Sikaflex

Sikaflex is the marine industry’s standard name in polyurethane adhesives and sealants, used for everything from bedding deck hardware to bonding structural joints below decks. We stock the core marine grades for both general bonding/sealing and higher-strength structural use.

The main choice within the range is flexibility versus strength. A general-purpose adhesive/sealant grade suits bedding deck fittings, portlights and hardware where some movement between materials is normal and a rigid bond would eventually crack. A higher-strength structural grade is formulated for permanent bonding – such as hull-to-deck joints or structural panels – where holding power matters more than flexibility.

For below-the-waterline use, always check the specific product is rated for permanent water immersion, since not every Sikaflex grade is. Surface prep matters as much as the product itself: clean, dry and correctly primed surfaces (where the product calls for a primer) make the difference between a joint that lasts years and one that fails within a season. Mask off cleanly before application – cured polyurethane sealant is very difficult to remove from gel coat without damaging the surface.

Frequently asked questions

Which Sikaflex grade should I use for deck hardware?

A general-purpose marine adhesive/sealant grade is right for most deck fittings, where some flexibility between the fitting and the deck is expected.

Can I use Sikaflex below the waterline?

Only a grade specifically rated for permanent water immersion – check the product data sheet before using any polyurethane sealant below the waterline.

How do I remove excess Sikaflex before it cures?

Wipe it away immediately with the solvent/cleaner recommended for that product – once cured, polyurethane sealant is very difficult to remove without risking damage to gel coat.