Any example of a 60 footer laminate?

[Gades]

I'm reading through the Scantling Determination at Larsson, and for their 40 footer they give the following laminate:


50% CSM + 50% WR ; Wf = 39%


Will any of you share the laminate for a bigger boat?

Thanks

Fernando

[Polarity]

Hi Fernando.

Did you see the GL rules all now on line for 6-24 m boats? here:http://www.germanlloyd.org/infoServi...ish/glrp-e.pdf

Also do you have a copy of Dashews book "The cuising encyclopedia" I think that has grp scantlings/ laminate schedule for their strongly built yachts, (56 ft +) if not let me know I can probably help out..

Paul

[Gades]

Hi Paul,

I'm not suing GL, I prefer ABS cause it's simpler. Even I've got the GL CD with its own software; it seems that you've got to design and calculate the whole thing to get into the scantling. I mean, like you need to know everything about the keel bolts (I made this up, I don't remember exactly what happens with the keel bolts) to calculate their diameter.

What I'm looking for is not an example of how to calculate; but a final result, so that I can compare with my results. It's something as short as a single line.

If you think you've got one, could you share it please? (either posting here or PMing or e-mailing, as you prefer).

Thanks again Paul

[Polarity]

OK Will do, give me a day or so...

Paul

[gonzo]

What are you laminating with? What kind of framing or structure do you have? Seems like you want a quick answer without having to think about it. Usually that ends up in disaster. Also, what kind of service will the boat have? What kind of power? Every one of these variables will change the scantlings.

[Tim Dunn]

The more framing you have, the thinner the laminate can be. I have a copy of "Boat Strength" by Dave Gerr. He uses the height of the hull, from gunnel to bottom of the hull (not keel) as a major factor in determining scantlings. A 70' sailboat with a 7 foot height (gunnel to depth of hull, excluding keel) requires only a 1/2" thick mat/roving/mat hull, six layers of the usual 24 oz. roving and, I think, 8 oz. mat. will do this. But---his rule requires lots of fiberglass frames and structural bulkheads, and some stringers, with wood cores where there are point loads, like keelboats and engine beds.

In comparison, a 34' offshore keelboat I had in the 70's had a least hull thickness of 1/2", mat/roving/mat. But, it was reinforced only by glassing the bulkheads and furnishings to the hull (with a bit of a gap, to make the reinforcing a bit flexible.)

In general, a boat with a core of foam or balsa will have about half as much glass in it as a solid laminate.

Also, exotics, such as all vinylester resin, or better yet, all epoxy resin, all tri-axial matt/roving, "s" instead of "e" glass, etc. reduces this requirement.

[gonzo]

There is a inverse relation between laminate thickness and framing as you say. However, there are methods of construction that rely on flexibility instead of rigidity. It is a very different approach that also works well. Gerr has the formula for those scantlings too.

[Tim Dunn]

Gonzo, where? On what page number does each rule start? As I read Gerr, he has rules for cored hulls, and for solid laminate hulls. The framing is the same for each, and the framing is the industry standard--stiff framing and bulkheads, but designed so that bulkheads have a foam fillet between them and the hull, so that there can be a bit of flex at that point.

[gonzo]

I'll check and let you know.

[SailDesign]

Service and performance characteristics are going to play a laaaaaaarge part in the scantling determination. Can you give us some idea of whether we're building a Ferrari, a LandRover, or an Escort?

[gonzo]

Tim, look on page 162 of Gerr's book. It is Linday Lord's method developed in the late '40s.