Composite Chainplates or External Stainless Chainplates?

[Narfi]

Does the designer not support his plans and help with interpretation? I would think that would be part of the deal.
I've never built anything so large, but all the plans I have purchased and built the designer was prompt with answering any questions I had regarding the plans.

[Chotu]

Originally Posted by Narfi

Does the designer not support his plans and help with interpretation? I would think that would be part of the deal.
I've never built anything so large, but all the plans I have purchased and built the designer was prompt with answering any questions I had regarding the plans.

The designer has abandoned me.

Maybe it’s time to just throw in the towel. I can beat the odds a lot of times but there is so much stacked against me in this endeavor, I’m losing it.

The designer would help someone who buys the boat, but not me.

[Narfi]

Originally Posted by Chotu

The designer would help someone who buys the boat, but not me.

As in personality conflicts? (you do have a strong personality )
Isn't there another builder here who built the same boat as you? Could he get the info you need from the designer?

Don't throw in the towel... even worst case, you know what is required for stainless and how to do it and perhaps that's not even a bad thing. One bite at a time, you have already consumed most of the carcass, don't stop now.

[Chotu]

Originally Posted by Narfi

As in personality conflicts? (you do have a strong personality )
Isn't there another builder here who built the same boat as you? Could he get the info you need from the designer?

Don't throw in the towel... even worst case, you know what is required for stainless and how to do it and perhaps that's not even a bad thing. One bite at a time, you have already consumed most of the carcass, don't stop now.

Yes, he has an even stronger personality. LOL There is bad blood between us.

There is another builder here who has already done all of this but I need remedial help on rigging this boat. As in... I can’t figure out the chain plates or the bow tube or how to do the rigging work in general from the plans.

I understand what the plans are showing, but can’t come up with a process to produce what they show.

But I’d feel awful asking him for all that help. He’s a nice guy trying to enjoy some time on his newly built boat. It’s a lot of work to explain all this and I just can’t ask him to. Because he’d probably do it. He’s a really good guy.

Trouble is, I’m just not hungry anymore. I’ve had enough years doing this. If there was a clear path to the end, I could persevere. There isn’t. Making wrong choices is very costly in terms of hours and dollars and I’m running a bit low on both. 80% of the stress in my life comes from this boat. That’s not good for my health after a heart attack. I like sailing. Not this

It sucks because there is so much done. Yet I’m stuck on the rigging of the boat. Was considering just leaving it a power cat to reduce stress but that takes away all the fun and the whole reason I built such a cool boat in the first place.

Sorry. Having a very off day here. But some realizations

[Matt Johnson]

Warning - the extent of my experience with composite chainplates is sailing aboard boats with them.

If nobody with proper credentials steps up to help interpret your plans, I'd be happy to give it a shot. I have two sets of designs for smaller cat's composite chainplates - that I dont feel comfortable sharing - but they may help me compare to yours to fill in the blanks.

I do have some real expert help that I can relay this question to as well if we're still lost.

Matt

[Chotu]

Originally Posted by Matt Johnson

Warning - the extent of my experience with composite chainplates is sailing aboard boats with them.

If nobody with proper credentials steps up to help interpret your plans, I'd be happy to give it a shot. I have two sets of designs for smaller cat's composite chainplates - that I dont feel comfortable sharing - but they may help me compare to yours to fill in the blanks.

I do have some real expert help that I can relay this question to as well if we're still lost.

Matt

Ok! That sounds great!

I’ll send you a private message about it.

It’s not that I don’t understand what’s on the plans. It’s more that I don’t understand the steps I need to take to make what’s on the plans.

The stainless ones are every bit as complicated as the composite ones (but in different ways) and involve wood. Something I’m not comfortable with structurally, in my boat.

[Matt Johnson]

Without seeing the plans, I'd guess the wood is a high density core replacement where the chainplates land. Typically, this can be done with 400kg/m3 foam for a 1:1 ratio to wood. Coosa 26 works well here.

Matt

[Chotu]

Originally Posted by Matt Johnson

Without seeing the plans, I'd guess the wood is a high density core replacement where the chainplates land. Typically, this can be done with 400kg/m3 foam for a 1:1 ratio to wood. Coosa 26 works well here.

Matt

Ah. No... the wood is part of the surface load spread setup on the stainless chainplate. I already have a high density Corecell in place where the chainplates go. I dropped that in during the construction of the hulls.

Which is why I am firmly in the camp of the composite chainplates now. I’d like to do these once and once only.

Sending some info to you today.

[Captain Bill]

My boat came with chrome plated bronze chainplates 1/2" thick. They are 20 years old now and still look new. No crevice corrosion worries and just as strong as stainless. I'm not sure about cost, but it might be an alternative to titanium or stainless.

