How many layers of fiberglass?

[Ad Hoc]

..... I never said 1708 was a mistake, ...

Oh...so what does this mean then?

How can one claim that laminate is sufficient when the conditions in which the catamaran will sail are unknown?

Sure sounds like it to me.

So, again....if you have such negative thoughts/feelings/impression of the comment/suggest given....rather than just criticising others.....please state what you think the laminate should be.
Since you clearly have very very strong opines about it, ergo, you must know better....please state so and why.

... I will refrain from replying to you further in this thread....

Oh how I wish, But.....Well, you can't can you....as you still keep replying because you cannot answer the question, yet protestating otherwise.

 

[fallguy]

This is the classic case of deciding not to contribute or not being able to and then becoming upset when others step up.

At least my disagreement with old wisdom was substantive and not shush, nor offensive.

I still say 2 min layers with local reinforcing as needed and up to 3 if it can make her lines

Most likely, the OP has never returned.

 

[TANSL]

@fallguy, I assume you're referring to me, and therefore I'll try to answer you.
I'm not angry with anyone; I don't know why you assume that. I'm just saying that I think it's wrong to give answers with the information we have.
It's not that I don't want to contribute; it's simply that, with the information we have, I'm unable to provide a valid answer. I don't know the boat's structure, nor do I know how it will be used. I can't identify the problems that structure might face, and therefore I'm unable to offer a valid solution. If that's a sin, fine, I'm a sinner.

 

[fallguy]

@fallguy, I assume you're referring to me, and therefore I'll try to answer you.
I'm not angry with anyone; I don't know why you assume that. I'm just saying that I think it's wrong to give answers with the information we have.
It's not that I don't want to contribute; it's simply that, with the information we have, I'm unable to provide a valid answer. I don't know the boat's structure, nor do I know how it will be used. I can't identify the problems that structure might face, and therefore I'm unable to offer a valid solution. If that's a sin, fine, I'm a sinner.

We have descended into a likely place on this thread because the OP never followed up. The OP said the hull skin was the only structure. It is in black and white. Now, we can expect this to be a bit of an error, but ftmp, this was how we went forward. I say a bit of an error because a catamaran has a beam or two and attachments and some propulsion even. He also said 1708, which we assume he has available and constrains us. For me, I’d want two layers of 1708 if no other option; three if waterlines would be made. A much wiser man than me said one would work.

Then you really went after him for it to drive home your idea ‘not enough information’. But ambiguity is common here. And so, make your own point and position, but for a 1.5 meter model boat; give your position a rest. Attacking someone else for offering how to build a model too small to board is rather silly.

If the guy builds a single skin craft without local reinforcing and glues on a 2x4 and attempts to cross to Andros from Turkey; it is hardly our fault.

 

[Ad Hoc]

This is the classic case of deciding not to contribute or not being able to and then becoming upset when others step up....

Indeed!!

.... For me, I’d want two layers of 1708 if no other option; three if waterlines would be made. A much wiser man than me said one would work....

Indeed.
FYI
...the small dinghies i sailed in as a teenager, had merely 1 or 2 layers of CSM at most, and that was it.
Not rocket science and not much bigger than me in size....don't crack a walnut with a nuclear warhead.

 

[rxcomposite]

I will say that, just as you are surrounded by great boat engineers and designers, I have always been surrounded by doctors (my ex-wife, two of my brothers-in-law, one of my brothers, several of my best friends), and you won't hear me claim to know how to cure the sick. Knowledge and experience are not transmitted by osmosis, my friend, from one organism to another. You have to work hard to acquire them.

It is also called “inductive learning” when you are close to the intelligent people discussing it. An “inference” where you form your own conclusion learning from them.

And when the engineers do the heavy lifting and hands you over the blueprint because you are the “go to guy”, you are involved and can imply you participated in “brainstorming”

When you are in an aerospace environment where they are discussing, you can say that you build the product that went to the moon.

 

[montero]

List of missions to the Moon - Wikipedia

en.wikipedia.org

 

[TANSL]

I hope, Mr. Moderator, that you won't censor this response, as you did with my previous post, since it's similar to another participant's in this thread.

When you are in a boatbuilding environment where they are discussing, you can say that you build the product that went to the water.

 

[ondarvr]

It is also called “inductive learning” when you are close to the intelligent people discussing it. An “inference” where you form your own conclusion learning from them.

And when the engineers do the heavy lifting and hands you over the blueprint because you are the “go to guy”, you are involved and can imply you participated in “brainstorming”

When you are in an aerospace environment where they are discussing, you can say that you build the product that went to the moon.

I think I remember someone recommending what to add to resin to achieve a certain property. That person was completely wrong and had no understanding of what they were saying, but said they had "been in the room" so to speak when stuff was added.

My in the room comments do not mean I think I'm an engineer, not even close. What it means is I'm involved in many projects that cover just about all aspects of composites and products made with them. I'm not restricted to just marine applications, or certain size range builds. Nor methods of production.

The marine stuff discussed here is a smaller part of the space I work in now, and I'm bouncing from one market segment to another several times per day. This allows me to have a far broader overview of what goes on in the composites world than most in the industry.

Working with these engineers gives me insight as to how that industry thinks and the language they speak. And different industries have very different priorities in how the product needs to be built to achieve their specific goals.

So when someone asks about laminate thickness for what is basically an RC boat, and I have first hand knowledge of it, it's probably OK for me to have an opinion. Absolute worst case scenario they build a prototype and learn they need to make some adjustments, which is very common when building something new.

