Adhesives at Sea: Structural Bonding and Safety in Modern Shipbuilding

Welcome back to the Adhesion Matters podcast. How do adhesives survive salt spray, constant shock, and the world’s toughest fire standards?
In this episode, we dive into the unique challenges of marine and shipbuilding applications. From composite superstructures and deck bonding to corrosion-resistant sealing, adhesives are now replacing welds and rivets in some of the harshest environments on earth.

We highlight some epoxy adhesies for structural bonding, along with silicone sealants that deliver fire resistance and weather durability in line with IMO safety codes. Finally, we look ahead at the role adhesives will play in greener shipping—hydrogen ferries, lightweight composites, and wind-assisted propulsion.

Whether you’re a naval architect, shipyard engineer, or materials specialist, this episode shows how modern adhesives keep the world’s fleets lighter, safer, and ready for the future. 

Transcript

Lucas Adheron 0:00

Saltwater, constant vibration, and incredibly strict safety codes. Marine adhesives face some of the toughest conditions out there.

Elena Bondwell 0:09

Absolutely. Just brutal.

Lucas Adheron 0:11

From bonding massive deck structures to assembling advanced composite superstructures, the stakes are just undeniably high.

Elena Bondwell 0:17

And the standards are unforgiving. No room for error.

Lucas Adheron 0:20

Today, we're taking a deep dive into this fascinating world of marine and shipbuilding adhesives.

Elena Bondwell 0:27

Yeah, looking at the advanced solutions.

Lucas Adheron 0:29

Exactly. Solutions crucial for everything from, say, high-speed boats cutting through waves to those huge components. Right. So to kick us off, what actually makes the marine environment so uniquely challenging for materials and shipbuilding? It seems like more than just getting wet.

Elena Bondwell 1:00

Oh, it's really a combination of relentless forces all sort of working against you.

Lucas Adheron 1:06

Like what specifically?

Elena Bondwell 1:07

Well, you're dealing with constant exposure to salt fog, salt water, creates incredibly corrosive conditions, and it gets particularly nasty when you have dissimilar metals involved. That leads to galvanic corrosion.

Lucas Adheron 1:23

Right, I've heard of that.

Elena Bondwell 1:24

Yeah, it's this subtle but really destructive process. Saltwater acts as an electrolyte, and the two different metals basically form a little battery. And one metal corrodes way faster than it normally would. Adhesives can act as an insulator there, stopping that reaction. That makes sense. And then you've got the dynamic loading, constant vibrations, shocks. from waves, engine thrum.

Lucas Adheron 1:45

Right.

Elena Bondwell 1:46

It's a major factor in material fatigue over time, just constantly stressing the components.

Lucas Adheron 1:50

Okay, so it's the chemical attack and the physical stress. But it's not just about durability under normal conditions, is it? The safety regulations, they're famously strict.

Elena Bondwell 1:59

Oh, incredibly strict, and for good reason. The consequences of any failure at sea are just too high. Exactly. The International Maritime Organization, the IMO, sets these really stringent fire retardancy requirements.

Lucas Adheron 2:12

Okay.

Elena Bondwell 2:13

You'll hear about IMO FTPC Part 2 and Part 5. These aren't just guidelines. They dictate critical things like smoke density, toxicity of fumes if something burns, and really importantly, flame spread, how quickly fire moves across a surface.

Lucas Adheron 2:27

So adhesives have to pass all that.

Elena Bondwell 2:29

Rigorously qualified. They absolutely cannot become an accelerant in a fire. Plus, we're seeing a definite trend towards halogen-free and MCCP-free adhesives.

Lucas Adheron 2:40

Why is that?

Elena Bondwell 2:41

Safer in a fire. They release significantly fewer toxic and corrosive fumes. Huge benefit for anyone on board.

Lucas Adheron 2:48

Sounds like a totally non-negotiable set of requirements. So given these intense challenges, the corrosion, the loads, the safety rules, why are we seeing this a big shift towards using structural adhesives instead of the old ways, like rivets and welding.

Elena Bondwell 3:05

Ah, yeah, that's where it gets really interesting.

Lucas Adheron 3:06

Seems like a fundamental change.

Elena Bondwell 3:07

It is. It's a real paradigm shift driven by some compelling advantages. The biggest one, weight reduction. Okay.

Lucas Adheron 3:13

Think about speedboats. To hit speeds up to maybe 99 kilometers per hour, they have to be incredibly light.

Elena Bondwell 3:20

Makes sense.

Lucas Adheron 3:21

So structural adhesives are a fantastic way to replace heavier mechanical fasteners, screws, rivets, weld

Elena Bondwell 3:28

Right.