[team karst]

Originally Posted by Captain Bill

My boat came with chrome plated bronze chainplates 1/2" thick. They are 20 years old now and still look new. No crevice corrosion worries and just as strong as stainless. I'm not sure about cost, but it might be an alternative to titanium or stainless.

yes, that's a credible option. however,watch the tensile strength differences. NOT the same.

316~ 150kpsi ultimate
Manganese bronze ~ 65kpsi; so, about 1/2 the strength; as noted, when new


I'm not against Bronze at all; in fact, what is the turnbuckle body made of ? And, the threads too!

to kill this horse; look up Ti tensile. you won't be impressed.

My 38 Lagoon, the cost sensitive pig that it is; has 3/4" 316 plate with 7x 12mm bolts in shear thru the hull to a similar sized back Al up plate.

[catsketcher]

Gday Chotu,

I am sorry to hear the project is getting you down. Having been through a few builds, I am very aware there is always a down time.

As to the chainplates - could you not be overthinking the whole thing? Uni glass or uni carbon laminate has a certain tensile strength. Other designs have had lots of chainplates that have not failed. You have a load that needs to be distributed throughout a bulkhead. There are important things to remember - not exceeding core shear strength, having no notches, getting good bonds. But it has all been done before - lots of times.

I reverse engineered my own composite chainplates back 22 years ago. I looked up the tensile strength of a low modulus uni carbon laminate. I measured the cross sectional area of an equivalent stainless chainplate. I then calculated the cross section required in carbon. Then laid up the carbon unis wet on wet (I was doing lots of vacuum bagging at the time but was happy just using a squeegee and peel ply). I fanned the unis out radially onto the inner hull skin and double bias on top.

The stainless chainplates have to get the load from them into your bulkhead. Composite chainplates are just better arranged to direct the loads without stress concentrations or load concentrators (bolts). Its like tying the shrouds onto the boat.

If you are worried by your current chainplates, you could just increase the laminate. I would be wary of thinking that the designers have had NASA get involved. There is probably a fair bit of over engineering and peer to peer engineering involved (copying boats that work). I find the Schionning type chainplates easy to understand and my friends found them easy to build and use. They use a "bridge" with stainless through it, that lots of 100mm wide uni tape is draped over and fanned out over. Pretty bulletproof and easy to understand - tapes splayed out each side/skin of a bulkhead.

When doing such heavy laminates I find that a slow and not hot epoxy is required - cool epoxy is a pain because it is hard to work in. So not cold but the last thing you want is the exotherm kicking the chainplate off before finishing. When my mate was building his large Schionning he worked really fast and consistently with all tapes precut and everything to hand before starting. He was able to lay up his 1320 chainplates with no worries. Again no vacuum, just lots of squeeging. Like all thick laminates, after two passes you can reduce the resin content as the previous layers are already wet in the overlapping areas but keep up resin in the ends of the tapes where they land on new bulkhead.

[TeddyDiver]

^ what he says..

[Chotu]

I don’t think I’m overthinking anything. Maybe with the other rigging stuff. I am lost on that. I’m going to open a new thread for that.

But, this thread was just a binary choice between stainless chain plates and composite chain plates. I think a lot of other people on the thread may have been overthinking things. But I sure haven’t.

Because I don’t like the plywood involved with distributing the loads in my stainless chain plate version of the plans, I’m going to go with the composite version. As you said. It just makes a lot more sense. It spreads the loads out properly. It’s like tying 1 million little strings to the side of the boat.

[Redreuben]

@Chotu; I think you have chosen the right path and I would agree with catsketcher about the laying up, look infusion is marvellous but it’s not essential, if you have the gear and the skills at hand then by all means infuse it but it’s not critical, experience laying carbon is though as it is a bit hmm deceptive ? to wet out.
I haven’t worked as a laminator in over 15 years so I’m not sure what the availability of infusion skilled laminators is like but I wouldn’t let it hold you back or unsettle your confidence in the job at hand.
Where in the world are you ?

[GRIT]

I've been away from the forum for a bit, and my keyboard has given up the ghost. Since I'm in the Bahamas, ill not replace it until I get back to the USA.

CHOTU, please call me, or write me. I've always got time for you, and would enjoy talking this through with you.

It's not as hard as the plans make out. I wouldn't, and didn't, infuse my chain plates because, that type of layup has a tendency to move the glass up to the top when debulking under vacuum, causing a void. It can be done, of course, but its prone to either having the glass ride up the stack, or leaving dry areas near the top if infused, as its so narrow up there. Vac bagging also encourages the glass to ride up the stack to the turn at the top, causing a void. Hand layup and rolling with a bubble buster is the way to go.

Happy to help, but I'm not on CF much these days. Please contact me directly.

Cheers all.
Paul.