Best Marine Sealant for Aluminum Boats Review

Here is the truth: no matter how expensive your boat is, over time, Mother Nature will make it deteriorate. That’s just how it is: elements “eat away” at the most durable and sturdiest materials, including aluminum. This is especially true if there’s a tiny crack that’s letting water, air, dust, and pollen in. Rust can also be a factor since the boat is constantly in contact with water.

Well, that’s why we have sealants. Essentially, they serve as an extra layer of protection. They are equally good at containing gas, liquids, and keeping contaminants, dirt, and dust at bay. So, if you’ve got a lovely boat and care for it, I highly recommend getting the Best marine sealant for aluminum boats. It will definitely be money well-spent. Here are my top picks – check them out!

Best Marine Sealant for Aluminum Boats Review

1. 3M Marine Adhesive Sealant 5200

3M Marine Adhesive Sealant 5200

I want to start with one of the most popular marine sealants the market has to offer. 3M 5200 will be a safe bet for the average boat owner, as it’s very easy to use. You won’t have to mix it with anything to achieve maximum results, which is always great news. On top of that, it is very strong against weather elements, including salt, rust, dust, air, and, of course, water. Another big pro: 3M retains a strong bond during heavy shocks/vibrations.

It doesn’t matter whether you use it below or above the waterline. Now, this formula does take a while to set in. Officially, the specs indicate up to a full week for 5200 to cure. On the bright side, once it sets in, this solution is highly reliable, durable, and long-lasting. Oh, and it comes recommended by many big-time experts in the industry.

Pros and Cons
Strong protection against weathering and salt
Easily handles vibrations and shocks
Trusted by many experts in the field
Takes a bit too long to cure

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Corey Petersen
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In many ways, the 3M 5200 marine sealant is a bargain. It’s equally effective for boats, trucks, SUVs, and RVs. And, it’s the formula of choice for many pros. This solution is equally strong against pretty much all weather elements, including vibrations. The curing time is rather long, though.

2. Hy-Poxy H-450 Alumbond


Next up, we’ve got a solid putty repair kit by Hy-Poxy. The first thing that will probably catch your eye is that you get two tubes instead of one. Well, that means you’ll have to mix them. That’s right: while most brands deliver their sealants pre-mixed, with H-450, it’s up to the boat owner to combine the hardener with the resin to achieve the desired effect. This is a minor con, of course – not something you won’t be able to handle.

Another downside – this formula isn’t very efficient against extremely hot temperatures. But what about the pros, though? There are plenty: mainly, this is a US-made product, with no foreign involvement. Secondly, once it cures, H-450 can be sanded, painted, or even drilled over and won’t lose its strength. Last but not least, it is compatible with dozens of different materials and equipment. So, yes, you can use it not only on a boat.

Pros and Cons
Doesn’t lose its properties when sanded or painted over
Efficient with a long list of surfaces/materials
A 100% US-made product
Not very strong against heat

Hy-Poxy H-450 Alumbond

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Made in the States, flexible, and versatile, the Hy-Poxy repair kit is a great all-around product. It is especially effective on aluminum but can be used for other surfaces as well. Plus, H-450 doesn’t lose its qualities when painted over. But, you’ll have to mix the two tubes (resin + hardener) for it to work.

3. Dap 00694 2.8-Ounce Silicone Rubber Auto/Marine Sealant


Got a leak or crack in your boat and need a sealant to patch it up? Dap might have exactly what you need. This silicone rubber solution comes at a very reasonable price and won’t break your bank even if you’re on a very tight budget. It doesn’t only seal, but also bonds, thanks to the brick-strong water- and weather-proof formula. Dap is resistant to UV rays as well and isn’t “afraid” of the sun (which isn’t always the case with similar products).

But wait – will 2.8 ounces be enough to fix anything? The answer is yes, it will be for most repairs. So, don’t let that compact tube size fool you. Now, what I didn’t like about the tube was its cheap seal. The screw-cap isn’t at all resistant to the sealant and tends to split apart, letting the silicone dry up inside of the tube. On the bright side – this can be avoided if you’re careful.

Pros and Cons
UV-resistant: doesn’t deteriorate under sunlight
100% silicone rubber formula
Available at a very affordable price
Arrives in a cheap tube

Dap 00694 Silicone Rubber

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Dap did a great job with this silicone rubber marine sealant. It is affordable, resistant to water, UV rays, and other weather elements, and doesn’t take forever to cure. Sadly, the tube is pretty cheap and needs special care. Other than that, this is a safe bet for most boat owners.

4. Travaco Marine-Tex RM330K Gluvit Waterproof Epoxy Sealer

Travaco Marine-Tex RM330K Gluvit Waterproof Epoxy Sealer

In contrast to the previous three products, this one arrives in two cans, like any old-school sealant. And, it needs to be mixed (as you’ve probably already figured out by the picture). This is a waterproof epoxy sealer and was originally formulated for construction workers. However, since it’s pretty great at fixing aluminum surfaces, it will be a decent investment for your boat.