Lucas Adheron 3:30

And it's not just the overall weight. You also eliminate the stress concentration points that fasteners can create. Yeah. Leads to stronger, more durable structures.

Elena Bondwell 3:38

Okay. So shedding weight is key. What's another major advantage adhesives bring compared to traditional methods?

Lucas Adheron 3:47

The ability to bond different materials together. That's crucial now.

Elena Bondwell 3:50

How so?

Lucas Adheron 3:51

Well, more shipyards are replacing steel with lighter composites, right, for big weight savings. Adhesives let you create really durable assemblies bonding dissimilar things like aluminum to composites or stainless steel to fiberglass effectively, efficiently.

Elena Bondwell 4:06

And without the corrosion issues you'd get with metal fasteners.

Lucas Adheron 4:09

Exactly. You avoid that whole galvanic corrosion problem we talked about. It just opens up huge design possibilities that weren't really practical before. That really does sound like a game changer. Let's dive into some specific solutions then. Starting with Eroldite from Huntsman. It's a really well-known name.

Elena Bondwell 4:24

Definitely.

Lucas Adheron 4:24

Tell us about Eroldite 2015-1.

Elena Bondwell 4:27

Okay, so Eroldite 2015 It's a two-component epoxy.

Lucas Adheron 4:31

Right.

Elena Bondwell 4:31

And it's specifically designed for bonding medium to large metal and composite parts. Really good for assembling moving components where you have that dynamic stress. What

Lucas Adheron 4:41

makes it so good for that?

Elena Bondwell 4:43

Well, it's properties. It's got impressive resistance to dynamic loading, great weathering stability, high fracture toughness, meaning it resists cracking. Okay. And really good fatigue performance over time. And crucially, it's qualified by Lloyd's Register.

Lucas Adheron 4:57

Which is a big deal in maritime.

Elena Bondwell 4:58

Huge deal. It's like a global stamp of approval for safety and performance. It also meets EN 455452 HL3 for R1 and R7.

Lucas Adheron 5:08

Fire safety again?

Elena Bondwell 5:09

Extremely high European fire safety standards. Smoke, toxicity, the works, vital for ships.

Lucas Adheron 5:16

That Lloyd's Register qualification alone gives you a lot of confidence. What about actually using it? Is it workable for large parts?

Elena Bondwell 5:22

Yeah, it's designed for that. It has a 45-minute pot life at room temperature.

Lucas Adheron 5:27

So time to work with it once mixed.

Elena Bondwell 5:28

Exactly. Exactly. And a four-hour fixture time when it's strong enough to hold itself, that gives you flexibility, even on big jobs like hull-to-deck bonding.

Lucas Adheron 5:36

Crews aren't rushed.

Elena Bondwell 5:37

Right. And it's strong. Tensile strength of 31 MPa, that's a lot of pulling force it can handle.

Lucas Adheron 5:43

You mentioned elongation. Only 4%.

Elena Bondwell 5:45

Yeah, which sounds small, but for an epoxy, that actually indicates really good rigidity. It means parts stay precisely aligned, even under load. Doesn't deform easily.

Lucas Adheron 5:54

Got it.

Elena Bondwell 5:54

It handles heat up to 100 degrees C continuously, and a big plus no specific primer needed. Simplifies the whole process. You bond directly.

Lucas Adheron 6:03

Okay, 2015-1 sounds like the choice for precision, high strength. What about eraldite 2023? Sounds like it tackles different problems, maybe those big deck-to-hole joints where fits aren't perfect.

Elena Bondwell 6:14

Exactly. Aerolite 2023 came out in 2019. It's a two-component acrylic adhesive.

Lucas Adheron 6:19

Different chemistry.

Elena Bondwell 6:20

Totally different. It was engineered for joining and sealing large parts, specifically addressing that challenge of getting a fast, tough, fatigue-resistant joint in deck-to-hole connections.

Lucas Adheron 6:31

Why are those joints so tricky?

Elena Bondwell 6:32

Well, they often have large production tolerances. You know, building something that huge, you don't always get perfect fits.

Lucas Adheron 6:38

Right. Millimeter precision is tough on that scale.

Elena Bondwell 6:40

Exactly. So you need an adhesive that can stretch high along But it's still stiff enough. High modulus E and critically can fill big gaps.

Lucas Adheron 6:50

And 2023 does that. You mentioned 30 millimeters gap fill. That sounds huge.

Elena Bondwell 6:55

It is huge. Think about trying to align two massive ship sections. There are always going to be variations from the design. Sure. If your adhesive can fill gaps up to 30 millimeter, it massively cuts down on shimming, rework, custom fitting.

Lucas Adheron 7:09

Saves a ton of time and labor.

