Composite Chainplates or External Stainless Chainplates?

[Trackskinz]

Originally Posted by Chotu

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.

I thought from the original post you were looking (possibly) for some knowledgeable help in doing this. I'd be interested.

The other thing: boats are generally built from polyester, sometimes vinylester resin (I dont happen to know of any cruisers built from epoxy), so the bond is still the issue.

[Chotu]

Originally Posted by Trackskinz

I thought from the original post you were looking (possibly) for some knowledgeable help in doing this. I'd be interested.

The other thing: boats are generally built from polyester, sometimes vinylester resin (I dont happen to know of any cruisers built from epoxy), so the bond is still the issue.

The best boats are made from epoxy. Are you familiar with boats and their construction? I’m wondering why you are unaware of this.

The bond is not an issue. At all.

My question was, given my circumstances with both health and life, if I should do composite chain plates or stainless.

I already have the plans for both, but appreciate your offer of want to pitch in on the engineering. I’m grateful for that. Thank you.

There will be other threads that need engineering input. This one doesn’t. It’s simpley a choice between 2 paths which are already laid out.

[team karst]

The horse may have left the barn, but. My ext chainplates are 3/4" SS plate. I like metal, since inside, I attach ground straps to the waterline for a lightning path. Can't do that realistically with composites.

[Chotu]

Originally Posted by team karst

The horse may have left the barn, but. My ext chainplates are 3/4" SS plate. I like metal, since inside, I attach ground straps to the waterline for a lightning path. Can't do that realistically with composites.

Horses are still in the stalls inside the barn licking a salt lick. Ha ha ha

However, it’s my determination after years of looking through boat lightning strike data and years as a physicist that you aren’t going to be protecting anything in even a near strike.

Nature will have its way with you.

If the lightning doesn’t get you, all the induction currents will.

To me, lightning is one of those “if your number is up, it’s up” type of things. Like designing out a whale breach crushing your boat.

I realize we obviously share different opinions on this one, but I’m not overly concerned with lightning at all. If it hits, it’s going where it wants mostly. It’ll arc as it sees fit.



Looking at the poll results, it’s actually 13 to 6 for stainless. They probably are the more intelligent way to go given my limitations.

[Redreuben]

@Chotu; I’m assuming being an epoxy construction the hulls are also foam cored or core of some sort ?
Was any reinforcement incorporated in the lay up in way of the chainplates ?
If not then your going to have to do epoxy work even to install stainless chainplates are you not ?

[team karst]

Sounds too fatalistic for me. My job is to actually protect electronics from lightning and other mayhem in critical applications. Rocket ships, el substations, airliners, etc design, successfully, for lightning mitigation.
Anyway, my first step in the "I don't want to die/sink", is to give lightning a place to go, besides thru my hull(s) and thru my body. to that end, I provide a thick, and straightish path to the sea surface. Yes, this induction you speak of, is significant and even protected electronics will still go away in a flash. But, its not going to shoot thru my hull(s), like the 30kA strike current. I'm in the lightning belt of FL, and not many other tall things around to compete for hits. Savvy??

[Chotu]

Originally Posted by Redreuben

@Chotu; I’m assuming being an epoxy construction the hulls are also foam cored or core of some sort ?
Was any reinforcement incorporated in the lay up in way of the chainplates ?
If not then your going to have to do epoxy work even to install stainless chainplates are you not ?

Yes. The hulls were set up from the start ready for the chain plates. There is special core material involved where the chain plates go.

But yes. Epoxy work.

Frightening to have that anywhere around the boat at all, but, if it is painted over with polyester at the end, it will be sealed away from me.

[Jopinot]

Originally Posted by GRIT

That's all true. But silver is a better conductor than copper, and for most things, due to silver's cost, copper is good enough.

I respectfully submit that stainless, monel, or bronze, would be a more appropriate choice, given that most of us build on a budget.

If Titanium were easily acquired, and cost efficient, we'd see many more boats out there with titanium chainplates, rudder shafts, and prop shafts. I'd think the latter two uses would have a better argument for using titanium, but it never happens. There's far more chance of them corroding than the chainplate. Yet, I only ever see titanium chainplates, as bling I suppose.

I'd bet that bronze would be a very good choice as well, but it's not as clean, and doesn't shine as well as stainless and titanium, which I'd suggest is another reason it's not used for chainplates anymore. I'd bet the cost is much less than titanium, and about twice the price of stainless for the raw material. But it's softer, easier to work and seems to last forever.

PS, for those using bronze, it's better to use barstock than try to cast your own.

Horses for courses.

Cheers.
Paul.

