Adhesion Matters - Adhesives at Sea: Structural Bonding and Safety in Modern Shipbuilding

Episode Date: August 24, 2025

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. 

Salt water, constant vibration, and incredibly strict safety codes. Marine adhesives face some of the toughest conditions out there. Absolutely. Just brutal. From bonding massive deck structures to assembling advanced composite superstructures, the stakes are just undeniably high. And the standards are unforgiving. No room for air. Today, we're taking a deep dive into this fascinating world of marine and shipbuilding adhesives. Yeah, looking at the advanced solutions.

Exactly. Solutions crucial for everything from, say, high-speed boats, cutting through waves to those huge commercial vessels. Right. Our mission is to understand how companies like Boto Miller-Kemmy distribute these cutting-edge products from the big names like Huntsman, Dow, Henkel, to tackle these intense demands, basically giving you a shortcut to understanding the innovations keeping our ships afloat and safe. 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. Oh, it's really a combination of relentless forces all sort of working against you. Like what specifically? Well, you're dealing with constant exposure to salt fog, salt water, creates incredibly corrosive conditions.

Okay. And it gets particularly nasty when you have dissimilar metals involved. That leads to galvanic corrosion. Right. I've heard of that. Yeah. It's this subtle but really destructive process. Salt water acts as an electrolyte, and the two different metals basically form a little battery. And one metal corrogs 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. It's a major factor in material fatigue over time, just constantly stressing the component. 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. 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. Okay. You'll hear about IMO FTP 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. moves across a surface.

So adhesives have to pass all that. Rigorously qualified. They absolutely cannot become an accelerant in a fire. Plus, we're seeing a definite trend towards allergen-free and MCCP-free adhesives. Why is that? Safer in a fire. They release significantly fewer toxic and corrosive fumes. Huge benefit for anyone on board.

Sounds like a totally non-negotiable set of requirements. Pretty much. So given these intense challenges, the corrosion, the loads, the safety rules. Why are we seeing this big shift towards using structural adhesives instead of the old ways like rivets and welding? Ah, yeah, that's where it gets really interesting. Seems like a fundamental change. It is. It's a real paradigm shift driven by some compelling advantages.

The biggest one, weight reduction. Okay. Think about speedboats. To hit, you know, speeds up to maybe 99 kilometers per hour, they have to be incredibly light. Makes sense. So structural adhesives are a fantastic way to replace heavier mechanical fasteners, screws, rivets, welding. Right.

And it's not just the overall weight. You also eliminate the stress concentration points that fasteners can create. Leads to stronger, more durable structures. Okay. So shedding weight is key. What's another major advantage adhesives bring compared to traditional methods? The ability to bond different materials together. That's crucial now.

How so? Well, more shipyards are replacing steel with lighter composites, right, for big weight saving. Adhesives let you create really durable assemblies bonding to similar things like aluminum to composites or stainless steel to fiberglass effectively efficiently. And without the corrosion issues you'd get with metal fasteners. 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 Aeroldite from Huntsman, it's a really well-known name. Definitely. Tell us about Aeroldite 2015. Okay, so Aerolyte 20151. It's a two-component epoxy. Right. 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 makes it so good for that? 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. Which is a big deal in maritime. Huge deal. It's like a global stamp of approval for safety and performance. It also meets EN 455452, HL3 for R1 and R7. Fire safety again.

Extremely high European fire safety standards. Smoke, toxicity, the works, vital for ships. That Lloyd's Register qualification alone gives you a lot of confidence. What about actually using it? Is it workable for large parts? Yeah, it's designed for that. It has a 45-minute pot life at room temperature. So time to work with it once mixed. 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. Crews aren't rushed. Right. And it's strong. Tensile strength of 31M pay. That's a lot of pulling force it can handle. You mentioned elongation. Only 4%. 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. Got it. It handles heat up to 100 degrees. see continuously, and a big plus no specific primer needed, simplifies the whole process. You bond directly. Okay, 2015-1 sounds like the choice for precision, high strength. What about Aerolyte 2023? Sounds like it tackles different problems, maybe those big deck-to-hole joints where fits aren't perfect. Exactly.

Aerolyte 2023 came out in 2019. It's a two-component acrylic adhesive. Different chemistry. 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. Why are those joints so tricky? Well, they often have large production tolerances. You know, building something that huge,

you don't always get perfect fits. Right. Millimeter precision is tough on that scale. Exactly. So you need an adhesive that can stretch a high elongation, but is still stiff enough, high modulus E and critically, can fill big gaps. And 2023 does that. You mentioned 30 millimeters gap fill. That sounds huge. 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. Saves a ton of time in labor. Absolutely. Plus, its elumvation 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.

