Composite Chainplates or External Stainless Chainplates?

[BigBeakie]

Originally Posted by Chotu

Yes, it’s a lifetime thing once epoxy gets to you.

I am not sure I’d trust the VE to epoxy bond. Is that what you’re suggesting? That I use VE to make the composite chain plates and do the secondary bond to my hull using vinylester?

I thought that absolutely, positively needed to be an epoxy to epoxy bond?

Yes, that's what I'm suggesting, but you must use high solids VE, not the stuff full of styrene. Polyester-epoxy is a no no.

High solids VE is on a continuum of the epoxy family, and can cross link. Of course, you would still go for as much mechanical bond as possible by deep scratching with 40 grit, but our test was on 2 pieces of marine ply pulled apart in sheer with block & tackle. The wood failed, not the bond.

But Scott Bader have excellent tech support, I'd have a chat to them re which product would give the best sheer strength onto your epoxy substrate.

And, as always, test it yourself, to be sure. Don't forget, there is alot of surface bonding area in this application, which helps a great deal.

Just get someone else to sand the epoxy test panel

[Redreuben]

Build VE components for sure but your right only bond to epoxy with epoxy.

[BigBeakie]

Originally Posted by Redreuben

Build VE components for sure but your right only bond to epoxy with epoxy.

A good general rule, but there are exceptions depending on the specifics of the materials involved.

[Chotu]

Ahhh. But my hull has been complete for years. It’s a secondary bond from hull to chainplates.

Nothing other than the sanding job tooth holding it together.

[BigBeakie]

I think you might be under estimating the sheer strength of the DB foundation layer if you vacuum bag it with the right resin, and cloth to resin fill ratio, and cross hatch sand the epoxy with 40 grit . It's a big area, well over a square meter of grip. When in doubt, test it.

My composites guy makes mods to racing multis here in Oz, and uses mechanical bond to epoxy boats all the time with the right materials and techniques. Done well, they work and have been well tested in the real world of racing.

[Dieseldude]

Members have contributed some good info about strength of stainless vs. strength of composites. Also been discussion about quality control of hand lay up of composites. How does composite material abrasion and impact resistance compare with stainless? I suspect that stainless would win at this. Quality of water jet cut stainless should not be an issue. But the interface between substrate material (hull) and the stainless itself must be perfectly sealed to prevent pitting. Same alloy fasteners should be used to prevent galvanic corrosion. It can be a challenge to seal around fasteners though.


Has anyone examined the possibility of High Density Polyethylene? Or Delrin (trade mark) plastic?


MaterialTensile StrengthImpact StrengthHeat DeflectionElongation at BreakDelrin6,000 - 22,000 psi0.75-2ft-lb/in180-300 °F10-40%

• Good dimensional stability
• Excellent machinability
• Superior impact and creep resistance
• High fatigue endurance
• High strength and stiffness properties
• Chemical resistance to fuels and solvents
• Low moisture absorption: Delrin can operate in wet environments with little effect on performance or dimensions
• Good wear and abrasion properties - with its low coefficient of friction and hard and resilient surface, Delrin is the material of choice in many wear applications.

https://www.protolabs.com/resources/...tive-to-metal/




For sealing fasteners in plastics, a slight interference fit (hole slightly smaller than bolt) can make a tight seal. Precision drilling would be required with high quality drill bit that is carefully sized. Achieving good bolt hole pattern match between hull and plate would require drilling in assembly.



While working as a Remotely Operated Vehicle Pilot/Tech, I found Delrin used on ROV's for such applications as bumpers and machinery brackets. It is very strong and very tough. Anyone on the forum have some more insight into plastic sheet stock material that might be useful for chain plates?

[Dieseldude]

Sorry, Delrin properties chart did not paste in well.


MaterialTensile StrengthImpact StrengthHeat DeflectionElongation at BreakDelrin6,000 - 22,000 psi0.75-2ft-lb/in180-300 °F10-40%

[Cpt Mark]

Could you not just glass in some G-10 that is easy to purchase and already done?

[rslifkin]

Originally Posted by Cpt Mark

Could you not just glass in some G-10 that is easy to purchase and already done?

Or even (with appropriate load spreading on the bolts) get thick pieces of G10 cut to shape and then paint it and mount it like a stainless chainplate (with appropriate bolts with load spreading on the outside and an appropriate backing plate). It would just need to be drilled and painted by someone else.

[Trackskinz]

I've worked in structural composites for about 34 years.

I'd really like to discuss this with you.

Originally Posted by Chotu

Important factors:

Speed/ease of assembly
Longevity
Cost
Value
Weight/Performance


Important Considerations:

Composite - Have to hire a helper for complex composite lamination requiring 3 types of glass. Must hand laminate dozens of layers with epoxy that is painted over with polyester so I can go near the boat. Requires 2 employees. Have to buy epoxy and 3 types of glass. Chance employees could botch the lamination or leave bubbles. I can’t supervise (micro manage) that part.


