Catamaran beams

[bob the builder]

hi all


building a catamaran, 31ft long, 14ft wide, strip plank, epoxy and glass. 1200Kg fully loaded for cruising, 30M2 sail all up.



need advice on aluminium cross beams for the;

1. front

2. and back. the transom (50Kg outboard hung in the middle)


instead of single round tube, wanna use two tubes, 60cm apart, one on top of the other, with welded webbing connecting them.




so then,
the question is,
who suggests what? (square, rectangular,or round)
and how thick should they be.


thank you for any advice,
mal.

[jamez]

Alloy tubes or mast sections can make great beams for a small cat, and your boat certainly is light for its length, but fabricating the way you suggest, I dunno, you may be better to consider a couple of wood and ply box-beams, glassed over; and a wood or alloy forebeam. A suggestion; Find a tube cat the size and config you want to build, buy the study plans and get the info from the materials list.

[jaydh]

mal,

An option is to bend up your own if you can find a wide-enough press close to you. We used 4mm sheet for the front cross beam and a full box transom (I realize you need a round beam/section). The transom takes minutes to fold or bend if the operator knows what he's doing. The front cross beam can be custom shaped to to suit your needs also...flat on top for chainplates seagull striker, etc...then curved nicely to a flat bottom or whatever. You can easily weld in gussets/beckets to the ID shape and stiffen the heck out it. If you look into that, make sure the bender people have a 30mm or so diameter round bar on the press. The angled ones used for steel make little chop lines and they can also split alloy depending on the material thickness and severity of the fold. just make up a cross section template on plastic or cardboard and they should be able to match it near perfect. It almost pathetic how easy and quick it is....and how affordable IF you don't have a pre-extruded mast section that fits your needs.

As a side note for a stab in the dark reference....our old 35 foot Seawind cat had slightly oval shaped back, mid and front beams about 200mm x 150mm in 4mm wall. they were encased in glass roughly 300 mm in the mid part and all the way though the hull in the front and back beams. No dramas with it and it had alot of use/abuse/miles. ...vague info I know!

have fun - Jay

[bob the builder]

onya j

measured a large tinny here an thats what they used for their transom, 4mm box beam, to hold a huge outboard.

a seawind 24 full of toys would weigh about the same.
and they have 5m x 190 x 128 x 4mm wall beams
weird how the 24 and 35 have such similar beam strengths




instead of folding,
i was thinking rectangular tube T6 80 x 40 2mm walls for the top and bottom

maybe round tube 40 with 2mm walls for the truss webs

easier. just buy it and weld it together.





"
(I realize you need a round beam/section).
"

NO. thats exactly what i don't want.

the reason for this post is to try and spec a space frame/box beam/house truss thing to do the same job as a mast section,






if the hulls weigh 600Kgs each, 2.5m apart, is this a good space frame for them?

should i up the strength


tell me more about your front cross beam and what is it for (please)
whats the all up kilos of aluminium per meter, what does a hull weigh?
(and why did you fold you own?


cheers,
mal

[Ad Hoc]

a sketch would help

[bob the builder]

no it wouldn't

[Rick Willoughby]

.......
instead of single round tube, wanna use two tubes, 60cm apart, one on top of the other, with welded webbing connecting them.

......
mal.

Mal
A catamaran in quartering seas generates relatively large moments between the two hulls as one bow digs in and the stern on the other hull is pressed below its waterline. The opposite bow and stern are unloaded in this condition.

The cross beams have to resolve the moment without undue flexing. With two beams, the moment will be resolved through the combination of vertical bending and torsional shear in the beams.

Your proposed beams do not make the best use of material to provide a rigid connection for this twisting moment between the hulls. The lightest section, to provide adequate rigidity, will have large enclosed area with the thinnest wall that will withstand the localised impact loads.

The type of beam that Jay describes will result in a light beam with high torsional rigidity. A standard section is preferred though because it avoids welding and the associated reduction in allowable cyclic stress range.

It is quite easy to appreciate the difference in rigidity using cardboard taped up to form the different sections and make comparisons.

Rick W

[bob the builder]

rick,
i grabbed me little balsa truss and did you know you're right? the little bugger did flex a bit. fantastic in up and down though. bad in twisting

i got a different picture from what jay said. i thought he meant his transom was folded to be 40mm wide and say 60cm deep, and if so, then why not use two tubes?, but i think you and he are talking one thing and i'm picturing another boat



the front i'll make into a box beam then.


the back i might have to add something in addition to the truss to handle torsional shear

i sorta wanted a normal aluminium transom so i could just drop an outboard on with no fuss



hmmm

[Rick Willoughby]

rick,
i grabbed me little balsa truss and did you know you're right? the little bugger did flex a bit. fantastic in up and down though. bad in twisting

........

hmmm

Mal
Understanding how to resolve moments can be a challenge for experienced structural designers. I have seen some world renowned engineering firms produce structures that fall apart prematurely because there was inadequate means of resolving moments. Five minutes with some cardboard and sticky tape can be illuminating.

Anyhow I saw you other post on the beam analysis. The analysis and diagram shown are not relevant to the cat cross beams as the beam was simply supported. The ends of your beam are rigidly supported so whole other case. There is a thread somewhere here that goes through some of this analysis.

Analysing the combined condition of torque and vertical bending to determine deflection is complex. If you work them as separate cases rather than combined and take whichever is the stiffest you will have a conservative design for deflection.

Another load case you have to contend with is a high speed collision of one hull against something solid. One hull shudders to a stop while the other tries to keep going. This is extreme case and an ultimate condition but the fatigue condition with the leeward hull slamming into waves on a regular basis will be as demanding on the beams. This produces bending of the beams in the horizontal plane.

Another significant load case for one of the beams will be the vertical bending from the mast compression.