I’d choose any of the above metals over composite as the life cost advantage is clear and no special requirements for oversized fasteners to reduce point loading.
Any Duplex stainless grade (2205 is most common) usually will likely be the best overall mechanical/corrosion performance option for this application. You can probably loose some weight over 316 as well. Over priced Waterjet cutting is not required unless you’re building rocket sails. A simple laser job with undersized holes for drilling to size (if you’re paranoid about heat processed holes) and a final passivation after your cosmetic surgery of choice.
If your talking AC boat chainplates then printed Unobtainium is the solution of choice😜

[Chotu]

Originally Posted by team karst

Sounds too fatalistic for me. My job is to actually protect electronics from lightning and other mayhem in critical applications. Rocket ships, el substations, airliners, etc design, successfully, for lightning mitigation.
Anyway, my first step in the "I don't want to die/sink", is to give lightning a place to go, besides thru my hull(s) and thru my body. to that end, I provide a thick, and straightish path to the sea surface. Yes, this induction you speak of, is significant and even protected electronics will still go away in a flash. But, its not going to shoot thru my hull(s), like the 30kA strike current. I'm in the lightning belt of FL, and not many other tall things around to compete for hits. Savvy??

So you have a lightning strike dissipation plate externally outside the hull all this is bonded to?

And it won’t heat up and melt the boat below the waterline?

Do you have stainless rigging and an aluminum mast?

Not sure which is a better conductor. I forget. But the path to your mast base is shorter and the there is a lot more aluminum than steel wire to help conduct the main strike better.

So as it dumps out of your mast made on deck, where do you go with it? Do you attempt to send it to the hulls or do you have a plate to attach to the mast and drop through a hole in the bridgedeck to the water?

Because anything short of dropping a high amp capable cable from the mast base straight to the water isn’t going to make the lightning do anything. You can’t really wire it around corners if it doesn’t want to go.

That’s why I think this is an area to just leave alone. It’s going where it wants despite our efforts to try and control it. And... it can do so via induction.

[Chotu]

Originally Posted by Jopinot

I’d choose any of the above metals over composite as the life cost advantage is clear and no special requirements for oversized fasteners to reduce point loading.
Any Duplex stainless grade (2205 is most common) usually will likely be the best overall mechanical/corrosion performance option for this application. You can probably loose some weight over 316 as well. Over priced Waterjet cutting is not required unless you’re building rocket sails. A simple laser job with undersized holes for drilling to size (if you’re paranoid about heat processed holes) and a final passivation after your cosmetic surgery of choice.
If your talking AC boat chainplates then printed Unobtainium is the solution of choice😜

I like these ideas, but are you another one who doesn’t understand what a composite chain plate is?

Why are you talking about oversized fasteners being a problem with composite chain plates?

[team karst]

Originally Posted by Chotu

So you have a lightning strike dissipation plate externally outside the hull all this is bonded to?

And it won’t heat up and melt the boat below the waterline?

Do you have stainless rigging and an aluminum mast?

.

dissipation device is just above W/L; which is where the bolt is headed.

My 1/2" SiBr HW may heat up, OK.... It won't melt. Strikes are ~ 100uS in duration. and there are several in series, true.

12mm 1x19 rigging; definitely won't hit 3500 deg melting point...

The bolt wants to hit that surface charge on the water's surface. Not buried deep. It will get there, no matter what you do. So, providing a path with >> better conductivity than air, means, it will take it.. If your path is a carbon fiber mast or Al mast, or whatever, means it is very likely to sustain the full current, and its headed down. My plan is to give every stay a clean shot at a non-destructive path to seawater. No plan is 100%; but a mast that stops 5' from seawater will leave that poor lightning bolt no choice but to elevate that mast-end voltage to levels that will either make the air jump to ocean, or make a carbon path in epoxy/poly/whatever plastic you pick for a crossmember in the area. We are talking perhaps 10kV/cm levels. Even the Raymarine equipment wont handle that. No bueno...

[Redreuben]

@Chotu if you haven’t already have a browse around boat design net.
I think there is a thread in fibreglass and composite boat building. [emoji106][emoji2]

[Chotu]

Originally Posted by Redreuben

@Chotu if you haven’t already have a browse around boat design net.
I think there is a thread in fibreglass and composite boat building. [emoji106][emoji2]

I appreciate the thought, but for what?

This thread is me asking which chain plates I should go with. Composite or stainless. Those are the ones I have the plans for. I have many factors involved in the decision.

No offense, but at this point I feel like smashing my head against a brick wall.

Nobody reads anything. Can we close the thread?

Stainless won the poll and most of the people voting for stainless did read the thread, I think. Everyone knows composite is superior, but they considered the factors I listed and probably said stainless is good enough. I’m probably in agreement with them.

Stay tuned for the really big thread coming up within a couple weeks where we really get a lot more open ended with things. I’ll call it “let’s rig the boat”

I’ve got a mast that needs a 6ft extension and a lot of factors going into it. Should be a big crazy design thread like the davits one.

[Redreuben]

If your the full bottle on the pros and cons then what do you need us for ?
How about you tell us what design it is.
Ok I’ll help, if it’s a Wharram then composite is lipstick on a pig.
If it’s a Grainger or Schionning then stainless is “but for a ha’penny of tar the job were ruined”

The rig is relevant, if your going stainless wire then stainless chainplates make sense.
If your going textile rigging then why are you even considering stainless chainplates ?

[Redreuben]

P.S. You might find a good post cure at elevated temperatures might help the allergy, talk to resin suppliers.
If the boat is already epoxy then really composite chainplates is moot.
Your already in the fire.