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. 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 broader strategy, matching the adhesive to the specific joints needs? That's 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. Right. Acrylics, like 2023, offer amazing flexibility, impact resistance. They're brilliant at gap

filling and bonding, trickier plastics or composites. They may be faster or easier to use. 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. So it's not about one being better, just different tools for different jobs. Exactly.

Picking the right chemistry tailored to the mechanical stress, the heat, the manufacturing reality of that specific bond. Makes sense. Okay, moving beyond just structural bonding, sealing is obviously critical at sea, all that salt water trying to get in. What are the go-to solutions there? Yeah, good point. This brings us to things like Dowzel, silicone sealance from Dow. Silicon, okay. silicon-based durable RTV sealants that's room temperature vulcanizing they cure without heat 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 which is key in that harsh UV environment absolutely where would you typically find these doso sealants on a ship oh all sorts of industrial bonding and ceiling jobs but particularly for things like marine windows deck glazing healing glass exactly and

creating watertight, flexible joints that have to withstand constant movement and weather. Dow even has grades certified for those IMO, low flame, smoke, and toxicity rules. Ah, tying back to the safety rigs again. Always comes back to safety. It's a huge plus. And Hangle, they're another big player with their Tereson brand. Yes, definitely. Hankle's Tereson line has some crucial solutions too.

Like what? Well, take Tereson MS-9-39-FR, that FRR is for fire-resistant. Okay. It's an industrial, elastomeric bonding adhesive specifically for fire-resistant. meets a whole bunch of stringent European fire standards, din, NF codes, really comprehensive testing. So top-notch fire safety. What else? Beyond fire safety, it gives you high-strength assembly, great elasticity, which helps with vibration damping. Quieter ship, longer life for components.

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 MP, a real workhorse. Sounds like a solid all-rounder, especially where fire safety is paramount. What about Tereson-S-939-9-9-9-9-9-9-9 is another key one, highly viscous, sag-resistant again. It's a two-part, elastic adhesive, great for ship building. What's special about it? It cures at room temperature, has a short tack-free time, and really high initial strength.

So you can handle parts sooner. Speeds things up. Mm-hmm, exactly. And what's really neat is it securing is independent of air humidity. Ah, that's useful in a shipyard. Conditions change. Huge advantage. No worries about moisture or messing up the cure.

It's also free from solvents, isocyanates, silicones big plus for worker safety and the environment. Good points. And again, excellent UV and weathering resistance, really good for elastic bonding where you need long-term durability and that environmental safety aspect. Okay, we've looked at structural epoxy, 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. Oh, it's way more. It means significant improvements right across the board, from manufacturing efficiency to totally new levels of design freedom.

How so on efficiency. 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. Right, fewer weak points. Exactly. Think about a traditional hull deck joint, thousands of rivets maybe. Or extensive welding, super labor intensive, needs special skills.

Creates potential stress points, too. Right. Adhesives simplify that. You can automate application sometimes, use less. labor. So they're genuinely enabling innovation, really shaping the industry's future. What about some less obvious benefits, things happening behind the scenes? Well, yeah. Adhesives are critical now for rapidly assembling big panels, even in wet conditions that might stop other work. Okay. And for noise and vibration damping and floors makes the ship quieter, more comfortable. Hygienic sealants and

cabins, galleys, even medical areas on board. Quieter, safer, more comfortable. But it's not seamless. There must be challenges for shipyards adopting this. 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. 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? That's a great forward-looking question. Adhesives are going to be absolutely central to that green shift. How? Well, as we use new materials, lighter composites for hulls, materials for battery systems, maybe even cryogenic tanks for hydrogen, the demand for specialized adhesives that can bomb those materials will just explode. We'll need adheses that handle extreme cold for hydrogen, maybe extreme heat cycles for batteries, resist new fuel types.

while still meeting safety rules. Exactly. Meeting or even exceeding tighter environmental and safety regulations. Adhesives won't just hold these green ships together. They'll be fundamental to making them efficient, resilient, and actually sustainable. It's amazing how much invisible tech goes into a modern ship. Easy to take for granted. It really is a testament to material science.

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. 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. 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. Good idea. 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. Three, how critical is fire safety, smoke, toxicity for this specific location on the vessel? Four, what are your production line realities? How fast you needed to cure? What application methods do you have? And five, what's the long-term environment? Constant UV, big temperature swings, chemical exposure.

Answering those gets you a long way there. And maybe a final thought to mall over. Yeah. Don't just think about the initial bond strength or the cost per tube. Consider the entire life cycle of the vessel. How so? Factor in assembly efficiency, how well it handles those real-world production tolerances we talked about. How the gap billing.

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 real deep dive taking that holistic view.