This guide covers the adhesives, sealants and fasteners we supply to boat builders, custom builders, workboat shops and repair yards. It’s organized by where the work happens on the boat, so you can jump straight to the joint in front of you.

Jump to: Stringers and bulkheads Drums, pails or SmartPak Deck‑to‑hull and 5200 alternative Marine sealants StarBoard bonding Laminating and fairing Spray adhesives Fasteners How to plan a bond FAQ

Which Marine Adhesive Goes Where

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Stringer, Bulkhead and Liner Bonding with Gap-Filling MMA

Stringers, bulkheads and liners rarely fit tight. A laid-up hull leaves gaps that change along the length of the part, so the adhesive has to fill them, hold on vertical faces, and stay open long enough to set a large part. Methacrylate (MMA) structural adhesives were built for this work.

All three lines below fill large gaps. Pick by working time first: how long your crew needs to dispense the full bead, place the part and set fixtures at your shop temperature.

All times at about 75°F (24°C). Plexus values from current ITW TDS, with fixture listed as time to 50 psi. SciGrip values from the SG230HV TDS, with fixture listed as time to 70% of ultimate lap shear. UltraLok values from Chem-Set TDS. Fixture definitions differ by manufacturer, so compare within a line. Typical values, not for specification. On a phone, swipe the table left to see every column.

	Plexus MA530, MA560-1 and MA590 1:1 | Gray when mixed | Gap fill to 0.7, 1.0 and 1.5 in ITW designed these three for large structures, and says MA560-1 and MA590 are commonly used to bond stringers and liners into large fiberglass boats. ITW also lists them for deck to hull mating, hard tops, swim platforms and radar arches, with little to no surface preparation and a room temperature cure. Sold in 400 mL cartridges, 5-gallon pails and 50-gallon drums.
	UltraLok UL530, UL560 and UL590 1:1 | 25 to 100 minute working times | Gap fill to 1.5 in Chem-Set’s 1:1 methacrylates bond fiberglass, steel, stainless, aluminum and various plastics, generally with no surface prep. Low surface energy plastics are out. UL590 gives you 70 to 100 minutes of working time and fixtures in 180 to 240 minutes at 75°F. Sold in 400 mL cartridges and SmartPak foil packs, and UL530 also comes in 5-gallon pails. UltraLok isn’t UV stable and yellows over time. Bond strength isn’t affected, but keep it off show surfaces and visible seams.
	SciGrip SG230HV 10:1 | 30, 40 and 60 minute versions | Lloyd’s Register and DNV GL One Part A with a choice of activators for different working times, so you stock less. It holds a large bead on vertical and overhead faces and fills gaps up to 1.5 in. SciGrip lists it for deck-to-hull bonding, hatches, hardtops and mounting hardware. Sold in 490 mL cartridges, 5-gallon pails and 55-gallon drums.

Running smaller parts or bonding metal and plastic in the same assembly? SciGrip SG300 is a 10:1 MMA with shorter working times, and SciGrip lists it alongside SG230HV for bulkheads, stringers, transoms and window frames.

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Drums, Pails, Cartridges or SmartPak

Large production builders run these adhesives from 50-gallon drum and 5-gallon pail kits through meter-mix equipment. That gets the lowest cost per gallon, and it comes with pumps, hoses and upkeep. Cartridges sit at the other end: no equipment, but more reloads and more packaging to throw away.

UltraLok SmartPak sits in between. The adhesive comes in foil packs, 600 mL (300 mL Part A plus 300 mL Part B) or 1,200 mL (600 mL plus 600 mL), and dispenses from a battery-powered gun. Shops that bond too much for cartridges but don’t want to pump out of drums and pails get production volume with no meter-mix equipment, and there’s less plastic to toss than with rigid cartridges. SmartPak is available in UL560, UL590 and other UltraLok grades.

UltraLok SmartPak Starter Kit Battery gun | 600 or 1,200 mL foil packs | No meter-mix pumps Includes the gun, four manifolds for quick changeover, two batteries, a charger and twelve high-flow static mixers, plus your choice of four 600 mL sets or two 1,200 mL sets of UltraLok MMA.

