Welding 1950s riveted Iron

Hi all, I am considering a tug/houseboat conversion. I'm not committed to the project yet as I am still researching, I'm not considering taking on major hull repair but would like fabricate on deck and make interior alterations which would be easier and faster to weld than to mechanically fix

I am experienced in welding and fabrication but don't have much experience with Iron, I have welded cast iron and know it to be troublesome and difficult to guarantee as the only reliable strength test is to break it !
I have read a thread on this forum :
http://www.boatdesign.net/forums/me...ted-hulls-any-good-what-lies-ahead-38908.html
in which Mike Johns (thanks John, well described ) indicates that his experience with welding iron has been reasonably straightforward as the materials he has had tested have proved to be low grade steel. I guess what I'm asking here is "has anybody had any nightmares failing to repair riveted iron boats with welding" and "should I walk away, go and find steel hull to play with" ?
thanks in advance
Ian

 

TRY A Phillips 56 low hydrogen rod
you will need plenty of open circuit voltage
These rods are good overhead, vertical ups great Depending on ambient a lil preheat will help
Used to do a lot of special steels like bisalloy and big forks on log loaders like 3 inch plate so the prep was huge

 

There are nickel alloy rods that work well too. Some welding suppliers have one day courses on using specialty rods.

 

I am 67 and a former shipwright, certified welder, and other trades. I've worked in boat/shipyards and other marine fields.
I'd be surprised if the 1950's hull is iron. Maybe if it was built by the British. Iron plate went out when mild steel plate became cheaper to make. I don't know when that happened, but of the riveted hulls I have worked on, all were steel plate. Rivets, too. The oldest was 1925. All the hulls were small ships or bigger. Sometimes we welded all the exterior rivet heads and plate seams. But it makes the hull very stiff and usually some welds crack. Sometimes when the hull plating was badly wasted, we replaced the plating with welded plates. We either did all the plating or none. Having a part of the hull stiff while the rest is flexible can lead to problems.
If the hull is in good condition, I would leave it and the rivets alone. Just add zincs.
As to a welded deck, I don't think the stiffness of the deck would matter. Wood commercial fishing boats often had plywood decks with fiberglass on top. The stiffness increase seemed to be helpful. Less working of the hull and seams.
If you're going to use your hull in the ocean, I would allow any new bulkheads to flex with the hull. Because you have a flexible hull, any wood walls, cabinets should be bolted or screwed, not nailed. Otherwise you'll have the nails working their way out.

 

cast welding

Preheat casting if you can? bevel the joint for 100% penetration , Vee out back side for full penetration Peen with chipping hammer each pass as it it is cooling after welding post heat /slow cool down what is it a casting/ never heard of a cast steel p;ate? call weld rod supplier for tips. when welding an insert you have to back step weld passes to get enough strength to overcome the restricted weld shrinkage on last butt or seam or on circular inserts new method uses ceramic backup strip behind full vee out with root opening of 1/16 gap . NICKEL IRON ROD FOR CAST IRON 7018 for everything else.

 

Cast steel comes in a wide variety of control specifications. In USA this is covered by ASTM. ASTM A27 is a cheap, low grade steel casting, often full of blow holes, and difficult to weld. On the other end of the spectrum of steel castings you will find ASTM A216, which is chemically identical to AISI 1018 rolled plate, and is very clean, and easily weldable with low hydrogen or rutile wire processes.

in any case, you can determine what kind of metal you have by spark testing, and a visual examination, if you lack spectography:

https://www.youtube.com/watch?v=D094eBa4S7c
https://www.youtube.com/watch?v=cFf_x97vcQ0