Stainless - these are approximately 24” x 12” pieces of 316L Stainless 3/4” thick.
VERY pricey. Still some outside work to be done with epoxy. To mount them.


I’m leaning toward stainless since I think it’ll be cheaper and easier, but wanted to see if I’m missing anything via public input before I go for it.

[Chotu]

Right, but I don’t have the plans for G10 to substitute in for stainless steel. I hate to be one of those people with a can’t do attitude, but I have to be in this case. These are one of the most important structural components of the boat. I cannot just make this part up. That’s for my other threads. LOL.

I have the plans for composite chain plates. They do not act like stainless. I think some people missed what composite chain plates are. They are an integral part of the hull. They spread the load incredibly efficiently and do not require any bolting or holes. They are not something you bolt on.

I also have the plans for stainless chainplates. Those are what you bolt onto the hull.

[Trackskinz]

Originally Posted by Chotu

Right, but I don’t have the plans for G10 to substitute in for stainless steel. I hate to be one of those people with a can’t do attitude, but I have to be in this case. These are one of the most important structural components of the boat. I cannot just make this part up. That’s for my other threads. LOL.

I have the plans for composite chain plates. They do not act like stainless. I think some people missed what composite chain plates are. They are an integral part of the hull. They spread the load incredibly efficiently and do not require any bolting or holes. They are not something you bolt on.

I also have the plans for stainless chainplates. Those are what you bolt onto the hull.

Absolutely!

I'm aware of the challenges.

The stress loads need to be maintained in tension. I work with G10 regularly, have also fabricated this sort of thing.

I think it's an interesting solution. Fibers (obviously) work only in tension, but then the entire rig is based on tension, so it's a natural fit.

[Chotu]

Originally Posted by Trackskinz

Absolutely!

I'm aware of the challenges.

The stress loads need to be maintained in tension. I work with G10 regularly, have also fabricated this sort of thing.

I think it's an interesting solution. Fibers (obviously) work only in tension, but then the entire rig is based on tension, so it's a natural fit.

I wasn’t necessarily responding to you, but thank you.

I had seen a couple different posts in this thread where people seem to be implying that composite chain plates are something separate. Like stainless ones would be. Trying to make it clear that they are an integral part of the hull. They are not bolted on.

I’m not sure that I would want to go experimenting around designing composite bolt on chain plates. They lose all of the advantages of real composite chain plates. With the real ones, the load is transferred much more efficiently to the huge section of hull they interact with.

[Trackskinz]

Originally Posted by Chotu

I wasn’t necessarily responding to you, but thank you.

I had seen a couple different posts in this thread where people seem to be implying that composite chain plates are something separate. Like stainless ones would be. Trying to make it clear that they are an integral part of the hull. They are not bolted on.

I’m not sure that I would want to go experimenting around designing composite bolt on chain plates. They lose all of the advantages of real composite chain plates. With the real ones, the load is transferred much more efficiently to the huge section of hull they interact with.

I agree with the load-spread idea, although they could be bolted on.

I believe I would do both.

And the work required to add them as a n integral part of the hull would be idea but challenging unless the boat were really opened up. I know you know this. Thus, a combination is what I would do.

Ultimately, the chemical bond is only as strong as whatever it is bonded to. The REAL way to do this is while the hull is being laminated. Post construction always has these challenges.

I still like the idea. If done properly, it would never need replacement anymore than the hull does.

I'd be interested in seeing your plans.

[Chotu]

Originally Posted by Trackskinz

I agree with the load-spread idea, although they could be bolted on.

I believe I would do both.

And the work required to add them as a n integral part of the hull would be idea but challenging unless the boat were really opened up. I know you know this. Thus, a combination is what I would do.

Ultimately, the chemical bond is only as strong as whatever it is bonded to. The REAL way to do this is while the hull is being laminated. Post construction always has these challenges.

I still like the idea. If done properly, it would never need replacement anymore than the hull does.

I'd be interested in seeing your plans.

Of course. The whole boat being built in one single infusion would be amazing. But that’s just not possible. That’s why there are teams of people working on boats. There is secondary bonding everywhere when you build a boat. That’s how the bulkheads are attached. That’s how the beams going across the boat are attached. That’s how the bridge deck is attached. That’s how the hull haves are taped together. And yes, that is how the composite plates are put on to basically all composite boats.

It’s all epoxy to epoxy secondary bonding.

The boat already is opened up. It’s being built. But really this is just a question of practicality here. Trying to reason out which will be the most practical way to do this.

If I get 20 years out of stainless, that doesn’t seem like a big problem to me. It’s just not as cool. It’s not as light weight. And it doesn’t spread out the load as well as the composite chain plate would.

For all of the benefits they have, that’s why I haven’t completely eliminated them yet. It’s enticing to get that extra performance and longevity, and even the cool factor.