I have worked extensively in the filament winding tank world, with a great deal of that in the high pressure style tanks area, some of my build methods were patented. I have also worked with companies making submarines. Would I give advice to someone filament winding a submarine for deep water exploration, absolutely not. Well, that's not true, I'd tell them to find an engineer qualified to do that type of work and walk away.

Have you worked with Blue Origin, SpaceX, L3 Harris, Desault jet, Boeing, etc, and their many subcontractors? Then the next conversation is with a bush pilot in Alaska building custom lightweight parts for his plane and for others. Its a very different conversation.

 

[Boat Design Net Moderator]

I hope, Mr. Moderator, that you won't censor this response, as you did with my previous post, since it's similar to another participant's in this thread.

The forum is not a place for people to simply jab at other members. If you want to post a jab at another member, please do not post it. Thank you.

 

[TANSL]

The forum is not a place for people to simply jab at other members. If you want to post a jab at another member, please do not post it. Thank you.

Frankly, I have seen people on this forum, on numerous occasions, taking potshots at one another or explicitly telling others that they had no idea what they were talking about on a particular subject. I believe that, provided the appropriate degree of civility is maintained, this is perfectly admissible on a forum of this technical calibre, where we are constantly expressing opinions on subjects that we do not necessarily know very well.

I am even being urged to respond, despite my repeatedly explaining that I neither can nor should do so. Are they having a go at me?

I sincerely do not believe that stating that certain experiences or areas of knowledge are, in my opinion, insufficient to enable someone to give sound advice on hull engineering—however small or simple the hulls in question may be—is in itself objectionable. I believe I have expressed this politely. But when something is truly preposterous, why should my response not be equally forthright?

Thank you for not censoring me.

 

[Boat Design Net Moderator]

telling others that they had no idea what they were talking about on a particular subject. I believe that, provided the appropriate degree of civility is maintained, this is perfectly admissible on a forum of this technical calibre,

If you have time to reply, maybe it would make the thread more interesting at this point (or at least until the OP replies with more actual details to discuss) to refocus this thread to a theoretical question:

I know, understand, and agree with your previous argument that you would not specify a laminate schedule for a real boat with so little information -- I don't think anyone here is arguing your point there.

However I think people found ondarvr's post 2 to be thought provoking and interesting to think about.

It would be interesting to know, if you feel that 1 layer is definitely not correct -- what would you hypothesize the minimum theoretical limit is for minimum thickness fiberglass or 1708 layer count for a model-size catamaran hull "5.25 feet long, 0.7 feet wide, and 1.48 feet tall" if you design the optimal shape to minimize fiberglass thickness? (assuming there will also be additional reinforcement for specific load points.)

 

[TANSL]

I don’t know how else to explain it, but I will try one more time.

I am not saying that ondarrvr’s answer is incorrect; it is impossible to know that. What I am saying is that I find it unprofessional to give such a specific answer without having been able to analyze the multiple variables that influence the scantling of a structure.

I find it highly unprofessional to give a definitive answer to a problem for which we simply do not have the necessary information or the elements required to analyze it properly.

I believe—and I am convinced—that anyone with experience in scantling boats will agree with me.

I do not know whether a 1708 layer is too much or too little. I simply do not know, and that is precisely why I am not criticizing that specification or recommending any other. And, once again, and hopefully for the last time, it is not possible to give a professional and honest answer without knowing, for example, what reinforcements the structure has or what the dimensions of the panel we are talking about are.

Is that really so difficult to understand? Does saying this mean that I am disparaging anyone? I don’t believe so.
Is it so difficult to say: "give me more data and I will give you a technically correct answer suitable for your project?". Is it necessary to answer, even if the answer has no basis, to appear to be great experts? (in fact, answering indicates that we are not.)

Thank you for your time. I will repeat, for the last time, what I have already said on multiple occasions: we cannot, and we should not, give an answer when we do not have the information necessary to support it.

 

[Boat Design Net Moderator]

I don't see anything wrong with your post above. And I don't disagree, as I didn't disagree previously.

But, especially when there is not enough detail for an answer or when a project is at an early stage, I think it can be interesting and thought provoking when people share similar projects and ideas to think about at a preliminary stage (with the clear disclaimers/qualifications already given.)

 

[rxcomposite]

I have been a member here since 2005. In the early days, members often jab at each other. Often hilarious and makes for interesting read. I learned much and developed professionally from this forum so I am not letting go. I am proud to be a member.

This BD.Net forum is big and has some very notable members. I am in awe and when they talk, I listen. Though they sometimes hide in their avatar and uses handles to conceal their identity, there are some who are truly knowledgeable and intelligent individuals. With the advent of AI, I searched most of them. Oftentimes, their company, positions, educational attainments, articles written, research papers, associations, experience and even the date they joined Boat Design Net. Creepy but they cannot hide. If you use the Net, AI will see you.

I dread the day when I find a member is an AI.

Lately, I have noticed that some members have their ego bloated because a number of members have positively responded to their post. They are treating the forum as their own fiefdom and you do not dare upstage them. Then I also use the AI. Oftentimes, their claim to their greatness is the self-serving accomplishment posted in the BD Forum. Nothing much, no company affiliations, no titles, no nothing. AI can only see what is in the wide world of the net.

However, nothing beats a personal investigation if something seems not right.

A member once claimed he participates in the “brainstorming” session of our company. I called my overseas boss to ask if he is an employee. My boss said “Naah. Must be another salesman”.

Another, a member who is belittling a marine article written by an author with a Doctorate degree (who happens to be my friend). I showed him the article and he said, he is seeing it as he is a member of the forum, just using a different name/handle. As a true professional, he did not bother to respond.