Welding the skin to the frames demystified

[MikeJohns]

....... You a have a self delusion problem.
Brent

Take a deep breath Brent and please stop driving off on enraged tangents.

Your 26 footer flimsy? please try and read the posts properly. Also anecdotal marketing doesn't prove anything, anecdotal tales can be very misleading.

Arguments such as the pressure vessel are not even remotely applicable and has nothing whatsoever to do with hull structure and global strength, you are quite confused here. Neither is your design remotely related to a gas bottle. If you really want a better analogy take a frameless hull and a framed hull and then apply a partial vaccuum (not pressure) and see how the shape collapses.

Of course panel shape has an influence, if you want to be more scientific just read some of the modern scantling rules eg 12215-5 which go into detail on just how much support you can count from the shape, but for the full effect you have to stop this shape collapsing which comes back to the elastic instability I was talking of earlier.

 

[Guest62110524]

in the 28 years I have been building alloy sailing yachts, I found what never fails
I looked at such boats as Flyer 1 and 2 won around world whitbread races
fast, long lived sailing boats do need this type of construction in alloy
fully framed up , fully welded floors, overlaps on frames to floors and brackets too 300-400 centres
Stringers with short welds to floating frames, will fail over time and severe pounding, as will lightly plated yachts
Some folks laughed when I said you should be able whack the hull with a big hammer, because this what heavy seas do, over and over Well try larfing when you are falling off huge waves, counting the silence as the boat drops Do use cropped intercostals in slam zone where plates are flat, up forewards in topsides
Poorly built boats in Alloy do not survive, Look at Burton Cutter, first leg 78 Whitbread, broke , lightly built, lightly welded
I rest easy with this because I have to give 5 years warranty which I have upped to 10 years
on a modern boat, if the forefoot is well designed, it changes shape so rapidly, , imagine 1200 spaced frames, stringers, you could not achieve this complex shape imagine the mess as the stringers all bunched as they came together
THATS why Euro yards that are good and there are 100,s of them , stay with framed up boats
where did I learn such things, well fortuately I once built under Lloyds for an owner one JOHN HOLLINGS a eminent engineer, founder of CARTER BECKER FURNEAUX HOLLINGS the biggest civil practice down under, he taught me many fine things, like the plates on the flanges t to t floor to frame He was also navigator on renamed Flyer, Alaska Eagle, so I was able to learn how Huismans did it I then threw in some of my own ideas and over the years we got as near as perfect a structure as is possible

 

[welder/fitter]

The Wife and I desided on building the Roberts 345 pilot for a retirement boat to live on. Found a lot of contruction photos on the net and here is a couple of the framing, not sure if this is from the builder or its on the plans that way, Cant see any frames welded to the hull skin and no limbers. Looks to me the chines are flush and they pushed out the stiffners a bit. In the one photo it does look fair.
Tom

Tom,
There was once a member of the origamiboats group, Stephen Wandling, whom had a 345. When he was selling it, I went & had a look at it. Without a word of exageration, the boat looked like someone had picked it up by the stern with a crane, raised it to about 30 feet, then dropped it on it's nose.

Evan & Brent did some work on the skeg & pilothouse. For whatever reason, the owner didn't have them straighten out the hull. When a young couple from Oregon - Jason & Lauren(?) - bought the boat, they contacted me to discuss repairs. I worked on the boat on weekends, for about a month, in Spring2008. They lost their worksite in the summer and, last I heard, were moving it to the sunshine coast.

To be fair, I don't know how this boat became so damaged, but, remembering that boat & viewing the photos you've posted here, I'd like to share my thoughts with you.

