Transverse frame calculation

Chine tacks crack. That is why , after the hull is pulled together, you go over them and redo them. They are temporary welds. I've seen people waste a huge amount of time trying to keep a job looking pretty while under construction. It's only the finished product which counts. None of my finished boats has ever had a chine weld crack, despite the 30 years of torture s test they have endured
As Picasso said "Fools and children should never be allowed to see a work of art incomplete."
Stainless trim can be polished after you are out cruising . Interior trim can be added after you are off the treadmill and cruising.
Cheap fibreglass boats are a good solution for a first boat to get ones self out cruising quickly, a solution I often recommend. Most cruisers will, after a few years experience, want something tougher and more forgiving. That's when they hire me.
The experience they get from the cheapie is priceless, and will make the eventual steel boatbuilding process far easier. The cheapies, after a couple of years, owe their owner nothing.
In one of his Books. Rodger Mcafee quoted his father, a lifetime heavy duty mechanic, who said ' A rebuilt diesel is always far more reliable than a new one" He goes on to provide a long list of diesels which crapped out in the first 100 hours. Those few of my clients who have bought new diesels have had the same experience .
Plywood which has been around a long time is not likely to delaminate any time soon. It has been well tested. This is not the case with untested plywood from the building supply.
Older fir plywood in BC is all fir, newer stuff has alder and other rot prone wood veneers inside. Only the outside is fir.
In my early 20's I shocked fellow boat builders by using plywood from the roof of my shed for decks and cabin top. They said so much of it's life expectancy was already used up. I set sail for the South Pacific at age 23. They never left, and ended up selling their boats and spending their lives on the treadmill. I'm sure glad I didn't follow their advice, or I might have ended up doing the same , making life expectancy of my decks totally irrelevant. Again, you can judge the value of advice by what it has done for the person offering it.
Motor cycle and other shipping containers from the far east are built from some beautiful tropical hardwoods. Taiwanese boats used to be shipped on teak cradles.

 

If a boat survives pounding in 8 to 12 foot surf for 16 days ,is winched off in 8 ft surf , being lifted an dropped 8 ft off each wave onto sand almost too hard to make a footprint in, pounding across a coral reef for 300 yards, T- boning a steel barge at 8 knots, and 30 years of offshore cruising, in all the conditions a boat will ever encounter, she has been subjected to all the loads she will ever encounter, buckling loads included. These are tests far beyond anything which can be mathematically calculated, and far more relevant.

I've answered all your questions. I apologize for having talked so far over your heads, but I'm not used to talking down to such a low level of comprehension.

 

Brent I had no problem following the explanations given by these guys in this thread. I did not fully understand why a traverse frame was necessary but I do now. I could not myself understand why many boats seem to have traverse frames only and very few stringers. I do now. I do not think your boats have been subjected to large buckling loads given your explanation above.

You seem to a appeal to the type of person for whom their own time is of little value. That is fine and I am sure you have enough business because I have come across a lot of those folks in boating who do not value their time.

Myself I cannot see it taking more time to build by frame and plate if you have good NC cut files to speed the process. Yes its more money for the designer but fewer hours of assembly. I can spend a bit more to save time. I consider time shopping and time fitting and correcting to be hours of valuable time. You have stated that you do not and its part of the fun. Bravo, for me, it is not. You are trading hours for money. In my opinion you could take a minimum wage extra job and be just as far ahead. My time is more valuable than that.

When I take the shop rates of the builders and subtract the cost of materials and overhead out of the final price of the boat I am amazed at the low number of hours it takes to build in comparison to what I have done by the scrounge methods of my past.

When I am done, I want proven a proven design and construction method that is fully insurable. I cannot see your methods holding up in a claim or a lawsuit.

My next boat within the next five years will be a long narrow passagemaker. I have not decided on the final materials or the build venue yet. I will be having an NA do the final work on the plans and yes, it will cost a gazzillion dollars. Unlike you I am not totally sold on steel.

 

A lawyer told me that the impeccable track record of my boats in all conditions over so many decades would wipe out any lawsuit.
One client in 1983 ,went to a shipyard with my drawings and asked for a quote for a shell for a 31. They quoted him $80,000. I built the same shell in three weeks for $3500
Weld seams are mostly longitudina, and thus shrinkage is longitudinal ,which frames alone do nothing to control. A boat with frames and no longs can be an ugly hungry horse, something I've seen drastic examples of , and somethin longs eliminate.
The reason you see so many frames , in smaller steel sailing craft, is strictly because of wooden boat copying tradition.
Busted!