Already running meter-mix? Check your equipment against the TDS for the adhesive you’re switching to. ITW calls for explosion-proof bulk equipment with stainless wetted parts and seals of Teflon, ethylene/propylene or polyethylene, and no brass, copper, carbon steel, Viton, Buna-N or neoprene. SciGrip allows stainless or aluminum wetted parts with PTFE or UHMW seals, and no copper, zinc or brass.

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Deck-to-Hull and Hardware: Sikaflex 292 as a 3M 5200 Alternative

Most yards keep 3M 5200 on the shelf for deck-to-hull joints, hardware and anything that has to stay put. Sikaflex 292 is Sika’s alternative for the same work. It’s a one-part, moisture-curing polyurethane built for structural joints that see high dynamic stress, and it bonds aluminum (including anodized), metal primers, two-part paint coatings, GRP and ABS. It can be painted.

Sika positions 292 against 5200 on three points. It builds green strength faster, so parts can be handled sooner. It’s non-sag, so the bead holds on vertical and overhead joints. And the joint stays serviceable, so parts can come apart later for repair.

Sika’s green strength test board. In the build-out comparison, the Sikaflex 292 bead holds a compact shape next to Competitor X.

Sikaflex 292 Marine Adhesive Sealant 1-part polyurethane | 35 minute open time | White, 300 mL Skins in about 40 minutes at 73°F, with good gap fill and good non-sag. Test on your parts before switching a production process.

Two-part options for big joints, aluminum and composites

	Adekit A236 1:1 polyurethane | 25 or 120 minute versions | Gap fill to 30 mm vertical, 60 mm horizontal Sika’s two-part adhesive for large composite parts, listed for hull bonding, deck bonding and interior work. Pot life runs 25 to 35 minutes or 90 to 120 minutes, and the non-sag paste is odor and solvent free with zero exotherm. The 400 mL cartridges need a pneumatic gun. Prime or grind wet lay-up polyester and vinyl ester before bonding, and pull peel ply on infused parts just before you bond.
	SikaPower 880 1:1 epoxy | 45 minute open time | Lloyd’s certification for aluminum A toughened, non-sag structural epoxy for steel, aluminum and GFRP or CFRP laminates. Handling time is 5 hours at 73°F, and 0.3 mm glass beads in the adhesive hold bond line thickness. It also runs in hybrid joints with spot welds, rivets or clinching.
	SikaPower 1200 2:1 epoxy | 45 minute open time | Full cure in 48 hours at 73°F A tough, solvent-free epoxy for highly stressed composite and metal assemblies. It keeps a long open time in heat and humidity, and a 158°F (70°C) cure cuts full cure to 2 hours.

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Marine Sealants for Thru-Hulls, Teak Decks, Windows and Hatches

Where marine sealants and adhesives go on a boat: deck fittings, deck caulking, rub rails, interior seams, sinks and showers, vents, through-hull fittings, deck-hull sealing and deck-to-hull bonding.

Bedding teak decking with Sikaflex 291 LOT

Sika lists Sikaflex 291 LOT for bedding teak plank decking laid on top of the sub deck. It skins in about 4 hours at 73°F, so the crew can lay and adjust planks without racing the sealant. It bonds wood, metals, metal primers, two-part paint coatings and fiberglass, and comes in white, black and mahogany.

Sabatack MS polymer adhesive sealants

Sabatack 760 XL HT is a one-component, high-tack window adhesive. Solvent free, non-sagging and UV stable.

Sabatack 750 is a one-component MS polymer general adhesive and sealant. Solvent free, non-sagging and UV stable.

Sabatack 780 is a humidity-curing MS polymer adhesive and sealant, also solvent free and non-sagging.

Sabatack 950 Boost is a two-component boosted MS hybrid in a 600 mL sausage pack.

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StarBoard and HDPE Bonding Without Flame Treatment

King StarBoard and other HDPE sheet are popular with boat builders and restorers, but polyethylene is a low surface energy plastic and most adhesives won’t hold on it. The usual workaround is sanding, a solvent wipe and flame treatment with a propane torch, then bonding within the hour. Plenty of shops skip all of that and use screws.

