Skantling rules for 37' (Frp) cruiser

[ratrace2]

OK, really stupid, idiot question:
Do I need, have to apply, give lip service to, or otherwise consider skantling rules for a 37' Frp cruiser?

[Willallison]

OK, really stupid, idiot question:


...Well, you said it!;)
A little more info perhaps might extract a more sensible answer... why do you want to know - what are you trying to do?

[Landlubber]

ratrace2,

Yes mate, every vessel built needs to be constructed in a safe manner , suitable for the purpose of the design. What you are considering is an offshore vessel, it particularly would need to be built to at least the minimum scantling requirements.

There are dozens of scantling rules, but basically they have all been written from both practical experiences and engineered design parameters by naval architects.

We build private vessels in Australia to two commercial codes presently, the old USLC (Uniform Shipping Laws Code) and the new NSCV (National Standard for Commercial Vessels). The USLC will eventually be entirely replaced.

We also build to ABYC Standard recommendations.

If you want to read some info on glass structural scantlings, try the Germanisher Lloyds web site, it is very easily followed and easy to find.
http://www.gl-group.com/rulestandard/3494.htm

Hope this helps a bit.

[ratrace2]

ratrace2,

Yes mate, every vessel built needs to be constructed in a safe manner , suitable for the purpose of the design. What you are considering is an offshore vessel, it particularly would need to be built to at least the minimum scantling requirements.

There are dozens of scantling rules, but basically they have all been written from both practical experiences and engineered design parameters by naval architects.

We build private vessels in Australia to two commercial codes presently, the old USLC (Uniform Shipping Laws Code) and the new NSCV (National Standard for Commercial Vessels). The USLC will eventually be entirely replaced.

We also build to ABYC Standard recommendations.

If you want to read some info on glass structural scantlings, try the Germanisher Lloyds web site, it is very easily followed and easy to find.
http://www.gl-group.com/rulestandard/3494.htm

Hope this helps a bit.

LL,
that helps alot and as always, right on point. Great, I'll go read up on this topic for a while. Hey, LL, remember the WWII Echo class PT boats. 80 ft'ers
What ya'think of their design......
Regards, rat

[ratrace2]

...Well, you said it!;)
A little more info perhaps might extract a more sensible answer... why do you want to know - what are you trying to do?
WA,
well, on the one hand, I'm just trying to make sure that "I know what I do not know"; on the other hand, I have some questions regarding stringer design, spacing, materials. Because, if, and only if, I have a sound design strategy for this thing I'm contemplating will I go forward. I working on another set of questions to satisfy the sections of "ratrace2's need to know book" before he makes a big mess, hurts someone, or just gets it wrong. In other words, don't want to build something that performs poorly, is unsafe or just bad design and ugly.
For example, I'm considering using aluminium stringers epoxied to the hull (after the NA signs off on the layup schedule). Engine mounts will be on aluminium racks, Salon will have an aluminium frame, that bolts to the subframe in the hull......welded together..basically an aluminium skeleton skinned with FRP..

[ratrace2]

LL,
Ok. what'am I looking for????:confused:

[Landlubber]

Hey you donkey, whatever section is is that you are interested in, what is it mate that you really want to know, specifically.

[ratrace2]

haha...I'm a donkey now.....OK.
I don't know, you tell me. All I see is stuff about 400' Container ships.
Where is the part that applies to 37' Frp cruisers....ruuuuuu:)

[Landlubber]

Hi mate, You need to let me know mate what it is you are looking for, do you want to know how many stringers, what size, how thick, what is it you are trying to find out. I hope that you are not just trying to avoid designer fees or something.

NA's get paid for their information, just as you get paid fpor whatever you do, follow the process and all will be revealed.

[waikikin]

Great advice for you Ratrace2 from Lubber, good design information saves you time, $$ & weight in structure by eliminating guesswork with experience & engineering so in the end you get a better boat that goes faster that you get sooner for less cost & better resale potential in the future. All the best in your endeavours from Jeff.

[ratrace2]

Hi mate, You need to let me know mate what it is you are looking for, do you want to know how many stringers, what size, how thick, what is it you are trying to find out. I hope that you are not just trying to avoid designer fees or something.

NA's get paid for their information, just as you get paid fpor whatever you do, follow the process and all will be revealed.
Landlubber, You are the best, bud.
I just want to develop good judgement about boat construction. I want to know the rules for a class of boats, i.e. 24' to 70' Frp boats.
So when I think about doing something like using aluminium stringer inside an FRP hull--no wood allowed--I can think about it in an intelligent way, not just wonder.
Also, insurance companies, and surveyors--Wakikin, I listened and undertood every word you said, you make a great point--I won't get into trouble.
Right now, I don't know enough to even talk to an NA....

[PAR]

"Elements of Boat Strength" by Dave Geer, will answer many of your questions, though an understanding of marine design and engineering practices will make the book more useful.

