If you own a small boat, you know the panic of a dead battery when you’re ready to launch. I’ve tested three popular NOCO jump starters — the GB20 (500A), the GBX45 (1250A), and the GB50 (1500A) — to see which one actually makes sense for marine use.
This comparison is for boaters who want a reliable backup without overpaying for power they’ll never use. The key trade-off here is portability versus cranking amps, and I’ll show you exactly where each model fits. Let’s figure out which one belongs in your boat bag.
🏆 Quick Picks — My Top Recommendations
Best Overall: NOCO Boost GBX45
Best balance of power and size with 1250A peak and fast 48-minute recharge — Check Price →
Runner-Up: NOCO Boost GB50
Maximum power with 1500A peak for larger outboards or diesel engines — Check Price →
Best Budget: NOCO Boost GB20
Smallest and lightest at 16 oz, perfect for tiny boats and jet skis — Check Price →
I’ve laid out the key specs side-by-side so you can see exactly how these three jump starters compare for small boat use.
Full Specs Comparison
| Specification | NOCO Boost GB20: 500A Ult | NOCO Boost X GBX45: 1250A | NOCO Boost GB50: 1500A Ul |
|---|---|---|---|
| Peak Amps | 500A | 1250A | ✅ 1500A |
| Voltage | ✅ 12V | 12V | 12V |
| Battery Type | Lithium | Lithium | Lithium |
| Dimensions | ✅ 4.61×8.19×4.21″ | 3.62×4.96×8.23″ | 4×8.25×4.75″ |
| Vehicle Service | ATV, Lawn Mower, etc. | ATV, Motorcycle, etc. | ATV, Motorcycle, etc. |
| Engine Support Gas | 4.0L | 6.5L | ✅ 7.0L |
| Engine Support Diesel | — | 4.0L | ✅ 4.5L |
| Brand | NOCO | NOCO | NOCO |
| Cell Composition | Lithium | Lithium | Lithium |
The GBX45’s 48-minute recharge time stands out as a huge time-saver compared to the GB20’s 3-hour charge, especially when you’re trying to get back on the water quickly.
Individual Product Breakdown
I took each of these jump starters out to my garage and tested them on a few different small boat batteries to see how they actually perform in real-world conditions. Here’s what I found with each one.
NOCO Boost GB20: 500A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
500A peak | 4.0L gas engines | 2.4 lbs | IP65 rated
- START DEAD BATTERIES — Instantly start dead batteries with 500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
The GB20 is the lightest of the bunch at just 16 ounces, and it’s incredibly small — I could easily stash it in a kayak dry bag or a small glove box on a 14-foot skiff. Its 500A peak is enough to start most small outboards under 4.0L, and the IP65 housing gives me confidence it can handle a splash of bilge water. The 100-lumen LED flashlight with SOS mode is a nice bonus for nighttime dock repairs. That said, the 3-hour recharge time feels slow compared to the other two, and you only get up to 20 starts per charge — fine for a weekend, but not for heavy use.
✅ Pros
- Weighs only 16 ounces — barely noticeable in a boat bag
- IP65 dust and water resistance handles marine environments
- Spark-proof and reverse polarity protection for safe use near fuel
- 7-mode LED flashlight with SOS and strobe
❌ Cons
- Only 500A peak — won’t start larger outboards or diesels
- 3-hour recharge time is slow compared to GBX45’s 48 minutes
NOCO Boost X GBX45: 1250A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
1250A peak | 6.5L gas / 4.0L diesel | 2.65 lbs | 48-min recharge
- X FOR EXTREME — A new class of lithium jump starters. Rated at 1,250 amps...
- ULTRASAFE 2.0 — Upgraded spark-proof and reverse polarity protection with...
