Unusual boatbuilding technique for steel yachts 26'-40'

That is a mad idea, nothing else. A round bilge vessel is completely different designed than these so called origami boats. The latter has not found a single supporter amongst our dozens of NA´s and builders here btw.!

Redesigning (as you constantly plan to do), needs some deep understanding of the elements of boatdesign (Naval Architecture).
It is not only "scaling" the given plans up or down

You should choose whatever design fits your requirements and build to the plans.

(and you should be more careful with enthusiastic statements about methods or materials, our boatbuilding world is much more complex than you might assume)

 

Hello Tug
Yes that 45' does have nice lines. The way it looks flatish bottom and minumal rocker for and aft she needs frames, how many I cant say. What you might want to do there is get a copy of Dave Gerr elements of boat strength, you can use that as a guide for the scantlings.
I am working on a 38' schooner scantlings that I will start building shortly, a lot of it is kinda catch 22, space my frames farther apart and add extra longs to compinsate and your back to same weight and about the same welding. Thicker skins and lighter frames and you have a heavier boat.
One thing you need to keep in mind is yes you do get a lot of strength from steel as a whole but you still need panel stiffness, get your frames to far apart and the flater sections flex in and out, your gona have some serious problems down the road. also youve mentioned skinning it with out rolling the plates, without strong framing holding the longs that may create a problem ?
Tom

 

Moot point.

How many NA/builders build only in wood and never dream of steel,or build in steel and never build in glass, etc.?

Or trawlers vs. sail,or multihull vs. monohull,etc etc.

 

Come on guys - take it easy!

Tugboat, it seems to me that your version of being "constructive" is to tell you that everything you say is true, and that your way of doing things is the only way to do them.

People with many years of professional experience are trying to tell you that the origami way - in their opinion - isn't the best way. That - in my opinion - is being constructive.

The origami way is a possible way, but - in my opinion - not the best way if you want an efficient structure. Plating with reasonably spaced frames and longitudinals will allways show the best stiffness-to-weight and strength-to-weight ratios.

Another thing: You have mentioned scaling of existing designs. Please don't do this unless you are an experienced designer or NA yourself! Boats scale, but their characteristics do not. You may end up with something dangerous, but you may not discover it before it is too late!

 

Sorenfdk--no if i thought i knew everything in wouoldnt be here-- and the ones who have been respectful about it i have listened to---trust me there have been some nasty posts directed personally at me and for what reason im not sure --im tired of that idiocy and i am going to attack back now -

anyway- yes i actually have taken a lot into consideration about this method- i tend to think things through given the advice and statements and my own experience and the advice of others more quaified than myself- I have understood that a 10% reduction or increase is the maximum rescale that can be done--to illustrate my understanding of this is that when i rescaled the 45 ft hull to say 30 ft the beam then becomes about 8.5 ft--not acceptable for stability but the 12.5 beam of the 45 ft version is 12ft 6 which was the designed beam reduced 10% is 11.9 ft. it doesnt chnage much. i was never able to figure out whether to scale the depth or not...so i have kept those plans to the original dimensions...-- so basically all i wanted to do was reduce framing and add long'tdnl stiffeners. since there were none in that design. just thick closely spaced transverse frames.now again im no NA yet i wonder if this boat wasnt over built?..using 1 inch x 6 inch thick keel and stem. AND 33 3/8TH thick x 2.5 flatbar?... i was going to reduce the framing to 1/4 inch x 3 inch and space about 18-20 inc hes and add longitudinals at 12 inch intervals? six of one half doz of the other???
the other problem that i seem to go back and forth on is the size--i love this design --it is my favorite design but it a huge vessel- especially for a first time build of this magnitude. this is why i was desperatley trying to figure out a way to rescale...i have not seen other plans that i fell in love with in the same way...so its tentative right now--all i know is --in another month or two i am laying a keel and i dont care if its a rowboat or a 45 ft tugboat...i am getting the ball going...i have been in analysis paralysis for too long....

