, my daughter doesn’t like them so we’ve removed them.

My daughter just turned 5 and is 42″ (107 cm) tall and weighs 37 lb (16.8 kg). She was rear-facing until she turned 4 last summer, and before testing the Nautilus for me, she was using our Baby Jogger City View.

She has no complaints about the comfort of the seat. She has tons of room before she outgrows the harness, which is good since she is still 7″ (18 cm) below the standing height maximum. (Believe it or not, some seats with the same standing height maximum do not have enough harness height to actually accommodate children that are that tall.)

As you raise the headrest of the Nautilus to expose more harness, there is some exposed plastic that is not covered by the seat padding. This hasn’t bothered my daughter, but I would definitely advise caregivers with children who are sensitive to how things feel against their bodies to test this aspect of the seat to make sure it’s not a problem.

The big head wings on this seat make it comfortable for car naps, of which Miss Cub took many on our 13-hour drives to and from Vancouver. Although there were lots of “are we there yet”-style complaints, no complaints were filed about the comfort of her car seat.


Because the seat belt installation of the Nautilus SnugLock is so easy and efficient, caregivers need not worry about switching over to the seat belt once their child reaches 45 lb (20 kg), the maximum weight for lower anchor use for the Nautilus. Simply install it with the seat belt from day one, as I have with my 37-lb daughter. (If you’d like an overview of the lower anchor installation, you’ll find that in CSFTL’s review.)

Here is an installation video I made:

The Nautilus SnugLock has four recline settings. The base of the car seat needs to sit as flat as possible on the vehicle seat, and using this recline mechanism can help with this. Both in the captain’s seat and the back row of my 2014 Odyssey, I install the seat at its most upright.

I also installed the Nautilus in my brother’s 2013 Mazda 3 and my parents’ 2010 Mitsubishi Outlander without issue.

In my parents’ 2010 Outlander

Overview of high-back booster mode:

Fit to child:

  • Child height range: 43”–57″ (110–145 cm)
  • Child weight range: 40–100 lb (18–45 kg)
  • Maximum belt guide height: 19.5″ (49.5 cm)
  • Minimum age 4 (but let’s definitely aim for over 5)

My son is turning 8 in September and has been riding in a high-back booster since he was 5-and-a-half. He is an eager participant in my booster testing because he now earns $5 for his efforts. He is 57 lb (25.8 kg) and 52″ (132 cm).

Cub needs the headrest on the Nautilus at its highest height to get a good shoulder belt fit, which is also the case for the dedicated booster he uses regularly. I like to see kids use the back on their booster until they’ve outgrown it. The backrest helps a child maintain a proper seated position and also provides a place to rest their head if they fall asleep.

Overall, the belt fit on my son is good. The lap belt sits low on his hips and the shoulder belt is centred between his neck and shoulder. My son says the seat is perfectly comfortable and doesn’t have any complaints. The seat itself is a bit taller than his regular booster so he has to work a bit harder to buckle himself, but has gotten the hang of it with practice.


Transforming the Nautilus into a booster is easy breezy and clearly detailed in the manual.

I love that there’s a storage compartment for everything. The crotch buckle tucks into its own little hidey hole and the chest clip and crotch buckle tongues have their own little closet.

You can use the seat’s lower anchors and top tether to secure the booster to the vehicle if you choose and if the seating position and vehicle manufacturer allows it. This is just to keep the booster in place when the child gets in and out and to prevent it from becoming a projectile when unoccupied.

UAS anchors are stored in a compartment on the back of the seat.

Note that as per the manual, the vehicle headrest must not create a gap between the back of the booster seat and the vehicle seat, and the booster seat must not overhang the vehicle seat. (There are great diagrams in the manual to help you understand this!) Before removing your vehicle’s headrest to accommodate a car seat, always ensure it is permitted as per your vehicle owner’s manual.

Overview of backless booster mode

Fit to child:

  • Child height range: 43″–57″ (110–145 cm)
  • Child weight range: 40–120 lb (18–54 kg)
  • Minimum age 4 (but let’s definitely aim for over 5 and, ideally, keep the back portion on until it is outgrown)
Using the seat with armrests.

My son still uses the back portion on his booster seat because it still fits him, but he tests out backless boosters for me on short rides. As he so keenly observed (as if his mother is a car seat tech), riding without a back on his booster means he wouldn’t be as comfortable if he fell asleep.

Here he is using the seat without the armrests.


Removing the back from the Nautilus is quick and painless, you unthread the harness and there’s a convenient spot to put the harness splitter plate. Note that in backless booster mode, you cannot secure the seat to the vehicle using the UAS, as the UAS is attached to the backrest.

Storage compartment for buckle and harness splitter plate, found under the seat cover.

You can remove the armrests on the Nautilus in backless mode to create a bit of a wider seat pan for a growing child. We tried it both ways, but I didn’t think removing them made that much of a difference and my son didn’t notice at all.

There are some gaps in the seat pan once you remove the backrest that look to me like the seat might be uncomfortable for little bums. My son didn’t seem to care about it, but I did notice he still needed reminders to get his bum all the way to the back of the seat.

Like the majority of backless booster seats, the Nautilus comes with a seat belt guide that you may need to use if the shoulder belt doesn’t sit centred between the shoulder and the neck without it. In the back row of our Odyssey, I was happy with the belt fit without the guide, but I recommend keeping it attached to your booster just in case it’s needed if you move to a different vehicle. (Also remember to keep it somewhere safe when you’re still using the seat in harness mode, so it doesn’t get lost!)

Important considerations

The Nautilus doesn’t have the highest harness height or standing height maximums on the market, so for very tall children who need a harness, it won’t be the right choice. (However, the majority of children will easily fit the harness until booster readiness.)

The Nautilus is fairly wide, so it won’t be a good option for three-across scenarios.

Some children may not like the exposed plastic of the backrest as the headrest is moved up or on the seat pan when the backrest is removed.

If for any reason you won’t be installing the Nautilus using the seat belt, opt for the less expensive, non-SnugLock version.


Not every child’s car seat journey requires a combination seat, but when it does, the Graco Nautilus SnugLock is one of my top recommendations because it is easy to install, it will keep the majority of children harnessed until booster readiness and it provides a safe belt fit in both high-back and backless booster modes.

Buy the Nautilus SnugLock on Amazon.ca or Amazon.com.

One response to “Graco Nautilus SnugLock LX Review”

  1. […] I don’t have a model to test the 4Ever in high-back mode, but having worked with the Graco Nautilus, which is very similarly designed, I have no big concerns about this seat as a high-back […]

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Welcome to my Wolf Pack!

My name is Lindsay and I am a 40-year-old mama of four trying to live an eco-friendly, budget-friendly life! I am a substitute teacher and Child Passenger Safety technician in Calgary, Alberta. Join me on my adventures!

Wildcard SSL Certificates