1.2.1.2.3 Shipyard - Building - Hull - Welding - Boat Welding sequence

Hull - Welding - Boat Welding Sequence (last update 12/10/05)

Fig. 2.2.1 shows the principal layout of the plating on Joohee R14. Plates 4,5,8-10 are 5mm alustar 5059 O/H111 plates, plates 1-3, 6,7 are 4mm alustar 5059 O/H111. For complexity although not exactly belonging here: the internal transversal frames are 4, 5 and 10mm alustar 5059-H321, temper H321 is also used on plating and frames of skeg and keel (in general all plasma-cut alustar is H321, plating is O/H111). Central axis is 5059-H321, stringers are 6x50mm and 10x50mm flat extrusions made of 6082 T6; the deck edge tube and keel leading edge tube is 5082 O/H111.

Now back to the welding sequence (after reading a lot and talking a lot we have opted for following welding sequence which actually proved to give minimum welding distortion so far (i.e. 12/10/2005) (just to clarify for non-technical people: there is always welding distortion and build up stress when hot fusion welding is concerned).

1. Absolutely no structural welding was done before the plating was welded together. Only exceptions were a few welds which would not be accessible after the plating is on the frames (i.e. the mast base, inside the keel etc). The whole structure, i.e. frames, stringers, plates, tubes etc. are only tack (spot) welded to barely hold together.

2. The structural welding has started with vertical welds of plates inside the boat (i.e. welds between plates 8-9,6-7 etc). The actual sequence on individual vertical welds was back-stepping (more info in welding techniques), however, the welds were timed randomly over all vertical welds. The idea here was to make a three virtual strips of alu-plates composed of (1-3), (5-7), (4-10). At this stage each individual weld was about 10cm long. It should also be noted that naturally each weld has to be done symmetrically on both sides of the boat (this applies for all the welding described below.)

3. After all vertical welds (from inside only) were finished, we used 'random walk' technique to weld the horizontal plates together and also to central axis and sheer tube. Still all from inside only!

4. After all inside welds were finished, we started random walk technique on horizontal welds and back-stepping on vertical welds in random manner from outside (see welding technique for back chipping etc...). Here the welds were about 15cm long, the sheer tube was already held firmly from inside and was welded after the outside plate welds were finished (the reason for this is to avoid a frequent adjustment on the welder; it did not give any problem with the distortion).

5. and thats were we are at present, next will be added after the welding continues :) 12/10/2004

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