 

Tom- sound slike a nice boat your building - i think you might get away with lighter plate...I hear a lot of designers call for cor-ten, but its expensive and my supplier says it special order. I think it is stiffer too...
One thing you brough up i did not think about and that is the flexing of the hull between frames if spaced farther apart. do you think it would be very signifigant if i use 3/8- or 1/4 inch plate for the shell?

i designed and built a barge three years ago
everything was perfect-it sat on its lines and it performed well- i didnt use
a raked bow but a curved upswept bow for gentle entry. the only problem was the hull flexed in a seaway. i know soem flex is necessary but i didnt like the feel of that.
the reason was I didnt use enough longitudinal strength. so i am inclined to take the scantlings for the 45 ft'er and space them (as mentioned above in another post) 20 inch spacing and 10 inch long'tdnl spacing-- shouldnt this be adequate for strength and stiffness??..it might wiegh less than the original boat as built but i would just have to ballast it a bit more...
then there is the plating problem --i know amateurs can plate a round bilge hull by using come alongs and clamps etc...but it does sound like a real chore...the advice others have given me on here is that find a chined hull--well i could go to my 30 ft'er design...it's cheaper and smaller and for one person probably easier to build and ultimately drive....but i sooooo do not want to give up on my fav design...i guess sometimes its a comprimise. and i despise comprimises...i will look around ebay for a copy of that gerr book..thanks

 

Tug
My understanding of scaling 10% is length only to keep the same crarcturistics and that only applies to some boats not all. Be carfull there.
Top heavy and less stable come to mind with the changes your making there
3/8" vs 1/4" huge strength difference and also about 5 Lbs a square foot.
Building the 45' in a round bilge is going to be quite a project, time and money. If you pencil it out shortning it 10% in not going to be much different. Pretty much the same going with lighter scantlings, if you manage to shave off 5000 pounds you would save maybe 3k , by the time youre done thats going to be minor and then you have a tug boat built thats not built for tug boat service.
Tom

 

can you please write down what you want to hear

 

sure-- positive constructive advice---how hard is that to understand?

 

I hear you Tom-- I did a mock up of that design on my building area yesterday and it is REALLY big.. its definitely too big a build for my needs and expense...the tug actually wont be for commercial operation--its just a character vessel that I love...and will use to push my houseboat barge... so I think ill scrap the 45 ft design for the smaller one--

 

quote,tugboat
the only problem was the hull flexed in a seaway. i know soem flex is necessary but i didnt like the feel of that.

 

Do´nt worry Peter,

he will recalculate that!

 

origami

The "origami" technique for building boats is not new. Stitch and glue plywood contruction uses many of the same concepts.

Origami is not suited to building round hulls. That is better achieved using conventionally framed construction. Origami is suited to creating developed surfaces.

The idea that origami = frameless is a misconception. Origami hulls, like chined hulls, are developed surfaces. One unique property of a developed surface is that the ruling lines are all straight lines.

Thus, by aligning the framing with the ruling lines, you can replace complicated framing shapes with straight "T"'s and "L"'s. These can all be welded onto the skin of the hull before assembly, while everything is laying on the flat. This reduces the skill, time, and distortion while welding, yielding a fairer result for less cost.

One of the significant problems in metal boat construction is the skill level required to obtain a fair result. This tends to price metal boats out of the market, except in specialized applications where strength demands a premium price.

One problem area is that origami increases the span length of the frames. However, this is overcome by incorporating transverse bulkheads, girders, floors, tanks, furnishings, etc. into the design to minimize the size and number of frames required. By varying the frame spacing, the hull can be strengthened locally below the waterline as required.

The chinese junk uses a similar approach, using bamboo as its structural model. The framing in bamboo is longitudinal, using regularly spaced bulkheads to minimize the span length, yielding a strong, light weight structure. Origami applies this technique to metal hull construction.

 

Moot point , many na design are very diversified. More than what you think.
As for builder you are right, they need to specialise, but not all eather.
More and more the wood does also alu, and the steel one make also alu.
We have to diversified or we are pretty dead...in the water
Daniel

 

I would say it is a valid point Daniel. Not moot.

Almost all of us builders / designers have had their "point" when it was to choose "the" material.
Sure, none of us did manage that to the very extend. Anyone to disagree?

We live and work in a uncertain environment, our best estimations are as valid, or better, than any calculations, we are better in guessing than knowing.

**** on science.

The scientist knows when the strucure collapses, but he is not there.
I do not know to the very extend when that might happen, BUT I AM THERE.

Let us (Peter, You, Sasha, and me), build our crappy junks and Sampans to our "gut feelings" and in accordance to Germanischer Lloyd, we must not fear much more than being buried by the heavy structure once it falls on our feet.

The idiots have to fear that the concept already falls on their feet, because it is unproven.

Not to belittle the experts here.
ALL of you know that we do not adore you due to our ignorance, but due to your knowledge. And much more due to your ability to share.

Have a nice day.

Richard