None of these calculations are trivial - unless you are experienced with structural design. Many good designs have been arrived at through trial and error because establishing the load cases and doing the maths (with adequate precision) is time consuming. One-off professional designs that are pushing the limits will often be fitted with strain guages during initial trials to verify that the load cases used in the design were appropriate. The other way is to fix the things as they break but this can be soul destroying or much worse.

Having a simple cardboard or balsa model that you can twist, force and press by hand to simulate different loading conditions is useful for a first-off design.

Rick W

[Ad Hoc]

"...Understanding how to resolve moments can be a challenge for experienced structural designers. I have seen some world renowned engineering firms produce structures that fall apart prematurely because there was inadequate means of resolving moments..."

No, it is about establishing the loads in the first place. resolving of forces is the easy part, what the magnitude of each load to apply is another matter.

"...Analysing the combined condition of torque and vertical bending to determine deflection is complex. If you work them as separate cases rather than combined and take whichever is the stiffest you will have a conservative design for deflection..."

No. Worse case scenarios are not individual load cases, but a combination or a summation of them, but must be demonstrated to ones satisfaction and not assumed.

"...Many good designs have been arrived at through trial and error because establishing the load cases and doing the maths (with adequate precision) is time consuming..."

No. It is a matter of establishing what is the actual load to apply.


"...Having a simple cardboard or balsa model that you can twist, force and press by hand to simulate different loading conditions is useful for a first-off design..."

To understand a concept or "action" that is not clearly understood, yes. But, it does not provide the magnitude of the loads since to establish the magnitude of load and its location there must be exact scaling and the exact same conditions. Which is next to impossible since the scaling of 3D structure is not linear

[bob the builder]

Ad Hoc
thanks. great stuff. does your philosophy also involve my truss specs?

(which would have taken a single line instead of 20)
ie truss 70x100x5mm 60cm apart, 45 degree webbing, gives a beam with 1200Kg @ 0.3% deflection

and do you think your undoubtedly brilliant philosophy will ever bear a single piece of fruit? linear or otherwise?



j - i just saw your cat
(nice! - (saw an aluminium jaguar once, no paint, just mirror polish, please consider))

,and understand now about your beams. good idea.



rick,
truss transom on it's own ain't so good with torsion, but if it's on a strip plank glass epoxy floor, bolted onto large bulkheads in the hull, isn't the floor a beam that's 3m deep? isn't this then 20 times more inertia than needed?

(full bridge deck cat , deck 15mm kiri 600gsm db top an bottom)

(really want a truss, but also want the thing to stay together at sea!


thanks all,
mal

[Ad Hoc]

Mal

Your questions are rather like, how long is a piece of string. Hence my reply in #5. No point discussing further without seeing what the actual proposed structure is like (application is everything) and where/how it is proposed to be attached, and to ensure "words" have not been misused/misunderstood etc, as so often happens, which leads to mistakes/errors. However, you selected to decline, that's your prerogative.

[Rick Willoughby]

....

rick,
truss transom on it's own ain't so good with torsion, but if it's on a strip plank glass epoxy floor, bolted onto large bulkheads in the hull, isn't the floor a beam that's 3m deep? isn't this then 20 times more inertia than needed?

(full bridge deck cat , deck 15mm kiri 600gsm db top an bottom)

(really want a truss, but also want the thing to stay together at sea!


thanks all,
mal
mal
You need to have an enclosed area to transmit torque. A floor and sides will have limited ability to do it. A floor, sides and roof will do it but it brings in a lot of issues in stress concentrations around any openings. As the hulls work relative to each other, the openings distort and experience stress concentration at corners the result in cracking unless suitably strengthened.

I am reminded of a structural design engineer's comments when I asked for some openings for cables to pass through. He commented that I was no better than a plane passenger wanting windows. The fuselage is the perfect structure and then some clown puts holes along it simply so that passengers can see out!

The bridge deck is the ideal structure for rigidly linking the two hulls providing it does not have any holes. Most people want holes for various purposes and there is a lot engineering detail around the openings to avoid problems. Simple test - make a cardboard mock up of the bridge deck without holes - twist cross wise. Now place all the openings and compare.

Rick W

[Ad Hoc]

"..The bridge deck is the ideal structure for rigidly linking the two hulls providing it does not have any holes..."

This is such a gross generalised comment and is in essence nonsense. Only those that do not understand structure nor design structure would make such a statement. Structure is all about establishing the loads, what/where the load paths are and what localised discontinuities exists that may affect the transfer of said load to the surrounding structure and then compare against the allowable design values and what is the environment.

Catamarans all over the world, including the many I ahve designed, all have holes. The size of the hole, or whether one wants a hole is dependent upon the magnitude of the load, the geometry and if production time (ie manufacturing costs) coupled with saving weight (ie a proper weight estimate has not been done at the beginning).

To place a hole through any structural member can be done and safely too, if you know what you're doing....how else would you be able to look out of a window when you're flying??? If is wasn't safe, there would be no windows, QED!

[Chris Ostlind]

Catamarans all over the world, including the many I have designed, all have holes. The size of the hole, or whether one wants a hole is dependent upon the magnitude of the load, the geometry and if production time (ie manufacturing costs) coupled with saving weight (ie a proper weight estimate has not been done at the beginning).



So, with this substantiating position, could you be so kind as to post a collection of examples of your work, as it would apply to the original boat and question asked?

Since I am a guy with no formal engineering training, it would be real solid info for me (and the rest of the folks here) if you would consent to sharing your, I'm sure, exemplary work for our reference.

I'm most interested in drawings of your design work, coupled with completed examples of each craft, to illustrate just how it was completed.

Thank you,

[Ad Hoc]

Chris

Unlike many on this site, I'm not here to say "look what I can do...aint i brilliant". I just offer advice based upon experience. This is to short circuit the many years of training and education as well as studying that that would other wise be required.

