Lamination Schedule Order - Which cloth type should be used where?

[onlineentity]

I read that using roving or biaxial on the exterior-most surface provides greater strength but experience tells that CSM is the typical exterior cloth in a normal layup schedule for it's smoothness, so which is preferable on the use of a hull?

 

[TANSL]

@onlineentity , welcome to this forum.
If you study the transversal section of a laminated panel subjected to bending, in each of the layers that form it, direct stresses are produced (in addition to the tangential ones) that are proportional to the distance of each layer from the neutral axis of the section. This means that the central fibers are less loaded than the outer ones. That is, the outer fibers must be more resistant than the inner ones. Now, the warp of the fabrics will leave marks visible from the outside, which would have to be hidden (for appearance) or sanded until smooth. To prevent these traces from being seen, a couple of layers of lighter MATs are usually placed.

 

[onlineentity]

Makes sense thanks TANSL I figured a thinner outer layer of CSM works the best like an exterior surfacing veil. I can picture it as a water balloon and the weight of the forces of the contained liquid are most amplified at the skin's surface

 

[TANSL]

Direct stresses distribution in the thickness of a laminate

Sigma(z) = Bending Moment * Z/Ixx

 

[onlineentity]

There's 2 methods to this thing, field-grade and the paperwork backed kind. As I move toward production from my personal use small-scale fiberfodder, learning these specific mathematics and physics becomes greatly more important. It also frustrates me greatly that I am simply not at an educated level for this, out of my paygrade still as they say lol. Hopefully one of these days I can go back to school for engineering and get a lot more involved in these sort of behind the scenes numbers which truly makes things make or break

 

[onlineentity]

I wasn't supposed to graduate high school so I turned around and worked for a college a few years later.
Honestly the brain challenge appeals to me almost as much as having fun on the water at this point as a sort of backhanded lifestyle remarking to my troubled youth and what things my teachers said about me

 

[C. Dog]

@onlineentity mainstream schools present information in a certain manner and if you're in the minority who struggle with this system you are often rated as a lost cause, even if you have high intelligence. Maybe experiment yourself with some basic mathematics and see if you can find a way that works for you. Some do perfectly well with little education (actually training or indoctrination), just a good eye, good hand skills, good memory and artistic.

 

[fallguy]

There's 2 methods to this thing, field-grade and the paperwork backed kind. As I move toward production from my personal use small-scale fiberfodder, learning these specific mathematics and physics becomes greatly more important. It also frustrates me greatly that I am simply not at an educated level for this, out of my paygrade still as they say lol. Hopefully one of these days I can go back to school for engineering and get a lot more involved in these sort of behind the scenes numbers which truly makes things make or break

Longest tows further away from the core is a simpler way to understand it, notwithstanding the surfacing layers. I found out the hard way and had to reject a $1500 panel and make it into furniture.. If you understand my oversimplified longer tows out, then reread @TANSL more technical remark and it'll make even more sense.

To be clear, out does NOT mean out toward the outside of the hull, but out and away from the neutral axis...

 

[onlineentity]

@onlineentity mainstream schools present information in a certain manner and if you're in the minority who struggle with this system you are often rated as a lost cause, even if you have high intelligence. Maybe experiment yourself with some basic mathematics and see if you can find a way that works for you. Some do perfectly well with little education (actually training or indoctrination), just a good eye, good hand skills, good memory and artistic.

We have great opportunities in America when we refuse to relent in advancing toward them. It's been amazingly inviting and informative and welcoming for me in the boat industry as I come to the light that it casts. I came from the fine art industry which is fairly disastrous and based almost solely on public funding resulting in some very strange industry-wide attitudes at their helms. It's simply not as professional of a group as the boat industry mandates in so many ways but I value my time doing painting a ton still - taught me business skills, life lessons, and the hand eye skills you mentioned which come greatly in handy doing epoxy work in particular! Plus when it's time to paint a hull I can apply my longer term built skillset. Really look forward to continuation on my boat design work this year and hopefully many to come. I started off just winging it but that only gets one so far before the numbers become crucial. I'm not daunted by the workload at all though because I love it

 

[TANSL]

Probably at some point you feel that it could be interesting to carry out some calculation, some study, or simply ask for a professional opinion, to successfully get out of a complicated issue or to avoid serious problems in the future. Time, when you enjoy your work, is not a problem but having to rectify it usually costs not only time but also money. Not to mention the frustration you feel when you think that a serious problem could have been avoided.
If at any time you feel the need to turn to a technician, you can count on me.
Good luck on your boat projects.

 

[fallguy]

Don't pretend to be a composites engineer. They are a wealth of knowledge.

 

[onlineentity]

Don't pretend to be a composites engineer. They are a wealth of knowledge.

I don't think admitting ignorance and asking pertinent questions is pretending anything

 

[onlineentity]

After some thought I realized I've been practicing in the garage and back yard for 4yrs now I could have a degree even but I learned the hands-on way on my own and I don't think anything could have replaced that in retrospect. That's the field grade vs paperwork thing again I guess, and it is hard to have a mind for both. I'm definitely more well fit to the hands on atmosphere of it and respect that other people have different models of thinking which may become necessary for me to refer to, and appreciate the food for thought. Hopefully I have my first vessel surveyed later this year and have been in contact with coast guard for the MIC. This site has taught me tons over the past 4-5yrs

 

[onlineentity]

ended up here https://pdhonline.com/courses/m372/m372content.pdf