 

I'd get another lawyer for a start since that is laughable. Your only defense, ever, at any stage is that you did what was accepted at the time as standard practice.

Welds shrink more across the weld seam not along it, it's restrained from shrinking along the weld if you think about it.

Lets get back to frames:

What about this argument you continually state that the framing systems are just based on wooden boat traditions?

I have said to you before that this is so far from the truth it's just more dishonest marketing.
If you look at the class societies guides and regulatory standards like the emerging world standard ISO12215 thats replaced ABSORY you will find that every member in contact with the plate derives part of its structure from that very plate. Allowance is given for curvature and for chine angles as self support. The framing system is the bare minimum that the rule makers consider safe. Although usually only racing boats and cheap production boats would opt for the bare minimum.

The design of the framing system is considered entirely on the possible usage induced loads and the merits of the material. It has absolutely nothing whatsoever to do with trad wooden boat building.

Here's a challenge for you, look at the current GL or BV rules (free online) or ISO if you can, and give one tiny example of this falsehood. Otherwise please desist making that statement.

You haven't actually said anything, but I presume by now you realise that you will need transverses of some description if you scale your 36 footer. You would be well advised to adopt one of the class scantling rules. And to advise your clients to fit some transverse frames.

 

You would be a goldmine on the stand for the plaintif.

 

Did he know about the boats that couldn't withstand a simple grounding at hullspeed?

 

Weld a seam across a cabintop without a beam under it and you will see the weld seam pull the plate downward in a longitudinal shrinkage. Weld up a hull out of ten gauge without longitudinals and you will see the plate oilcan between the frames , weld up side decks without longitudinals and you will see the longitidinal shrinkage cause the decks to warp into humps and hollows. the tension from weld shrinkage is in all directions , mainly the direction of the most weld , longitudinally.
There is a good example of the naivety of assuming calculations are infallible on this site under "Seaworthiness." It shows a boat returning from the inverted position in flat water. I'll bet the calculations didn't come anywhere near showing positive stability to 180 degrees, showing clearly the huge gap between calculations and reality.

 

The naivety of your arguments couldn't be more clearly demonstrated, in claiming that boats which have withstood hull speed collisions with rocks, steel hulls, and coral reefs in huge surf, cant withstand a simple grounding at hull speed. You make your argument by lying like a mountie in a courtroom,as is the case with most of the anti origami arguments here.
My boats are the some of most popular steel boats on the BC coast, over the last 30 years, for good reason.

Yes frames have their place , in huge boats. The dissagrement is at what size they become relevant. I'd say over 60 feet, but it is still far easier and more practical to pull the shell together first, before putting frames in ,as I have pointed out in time and cost considerations. It is far simpler, quicker and economical to fit frames to a shell than to fit a shell to frames.

 

So, after failing to answer any questions on structural analysis, welding quality and fabrication, not to mention dodgy economic reasoning to justify employing yourself, you’re now resorted to make claims on shrinkage and apply the usual very large thick brush statement.

Firstly we need to understand what causes distortion.

Distortion is a complex behaviour and is difficult to predict. Identical welded structures will exhibit different distortion characteristics, despite being welded in the same condition, the same welder and same procedure. Welding involves localised heating of joint edges to fuse material. This initiates non-uniform stress in the component because of expansion and contraction of the heated material. Initially, compressive stresses are created in the surrounding cold parent metal when the weld pool is formed due to the thermal expansion of the hot metal (HAZ) adjacent to the weld pool. Tensile stresses occur on cooling, as the contraction of the weld metal and the immediate heat affected zone is resisted by the bulk of the cold parent metal. It is during this tensile phase that ductile and brittle fracture crack propagation takes place. If the stresses generated from thermal expansion/contraction exceed the yield strength of the parent metal, localised plastic deformation of the metal occurs. Plastic deformation causes a permanent reduction in the component dimensions and distorts the structure.

Ok, now we understand the basics, lets look at weld shrinkage in detail. Since you are now wishing to deviate, again.

Here are two typical examples of weld shrinkage.

Longitudinal shrinkage



And



Transverse shrinkage.