However if you PM me your details, I would be happy to provide you with details, citing reference books and magazine where the designs are featured. I design in the commercial field, not luxury/leisure.

But the information given, is just about the boat, not details of hard engineering/structural design as you appear to want. I have written and co-authored many technical papers (all published), however, if you wish to read some of the papers identifying significantly more detail than the very brief summaries I have given above and elsewhere, i am happy to do so. Since you want some 'hard' details, i can send you some of these, rather than "glossy data" in magazines.

[bob the builder]

sorry Ad Hoc,
my mistake.

let me clarify,
the advice i really want is the specks for a single truss.
single line is what i'm after.
you're going to far too much trouble just for me, when all i want is a single line.



(why? see the specs above? done by me! so imagine betting your little bum on that baby a thousand miles from shore.

so if you can,
please improve my specs. is my math correct? i wouldn't put a single dollar on it.)






thanks rick,
you've helped me heaps.

definitely talked me into a normal mast section for the front beam, so this is half a victory for reality Vs me at any rate.





after i have a enjineer say "Great Work Mal!, but, you're truss calculations are OUT! (Shocked! tone), you need 4mm T6 to get 0.3% deflection with 1200Kg right in the middle."

then i'll try improve the twisting.

i think all the guys here should be able to come up with a good solution, but in the end it may be like the front beam, and just be more sensible to fit a big round tube, say 150mm round 4mm walls? then attach the 50Kg outboard with bolts in the middle of it.


right now i'm thinking maybe another truss the same say 7ft in. great! idea hey?




thanks all,
mal

[Ad Hoc]

mal

Your first post was asking which type of beam, now your saying the spec's; as in the scantling or the material or what? Single liners don't do it. If all you wnat is a quick one liner, you'll get plenty here.

For me, without knowing the application, the loads service life, method of attachment etc etc somewhat pointless, as i noted above, how long is a piece of string...or in your case no idea if your maths are correct because insufficient information.

But that's my tuppenc penny worth...

[Rick Willoughby]

...
after i have a enjineer say "Great Work Mal!, but, you're truss calculations are OUT! (Shocked! tone), you need 4mm T6 to get 0.3% deflection with 1200Kg right in the middle."

...
mal

Mal
To comment as you suggest requires a designer to do a design check, which involves work on their part. Most people seek payment for work.

If you pay them there is an obligation and the result has value. If you do not pay them there is no obligation and the result is just an opinion that you may or may not value. It was free after all.

There are examples on the forum where the opinion changes in subsequent posts from the same individual once the opinion is challenged.

I take any opinion offered in this forum with skepticism. Unless you have the means to validate it it is worthless. After all you did not pay for it. If payment is involved you seek references and look at past results.

Most opinions are given in good faith but often from limited experience or a myopic view of things because that is the way it has always been done. Hard for people trained a certain way to untrain themselves and be open minded enough to accept improved methods and new ideas from what they were taught.

I have learnt that no one knows what they don't know AND the more you know the more you know you don't know. So learning is an ever expanding horizon.

Given all of the above, I accept that anyone can build a boat. If the design is poor the launching will mark the start of a lengthy, frustrating and possibly expensive development process. If the design is good then expectations are met. You have to work out how much you need to know to achieve your ends.

This thread might give a better idea of my point:
http://www.boatdesign.net/forums/open-discussion/build-yourself-boat-do-lap-crazy-not-21058.html

Rick W

[bob the builder]

thanks adhoc,

try this then. pretend this is a real engineering exam question;

a moron built a truss, with 70 x 100 x 5mm T6 aluminium tube top and bottom, 60cm apart, the same material was used for the 45 degree webbing, and got a 4m beam on which he placed 1200Kg in the middle. how many mm's deflection occurred?

really looking forward to hearing from you this time,
and
thanks for all your time as well.

cheers,
mal.


also,

didn't "decline" (!),
just didn't understand.

i thought that;
you and rick were engineers,
that had known each other for years,
and were having some sort of philosophical re the mathematical mapping problems of deciding on the universe of discourse for translating your then agreed on logic into practical engineering math, all for my benefit, and how ricks empiricism (while precisely communicating to me in terms i appreciated) violated your far more expansive, though less pragmatic philosophical tenents.

all i was after was pragmatics.
i was hungry, an you gave me zen.

which i didn't decline,
just didn't understand.

But! Thank you for your time.

and stay passionate fellas!







(these forums are fun! :o)

(also; how honest should i be on these forums?
i've often seen australians abused elsewhere by americans for speaking perfectly normally.
cause what i really thought was you n rick were old mates havin a wank, and wished you'd done it elsewhere)

my position is
i'm far more focused than all of you guys out there in cyber space, cause i wanna start welding these beams now, whereas you guys can sit back an ponder the universe, have a scratch, adjust the fruitbowl, n say mal!, you've not considered the extra super powerful way! which is only gunna take you 5 years of study to understand, you lazy bugger. n then have another scratch,

i'm looking to start planking soonas.

so can i speak normal here (like the above) or do i have to dumb it down and speak american? (the long winded philosophical version of the above)

who thinks what?

am i in trouble yet? have i drunk too much coffee?

ps, i've just started smoking again 4 days ago after a year of no coffee and cigarettes.

thanks all,
mal.

[bob the builder]

rick,

i don't wish to appear light hearted, but i'm used to flippantly juggling abstracts all the way in one direction, and then all the way in the opposite.

so, although i'm a nerd and my verbiage is torrential and light, i have lived on a yacht before, and realise hard facts do exist.

it's not that big a deal to me, to ponder one way, then change to a more traditional method. i haven't looked at your other posts here on this forum, but from your tone, i would guess you do serious boat stuff for work. ie you have to take other peoples engineering seriously.