[ratrace2]

"Elements of Boat Strength" by Dave Geer, will answer many of your questions, though an understanding of marine design and engineering practices will make the book more useful.
Par,
thanks alot, bud (mate). Right, there are a couple of books by Geer that I want to get and also, "Fiberglass Boat Design and Construction" by Robert J. Scott is on my short list of things to study.
Right now, I'm just sort of trying to get the big picture, ya know: things we need to know, "the big categories".....i.e: Molds, FRP, Scantling, Hull Design, Engines are next.....that should be fun...
Have you read Geer's prop book...... Also, can you point me in the direction of good "survey" type material on Marine design and Engineering that you like..

[PAR]

Books are nice, but the thing you have to ask yourself and most importantly provide a truly honest answer to, is "can I be an engineer?" If you didn't have a good time with advanced high school math, then you're going to have difficulty with the and engineering elements of the process.

There are two types of brain wiring systems, with an occasional third, but it's rare. Most folks are analytically or philosophically inclined. Quite rarely a person is both, which is much more common among women, but some men are as well, because I'm one. A philosophically oriented person will pull their hair out, trying to absorb the engineering end of yacht design. An analytically minded person will not understand the subtle differences between a Phil Rhodes sheer and one done by L.F. Herreshoff, nor why it's an important distinction, though they may enjoy the clever arrangement of shelf and clamp supporting it's loveliness.

So, how well did you do in high school algebra, Ratrace?

[ratrace2]

Books are nice, but the thing you have to ask yourself and most importantly provide a truly honest answer to, is "can I be an engineer?" If you didn't have a good time with advanced high school math, then you're going to have difficulty with the and engineering elements of the process.

There are two types of brain wiring systems, with an occasional third, but it's rare. Most folks are analytically or philosophically inclined. Quite rarely a person is both, which is much more common among women, but some men are as well, because I'm one. A philosophically oriented person will pull their hair out, trying to absorb the engineering end of yacht design. An analytically minded person will not understand the subtle differences between a Phil Rhodes sheer and one done by L.F. Herreshoff, nor why it's an important distinction, though they may enjoy the clever arrangement of shelf and clamp supporting it's loveliness.

So, how well did you do in high school algebra, Ratrace?
Par,
Interesting parallels; personally, I like to think "top down". I like to survey the entire field of study and then work my way down to the molecular structure of the resin and modulus properties of different aluminium and it's reaction with an Frp/Grp structure.

Oh, yea, "the Rhodes school" of design. It is loveliness; personally, I can draw and change the chines, add bow-thrusters, redesign the salon, rework the transom--hints of the Spanish Main--widen the beam, and go on and on and on like that. Also, I love to know what makes things tick......Just can't stand not to know. For example, I went to an autoparts store and asked the clerk at the counter "what is the micron level of filtration with this oil filter--it was about $3.95--they guy looked at me like, "hey it's just an oil filter". It is not I rebuked the sales guy. It serves a very specific purpose, I said.
Number crunching, not a problem; am I good at it, it is not what I want to do all day. That is why they have Naval Engineers.....I just make'em beautiful but even as a designer I still need to know/understand the medium that I'm working in. I use the engineer to pick up the slack for the things I'm not up to professional speed on, or just don't want to do all day.

Correction: I said, "but even as a designer" for rhetorical reasons and function of prose. I am not a professional designer of boats.

[limeyus]

ISO 12215 is getting to be the 'standard' for fiberglass boats up to 25m
The regular classification societies have pretty much got out of the small boat business.

[ratrace2]

Know where to find a copy of that wonderful International Standards Organizations' work. Those ISO boys just love tell you what to do...Well, that was easy, I just typed in ISO 12215 and they popped up...Such silly names

ISO 12215-6:2008
Small craft -- Hull construction and scantlings -- Part 6: Structural arrangements and details

Abstract

ISO 12215-6:2008 concerns structural details and structural components not explicitly included in ISO 12215-5, ISO 12215-7, ISO 12215-8 and ISO 12215-9. It applies to monohull and multihull small craft constructed from fibre reinforced plastics (FRP), aluminium or steel alloys, wood or other suitable boat building material, with a hull length, in accordance with ISO 8666, of up to 24 m.

ISO 12215-6:2008 fulfils two functions. Firstly, it supports ISO 12215-5 by providing further explanations and calculation procedures and formulae. Secondly, it gives a number of examples of arrangements and structural details which illustrate principles of good practice. These principles provide a standard against which alternative arrangements and structural details can be benchmarked, using the equivalence criteria specified in ISO 12215-6:2008.



ISO 12215-5:2008
Small craft -- Hull construction and scantlings -- Part 5: Design pressures for monohulls, design stresses, scantlings determination
Abstract

ISO 12215-5:2008 applies to the determination of design pressures and stresses, and to the determination of the scantlings, including internal structural members of monohull small craft constructed from fibre reinforced plastics, aluminium or steel alloys, glued wood or other suitable boat building material, with a length of hull in accordance with ISO 8666, between 2,5 m and 24 m.

It only applies to boats in the intact condition and to craft with a maximum speed equal to or less than 50 knots in fully loaded, ready for use conditions.