Category Archives: Marine Epoxy

Aluminum Hull Repairs and More

jonboatHow to Fix a Leaking Seam or Rivet on Aluminum Boat

As aluminum boats age they show various signs of wear and tear. One of these signs may be a leaking seam or rivet. Over time, rivets can stretched and loosen, causing a gap in the hull integrity and this results in a leak. The solution to this problem is fairly simple and may be fixed at home using just a few tools and know-how. So, how should this problem be addressed?

Locate the Leaking Rivet or Seam

The first step is to find the exact seam or rivet that needs repair. To do this, put the boat in water and observe carefully. You could also put water inside the boat and see where it allows the water to escape from.

Assess the Damage

The second step is assessing the extent of damage to the rivet or seam. If the seam is too wide to be filled or caulked, it will need additional rivets in combination with a sealant product. If the damage is easily visible a sealant or caulk will be sufficient.

Choose a Sealant or Epoxy Product

There are hundreds of products out there that claim to fix leaks and seal cracks. How do you know which to choose? The Bottom Paint Store has done most of the hard work for you and can confidently recommend 3 products that really work.

Hawk Epoxy KitHawk Epoxy is an excellent product to repair aluminum hulls. We recommend getting one of the Hawk Epoxy Kits that will contain everything you need for filling in the aluminum. Hawk Epoxy is a versatile product that can be used for many other application too. Everyone should own this kit!

The second is BoatLife’s LifeCalk Sealant. This sealant may take a long time to cure (1 to 3 days), but it results in a waterproof, rubber seal that will adhere to almost anything. It can also be applied underwater for emergency repairs!

The third option is G/Flex 650 Epoxy made by West System. This liquid epoxy is more flexible and versatile than regular epoxies and will adhere to almost any surface. The bond that it creates can absorb shock, vibration, expansions and contractions. It will fully cure in 24 hours. Also, West System has created a detailed and comprehensive set of instructions for a wide variety of applications. They can be found at this link and below:

G Flex Epoxy by West SystemFix leaking seams and rivets

Patch holes in aluminum hulls

Repair pitted or pin holed surfaces

If your hull is bare aluminum you can cover the entire surface with a high build epoxy primer to help seal and protect it such as Tuff Stuff. For application details see our link for application of a marine epoxy.

Now that your leaky rivets and seams have been repaired, you are ready to paint! Check out this How To Article for more information on how to paint your aluminum vessel.

 

Which Resin Should I Choose?

Choosing the right resin depends on the type of project you are tackling. Listed below are the most common types of resins are their intended uses:

General Purpose Repair Epoxy Resin Kit

Hawk Epoxy KitEvery household should own a Hawk Epoxy Kit like this. You can use it to repair anything around your home or own your boat. This kit comes with the resin, catalyst and your choice of filler. Just mix them together and you have an excellent bonding, filling, or adhesive paste.

Polyester Resin:

MARINE ResinPolyester resins are unsaturated resins that are combined with hardeners, such as MEKP.

Polyester resin is used more for fiberglass lay-up or if you’re going to finish a repair with gelcoat, as the polyester resin will bond to the gelcoat better than epoxy.

Vinyl Ester Resin:

Vinyl ester resins are formulated with a base of polyester resin strengthened with epoxy molecules (a hybrid form of polyester and epoxy) and also use peroxides, such as MEKP, for hardening. These are cheaper than epoxy resins and more expensive than polyester.

Vinyl esters are more tolerant of stretching, less likely to show stress cracking and more resistant to water penetration. Vinyl ester is the choice when improved resistance to moisture is the goal (like repairing a blistered hull).

Long term water exposure (hull or water tank) or if impact resistance is important vinyl ester is usually chosen.

Epoxy Resin:

Epoxy ResinEpoxy resins are cured with the addition of a hardener. Unlike the polyester and vinyl ester resins, cured with a small amount of catalyst, epoxy resins usually require a lot more, often 1:1 or 2:1. A epoxy resin is the most expensive of these.

Epoxy resin has the best bonding strength as it will bond dissimilar or already cured materials for strong, reliable repair work. This is the most expensive resin but offers the most in its ability to flex, prevent delamination and ease of repair work.

If doing a repair and not overlaying with gelcoat then the epoxy will perform best as it tends to act as a stronger “glue” for the patch to the surrounding surface.