"To comment as you suggest requires a designer to do a design check"
no it doesn't. a design check implies hours of work.
a simple beam or truss inertia is a matter of a minute at the outside.
some people do formulas everyday, and might take some person here 10 seconds in a truss program to check my calculations. that is what i was after, all the rest is gravy.


you have to start somewhere. i started all by me little lonesome, after YEARS of reading and making other designs, seen lots of plans, and in my mind, think i can build much better than a foam cat. (professionals and food) http://www.boatdesign.net/forums/multihulls/good-reasons-not-design-13162-6.html

been on expensive foam cats recently, and refuse to even listen to these people anymore. won't let them put their biased info into my mind. walking on jellyfish. felt professional boat builders work after 20 years.

payment! absolutely not. all you get is one persons opinion. an i much prefer a gift like what you gave me. you had nothing to gain, and so spoke freely.

i prefer a menu, like what's happening here. a smorgas board of different opinions from all over the world. brilliant. and then choose the one that appeals.


my brother used to build drag racings cars. he's not an engineer. he would typically buy parts from engineers and then put them together. he didn't want a plain vanilla honda.

i talked to you and now i'm doing a plain vanilla beam on the front, MUCH better and easier.

i'm very happy. now to continue the refining process.

sure, i won't end up with a shiny! General Motors car, and that makes me very happy.

i just repaired a mazda e2000 van 9! years old. the paint fell off the roof, and there were rust holes big as your hand all through the roof.

professionals. all yours mate.

[Rick Willoughby]

...........
it's not that big a deal to me, to ponder one way, then change to a more traditional method. i haven't looked at your other posts here on this forum, but from your tone, i would guess you do serious boat stuff for work. ie you have to take other peoples engineering seriously.

"To comment as you suggest requires a designer to do a design check"
no it doesn't. a design check implies hours of work.
a simple beam or truss inertia is a matter of a minute at the outside.
some people do formulas everyday, and might take some person here 10 seconds in a truss program to check my calculations. that is what i was after, all the rest is gravy.


......

Mal
I have owned a few boats and boats are a lifetime hobby. I currently play with design concepts and have built some reasonable models that are large enough to pedal. I started this thread to catalog my recent efforts and hopefully encourage others:
http://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345-20.html
I have learnt about doing more with less in boats from these experiences.

My aim is to learn and have a nice retirement project for a boat I can get built and cruise the Australian coast and rivers economically and safely.

I am an electrical engineer and have managed multi-disciplined engineering teams for many years so I have reasonably wide knowledge across a number of engineering and business disciplines. I am currently paid by an insurance company to be the devil's advocate and work out how things might fail. I am in a position where I can have others do the detail engineering for my paid work.

Similar for boats. If I want design detail on a boat I pay a trusted Naval Architect to do the work as he is forced to know detail on crap that bores me to death. I can play with concepts and have acquired or developed some very good tools for preliminary design. I was suggesting you also find a good NA to bounce ideas off. A good one, like I use, does not bother charging for a casual minute here and there.

I give my opinions on boats in good faith and am glad you appreciated my input here.

I am not sure if you read much of that thread on Tin Can but one of the reviewers offered this:
Yet as Theodore Roosevelt said, …"credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly, who errs and comes short again and again, who knows the great enthusiasms, the great devotions, and spends himself in a worthy cause, who at best knows achievement and who at the worst if he fails at least fails while daring greatly."

There is nothing like getting the hands dirty. It is rewarding in itself and I find therapeutic. At present I build about 2 boats a year for myself and am helping about 10 others with various concepts they are developing. All input at no cost because it is all interesting and helps me learn. It rapidly amplifies my experience base on novel concepts.

I hope you take the time to post the progress on you boat and how you overcome the various challenges. Most here try to help and offer encouragement.

Rick W

[Ad Hoc]

mal

sorry, but without a picture how can i tell if it is "stable" or statically indeterminate or how many connections or how the connections are made, how the load is applied and where etc etc etc.

[bob the builder]

can i suggest downloading beamboy v2.2 or a truss program then?

good for you in your professional life to be able to answer the simplest beam question known.

[bob the builder]

no offense

[Ad Hoc]

Mal

In my professional life, the simplest questions are the hardest to answer.

No offense taken.

Those who are not naval architects or structural engineers always ask a simple question and wonder why the answer or reply is anything but. Or those who are not naval architects or structural engineers like to pop up with one line answers or wonder why "we" do not and constantly question their 'claim's. Because there is always much more involved. Which is why, one assumes, you seek advice. Since if it were that simple, you would download the "simple" program yourself and not require any validation from any posts here!

[Steve W]

Bob, on a small cat like yours im curious why you dont want to use the simple round aluminum tube approach, its well proven and cheap. As a reference i used to own a Macgregor 36 and all three beams were stock off the shelf round tubes between 16 and 17 ft long and 6 5/8 inch diameter, the mid and aft beams were 1/4 inch wall thickness and the fwd beam 1/8 inch. The mast beam had a substantal dolphin striker and the forestay used a bridle and no seagull striker.
Steve.

[bob the builder]

the front bridge deck lent itself naturally to an enclosed triangular space 3' x 2', so o thought, why not have a ply or aluminium box beam, since the outsides of the box beam are going to be present anyway. thus saving on weight.

there's open deck at the back with open hulls. a truss style transom would suit perfectly.

i've got oodles of other round aluminium beams specs suitable to do the job, and plain vanilla engineering is the default option.

i may well use both a truss and beam together in the end.
the truss to weld on wing seats outside the cat, cut and weld outboard fitting on, bolt on to the thick ply hull bulkheads, weld pole holders on, weld sampson post on etc etc etc.

the utility and ease of attaching fittings is astounding compared to the delicacy of the round beam, which some people don't even drill for the main bolt holes.