Chem-Set 6105 is a two-part, 1:1 toughened acrylic developed to bond polypropylene and polyethylene with no primer or surface treatment. It also bonds metals and composites, so it handles StarBoard to fiberglass or aluminum. In lap shear testing on polyethylene, the plastic failed before the bond did. Chem-Set 6110 is its sibling in the same 1:1, 400 mL format.

When PassageMaker deputy editor Capt. Bill Pike tested 6105 on quarter-inch StarBoard strips, he couldn’t break the joint, even with one end in a bench vise and the other in Vise-Grips. Read his write-up.

Chem-Set 6105 and 6110 Polyolefin Bonders 1:1 toughened acrylic | 1 mm max gap | Fixture in 5 to 10 minutes Bonds polyethylene, polypropylene and dissimilar substrates with no primer, sanding or flame treatment.

How to bond StarBoard with Chem-Set 6105

1. Fit the joint tight. 6105 fills gaps up to 1 mm (0.04 in). It’s a close-fit adhesive, so re-cut or shim anything wider.
2. Wipe with isopropyl alcohol. IPA removes mold release and shop grime from the sheet. Let it flash off completely. No primer and no torch.
3. Purge the cartridge. Run a little adhesive through the mixer until both sides flow evenly.
4. Work inside the pot life. Pot life is 2 to 4 minutes at 73°F (23°C), so dispense and mate small parts quickly.
5. Clamp and hold. Fixture comes at 5 to 10 minutes and handling strength at 20 to 25 minutes, both at 73°F.
6. Wait for full cure. Allow 24 hours at 73°F before you load the joint. Every 8°C (about 14°F) of extra heat roughly halves cure time, and cold slows it down.
7. Store it cold. Keep cartridges refrigerated at 35 to 45°F.
8. Test first. Bond offcuts from the same sheet and pull them apart before production.

SciGrip SG400LSE is another option built for polyolefins and other low surface energy plastics.

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Laminating Epoxy, Fairing Compound and Repair Fillers

	SikaBiresin CR72 and CR94 Laminating Epoxies 5:1 and 3:1 | Blendable hardeners Sika’s marine epoxy laminating systems, with improved wet-out and strong room temperature and post-cured properties. CR72 suits wet layup and vacuum bagging. CR94 is a 100% solids system for above and below waterline work.
	SikaBiresin AP861 Fairing Compound Trowelable epoxy | Less pinholing | Longer working window Mixes and spreads smoothly for fairing hulls and decks. SikaBiresin AP100 is Sika’s white epoxy coating for composite and wooden boats, with print-blocking capability.

Two faired panels side by side. The AP861 surface on the right shows far fewer pinholes.

For everyday repair work, Sika’s polyester repair fillers AP017 and AP077 come in quart and gallon sizes.

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Spray Adhesives for Interiors and Infusion

	TacBond S5907-ZF Non-flammable | Low VOC | Methylene chloride free Canister contact adhesive for laminate, panel and interior furnishing work. S5910 is a high-solids spray grade, and V-4540 is a solvent-based polychloroprene.
	Tensorgrip Infusion Molding Adhesives Holds laminate to core | Becomes part of the matrix M30 and M55 hold laminates to core surfaces during layup and become part of the polymer matrix after infusion. M55 is the heavy mat grade. M28 is a high-tack, CA compliant contact adhesive that builds well on porous and uneven surfaces.

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Mounting Hardware: IP68 Deform-Nuts and Fast-Con

Every hole in a deck, console or bulkhead is a possible leak path. IP68 Deform-Nuts are blind rivet nuts with a closed end and a sealing flange, rated IP68 against water and dust. They’re 18-8 stainless (303), install from one side, and come in round body and hex body versions from M5 to M8 and 1/4-20.

IP68 Deform-Nut 18-8 stainless | Closed end, sealed flange | M5 to M8, 1/4-20 Blind-installed rivet nut for panels you can’t reach behind. The hex body version adds twist resistance.

Fast-Con snap fasteners are a metal snap fastening system for panels that need to come off. They install quickly, resist flame and corrosion, and provide IP68 protection against water immersion.