On both boats, I've noticed that the longitudinals are crooked. On Stephen's/Jason's boat, they were like spaghetti. As the hullsides had flat & more rounded areas - not uniform, flat here, rounded there, etc. - and as the transverse frames were neither aligned nor straight(from section to section), The best approach, for me, was to start at midships and, moving side to side, working equally toward bow and stern, remove each frame from the keel plates/centerline. In order to make the hull look more like a boat, I chose to go with the more rounded aspect. Basically, I would cut out one side of a frame, weld a strongback from keel plate to chine, drive wedges until a uniform curve was observed, cut & shape a new frame section - rounding the outer edge - to fit the shell plate, cut suitable limber holes & slots for new stringers, align the frame section &, using some flattened 3/32" rod to leave a very slight gap, tack it to the rest of the frame/chine. When satisfied that everything was straight, I'd lay tacks along the frame/shell interface & fully weld the ends. The gapping along the frame/shell interface, combined with the rounded outer edge of the frame, allowed me to lay in tack welds that gave strength, without obvious demarcation on the outer surface of the shell.

The next procedure was to slide in as much length of stringer as would fit - once, again, rounding the outboard edge - and, using a saddle & wedge, force the stringer to the hull & tack, leaving some freeplay at the ends for joining the ends of the stringer sections. lol I used lo-hi mostly, but don't want to rehash that old discussion.



Like I said, I have no idea of how this hull became so mangled, so it is impossible to compare the results with the beating that a sailboat can experience. I discussed my thoughts on stand-off(floating) frames with one of the engineers at the shipyard & his opinion was to stick to the way the boat(lodestar) was designed. Now, recalling the 345 I worked on, viewing your photos and reading Mike Johns's post, perhaps, I'd do better to stick to the method suggested by my boat's designer.

Maybe, Jason is a member of origamiboats, in which case, you could see if he has any of the old photos. His email is: steel345@gmail.com . Though I tried to convince him that he'd be better off starting from scratch, hopefully, he'll finish it off & get it in the water, soon. By the look of the stringers in your photos, I'm wondering if BR's designers might have erred in where they suggest cutting the slots in the frames. Just a thought.
Mike

 

[tazmann]

Mike "welder/fitter"
It would be interesting to know what happened to the 245.
We just orderd the plans the other day, when I get them I will defenantly check out the stringer placment. I am planin to loft the lines so should be able to tell from there. From the info so far this was originaly designed as frameless multichine and there is a few options on the plans, I just have to wait and see.
I was lookin at the loadstar pictures the other day and the guy had the transom in, little more modern looking being forward raked. Looks to me he's doing a beutifull job on it.
LOL no argument from me 7018's fine as long as you know what your doin. I am going mig on the BR 245, bought another older LN-25 feeder and it works better than the new one I had, still cant figure that one out, mabee because its gray and matches the SA250 !
Tom

 

[rasorinc]

A hurmorous story I would like to share. As an educated man who for 40 years made my living building and land development (boat building being a hobby then) I went into the engineering firm I had dealt with for 34 years to pick up an engineered commercial site plan that my architect had laid out rough.
There were 4 young licensed professional engineers in the room when one rolled out my site plan. I said Louder than I should have "I left instructions that I wanted this done in LeRoy on Onion"............... 4 blank looks I saw, so I ragged on of course until the owner of the firm( a great friend of 35 years) came out
and asked what is the problem? I again stated that this was to be done in LeRoy on Onion. He smiled and then I cracked up. The 4 young engineers had heard of neither and of course could not hand draw. It was fun to stump the "experts". Stan
After, I asked if they knew how to use a slide rule? Not really they said.

 

[Guest62110524]

yes makes me smile Ras, I spose you mean script and paper, not bein a draftsman myself you see
i have never built a cad drawn sailing boat, but some of the plans hand drawn by designers I hired were darned good
it is still the best idea to draw a sheer by hand splines weights and to be able site along it, before finally putting onto pc, that is in my opinion
you might get a sweet sailing boat wonderful lines, but then you have to turn around do all the structure yourself, which is pretty easy if you have the experience, or pay a navel arch. to do it
or down here you can submit your own eng dwgs to the certifying body and they can stamp it

 

[rasorinc]

Whoosh, They did not know that every Bridge from the 1950s back was drawn with Le Roy and final drawings for repoduction were inked on Onion skin.
Everything drawn for many decades was done this way. We have some gorgeous Bridges. They do not even teach "How to print". It was a good day....Just think how many navy ships had final drawings this way. Le Roy was a set of 12 ink pens and about 5 different types of ink. No mistakes allowed...........................................................................!No one knows what a french curve is today.