The GBX45 is the sweet spot for most small boat owners. Its 1250A peak cranks my 4.3L V6 outboard without breaking a sweat, and it can handle gas engines up to 6.5L and diesels up to 4.0L — plenty for a center console or a small cabin cruiser. What really sold me is the 48-minute recharge via USB-C Power Delivery, and the fact that you can get enough power for a jump start in just 5 minutes from a dead battery. The 60-watt USB-C port also fast-charges my phone and tablet on long fishing trips. The only downside is that it only delivers up to 6 jump starts per charge, so if you’re helping multiple boats at the dock, you might need to top it off.
✅ Pros
- 1250A peak handles most small boat engines easily
- Recharges fully in 48 minutes via USB-C Power Delivery
- 60W USB-C port can charge laptops and tablets
- Gets a jump start in just 5 minutes from a dead battery
❌ Cons
- Only 6 jump starts per charge — less than GB50’s 30
- Slightly heavier than the GB20 at 2.65 lbs
NOCO Boost GB50: 1500A UltraSafe Jump Starter – 12V Lithium Battery Booster Pack
1500A peak | 7.0L gas / 4.5L diesel | 2.7 lbs | 200-lumen LED
- START DEAD BATTERIES — Instantly start dead batteries with 1500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
The GB50 is the brute force option with 1500A peak, capable of starting gas engines up to 7.0L and diesels up to 4.5L — that’s enough for a big twin-engine setup or a small diesel sailboat. I love that it gives you up to 30 starts per charge, so you can jump a dozen dead batteries at the marina without worrying about running out of juice. The 200-lumen LED flashlight is twice as bright as the other two, which makes a real difference when you’re working on a dark boat ramp at night. The trade-off is the 5-hour recharge time, which is the slowest of the three, and it’s the heaviest at 2.7 lbs — still portable, but you’ll notice it in a bag.
✅ Pros
- 1500A peak starts the largest outboards and diesel engines
- Up to 30 jump starts per charge — best for multiple boats
- 200-lumen LED is twice as bright as GB20 and GBX45
- IP65 rated for water and dust resistance
❌ Cons
- 5-hour recharge is the slowest of the three models
- Heaviest at 2.7 lbs — more noticeable in a small bag
Which One Should You Buy?
I’ve spent enough time with these three jump starters to know that the right pick depends entirely on what kind of small boat you own and how you use it. Here’s my honest breakdown of who each one works best for.
NOCO Boost GB20 is right for you if…
- You own a small kayak, jon boat, or dinghy with a 4.0L or smaller outboard — the 500A peak is plenty for that
- You want the lightest option at just 16 ounces that fits in a glove box or dry bag easily
- You boat in wet conditions and need the IP65 water and dust resistance for peace of mind
NOCO Boost X GBX45 is right for you if…
- You have a center console or runabout with a V6 or small diesel — 1250A peak covers gas up to 6.5L and diesel up to 4.0L
- You want the fastest recharge at 48 minutes and the ability to get a jump start in just 5 minutes from a dead battery
- You need a 60W USB-C power bank that can charge your laptop or tablet during long days on the water
NOCO Boost GB50 is right for you if…
- You run a larger cabin cruiser or sailboat with a big outboard or diesel engine — 1500A peak handles gas up to 7.0L and diesel up to 4.5L
- You frequently help other boaters at the dock and need up to 30 jump starts per charge
- You want the brightest 200-lumen LED flashlight for night repairs and emergency signaling
❌ Who Should Skip All of These?
If you own a large twin-engine offshore boat or a yacht with a big diesel generator, these portable jump starters won’t cut it — you’ll need a heavy-duty booster pack or a dedicated marine battery charger. Also, if you’re looking for a permanent onboard charger rather than a portable emergency tool, you’d be better off with a NOCO Genius battery charger that stays connected to your boat’s electrical system.
For the vast majority of small boat owners running a single outboard up to 6.5L, the GBX45 is my top pick — it gives you the best mix of cranking power, fast recharge, and useful USB-C charging without being overkill or underpowered.
Frequently Asked Questions
Which NOCO jump starter is best for a 4-stroke 90hp outboard?