Durable, reliable, and with an impressive lifespan, Gluvit is very effective at filling not only minor but also pretty severe cracks. There’s a catch, though: this formula isn’t a very good pick for white surfaces, as it has a brownish color when it dries up. The solution would be to cover it with a layer of paint, but that’s gonna cost you extra.

Pros and Cons
Very strong at filling and sealing cracks/leaks
An excellent product for aluminum boats
Durable and long-lasting
Not the best choice for white surfaces

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For sealing and protecting your boat’s deck, hulls, rivets, or anything else made of aluminum, Travaco’s sealant is a must-have. You might want to buy a can of white paint, though, because Gluvit doesn’t look very pretty once it sets in.

5. TotalBoat Aluminum Boat Leak Sealer

TotalBoat Aluminum Boat Leak Sealer

This leak sealer arrives in a cartridge, with the resin and hardener pre-mixed. You won’t have to mix or clean anything up. And, the package includes two mixing tips that come as a bonus. A quick note: TotalBoat is very compact and easily fits any caulking gun. However, if you don’t have one, it will be much harder to squeeze the sealant out of that tube. Caulk guns are available for +/- 10USD – keep that in mind.

On the bright side, this solution is highly resistant to low temperatures and can be applied on your boat even when it’s pretty cold outside. Moreover, it has a long working time (more than an hour): you won’t have to constantly worry about the solution thickening before you use it properly.

Pros and Cons
Can be applied at low temperatures
Compact size: easy to fit in a caulk gun
Rather long working time
Tricky to use without a gun

TotalBoat Aluminum Boat Leak Sealer

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Looking for a leak sealer in a cartridge? TotalBoat has got you covered. Its pros include resistance to cold temps, a long working time (up to 75 minutes), and a compact size. If this is your first time using a sealer, I’d say go for TotalBoat. But, it might be hard to use without a “caulk” gun.

6. Amazing GOOP 5400040 Coat-It Waterproof Epoxy Sealer & Protector

Amazing GOOP 5400040 Coat-It Waterproof Epoxy Sealer & Protector

Alright, we’ve got another mixable epoxy sealer. So, why would you consider it over the competition? What are its standout features? Most importantly, it takes very little time to set and dry. You won’t even have to wait a full day for it to cure – only 12 hours. And, this is a pro-grade product, meaning it’s used by construction workers to fix serious cracks.

Therefore, rest assured it will be able to patch up whatever leak you’ve got in the boat. This is mostly achieved thanks to the Kevlar fibers in the formula. The only minor downside: the working time is pretty short. Officially, it’s up to 30 minutes, but, realistically, the solution starts to thicken after 10 minutes.

Pros and Cons
Pro-grade sealer: used to cure severe cracks
Sets and dries in less than 12 hours
Kevlar fiber reinforcement for extra strength
Short working time

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GOOP’s epoxy sealer is one of the best products for aluminum boats. It can coat all kinds of cracks, including big leaks. Strong, dependable, and resistant, it’s what the doc ordered. However, while it sets very quickly, the working time is also short. Yet, if you know your way around sealants, that won’t be an issue!

7. Woody Wax Kit

Woody Wax Kit

This is the only spray on today’s list; so, let’s see what it’s got in stores for us. Obviously, for a novice, it will be much easier to, well, spray the sealant instead of squeezing it out and spreading it with a brush. But that’s not even this product’s biggest selling point. As the name suggests, with Woody Wax, you’ll get a kit, not one single protectant. Say, the included wax is pretty great at breaking down corrosion and fighting water spots.

The wool pad and brush, in turn, will help you keep the boat in great shape or prepare it for the sealant. Overall, this is a great package, and all four products are incredibly useful. Unfortunately, you’ll have to pay a pretty penny for that: Woody Wax isn’t very cheap.

Pros and Cons
Four products in one package
Handles tough stains and corrosion
Spray-able wax: very easy to use
Not particularly cheap

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Should you pay a top dollar for the Woody Wax kit, or maybe you’ll be better off with a different option? Do I recommend this kit? It’s actually up to you to decide whether you like this offer or not. If you want to take proper care of the boat, this will be money well spent. You’ll have to pay a bit extra, of course.

8. Star Brite 087004 Epoxy Aluminum Putty Stick

Star Brite 087004 Epoxy Aluminum Putty Stick

The final stop for us today is Star Brite – another well-respected name when it comes to sealant products. It’s a putty stick, though – you’ll run out of it in the blink of an eye. That’s its biggest con. The pros strongly outweigh it, however. For starters, the set + cure time is short. That means you won’t have to wait for hours (or even days) before this epoxy formula finally sets in.

