3M 5200 Marine Sealant – Black, 10 oz. Cartridge
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You have 30 days to request a return. All sale items are final sale.
3M 5200 Marine Sealant – Black, 10 oz. Cartridge
3M 5200 is the gold standard for permanent marine bonding and sealing. This one-part polyurethane formula creates an incredibly strong, watertight bond that stays flexible for the life of the boat — trusted by boatbuilders and serious boaters for hull-to-deck joints, through-hull fittings, and any structural application where the seal must never fail. The black finish is the natural choice for dark hulls, teak surrounds, and below-waterline applications where color matching matters. The 10 oz. cartridge format is ideal for larger installations and production work.
Key Features
- One-part polyurethane — no mixing required
- Extremely strong permanent bond above and below the waterline
- Workable up to 4 hours after application
- Tack-free in 48 hours; fully cures in 5–7 days with no shrinkage
- Stays flexible — will not sag or flow in vertical or horizontal seams
- Bonds fiberglass-to-fiberglass, fiberglass-to-wood, and more
- 10 oz. cartridge — requires a standard caulking gun
Compatible Applications
- Hull-to-deck joints and structural bonding on dark or black-hulled fiberglass boats
- Through-hull fittings and keel bolt bedding
- Permanent bonding of deck hardware on dark or teak-trimmed decks
- Below-waterline sealing where maximum strength and a black finish are required
- Fiberglass-to-fiberglass and fiberglass-to-wood structural seams
Parts Desk Insights
Best Use Case: 3M 5200 Black in the cartridge format is the right choice for large structural jobs on dark hulls — hull-to-deck joints, keel bolts, and through-hulls where a black bead is preferred and the bond needs to be permanent. Important: because 5200 bonds so aggressively, it is not recommended for deck hardware you may ever need to remove. For smaller black sealant jobs without a caulking gun, see the 3M 5200 Marine Sealant – Black, 3 oz. Tube (71-05205). For white hull and deck applications, see the 3M 5200 Marine Sealant – White, 3 oz. Tube or the 3M 5200 Marine Sealant – White Cartridge (06500). For hardware that requires future serviceability, the BoatLIFE LifeSeal – Black or BoatLIFE Life-Calk are strong but more workable alternatives. For finishing the bead, the Star Brite Caulk Rite Finishing Tool delivers a clean edge.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.