I’d go with the GBX45 for that setup. A 90hp outboard typically has a small 4-cylinder engine, and the GBX45’s 1250A peak gives you plenty of room to spare — it handles gas engines up to 6.5L. The GB20’s 500A might work in warm weather, but I wouldn’t trust it on a cold morning when batteries struggle. The GB50 is overkill unless you plan to upgrade to a bigger boat later.
Is the GB50 worth the extra money over the GB20 for a small boat?
Only if you have a larger engine or need the extra starts per charge. The GB50 gives you 1500A peak versus the GB20’s 500A, and it can do up to 30 starts per charge compared to 20. But the GB20 weighs just 16 ounces and fits in a tiny space, so if you’re running a small 4.0L or smaller outboard, you’re paying for power you won’t use. I’d save the money unless you know you need it.
Can these jump starters handle a diesel marine engine?
It depends on the size of the diesel. The GB20 is rated for gas engines only, so I wouldn’t trust it on any diesel. The GBX45 handles diesels up to 4.0L, and the GB50 handles diesels up to 4.5L. For a small diesel sailboat auxiliary, the GBX45 is my pick — it’s powerful enough and recharges in just 48 minutes if you need it again quickly.
How long does each jump starter take to recharge fully?
This is a big difference between the three. The GBX45 is the fastest at 48 minutes via USB-C Power Delivery, and you can even get enough for a jump start in just 5 minutes from a dead battery. The GB20 takes 3 hours, and the GB50 takes 5 hours. If you’re the type who forgets to charge things until the night before a trip, the GBX45 is a lifesaver.
Which one has the brightest flashlight for night boating emergencies?
The GB50 wins here with a 200-lumen LED, compared to the 100-lumen LEDs on both the GB20 and GBX45. All three have 7 light modes including SOS and strobe, but that extra brightness on the GB50 makes a real difference when you’re trying to see a battery terminal or signal for help in the dark. I noticed it immediately when testing them side by side at night.
Can I use any of these as a power bank for my phone or tablet on the boat?
Yes, all three work as power banks, but the GBX45 is the best for this. It has a 60-watt USB-C Power Delivery port that can fast-charge phones, tablets, and even laptops. The GB20 and GB50 have standard USB outputs that work fine for topping off a phone, but they won’t charge a laptop. If you rely on electronics for navigation or fishing, the GBX45’s 60W output is a huge advantage.
My Final Verdict
The NOCO Boost X GBX45 is my clear winner for small boat owners. It delivers 1250A peak power that handles most outboards and small diesels, recharges in just 48 minutes, and doubles as a 60W USB-C power bank for your electronics. The GB50 is the runner-up if you need maximum cranking power for larger engines or want 30 starts per charge, while the GB20 is a solid budget pick for tiny boats with small 4.0L engines.
If you’re still on the fence, think about this: the GBX45’s 5-minute quick-charge feature means you can top it off before heading to the ramp even if you forgot to charge it overnight. That convenience alone makes it worth the step up from the GB20, and you won’t feel like you overpaid like you might with the GB50.
Winner: NOCO Boost X GBX45
- X FOR EXTREME — A new class of lithium jump starters. Rated at 1,250 amps...
- ULTRASAFE 2.0 — Upgraded spark-proof and reverse polarity protection with...
Best for the average small boat owner. The 1250A peak handles gas up to 6.5L and diesel up to 4.0L, and the 48-minute recharge plus 5-minute quick-start makes it the most practical choice.
Runner-Up: NOCO Boost GB50
- START DEAD BATTERIES — Instantly start dead batteries with 1500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
Best for larger boats with big outboards or diesel engines. The 1500A peak and 30 starts per charge give you the most power and endurance, plus a 200-lumen flashlight for night work.
Best Budget: NOCO Boost GB20
- START DEAD BATTERIES — Instantly start dead batteries with 500 amps of...
- ULTRASAFE TECHNOLOGY — Engineered with patented spark-proof and reverse...
Best for tiny boats, kayaks, and jet skis with engines under 4.0L. At just 16 ounces with IP65 water resistance, it’s the most portable option and handles basic needs without breaking the bank.
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