 

[Guest62110524]

I bought my nephew a dwg set, and french curves, he kinda said, they are of no use
Alan Mummery whose designed Nimbus for me 10 yrs back still does it this way
It seems me that everyone wants shortcuts, and that is why people build with stringers, perhaps because they think it is faster, easier, the art of the boatbuilder is being lost as is the old designer, I dont see any pretty yachts coming through this board, but I do see some really ugly ones
There ARE some lovely steel yachts, but have not seen a real stunner for many a year, drawn by an artist and built by one

 

[rasorinc]

No experience with steel or aluminum boat building. I am a wood man and wood lasts generations. I build up to 40' or so and most have been 20+'-36'
I have a little nitch in the market and all my business is by referral. I'm slow now just 1 a year and I have to build 3 smaller ones plus my 30' cat. There are no shortcomings to quality and that is why I did good in construction and building boats. I never try to make the big buck and I'm honest as the day is long. Simple ideas but I've done OK for myself and hope I passed that on to my 3 children.
My idea of beauty and it's wood W/O fiberglass and 50 years old. http://www.ladyben.com/SearchResultsFull.asp?VesselID=2264

 

[tazmann]

I bought my nephew a dwg set, and french curves, he kinda said, they are of no use
Alan Mummery whose designed Nimbus for me 10 yrs back still does it this way
It seems me that everyone wants shortcuts, and that is why people build with stringers, perhaps because they think it is faster, easier, the art of the boatbuilder is being lost as is the old designer, I dont see any pretty yachts coming through this board, but I do see some really ugly ones
There ARE some lovely steel yachts, but have not seen a real stunner for many a year, drawn by an artist and built by one

Dang Stu you must be a hard one to please LOL.
Never heard stringers are a shortcut before. Are you saying a smaller size say in the 30' range, round chine, 10 gage hull plating could and should be built without stringers, closly spaced frames only? Or are you talking larger craft with thick skin that dont leave a nice ridge on outside at every weld.
Tom

 

[Guest62110524]

10 guage that 1/8th? 3.2 mm, , no seen many built close framed way, if they are round, it does require good skills, feeling for the metal, and maybe old fashioned panelbeater skills, dollys and hammers to stretch after welding seams
but there are other ways, restraints, that is pieces of metal put across the weld seems, notched(temporary) to hold the shape til welding is done, good fit up, small welds yes its possible
I decised on the new stuff Franious welders, after talking to many and getting over my mistrust of invertor welders

 

[tazmann]

10 guage that 1/8th? 3.2 mm,

Had to check with calapers 10 gage .1345" hair over 1/8" or 3.2 mm.
I havnt used the inverter type welder myself but never heard anything bad about them eather. Most my work is from a portable rig so not much use for one in the field.
Tom

 

[welder/fitter]

Inverters are great! In the Drydock, we are usually running LN25's hooked up to portables or shop machines, or SMAW with same power sources. For the past couple of ferry refits, however, some of the guys have been using these little inverters when working with the electricians - trays, collars, transits, A60s, etc. - and fitters(inside work). You can get a compact, lightweight inverter that runs on 110v & supplies enough juice for 1/8"rod, for tacking purposes. On a recent ferry build at the shipyard, I was playing both roles - fitter/welder - and welded with a little inverter. It was light enough to carry on my shoulder(strap) and ran both 7018 & 6011 1/8" rod well, though I would have prefered a more robust arc for flats/horizontals.

For boat building, where much of the welding is tacks or stitch welds, One could go a long way with one of these, not having to drag hundreds of feet of cable around.

Interesting comment on the LN25, Tom. I have an old model, use old models, & the Drydock bought some new ones in, last year. Perhaps, they have reduced resistance in the new ones, as I found that running my power source at 31-32V, which is where I like it, is now too hot! Go figure.

As for the transom on that Lodestar build, I hope he's planning to cut in some steps, after all that work. After looking at those photos, for the "millionth" time, I think I'll have to train my guys on a smaller boat first. Just too much work for babysitting while building. I'll have to have a chat with Dudley about his Hout Bays.