And one more thing: even if you apply Star Brite underwater, it will still stick and form a strong bond. Yep, this is a highly waterproof product. On top of that, it is incredibly resistant to extremely high temperatures. You can use it to patch up an engine, a manifold, or any other mechanisms/units that tend to heat up.

Pros and Cons
Incredibly short set and cure time
Forms a bond underwater
Withstands temperature extremes
Runs out quickly

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Corey Petersen
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Start Brite will be a sure pick for a wide range of customers. Although you won’t be able to fix every single leak on the boat with this one stick, the results will be quite alright. This aluminum sealant handles super-hot temps, can bond underwater, and sets in just 60 minutes!

Buyer’s Guide

Alright, now that we have familiarized ourselves with the list of the best marine sealants for aluminum boats, did you find your perfect pick? If not, don’t worry: this Buyer’s Guide was specifically written to help you with the choice. Here, I’ll share the most important factors to keep in mind when choosing a product for your boat. The formula, weather resistance, dry time, and working time – it all matters. Take a look!

The Formula

Did you know that there are three types of marine sealants out there? That’s right – here they are:

  • Silicone. This is the most common and user-friendly type. You won’t have a hard time applying it, simply because silicone is very elastic and flexible by nature. On top of that, this material is very strong against chemicals. Silicone isn’t particularly adhesive, though. So, you might have to prepare the surface before applying this sealant for it to be effective.
  • Polyurethane. In contrast to silicone, polyurethane has impressive adhesive abilities. Say, if you’ve got faulty hull fittings, rivets, or deck joints, this formula will do an excellent job of not only filling in the cracks but also keeping it all together. For aluminum boats, it is, indeed, a great choice. But, it’s not very impressive on plastic.
  • Polysulfide. Synthetic rubber has a strong presence in construction and industrial work. And, it has proven to be a reliable and flexible material for sealing. In some cases, you need to mix two different elements to create polysulfide. Or, it can arrive premixed in a can. Once cured, polysulfide creates a very strong bond.


What’s the #1 job of any sealant? To create a protective layer for the boat, of course. Now, for that coat to be effective, it needs to withstand water, chemicals/contaminants, rust, and salt. Protection against UV rays (the sun), the wind, dust, and pollen should also be a part of the deal. If I had to pick one, I’d say invest in a marine sealant that’s strong against moisture – for obvious reasons.

Set and Dry Time

For the sealant to reach its full potential, it needs some time to set and dry. Also known as “curing”, this process can take quite a while, depending on the formula. Say, some sealants require up to a full week to set. In contrast, the GOOP Coat-It epoxy sealer cures completely in 12 hours, which is a very impressive result. On average, you should give the solution at least a day or two to set unless the instructions say otherwise.

Does that mean you won’t be able to set sails while the sealant is bonding? Yes, that is true. So, plan your trips ahead.

Working Time

Next, we’ve got the working time. This term is used to describe how much time it takes before the sealant becomes too thick for you to work with it. Again, this largely depends on the formula. Some marine sealants set too quickly (like in ten minutes, or so), while others “stick around” for up to an hour, giving you more than enough room for maneuvers. Depending on the task at hand, you might have to apply quite a lot of the sealant.

In that case, the more time you’ve got before the solution loses its flexibility, the better. However, for most tasks, 10-15 minutes should suffice, especially if you know your way around the boat.


The Tube/Can

Depending on the substance, the formula, and the brand, the sealant may arrive in one of the following containers:

  • Cans. There’s nothing special about these. Cheap, easy to transport, and user-friendly – that’s the best way to describe them. Formulas found in cans usually take little time to set. To apply the sealant, all you’ll need is a brush.
  • Container sets. Some brands follow the two-container template and pack the hardener and the resin in two different cans. Yes, that means you’ll have to mix them, which can cause minor inconveniences.
  • Tubes. Just like cans, tubes are cheap and very practical. A little squeeze is all it’s gonna take to release the sealant. Sadly, since tubes are rather compact, you’ll run out of the formula sooner than you think.
  • Sprays. As the name suggests, sprayable marine sealants don’t require any brushes or separate cans for mixing. For most folks, this is the handiest option. But, again, containers/sprays only hold small volumes of the “magic formula”. Besides, they take a long time to set.
  • Cartridge. This one won’t work without a caulk gun. But if you have one, it will be like a walk in the park. Still, I find cartridges to be the less preferable containers.


You can’t overestimate the importance of marine sealants. They’re pretty great at protecting and fixing boats. The good news is – there’s no shortage of this stuff on the market, and it’s available at a very fair price. The trick is to find the product that will be an ideal match for your boat. Today, we checked out eight outstanding sealants from well-known brands.

There are no perfect formulas, however, which is why you should pay extra attention to the pros and cons. That way, it will be much easier to figure out which company offers the best bang for your buck. And to learn more about sealants, use my Buyer’s Guide: it will teach you everything there is to know. And, that’s it! I wish you fair winds, and I’ll see you next time!

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