[Rick Willoughby]

the front bridge deck lent itself naturally to an enclosed triangular space 3' x 2', so o thought, why not have a ply or aluminium box beam, since the outsides of the box beam are going to be present anyway. thus saving on weight.

......
Mal
Incorporating a box beam in the bridge deck is a good solution that I have seen others use. It is the ideal moment resisting member being near the centre of the hulls and with large enclosed space. Ideally the ends are enclosed and able to transmit the stress smoothly into the hulls.

Remember that any hole in this beam will see stress concentrations at the corners. If you can avoid holes all the better but generally such space needs to serve more than one purpose.

Rick W

[Ad Hoc]

Chris

“…I wish I could accept that position, Ad, but unfortunately, some of your posts do take on that... "Hey, Look At Me" sort of tone…”

Well that is a perception of your own making, I cannot control that.

“…I see a consistent process where you take others to task, without offering-up anything of your own work to drive the argument…”

That’s where you don’t understand what a technical debate is all about. It is not about the person, it is about the posting. The comments/claims made. Whether I am a newbie or a professor or whatever, doesn’t alter the comments, only your perspective of them. That in itself speaks volumes about how you understand technical debates and critiquing.

“..Nobody here knows who you are because you operate behind a nom de plume of a smoke screen…”

As noted above, what difference does it make who I am?...unless of course you’re more interested in the person than the comments made. Again, you’re missing the point of a debate/forum. How many boats I have designed doesn’t alter my posting, only your perception of me, not the comment.

If it were about how many boats etc and qualifications etc…this website would have a “validation” process to review those that wish to join to establish their “status/credibility” within the marine world and provide “levels of status” to know whether postings from said person are genuine or not. Trouble with that is, those that posture and rant and rave on this website of which there are many, would turn from the majority to the extreme minority in terms of “status”. That would diminish their raison d’etre!

As noted here, you fail to answer a simple question about a post you made. You like others question the questioner, rather than answer the claims being made by you, not by them.
http://www.boatdesign.net/forums/multihulls/solo16-sport-trimaran-26541.html

..you ignore the posts seeking clarification to your statements and twist in another direction, rather than answering your claims that you have made.

“..What is it about your posture that keeps you from being a regular guy among other, "regular guys"?..”

What is it about guys like you that have chips on their shoulders and have an inferiority complex when someone can speak in a manner different to yours? I have a friend who is very small, he is constantly aggressive and when we were young always trying to pick fights,…why?...because he felt inferior owing to his size. It is all in his mind, just as the statement above, it is in your mind and others.

“..You wish to conduct this substantiation of your credentials in private, yet you seek to castigate those on this Forum in public…”

Under what obligation am I or others to provide their personal details?....how many pseudonyms are there here and how many real names???

“..Act this way too often and the other guys like me will quickly find other sources of the same information, which you seem to think, is so exclusively precious…”

Please do, that is the point, if I’m wrong prove it, and we learn. But that means taking away the debate from me, which is your only focus, not the question at hand.

“…There’s nothing special about your knowledge…”

Never said there is, again that is your own personal perception. However your posts are contrary to this as you do not feel the need to answer direct questions about your postings. See above link again.

“…Of course, you can come out from behind your Wizard of Oz curtain and join the gang here,..”

Ahh..i see now. It is a clique!.....sorry I was under the impression this was an open forum, not a “come join our club, if you don’t you can’t play”...oh how pathetic and childish…that is school play ground mentality!

As Woody Allen put it, I don’t want to be a member of a club that wants me to join!

“…My email address is easy to find and I welcome your contribution to that which you seek;..”

See again, you do not comprehend.
1) It is you that wishes to know more, not me. So the onus is on you contacting me, but you choose not too.
2) I seek nothing. Many like you use this forum as some sort of acceptance or redemption or validation from others on this website. I seek none. I just offer advice, which can be taken or not. This forum is not where I conduct my business for business. I don’t need this forum to obtain some recognition, clearly you do. As such you view all comments in that vein.

“…Each and every Naval Architect, or Marine Engineer that I know, is so fully occupied in the business of their trade that they have absolutely no time at all to dick around on Forums of this type, even if they were so inclined…”

Ahh, so you have tarred everyone with the brush that…if they can reply on this forum more regularly than you they must be wasters, great conclusion!

You are like the many others on this website who are not formally trained nor professional, yet feel the need to act as so. You do not like being questioned, you attact the questioner, rather than the question. When asked for references, to try and deflect the question, like others below:
http://www.boatdesign.net/forums/multihulls/load-paths-catamaran-26229-5.html

Clearly, because you are not a naval architect or professional engineer, you feel intimidated by the stance taken by me, er…how is that my problem?

Obviously knowing who or what I am will therefore make no difference if one cannot even acknowledge sound references, or just twist away from justifying claims made on ones own design, what is one more of who I am going to make to your MO, none. It just points again to some inferiority complex, why I have no idea.

The fact you selected not to contact me directly just suggests that you have no concept of the professional integrity. If a client or person wishes to reveal themselves, to you personally but remain anonymous, you have selected to ignore that. That is grossly unprofessional.

There are several on this site who know who I am, some I have worked with over the years. Some even have had others contact me to try and see if I am real, as if I didn’t know!...but they have respected my anonymity.

In addition, comments that suggest “..Hardly any of the guys here are mechanical engineers, yet you hold this information over their heads as if you, and you alone, are capable of sorting these commonly phrased issues…”, again totally miss the point. To allow information that is clearly misguided and incorrect to be let loose on those that come on this site seeking advice, is unprofessional. It gives this site a bad name, as well as “professionals”. So I speak it as it is. This at least offers the poster an opportunity to see that there maybe another avenue to explore, rather than accepting one persons comment, simply because he/she is part of the “lets sit around a camp fire and sign songs and join hands” club.