Lets examine long.t shrinkage.
During welding, there is a ‘yield zone’ immediately behind the weld bead which is “compressed” by the surrounding much stiffer cold parent metal plate. The compression is balanced by the tensile stresses either side of the yield zone in the rest of the plate. When the gun moves along, the same area begins to cool down, the stress pattern reverses ie tension in the yield zone and compression in the rest of the plate. If the plate cannot resist the tension, the plate will shrink longitudinally, thus straining the plate/weld and surrounding structure.

Transverse shrinkage.
This is very similar to long.t shrinkage. That is, the heat of the gun/welding causes the base plate to heat up and expand. At this higher temp, the weld has no strength (it is near molten) and therefore contracts under this thermal expansion expansion. There comes a certain temperature (upon cooling) where the weld metal resists the additional thermal expansion of the plate. When that occurs the thermal deformation of the plate and the contract of the weldment during cooling, causes the shrinkage.

However, the killer two both these forms is restraint!

Restraint opposes shrinkage during welding and reduces distortion. However, as restraint is applied the final shape is controlled, BUT a build up of internal stresses begins in the structural member. As the amount of restraint increases, the amount stress and strain in the structure or weld has to accommodate to prevent cracking, must also increase, owing to the thermal gradients which introduces strain. This causes serious structural problems.

Brent has, again, made an assumption of how real professionally built boats (with frames), and it is incorrect.

I wont labour on the long sequencing of welding up an entire boat, however, the plate is rolled up and offered up to the framed structure. The plate is rolled therefore the edges are free have the correct gaps and have no restraint. The only internal stresses, are those caused by rolling. If done professionally and with proper plate expansions, these stresses are very minor, if flat plate then none at all.

So, the first structural member to be fully welded, is the plating. All the plate is welded up, in the correct sequence of course. Thus any shrinkage or distortion is in the plate and plate alone. The plate is NOT fully welded to any of the frames nor longitudinals. Therefore there is NO restraint. The edges of the plate are free to move and therefore do not impose any internal stresses owing to shrinkage/distortion. The plate takes up its own natural unstress shape. With correct weld sequencing, ie butts then seams, fwd v's aft and port v's stbd, the amount of shrinkage and distortion is minimal.

As soon as you weld the main structure, any structure, to the hull/deck plating before the plate is fully welded, you introduce a restraint and thus, asking for serious problems, namely cracking and distortion.

 

I didn't make this claim - you did! See Post no. 238:

When I hit a rock at hull speed just inside Ivory Island, the back of the keel pushed up into the hull...

By lying? Please tell me what I have lied about!

 

You have done a pretty thorough explanation already.

One of the first lessons that an apprentice received, I'm going back nearly 50 years here, was that metal would always contract more in cooling than it expanded when heated. A lot of work was done by the application of heat back then and this knowledge could be applied, using techniques known as "diamond heats" and "spot heats" to give very accurate changes in shapes and dimensions.

Nowadays, all this is not approved of, but welding replicates a lot of what happened in this process, hence the shrinkage, or as you say, internal stresses when restraint is applied.

 

Here's the quote, which is a bare faced lie ,as I have pointed out. Hull speed dead stop impact with a large rock is not a simple grounding , certainly not in your Lloyds aproved fibreglass boat.
I suggest you go back and read post 238, as often as needed, until the message penetrates the ivory. The damage was minimal, and insignificant. How would your Lloyds approved finbreglass boat survive a dead stop, hull speed collision with a rock in direct impact with the keel?
I've since drastically increased the strength of the hull where the keels attach , by building in a tank there, and switching to angles instead of flat bars for keel supports, which Evan flatly refuses to do.

 

This is good coverage of the sequence, which is far more forgiving on origami boats where the weld can shrink all it wants without any restraint. After the hull welding is done, you can see about 1 1/4 inch of outside curve betwen the decks and chine from longitudinal shrinkage of the weld seams, which adds to the strength of the hull. This is more pronounced in hull plate which has been cut with a torch.. The bigest screwup one can make with framed hulls, as you have pointed out, is to weld any plate to the frames before completely finishing the plate welding . Longitudinals are OK with being welded before the seams as long as they are free to float off the frames.
One way to mimise any weld problems is to minimise the amount of welding needed, which origami does, to a tiny fraction the amount of welding in traditionally welded framed boats , by using one 8 ft by 36 foot piece per side.

 

I've straightened out some pretty crooked steel masts ,to straighter than a custom pool cue, with this method. Simple and effective.