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How to Plan a Structural Bond on a Boat

1. Start with the gap. Measure the widest point of the joint and pick a product whose gap fill covers it. Close-fit adhesives fail in thick bond lines.
2. Pick working time from the part. Time how long it takes to lay the full bead, set the part and clamp it, then add margin. Large parts get the long grades.
3. Check temperature. Times are rated around 75°F. ITW calls for 65 to 85°F application on Plexus, and SciGrip wants product held between 65 and 80°F. Heat shortens working time and cold stretches it.
4. Mix only what you’ll place. Large masses of MMA generate heat as they cure, which can release trapped air and gas. Dispense only what you can place inside the working time, and keep bond lines within the product’s gap fill.
5. Prep by substrate. Composites and gelcoat take little prep with these MMAs, though mold release may need light abrasion. Raw metals vary with oxidation and contamination, and SciGrip calls for primer on steel for maximum strength. Polyolefins need a polyolefin bonder.
6. Purge, dispense, mate once. Run each new cartridge until both sides flow, lay the bead and set the part. Slide to adjust, but don’t pull the parts apart.
7. Hold until fixture. Don’t move the part before fixture time. SciGrip notes parts can generally go into service at 80% of full strength, about 2 to 3 times the fixture time.
8. Test on your own parts. Run a sample bond on the actual materials, at shop temperature, before production.

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Marine Adhesive FAQ

What adhesive do boat builders use for stringers and bulkheads?

Gap-filling methacrylate (MMA) structural adhesives. Plexus MA530, MA560-1 and MA590, UltraLok UL530, UL560 and UL590, and SciGrip SG230HV all fill large gaps and hold on vertical faces. ITW says MA560-1 and MA590 are commonly used to bond stringers and liners into large fiberglass boats.

Is Sikaflex 292 an alternative to 3M 5200?

Yes. Sikaflex 292 is Sika’s one-part polyurethane structural adhesive for the same deck-to-hull, hardware and structural sealing jobs. Sika positions it on faster green strength, non-sag application and joints that stay serviceable. Test it on your parts before switching a production process.

What glue bonds StarBoard?

Chem-Set 6105 bonds StarBoard and other polyethylene and polypropylene with no primer, sanding or flame treatment. Wipe with isopropyl alcohol, keep the joint within 1 mm (0.04 in), and let it cure 24 hours before loading it.

How big a gap can a marine structural adhesive fill?

Up to 1.5 in for Plexus MA590, SciGrip SG230HV and UltraLok UL530, UL560 and UL590. MA560-1 fills up to 1.0 in and MA530 up to 0.7 in. Adekit A236 fills up to 30 mm on vertical joints and 60 mm on horizontal ones.

Which marine sealant works above and below the waterline?

Sikaflex 291, 291 LOT and 591 are all rated for above and below the waterline. For acrylic or polycarbonate windows, use Sikaflex 295 UV.

What sealant do you use to bed teak decking?

Sikaflex 291 LOT. Sika lists it for bedding teak plank decking on top of the sub deck, and its long open time, with a skin forming in about 4 hours, gives the crew time to lay and adjust planks.

Can you use Sikaflex 291 on acrylic or polycarbonate?

No. Sika says 291 and 291 LOT must not be used on plastics prone to stress cracking, like acrylic and polycarbonate. Use Sikaflex 295 UV for plastic windows and glazing.

Can you bond aluminum on a boat with adhesive?

Yes. SikaPower 880 is a two-part epoxy with a 45 minute open time and Lloyd’s certification for aluminum bonding. Sikaflex 292 bonds aluminum too, including anodized finishes, and the MMAs in this guide bond aluminum as well.

Are UltraLok adhesives UV stable?

No. UltraLok UL530, UL560 and UL590 yellow over time. Bond strength isn’t affected, but keep them off show surfaces and visible seams.

Should we buy structural adhesive in drums, pails or SmartPak?

Drums and pails make sense if you already run meter-mix equipment. SmartPak gives you more volume than cartridges from a battery gun with no pumps. Cartridges suit repair work, small runs and trials.

Questions on fit for your boat build? Call (800) 220-1966 or email [email protected].

3M and 5200 are trademarks of 3M Company. King StarBoard is a trademark of King Plastic Corporation. Plexus, SciGrip, Sika, Sikaflex, Sabatack, TacBond and Tensorgrip are trademarks of their respective owners. Chemical Concepts is not affiliated with 3M or King Plastic Corporation.