“…Until that time, you have acquired the ignominious position of being a wannabe poser,..”

If that is yours, and others opinion, so what? The fact you cannot add or counter any technical argument put forward remains. Personal feelings are not part of the equation, only solutions. But you elect to probe who I am not what claims have been cited. When money is at stake, as it is for many seeking advice on here, time=money, not time=feelings.

[Leo Lazauskas]

Nobody here knows who you are because you operate behind a nom de plume of a smoke screen....

What is it about your posture that keeps you from being a regular guy among other, "regular guys"?



1. AdHoc told me his real name within a few minutes of our starting a discussion, so maybe you just aren't at the cool table, Chris. :cool:

2. I agree that AdHoc is just not a "regular guy". He keeps pushing that tiresome "Scientific Method" onto a group comprised of mainly graphic artists and interior designers. :p

Have fun!
Leo.

[bob the builder]

he also can't answer the most basic engineering 101 question about a simple beam.


there is a band in australia called TISM.

one of their biggest hits (music charts, top 40 song, HUGE airplay) was called "What Are Ya?"

they hypothesised, basically, that guys could be divided into two distinct categories, yobs and wankers.

basically they were alluding to a person being driven hard all their life with adrenalin so as to achieve good marks in school, as performance increases dramatically with adrenalin. the so called fight, flight, or f_ck system of brain stimulus, the most basic ON! ALERT! RUN! burn the candle faster.

or a person not driven, and akin to an analog device, speaks slow like a farmer, lazy, and has far less polished verbiage.

a yob or a wanker, make your f_in choice.



(
as a personal aside
i find it interesting, who has the most powerful brain? the farmer, and his insight? or the person driven all his life to spin his little wheels faster and faster, into ever smaller finer points?
)


(
as a personal aside
i find it interesting, who would actually feed you if you were hungry? is one so removed from reality they would just blankly stare at you while feeling nice and snug and secure?

who would actually give you a piece of fruit, rather than just wank?

[Leo Lazauskas]

there is a band in australia called TISM.

one of their biggest hits (music charts, top 40 song, HUGE airplay) was called "What Are Ya?"

they hypothesised, basically, that guys could be divided into two distinct categories, yobs and wankers.


So what? So a band of school teachers hypothesise something. It means nothing, except maybe to some drunken Humanities students.



(
as a personal aside
i find it interesting, who has the most powerful brain? the farmer, and his insight? or the person driven all his life to spin his little wheels faster and faster, into ever smaller finer points?
)


Complete nonsense.



(
as a personal aside
i find it interesting, who would actually feed you if you were hungry? is one so removed from reality they would just blankly stare at you while feeling nice and snug and secure?

who would actually give you a piece of fruit, rather than just wank?

Don't mix your grooves, man. Alcohol OR pills. Not both.

[Chris Ostlind]

1. AdHoc told me his real name within a few minutes of our starting a discussion, so maybe you just aren't at the cool table, Chris. :cool:

2. I agree that AdHoc is just not a "regular guy". He keeps pushing that tiresome "Scientific Method" onto a group comprised of mainly graphic artists and interior designers. :p




Nope, Leo... not at the cool table. Never have been and I kinda like it that way. I learned some time ago that when one starts to take themselves too seriously, they stop seeing in very important ways. Do you have an understanding of that lesson?

... and the graphic artists and marketing specialists just keep pushing that irritatingly humanist "Aesthetic Method" onto the group composed mainly of engineers and numbers collectors. ;-)

It's supposed to be collaborative, Leo, not antagonistic. But, then, you knew that.

[Ad Hoc]

well bob

there you have it.

A problem so simple no one has given you a reply. No idea what 101 means????

If the problem is so simple, why has no one given you the answer, why haven't you or someone else downloaded the sowfatre you noted above...why is that..what about those that wish to chime in about something totally unrelated and doesn't answer you question too? Why don't those who stay solely within the esoteric science world alone help out??

hmmm..who is that??...as you say, it is such a simple problem, surely one of the posters above must know, since they claim to know so much....surely....it is so simple it is child's as you say....why is that??

Well for a dummy like me, i would like to know why no one answers such a simple question.....since to me without knowing some very basic facts which have not been provided, for various reasons, the simple question cannot be answered properly and professionally. But hey, I'm just a nobody what do i know??

Ask one of those wonderful "lets sit around a camp fire and compare CV's" types...I'm sure they must know..otherwise why would they chime in??

Enjoy your simple calculations... :)

Oh, don't forget to ask what the fixity is, whether it is static or dynamic, what service history is required, what the environment is, whether the truss is "stable" or statically indeterminate, not forgetting the load transfer and shear paths, or how it is fixed, welded or bolted, what about the bearing stress and notwithstanding the deflections and and..opppssss......oh, silly me it is so simple, you and everyone else already know this :)

[yipster]

http://data.boomerang.nl/t/tzumb/image/going-bananas/s400/going-bananas.jpg
live aint simple but plz dont make me

[bob the builder]

LEO!

"So what? So a band of school teachers hypothesise something. It means nothing"

i'm stunned that you can not see the brilliance of their insight. so i'll explain it to you.
have you never wondered why scientists masturbate constantly? i've worked with many IT guys in many companies and seen them dribble (litterally, and i know why. i know why stockbrokers get ANGRY, it's all the same on system (did psychology). it's so much easier to lift mental weights when you got some ON!.


try this simple test yourself. download some IQ test from the net that has two versions (so you can do the test twice) mark the test.

THEN
drink coffee, smoke a cigarette, and masturbate furiously while doing the second IQ test. you will get a HUGE boost in IQ, roughly 15 points, a whole standard deviation.

try it.






