Layup schedule help

I see the issue. The beam I gave is the beam for the entire boat. The beam of the main hull is 3.5 ft at DWL. The design also specifies hull stringers such that there's no span over 20". I attached a pic from the design .. is this enough information?

 

What is the spacing between frames/bulkhead?

 

My understanding is that for foam there are two bulkheads that span all three hulls. Do you need the spacing between them? I don't believe there are any other frames.

 

In the picture the distance between those two bulkheads is 8' 8 1\2" at DWL

 

I've slogged through this whole thread and it sure seems like a total clusteruck. A lot of guessing and some mis-numbers. Mixing inches and metrics, ozs and grams.

The above is wrong. Here is the chart you posted. A DBM 1715 is 17 oz per sq yd fabrics and 1.5 oz PER SQ FT mat. That means it has 13.5 ozs of mat per square yd, which is not 50 gr/m2 but 382 gr/yd2. And a square meter being even bigger than a square yard, there would be even more than 382 grams CSM per square meter.

 

Making this two posts as it is easier.

Elsewhere (post #84) you stated...

According to this chart, (Fiberglass Boatbuilding for Amateurs- Ken Hankinson) 1.5 oz CSM has a finished thickness of .045 inches or in metrics, 1.143 mm. and that combined with a weight of more than 382 grms a sq meter, would seem to indicate all 3 layers of 1.5 oz mat would be very structural and to eliminate or substitute them would require further 'ciphering'.

Now, it is a distinct possibility I may have made some basic mistake here, but I don't think so.

 

Yeah, but even you had an error sam sam in just two posts on it.

Read 382 g/yd^2 in the first post. That was sort of right, but then you carried it as 382 g/m^2 in post two. It is more like 450 g/m^2. If you back out the 17oz glass weight, 448 of I did the math right at ten minutes to midnite. I guess you said more than 382....perhaps you just skipped the comversion..

The thread got confusing when it was decided a 31.2 oz fabric was equivalent strength to a 17 oz fabric. Not to be a nit, but 14.2 ounces is the actual weight of the csm per your document.

Now, all that said, I pointed out the error long ago, albeit poorly, and your main point is highly valid.

I will continue to be the curious idiot here.

 

No, I didn't bother reconverting back and forth between the confusing numbers, that's why I said "And a square meter being even bigger than a square yard, there would be even more than 382 grams CSM per square meter." Apparently that number would be 448. I didn't want to calculate how much bigger a meter is compared to a yard and then recalculate how many more grams were in a msq meter compared to a sq yard.

I know you pointed that out before and it was just kind of missed, flattened over and ignored. Almost from the start there is confusion about the mat, in post #96 you ask again, fairly plainly as far as I can see and are unequivocally shut down with wrong numbers based on wrong assumptions. CSM weights are based on square foot, not square yard.

The whole post is full of misinformation. Terms are misapplied, numbers are mis-read and mis-stated.The OP says in post #5,

If you go to the chart he furnishes and pop in DBM1708 (Thinner than 1715) you get a laminate thickness of .125 ". WTF is he talking about with .077?

That was the basic reason for my post, not to be exactly exact on the actual numbers, but that a serious miscalculation was afoot in figuring out the lamination schedule for a fairly technical lamination.

After 112 posts, It's hard to see what has been accomplished here but it's easy to see how big problems may have been caused.

 

Thanks for the input Sam Sam. I have no experience with laminate schedules or the modification of thereof. I started this thread because my understanding of the laminate schedule covered the use of polyester resins. The use of epoxy is supposed to provide better adhesion than polyester. I was hoping to be able to re-evaluate focusing soley on the use of epoxy. It seems there is a lot of weight in the mat. No harm done it seemed there isn't a clear cut answer to be found. I'm going to purchase materials in the fall. I will consult with them on the schedule. Thanks.

 

Understanding EH is the designer and that he won't help modify the schedule is important here.

I would NOT accept a supplier recommendation.

You would be far better off hiring a known designer willing to modify the design with a fee.

At that time; he will tell you that the boat will be above her lines and he might be able to advise a plan regarding.

I realize you have had a fair share of uncertainty on this thread, but suppliers are not the way to go here. I am struggling with an issue and suppliers this far have only added to questions.

The supplier won't be as good in the event of insurance or resale as a consultants letter in your file.

 

It sort of depends at what level the support is coming from. If you're relying on the guy behind the counter at your local store that sells some FG supplies, then the info for very basic stuff "might" be OK, move up to one of the larger distributors and it will get better, a distributor like Composites One may line you up with the actual manufacturer of the glass, resin, core, etc.
Many of the manufacturers have great programs in place to support customers, they can answer questions like these easily, Vectorply will give you a couple of options on a laminate schedule depending on you're exact requirements or preferences for the job.

 

Ondarvr, if the support is a salesman I'll pass. Sam Sam you need to input the material and desired thickness into that calculator. 1715 is not a selection .. but if you choose 1708 and a thickness of .077 the result will indicate 2 layers are required. I am GUESSING that a single layer of 1715 would meet the .077 specification. I tried scanning the schedule as a PDF and this site says it's too large. I'll try to reduce it somehow.

 

Ok layup attached as jpg.

 

I see now how that chart works, and that it is inter-actional in what seems an odd way. Using xxxx as the material it will tell you how many layers you will need for a given thickness. For DBM 1708, up to .048 inches you need 1 layer. From .049 to .096 inches you need 2 layers, etc.

They could have just skipped the interactive part and just listed how thick one layer of each of the fabrics listed would be, and then you could add and subtract on your own, which you end up doing anyway.

As an example, for the thickness you want, .o77, it says you need two layers of 1708. But that ends up to be .096 inches thick, .019" more than you need.

Or, if you needed a laminate .048" thick, it would say 1 layer. If you needed it just .001" thicker, .049", it would say 2 layers, almost doubling the actual thickness just to gain 2% needed thickness.

For thick laminations the chart would be sort of ok, but for thin ones such as you're doing it seems to be a little crude. If you fart around and find out the numbers of what each layer of each fabric listed actually is, it could be alright. Assuming they use correct numbers to begin with.

It would have been easier just to post another chart, but I wanted to explain this one in case you use it more, you will understand it's limitations.

 

To make your last chart readable, for me at least, click on it, it goes to another window, then click on the expand arrow at the top right corner, and then click again on the chart.

To come up with an alternative schedule is beyond my abilities, but there are others here who can. For instance, it's generally said that CSM isn't needed with epoxy and that's more than likely true, but CSM has actual properties that differ from woven type fabrics, stiffness being one, being an interface is another, waterproofness is another, and whether or not those properties are needed in the structure, or which ones are needed if not all of them, and how to substitute different materials and compensate for them using intuitive experience or mathematical formulas, well I can't figure out how to end the sentence but you get the picture. And it's not just the fabrics, the resins have much different properties.