Elena Bondwell 7:11

Absolutely. Plus, its elongation is over 100%. super flexible, vital for handling thermal expansion between different materials and those dynamic loads. It's also non-sagging, so you can use it on vertical surfaces without it dripping everywhere. And UV stable. Stays that bright gray color, doesn't yellow in the sun. And it offers modular curing, different opening cure times available from 10 to 60 minutes. Very adaptable.

Lucas Adheron 7:36

So we've got Huntsman with epoxy for strength and rigidity, acrylic for flexibility, and gap fill. How does this choice of chemistry reflect a broad That's

Elena Bondwell 7:48

a great question. It really shows how sophisticated adhesive engineering has become. Epoxies like 2015-1, they're known for incredible strength, rigidity, resistance to chemicals, heat. They're your go-to for maximum load bearing where you need dimensional stability. Precision stuff.

Lucas Adheron 8:05

Right.

Elena Bondwell 8:05

Acrylics like 2023 offer amazing flexibility, impact resistance. They're brilliant at gap filling and bonding trickier plastics or composites. They

Lucas Adheron 8:14

may be faster or easier to use.

Elena Bondwell 8:16

Often, yeah. They tend to cure quickly and can be more tolerant of, let's say, less than perfect surface prep. Good for high volume shipyard work.

Lucas Adheron 8:23

So it's not about one being better, just different tools for different jobs.

Elena Bondwell 8:27

Exactly. Picking the right chemistry tailored to the mechanical stress, the heat, the manufacturing reality of that specific bond.

Lucas Adheron 8:35

Makes sense. Okay. Moving beyond just structural bonding, sealing is obviously critical at sea, all that saltwater trying to get in. What are the go-to solutions there?

Elena Bondwell 8:44

Yeah. Yeah, good point. This brings us to things like Dowsel silicone sealants from Dow.

Lucas Adheron 8:50

Silicon, okay.

Elena Bondwell 8:51

Yep, silicon-based, durable RTV sealants that's room temperature vulcanizing.

Lucas Adheron 8:55

They cure without heat.

Elena Bondwell 8:56

Right, just at room temp into a tough, rubbery solid. And they offer really exceptional performance. They tend to last much longer and stay more flexible than typical organic polymer sealants.

Lucas Adheron 9:07

Which is key in that harsh UV environment.

Elena Bondwell 9:09

Absolutely.

Lucas Adheron 9:09

Where would you typically find these Dowsel sealants on a ship?

Elena Bondwell 9:12

Oh, all sorts of industrial bonding and sealants. Thank you. That FR is for fire resistant. It's an industrial elastomeric bonding adhesive specifically formulated for fire resistance, meets a whole bunch of stringent European fire standards, DIN, NF codes, really comprehensive testing.

Lucas Adheron 9:59

So top notch fire safety. What else?

Elena Bondwell 10:02

Beyond fire safety, it gives you high-strength assembly, great elasticity, which helps with vibration damping.

Lucas Adheron 10:07

Quieter ship, longer life for components.

Elena Bondwell 10:09

Right, and superior UV and weathering resistance. It comes as a thixotropic paste, thick but flows when you apply it, so no drips, black or gray, good elongation, about 180%, and decent tensile strength at 3.5 MPa, a real workhorse.

Lucas Adheron 10:25

Sounds like a solid all-rounder, especially where fire safety is paramount. What about Terrace and MS-9399?

Elena Bondwell 10:31

S-9399 is another key one, highly viscous, sag-resistant again. It's a two-part elastic adhesive, great for shipbuilding. What's

Lucas Adheron 10:38

special about it?

Elena Bondwell 10:39

It cures at room temperature, has a short tack-free time, and really high initial strength. So you can handle parts sooner.

Lucas Adheron 10:46

Speeds things up.

Elena Bondwell 10:47

Exactly. And what's really neat is its curing is independent of air humidity.

Lucas Adheron 10:52

Ah, that's useful in a shipyard. Conditions change.

Elena Bondwell 10:55

Huge advantage. No worries about moisture or messing up the cure. It's also free from solvents, isocyanates, Silicone's big plus for worker safety and the environment.

Lucas Adheron 11:05

Good points.

Elena Bondwell 11:06

And again, excellent UV and weathering resistance, really good for elastic bonding where you need long-term durability and that environmental safety aspect.

Lucas Adheron 11:14

Okay, we've looked at structural epoxies, acrylics, these versatile sealants. Taking a step back, what's the big picture impact of this whole adhesive revolution on shipbuilding and maintenance? It feels like more than just sticking bits together.

Elena Bondwell 11:28

Oh, it's way more. It means significant improvements right across the board, from manufacturing efficiency to totally new levels of design freedom.