Complete nonsense.

why?
(do you know that the really smart people get paid to be lazy? there are government facilities with trees and grass, no students to lecture, no interuptions, and their job is to LAZILY ponder. NOT publish or perish, but not produce any papers for years? the reason being 99% of all academic papers are worthless, produce no new insights into nature, are published in minor scientific journals, and . . are NEVER quoted or refered to EVER again. (thre worth of any scholarly work is how many citations, how many times other scientisists refer to their work over the years. )

did you know this?
that the key to POWERFUL thinking is to have the luxury of pondering?

do you know the difference between analog and digital? do you know that digital is as dumb as logic? (incomplete, inconsistent (mathamatical terms for saying 1 + 1 NEVER equals 2, ONLY when utterly removed from reality does 1+1=2, when applied to ANY part of nature this is never true, and so all logic systems DO in actual fact break down instantly. repeat instantly you can find flaws on the first step.

pondering on the other hand is spreading waves of activation of neurons, consciousness is the flow and pulse of waves. definitely analog.
powerful to ponder.





Complete nonsense!
why? do you really think that just because somebody has been forced to jump through other peoples hurdles and hoops all their life this makes them smart? (really like to know what you think about this)

according to mensa, the smartest guy in australia was a garbage collector in cairns. isn't it now obvious to you? who's insights are more full of chunky goodness? a trained animal forced to masturbate and dribble every day, or a cairns garbage collector.

lemme know if you followed this time.







"who would actually give you a piece of fruit, rather than just wank?"

are Nazi's smart? that was the point.
(no offense, but you did seem to miss this point of this as well,

perhaps you should quit your job and relax? go analog
(again, no offense, but you did miss every single point entirely. i can't belive you're australian. how can we be so far removed from understanding each other? )

cheers big ears,
mal

[bob the builder]

Ad Hoc,

let us be clear about this. this post right here, will be the VERY first time i speak truthfully to you. all my replies previously to you were a piss take.

a piss take.
(i didn't read through most of your other posts, even when replying to you.)

and whats the reason for this?
you posted thread destroying big-up-yourself wank.
it appears just to hurt the guy called rick.


i understand about stuff being so complicated you CAN'T explain to people what it's about. i've been in the forrest in several scientific disciplines and know EXACTLY what you're on about. i also know you will never see the forrest until you retire. great mastery of trees though! nobody here can deny you that.


"why no one answers my inertia, deflection, specs question?"
people answer what they can. have you noticed this?
guy with box beams answers with box beam.
guy with section contributes as he can.
etc


you? what have you contributed?

the same as everybody else, what you were able to contribute.
and once again, (how many times have i said this to you?)
thank you.

it is not your fault you can't answer the simplest engineering question ever and check my work! (i just thought from all your drivel you could and might, if i spent the verbiage on you. just because you can't do the simplest engineering beam load calculation (and i can) and you can't check my work, i still say thank you. artists contribute what they can. same as everybody else here has contributed.




(tips for feeling good about yourself;
realise that FEAR is a performance boosting drug. your IQ WILL impoove dramatically, and you WILL be able to lift heavy mental objects with ease,

however;
the cost is training; remember, education DOES work. training DOES work. you WILL learn. your brain paths WILL be modified so that in every sentence you speak there will be underlying fear, sexual arousal, and anger.

you WILL regurgiate words that show fear, anger, and erection, and won't be able to see this smell yourself, because you are floating in it in everyday life.

so then, the best single piece of advice i can give you that WILL have the most dramatic effect, is to avoid ALL forms of ON!,

ie coffee, cigaretts, heart rate, adrenalin, and especially fear.

instead try over YEARS, (for rewiring your brain will take YEARS) to get all your !ON! from sex. try masturbating for HOURS every day. over time, your brain will wash away these fear inducing pathways you have (the need to take down others, need for other peoples approval, need to be seen as a guru by others etc).

loose the Ad Hoc name and start agin here being anonymous. try it! you will enjoy the freedom. only use the Ad Hoc name again when you want the big-up-yourself. try and see the difference in fun!.

[bill broome]

a bridge deck with no holes is the best structural connecting member. it is strongest for the weight, but useless for any other purpose.

they are often used in catamaran design, but we call them 'beam boxes.'

a bridge beam with accomodation space must have doors, windows, and utility ports, and each must be re-enforced for local load to prevent tearing.

if you are welding aluminum tubes, why not build a real box structure, human-high, of triangulated tubes? this is very strong and stiff for the weight, and you can drape a thin ply and/or grp skin on it.

[bob the builder]

hi all new guys!

please don't post anything sensible to this thread any longer,
post all BEAM related stuff to the NEW! improved! cat beam thread.

this thread is only for drivel now.

cheers all,
mal.


(bill, i've moved your post over there)

[bob the builder]

Leo;
as a personal aside, now you read the above, don't you now agree that this is an interesting question?

yob or wanker, who would give you help?

who would actually feed you? don't you think this is a fascinating perspective to view people with? (let me know!)


(and for all international people who might not understand;

what are ya?
is a very common and much used australian saying.
can either be a question,

1/ which translated from australian into international english is "are you going to masturbate fruitlessly and waste my time, or will you actually contribute in reality?" generally stated as "come on pal, what are ya?"
(it is NOT mean, or offensive. friends say it to each other. it just indicates, wake up please.)
or
2/ or a description of a person removed from normal people. in australia, to call somebody a wanker, is to indicate that they are like all the people described above, addicted to !ON!, and drivel, (the over activation of the fight, flight and f_ck ON! circuits have diluted the impact and triggering of normal emotional responses in their brain. this generally means they are unable to understand normal conversation. seen it many times.)

generally used by people who deal with reality (ie bricklayer, fruit picker, normal person) to describe an academic or rich person, who usually doesn't understand. who doesn't have the emotional associations in their mind or memory to comprehend what the other person is saying.


so;
to yield fruit? or just a load of wank?
(children are fruit, a woman is real, a wank session)
to yield real results? or imaginary?)

they generally don't understand. they just can't see.

