Back in the 1970s or 80s (I forget) a new crab
boat was launched near Seattle. It got maybe 50 miles from the
dock on its maiden run to Alaska when suddenly a plate or two
blew off and she sank. The reason was the Welding
Sequence had been wrong, and stresses had been built in
that were so strong they exploded a plate off.
The correct way to weld long welds is well documented in several of the steel building texts. Essentially it boils down to skipping around and not doing to much at one time in one place. It isnt a big thing to learn the basics of. For proof of that, look at all the home made steel boats out there. This particular PROFESSIONALLY built boat is the only one Ive heard of where a plate actually blew although come to think of it I think a guy told me he had a Diesel Duck keel develop a bad warp because of welding all on one side.
Anyway, welding sequence is an important part of building a steel boat. As I said, it apparently is well discussed in the various steel books out there (again, look at all the home made steel boats!) and far as Im concerned, anybody who claims to be a professional steel boatbuilder should know all about it. Period.
But I guess its a New Age. A guy who has been trying to get bids on the west coast for a new 60 steel design (the Diesel Goose 60) told me the shops he talks to all say they want the designer to furnish the welding sequence.
Off hand I can think of only one designer who actually really knows steel and whos word I would take on welding sequence. Thats Tom Colvin. Im sure theres others of course. I can think of only a handful who I think know anything about wood construction, and if youll forgive me, I happen to be one of them. The majority of the designers out there may have read all the books but have NO first hand experience building anything.
So, if a pro shop tells you they want the welding sequence written out I would run. I dont believe any shop that knows what theyre doing would dream of asking for that. Ive worked with a number of pros and Ive never heard of such a question until this particular boat, in Nov. 03. Interestingly enough, all the yards he asked also want a cutting disk. Yet they claim they are experienced builders.....
Finally, keep this in mind. If a welding sequence is provided the odds are it was done by somebody who never welded in his life but read about the sequence in a book. As I said there isnt much to it. I would far rather rely on an experienced builders knowledge than the written down instructions of some guy who has never held a torch but has read a book. And for that matter, unless a trusted paid employee is standing there and watching every weld you have NO guarantee the shop is following the specced or any other correct welding sequence. That means the specced (is that spelled right???) sequence would be a useless court defense. How can anybody know if it was followed or not?
So, I do not provide a welding sequence. I see it as an attempt by a very few builders to avoid the liability of their own poor work. If you are building a steel boat yourself, be sure to read up on correct welding sequence. If you are hiring a yard to build it, if the yard wants a specced welding sequence I would, if you, assume they dont know what theyre doing.