 Klear Kote Epoxy Resin (Bar Top Epoxy Resin):

A Premium Commercial Grade Clear Epoxy Resin – Klear Kote Epoxy Resin is used extensively in coating surfaces and in table tops where a clear, hard and durable coating is required. Commonly seen on bar tops and restaurant tables. Easy to use 1:1 mixing ratio of resin and hardener.  Items coated with it will become permanently preserved and protected for your enjoyment throughout a lifetime. The epoxy resin will not exhibit blushing or sweat out under high humidity conditions.

Can you use water-based bottom paint over a marine epoxy primer?

Putting a water-based bottom paint  (WBP) over a solvent based primer can be done with some modified application procedures. You do NOT want to make the window, or hot coat the water based paint over the solvent based primer such as Tuff Stuff high build marine epoxy primer. If you do, it will mud crack. So instead of putting on the WBP over the Solvent Primer in the same day, you need to wait for the primer to totally cure. Then you have to sand it with 80 grit sandpaper before apply WBP. This is a lot of extra work and very difficult to sand = extremely hard surface. So the best thing to do when using a high build solvent based epoxy is to coat it with a solvent based paint. That way you skip the extra time and labor with sanding.

Application of Marine Epoxy Primer to a Boat

Marine Epoxy systems on the bottom of bare fiberglass is the best way to protect your boat against blisters. It also provides added adhesion of the bottom paint to the hull. Here are the steps that you need to take for proper application of a marine epoxy primer (barrier coat system) to the bottom of a boat.

Preparation

Clean
When painting a bare fiberglass / gel coat hull for the first time, it is extremely important that all contaminants such as grease, oil, wax, salt, or other foreign material are completed removed prior to sanding or application of a Sea Hawk System. Scrub the surface with a detergent soap and stiff bristle brush.

Sea Hawk s-80 Wax N Grease KillerA. Clean and de-wax fiberglass hull with S-80 Wax N’ Grease Killer solvent based dewax. Saturate cheeseclothrag and wipe thoroughly to remove any cleaner and contaminants. Be sure to remove any residue before it dries and change rags frequently to insure contaminants are completely removed.

OR

Sea Hawk S-90 Low VOC De-Waxing Etch & CleanerB. Apply S-90 De-Wax Etch & Cleaner with a maroon 3M Scotch-Brite® pad scrubbing thoroughly. Do not allow cleaner to dry on the surface and remove by flushing with water.Rinse entire surface with water and check for any beadingon the surface which will indicate that wax is still present. If necessary repeat step 2 again until the surface is contaminant-free. Choose your system below.

Sand and Clean
Sand to a uniformly frosty, dull looking surface with 80-100 grit (no finer) sandpaper, rewash with S-80 Wax N’ Grease Killer S-90 De-Wax Etch & Cleaner .

Apply Marine Epoxy Primer
TUFFSTUFFnewSeal the surface with 2-3 coats of Tuff Stuff Epoxy Primer. Apply the first coat of marine epoxy primer and allow the surface to dry to become tacky. Temperature and humidity affect the dry time, but you will know when to apply your next coat of marine epoxy primer once the paint film becomes “tacky”. You should be able to firmly press your thumb into the paint film and leave a thumbprint without any high build marine epoxy primer coming off the surface. You should use this method in between coats of marine epoxy primer and your first coat of bottom paint.

Tip: When applying marine epoxy primer over multiple days, it is always best to go overnight between coats of marine epoxy primer instead going overnight between the final coat of marine epoxy primer and the first coat of bottom paint. When over coating Tuff Stuff Epoxy Primer it is important to meet the required over coating times in order to achieve the best adhesion because temperature and humidity control dry times. It is hard to give exact times of cure. An easier rule in epoxies is when the coating is dry to the touch, yet still has some tack, it is ready to be over coated. However, if the coating is completely cured (after 24 hours) it needs to be thoroughly sanded with 80 grit sand paper to remove shine. If the marine epoxy primer is not sanded after full cure, bottom paint will not adhere.

Apply Bottom Paint to Marine Epoxy Primer
Apply minimum of two coats of  bottom paint. Allow 3 to 6 hours between coats and a minimum overnight dry. See the specific Technical Data Sheet for bottom paint being used. Some bottom paint may require more than 2 coats.