In terms of the "crooked" stringers I mentioned, I think that it may be due to builders cutting slots for the stringers which are too small for the thickness of the stringer when at an angle other than 90 degrees & the stringers forced through. Just a thought.
Mike

 

[Brent Swain]

plating

Tazmann
check the welding schedule with Roberts. if the plating is this close it's daft not to weld it. I'd also ask Roberts what scantling rules their plans comply with.


Brent
Anecdotal tales are very subjective, small ships have been washed over reefs and inshore 300m without damage, light foam cored grp racing boats have been stranded on surf beaches for weeks and been recovered undamaged. Real strength is not related to subjective anecdote and is easily and accurately demonstrated theoretically but involves much more than simple geometry.

Longitudinally supported hulls are common, once the vessels get over a certain size bulkheads are introduced since the required strength goes up relative to the square of the span.

In metal construction better strength to weight is achieved by the use of transverses and this will never change. Your (Brent's) small boats 26 and even 36 footers are not frameless they have floors, longitudinals integral tanks and achieve additional longitudinal strength from chines and radiuses.
Try designing a 60 foot sailing vessel of say 40 tons displacement and you will quickly see that there’s no sensible way you can design without transverse support/framing without having a very odd looking hull or massive longitudinal girders.
Regular transverse supports however make a metal boat far more rigid since they resist the transverse shape change as the hull girder bends.

Simple solution. Get yourself the light foam cored fibreglass hull you speak of, and lets have a demolition derby. Would you say the results are anecdotal?
How many light fibreglass boats have survived pounding across 300 yards of coral reef in a big swell , or collisions with freighters, steel barges at hull speed, etc?
The floors , tanks and all transverse members on my boats are to spread the transverse loads of the keel, engine , and skeg across the hull, not to stiffen the hull. With the single keeler none are needed, as the curve of the centreline and the width of the keel give far more stiffness than transverse frames ever could. With the twin keelers, the keels are in the middle of the plate, and taking the load to strong points like the chine and the tank edge is neccessary.
The experts ,with all their scantling rules, don't seem to have as much success at keeping their keels on in the Southern ocean lately. Maybe more common sense ( the least common of all the senses) is needed. None of my keels have fallen off.
There is an upper limit on how big you can go without trasnsverse frames , but using origami methods will drastically reduce the time and potential distortion of the boat , with frames put in after welding the hull up.
The Wandling boat was badly warped , before Evan or I ever worked on it, by welding the frames in before shrinking the edges. We could have built an origami 36 ft hull from scratch with fewer hours than we put in , but the hull was bought for $1,000 and the owner was trying to save the cost of new metal. He would have been far better of starting from scratch.
Glad someone got her straightened out. It looked like a horrendous job.
When Timo asked me where he could buy a hull and deck, I told him to buy a load of plate, and in less than three weeks we would have a shell tacked together, in far less time than he could find a hull, negotiate , buy and move it. He bought the plate, and in a couple of weeks he had his shell together .I don't know why people are intimidated by the thought of building the shell when it is the quickest, easiest part. That boat is now in New Guinea.
When someone builds boats for a living , then the more hours he puts in the more wages he makes. Thus Wynand has a large financial stake in denouncing any advancements that will reduce the number of hours he can charge for a boat, to keep his income up. He thus has a lot in common with Evan's practise of trying to maximise the number of hours he takes to get a boat built.
The flip side is, when steel boats become more affordable , and quicker and easier to build ,we will see a lot more of them around, and thus demand for steel boats will increase, increasing the opportunities for all steel boatbuilders, and cruisers, as will the much fairer, filler free, origami hulls. .
Brent

 

[welder/fitter]

Just to clarify two points:

1) As Brent points out, the Roberts 345 I was referring to was a disaster before he and Evan worked on it. In fact, their's was the only work worth saving.

2) I did not complete the hull work on this boat. The owner lost his work area & moved it to the sunshine coast for completion. I got him started & showed him & his wife how to burn rod. The stbd bow work was enough to make a barmaid eat her young!