Lucas Adheron 11:36

How so on efficiency?

Elena Bondwell 11:38

Well, when Huntsman says their solutions can save up to 50% in production time, that's massive. It's not just building faster. It frees up resources, gets ships delivered quicker, and actually reduces long-term maintenance. The bonds themselves are often more durable, less prone to fatigue than, say, rivets.

Lucas Adheron 11:57

Right. Fewer weak points.

Elena Bondwell 11:59

Exactly. Think about a traditional hull deck joint. thousands of rivets maybe, or extensive welding, super labor intensive, needs special skills.

Lucas Adheron 12:09

Creates potential stress points too.

Elena Bondwell 12:11

Right. Adhesives simplify that. You can automate applications sometimes, use less labor.

Lucas Adheron 12:16

So they're genuinely enabling innovation, really shaping the industry's future. What about some less obvious benefits, things happening behind the scenes?

Elena Bondwell 12:24

Well, yeah. Adhesives are critical now for rapidly assembling big panels, even in wet conditions that might stop other work.

Lucas Adheron 12:31

Okay.

Elena Bondwell 12:31

And for Noise and vibration damping in floors makes the ship quieter, more comfortable. Hygienic sealants in cabins, galleys, even medical areas onboard.

Lucas Adheron 12:39

Quieter, safer, more comfortable. But it's not seamless. There must be challenges for shipyards adopting this.

Elena Bondwell 12:45

That's fair. There's definitely a learning curve. You need new application techniques, specific storage for the adhesives, training for the crews. But the long-term winds, cost, weight, performance, they generally far outweigh those initial hurdles.

Lucas Adheron 12:58

That makes sense. It really sounds like these advances are pushing the industry forward. Thinking about the future then, we hear a lot about green shipping, wind assist, batteries, hydrogen ferries. What new adhesive challenges and solutions will that need? How do adhesives support sustainable maritime tech?

Elena Bondwell 13:19

That's a great forward looking question. Adhesives are going to be absolutely central to that green shift.

Lucas Adheron 13:24

How?

Elena Bondwell 13:25

Well, as we use new materials, lighter composites for hulls, materials for battery systems, maybe even cryogenic tanks for hydrogen.

Lucas Adheron 13:32

Right.

Elena Bondwell 13:33

The demand for specialized adhesives that can bomb those materials will just explode. We'll need adhesives that handle extreme cold for hydrogen, maybe extreme heat cycles for batteries, resist new fuel types.

Lucas Adheron 13:44

While still meeting safety rules.

Elena Bondwell 13:46

Exactly. Meeting or even exceeding tighter and It's amazing

Lucas Adheron 13:59

how much invisible tech goes into a modern ship. Easy to take for granted.

Elena Bondwell 14:03

It really is a testament to material science.

Lucas Adheron 14:06

And with all these specialized options we've discussed, picking the right one for a specific job must feel like a deep dive in itself.

Elena Bondwell 14:14

Absolutely. And that's why understanding the details is so vital. You know, what are the absolute critical things you need to focus on when you're choosing to make sure you get the best fit for your specific need?

Lucas Adheron 14:24

Right. So we want to leave you, our listeners, with a kind of spec sheet checklist. Five crucial questions every shipyard and marine engineer should probably ask before picking their next marine adhesive.

Elena Bondwell 14:35

Good idea.

Lucas Adheron 14:36

Think about things like, one, what exactly are the materials you're bonding? Steel to composite, aluminum to glass. Two, what are the precise load conditions? Static weight, constant vibration, shock impacts.

Elena Bondwell 14:49

Three, how critical is fire safety, smoke, toxicity for this specific location on the vessel?

Lucas Adheron 14:57

Four, what are your production line realities? Yeah. How fast do you need it to cure? What application methods do you have?

Elena Bondwell 15:04

And five, what's the long-term environment? Constant UV. Big temperature swings, chemical exposure.

Lucas Adheron 15:11

Answering those gets you a long way there.

Elena Bondwell 15:13

And maybe a final thought to mull over.

Lucas Adheron 15:15

Yeah.

Elena Bondwell 15:16

Don't just think about the initial bond strength or the cost per tube. Consider the entire life cycle of the vessel.

Lucas Adheron 15:22

How so?

Elena Bondwell 15:23

Factor in assembly efficiency, how well it handles those real-world production tolerances we talked

Lucas Adheron 15:28

about. Have a gap billing.

Elena Bondwell 15:29

It's long-term performance in those harsh conditions. And looking ahead, how adaptable is it? Does it support future sustainability goals or material changes? That's the It's a real deep dive taking that holistic view.