(the chorus of the TISM song by the way, is "what are ya? you're a wanker"
(leo, no offense, but are you sure? you're australian?)

whar are ya? is a nice way of either calling somebody a wanker, or asking them to stop driveling and be fruitful, and actually help.




so;

Ad Hoc, Leo, thanks for dropping by MY PLACE (here), but, what are ya?

[waynemarlow]

If Bob had spent as much time pondering as has winding up this thread and its participants, he probably would solved his own problems.

My advice to Bob is take his hand off his dick and start listening and learning, it may well have a major contribution to his end game. Perhaps over on Sailing Anarchy may have been a better place for this banter.:)

[bob the builder]

very true dwayne,
thanks for also contributing,

i honestly blame my drivel, running off so severely at the mouth, on taking up smoking and drinking coffee again after years of abstinence (i've since stopped)

so i really do apologise to all here who might have read any of this drivel.

sorry guys.

[bob the builder]

Dwayne,
it's also not my fault.

i blame my parents.

if your parents speak chinese, of course you will speak chinese. what choice have you got?

"give me the child until he is seven, and i will give you the man"
you see, by the time i was old enough to realise how badly they had raised me, it was already too late. :o(

i tried to set them straight often when i was growing up, but they would (strangely) rarely let themselves be drawn into discussion.

so just a little bit of compassion i feel is in order here dwayne.

just a tiny bit of niceness.

do remember my childhood.


also;
i appreciate your guidance so much that it's hard for me to tell you exactly what i think.

needless to say, since your FIRM guidance,(to get me hand off it), i now consider you to be the father figure i never had.


it was GOOD advice, . . . firm, . . .but fair.

(to be honest, i do however feel it lacked a certain something on your part. so that's the only thing i'm trying to get across here. instead, in future, treat me maybe, as a special person. wrap me in cotton wool sort of thing)

anyway,
once again thank you for your contribution.

[whoosh]

Chris
many of us have been trying to get this supernova Dork of the first water, to reveal who he is and to prove what he has done,
But I for one am nowhere near as polite as you
Do not hold your breath my son I for one am not the only one:)to have his measure
he purports to be an expert on all and all esp. al al construction
Now-- after a lifetime building al al boats, I think possibly , that I do know a thing or three, and I can see this pratt(see he went up from Dork to pratt) has absolutely no hands on experience of the medium
I really do think that uncle Jeff should insist that people who profess to earn their crust from the trade, shoud at least ID themselves
Surely some will cling slavishly to his coat tails, that is to be expected from beginners, But adults , like Apex are also sucked in
United we stand so come on, lets not indulge this fool, on the other hand let us unite to put him where he firmly belongs
Gusgot, bonjour,

[waynemarlow]

Dwayne,
needless to say, since your FIRM guidance,(to get me hand off it), i now consider you to be the father figure i never had.


it was GOOD advice, . . . firm, . . .but fair.


Bbbbob, stop blubbing and making yourself look like a real wanker, the sort of guy everyone wants to avoid.

If you are up for banter then move this over to the Sailing Anarchy Forum where there is such childish banter. You can have as much fun as you like over there.:cool:

[whoosh]

1. AdHoc told me his real name within a few minutes of our starting a discussion, so maybe you just aren't at the cool table, Chris. :cool:

2. I agree that AdHoc is just not a "regular guy". He keeps pushing that tiresome "Scientific Method" onto a group comprised of mainly graphic artists and interior designers. :p

Have fun!
Leo.

so , prey enlighten me, what zakkly IS his real name
when he first came, he made the astonishing claim, that he, had convinced the British M.OD. To change from steel to al al When I asked him who his contact was in that entity, there was silence,

[Ad Hoc]

For some real true professionalism:
http://www.boatdesign.net/forums/boat-building/welders-aluminum-1196-3.html
just check post #41 and 43

....whoosh you're a true gentleman and such a consumate professional. Answers his claims and is so polite too...great stuff, keep it up :)

[whoosh]

dont fret I will. But I will also back everything I make build or do
On the other hand you come across as a person striving to be accepted But digging yourself into a deeper and deeper trench, by you absurd claims
Sure you can fool 90% of the forum But to those of us who do earn a living in the business, you mean zilch and that is why you are known as Ad Zilch
The worst crime in my book, is to punt away at folk from an anonymous position
That is the mark of a coward and the position someone takes when they are afraid of something
Thats my take and now I will take the advice of my esteemed friends here and ignore all of your posts--- Because yes you are correct, you make me extremely angry

[Ad Hoc]

As noted
http://www.boatdesign.net/forums/boat-building/welders-aluminum-1196-3.html
Your behaviour and attitude is a fine example to the 90%, you can keep them.

Still not answered any of the questions i asked of you, "..thou who backs up everything"...er.where ahve you backed this up??!.....don't you have a current class cert to shut me up (please do, correct me, but not seen any evidence yet), that is what any professional welder would do, but you haven't. Why is that? You love pictures, so why not post a picture of your current Class cert and what it is valid for. If you can't or wont, that speaks volumes.

You simply fail to grasp that you make endless claims about yourself, so i ahve asked you to prove it since you claim (again) to back up everything...so where are these current Class certs to shut me up, that would shoot me down in flames instantly....but rather than posting your current class cert you decided on the only avenue left to you, you just repeatedly attack me rather than practicing what you preach, nay, insist/demand others to do....why is that???

You tried bashing away at others here too, yet all your claims are well, just that claims, as noted by many below:
http://www.boatdesign.net/forums/metal-boat-building/not-another-one-25443-5.html