Unusually built?

I am curious to the thoughts from some experienced steel hull builders about how this was built.
My original thought was that it is way underbuilt. Although it weighed 42k but designed for 26k which is not unusual for steel when builder takes liberties.
No chine bars
No stringers
2x2s wedge fit between ribs (otherwise known as water dams)
not one interior screw penetrated the ribs
solid steel floor in pilothouse with steel bulkheads (this must be the main stiffener?)

 

Sorry about the images. Im still learning how to do these and I just could not make them a decent size without them being to big to upload....

 

This does not look like a properly built boat: The stringers & framing are almost superfluous.
What is the plate thickness - the boat might be salvageable.

 

Twice design weight (of just the hull shell) is unusual even for steel...

What is the story behind it? Yeah, better pics would help.

 

I bought it this summer. I have done a few projects like these for others and always wanted to build my own, but knew that was not realistic for many reasons, with money being the biggest.

The boat was built in Sweden in 1982 and reportedly in a boat building facility. The owners kitted it out. The last two owners have spent tons of money on electronics, water makers, new engine and genie, sails, and running rigging. The last owner had it blasted and painted below the water line in 2012
.
Neither of the last 2 owners since 2002 ever sailed it. The original owners sailed it from Sweden to the BVIs and says it sailed beautifully.
The boat weighed 37300 when scaled on the truck but was stripped of all fluids, anchor & chain, sails, rigging etc. I have done the math and it would be 42500 in full cruise mode. The BR plans call for 26,967 displacement.

My plans call for replating where necessary, and considering Belzona 1121 for the electrolysis at water line.
Im not worried about the lack of strength in the hull as its easily addressed. It did however hold up very well like it is, with several haul outs and those alone could of caved in the sides.

The original owner claims that the hull was professionally built. The welds are very good and clean, and the hull has no fairing in it. The hull is 4mm Core Ten so that says something about build quality with no fairing.

Ive just never seen anything like it, and really was hoping find out that it is common. The pilot house is amidships, with steel bulkheads and floor over main. The water tanks under the galley were welded in place and they add some strength im sure. Aft stateroom has 2 posts and a piece of C channel header under the mast which may add strength but probably not.

The plans are Bruce Roberts, and he has seen the photos. I haven't paid him for the plans yet, so I did not get his input.
So far the opinons do not favor a professional hull build...Bummer

 

He would not confirm that it is his design? If she was originally built in Sweden for ice, that would explain the "built like a dumpster" construction.

 

Yes, Bruce confirmed it is his plans, the 392 C. He only asked if Ive removed stringers. He does not give out free information, so once I buy the plans, he will answer all my questions.

What is meant by "built like a dumpster" ?

 

Monocoque construction. If you make the skin strong enough you don't need structure like ribs or stringers.

 

Unless the plate is REALLY thick, it still needs some support by frames, girders, stringers, floors, etc

 

The hull is 4mm. I think that is on the light side, but to plans..

 

Update:
I started removing the water tanks (there are 2 at 150 gal each) and was sure they were both empty. I was wrong. One of the tanks was nearly full. That accounts for possibly 1000 lbs I can reduce from my weight calculations as I had factored it in twice.

I also discovered that the hollow portions of the keel were full of water. I did some rough calculations and came up with another 100 gal of water weight that I had not factored in. I think it's safe to say that my weight in full cruise mode would have been under 20 ton which is better.

My goal is to keep her around 17 ton loaded. With her size, and sail plan, she should ride like a cadillac but still move well under sail per this sail calculator.
http://tomdove.com/sailcalc/sailcalc.html

I would still love to get some more input on this type of hull construction. It obviously works as she has crossings as well as haul outs in her history.

In an effort to solve the weight mystery, this construction has me completely baffled. She appears to be very lightly built, so her extra weight could only come from the added tankage, large generator and over sized diesel. Unless the ballast is way off and I have yet to confirm it.

 

4mm (0.157") sounds okay for a 39' boat providing it is properly framed, built, and maintained.

 

The properly built part is what is in question. Hence the post..... As to the maintenance, that failed...

Leaking windows and those 2x2s wedged between the ribs causing water to become trapped, has nearly ruined this boat. I have lots of replating to do.
I have been looking at this concept of light weight steel hull construction, and it seems that done correctly is very strong. I read some place that welding technique is critical. Some thing about in order to have the strength in the skin, it has to be tight, which is accomplished by welding specific areas in sequence allowing the metal to heat and move much like stretching animal skin over a drum. As it heats and shrinks it gets tight.
That sounds plausible to me, however what happens if I cut out and weld in new sections? I imagine I risk altering the affect.
I have enough welding experience to know anyone can stick two pieces of metal together. A little practice and one can make pretty welds. It takes a master to make strong, pretty welds that move metal where you want without distortion.... I think this project will challenge all my skills... I cant wait....

 

my 2 cents worth based on past experience:
You might want to get the hull plate tested for thickness. Little 'spots' here and there can 'thin' the metal. Steel boats can rust from the inside out. First places to look are under the 'wet' spots: galley, pumps, 'head', chain lkr. engine .... etc.
Welding sequence is critical. I have seen boats ruined by improper sequence and over-welding.
Had a look (thanks for the better photos) & the 'framing' and it minimal. Check against the original design drawings.

 

Thank you,,, sound advice.
The hull is stripped of everything (except main engine and gennie) and I looked everywhere I could prior to buying.
There will be a lot of replating, which is mostly under windows, toilet, and sinks where corrosion is past leaveable.
Im working on a plan for the electrolysis pitting at the water line. Some is bad which some fillet welding can handle, and I am working with a Belzona rep regarding the smaller pits.. They claim, that with proper prep, their epoxy will add the strength back to the pitted areas..