Boat Project Checklist Before Spring Launch Season!
Spring always arrives faster than the calendar suggests. If your boat has areas that need attention - hairline cracks, bumps and dents, a soft spot in the deck, a loose trim piece, a “mystery leak,” or old filler repairs - winter is the best time to tackle the jobs that will save you time (and nerves) when the season starts.
Start with a quick condition check
Do a fast inspection and mark the spots you’ll come back to with masking tape:
- Cracks and dents (is the gelcoat/laminate damaged, or is it only a surface scratch?)
- Soft areas in the deck/hull (the core material may be wet or damaged)
- Through-hulls and fittings (are they moving? any leak marks or moisture trails?)
- Inner laminate (is an old repair coming loose? signs of delamination?)
Once you know what you’re repairing, you’ll also know what materials to choose.
Epoxy or Polyester resin?
Many fiberglass boat repairs can be done with either epoxy or polyester resin, but the workflow and reinforcements are different.
Epoxy repairs are typically the “strong and reliable” route
- With epoxy, laminating is done with fiberglass cloth or multiaxial fabric—not chopped strand mat, because standard mat is generally not compatible with epoxy systems.
- A great choice when you want better water resistance, strength, adhesion, and a long-lasting repair.
- See detailed instructions here
Polyester repairs are a fast, familiar “classic” option
- With polyester resin, guidance often starts from doing the structural laminate from the inside when possible, using chopped strand mat and also fiberglass cloth when needed.
- The repaired surface is typically finished with a topcoat.
- See detailed instructions here
Boat Project Checklist
How to choose the right resin
The most important choice in boat repairs is the resin: epoxy or polyester.
Epoxy is often the “strong and reliable” option because it bonds very well, typically shrinks less, and makes it easier to achieve a structurally durable patch or bond. However, epoxy is not compatible with gelcoat/topcoat finishing. If you choose an epoxy repair, the surface is not finished with topcoat—instead it’s typically finished with an epoxy primer/epoxy paint and a 2K polyurethane topcoat (or another coating system that is compatible with epoxy).
Epoxy also comes with a few practical essentials: it requires an accurate mixing ratio, the working time depends on the hardener, and some epoxy systems can form a surface film (amine blush) that should be washed/sanded before applying additional layers or paint. Peel ply (release fabric) helps a lot here by leaving a clean, ready-to-bond surface.
Polyester resin is the traditional “classic repair path” when you want a gelcoat/topcoat-style finish. Polyester laminating is usually done with chopped strand mat, and the surface is finished with topcoat, which cures “tack-free” in air—when you remember the catalyst/hardener. Polyester is often quick and familiar, but in practice it has a stronger odor, typically shrinks more, and can be a bit “harder/more brittle” than epoxy. That’s why it’s especially well suited for surface repairs and gelcoat/topcoat-type finishing work.
In short:
- For strength and reliable adhesion → epoxy + fiberglass cloth/multiaxial + epoxy-compatible paint system
- For a classic gelcoat/topcoat finish → polyester + chopped strand mat + topcoat
How to choose the right reinforcement (fiberglass)
Your resin choice also determines the reinforcement.
With epoxy you typically use twill fiberglass cloth or multiaxial fabric, while with polyester the standard choice is chopped strand mat. For epoxy work, a good general-purpose option is EPOKSI AMPRO and for clearer laminating EPOKSI AMPRO 115 works well. On the polyester side, a solid basic setup is POLYESTER RESIN AROPOL M 105 TB with MEK-50 HARDENER.
How to choose the right fillers
Fillers let you turn the same resin into the exact “mix” your project needs.
Microballoons make a lightweight, easy-to-sand fairing compound. Silica (fumed silica) makes the mix non-sag and firm, which helps on vertical surfaces and shaping. Cellulose fibers add toughness and structural strength for more “glue-like” mixes. When you need a particularly strong fill, fiberglass powder increases the load-bearing strength of the compound.
Tools and safety
When working with resins and sanding, safety affects both the result and your wellbeing. Always ensure good ventilation and use proper respiratory protection (Half Mask EN405). Wear nitrile gloves and protect your skin - especially with epoxy, because repeated skin contact can lead to sensitization!
Make spring repairs easier
To avoid delays later, get the essentials early: resin + reinforcement + protective gear + basic tools. That way you can start repairs as soon as conditions allow—without waiting for “one missing material.”