Interior welding of hull

Once the hull was upright, tempoary tarpaulins went up to keep the rain out and the sun off. Sheets of roof iron covered the bow and stern deck areas.

Then a corrugated iron roof was attached over the deck beams for longer term protection of the hull. Any rain at this stage could cause corrosion. (NB: prior to hull plating, the stringers outer edges, were treated with wirebrush, phosphoric acid and zinc primer.)

 

The stringers were again treated with phosphoric acid and zinc primer. This does take a bit of time, so getting the flat bar stock block blasted and zinc primed before delivery to site is always the better option.

Now the hull was rolled, downhand interior welding proceded in a similar pattern to the outer hull welds. Before a weld was done the seam was ground out to remove any slag from the outer welds. The back-step method with short 2-3" runs was used.  3.2mm rods were used for the 5mm plate seams and 2.5mm rods for the chine/3mm plate seams.

The welding pattern was similar to the outer hull.  Once the welds were done..the tempoary 1" flat anti-distortion bars on the outside were removed. Interior welds were ground slightly to clean them up but the convex weld profile was kept for maximum strength.

For safety and comfort electric fans and ample ventilation are needed to blow weld fumes away. It could be worth wearing a welders respirator under the weld helmet at this stage.

Exterior grinding and staircase

The exterior double chine welds were ground down. A 9" angle grinder was used. It's a heavy and dangerously powerfull tool, so to suspend the weight, it was hung off a chain with rubber strap.  The top was a hook over the gunwale which could be moved along . A lightweight 4" grinder finished the seam.

Old highset house stairs from the house wreckers provided much easier-safer access into the hull than a ladder would. The stairs allow hands to be free and used for carrying tools and materials up safely.

Hull rollover

The Hull inside prior to rollover.



The waterline-pivot rollover method was used (also known as "pig on a spit" method). This was beacause there was not much space around the hull, low budget, far from crane hire yards and already had the materials on site.   Also the hull stays in the same location. It uses A-frames, heavy-duty chainblocks and pivot pipe frames welded to the hull.

Its probably a good method if an existing very strong shed already exists over the hull and the chainblocks can be attached to this instead of building A-frames.

My A-frames were made from 14ft long 6" x 12" hardwood railway bridge sleepers (as used for my building jig) and paperbark tree posts cemented in. 1/2" threadeded rods augered through held them together.

The pivots were 2" pipe welded to the hull at both ends horizontally at the design water-line. The pivot pipes were braced back to the hull with 40mm steel pipes. The building jig-angles coachbolts were removed to detach the hull from the jigs railway sleepers.

Roll-over day

This was done with the help of a few friends.  None of us had ever rolled a 2-3 ton 35ft hull over before. Three ton chainblocks were hired and chained onto the A-frame tops.

I wasn't sure if the center of balance was guesstimated right. So just incase it was a few hunded kilos lopsided, Dr Con bought his 2 ton? turfer winch, usually used haul his 4WD out of bogs. It consisted of a thick steel cable and the lever winch could pull itself along the wire rope. It was rigged amidships to help roll the boat once the chainblocks elevated the hull. A brake rope was also rigged amidships incase the hull decided to roll by its own weight.

Once all was in place the chainblock falls were hauled down simultaneously at each end and the hull began to lift and inch, two inches..a flying boat! When the wylo was about 2-3feet high, which seemed very far to fall, the turfer was hauled on..but it proved redundant because the hulls balance point was just about perfect, so only 2 half inch ropes (without block purchases) were easily enough to roll the hull around 180 degrees by hand, well almost. I had forgotten to cut a wooden A-frame brace pole off and it got caught up on the transom corner! (at about 160 degrees roll) so up the ladder to try to free it with a come-along, then the 2" aft pivot pipe began to bend!  it stopped after about 6 degrees bend as the transom corner released itself from the pole. (The pivot pipes had end plates welded on just incase the pivot pipe bent to a worst case scenario and the roll chains began slipping off). Its hard to describe the feeling of tons of hard work potentially about to crash downwards. We weren't standing anywhere under it that for sure. During all the action no-one even thought of taking a photo! (don't forget to bring a dedicated photographer to rollover day)

The final small lowering onto the keel, was needless to say, a big relief. Props quickly went in under the hull.



Note: The forgotten bush pole that caught the transom.

The wylo suddenly looked different. More like a boat than beached sub.

 Note: The tempoary cross brace amidships.

The foward A-frame and  hull pivot -bracing detail is shown in tree-cam shot above. The exposed hull was quickly covered with old roofing iron to keep any rain out.

Pivot rolling  in retrospect - Place roll-pipe braces very close to the roll chain attachment points. (On the pipe that bent was cause by the roll chain being about 9" out from the side braces attachment point.) or use a wider-stronger walled pipe, a ton or two is hanging off it. Also make sure nothing can snag up during the roll.

Other hull rollover methods

1) Another, probably better technique, is the the "jack-up and lower" method used by Nick for Wylo2. This method needs a large open area one side of the hull maybe 10m wide for rolling (best planned and set up when setting up the boat yard and build jig at the beginning of the project). Then the hull can be rolled by jacking the gunwale up to topple-point, lower the keel to ground with a block-tackle or turfer winch - 4WD winch?, then jack-up/block up the hull to upright position. The boat moves sideways about 3-4m? during this type of rollover.

2) If in town, crane hire with good operator is the quickest way to rollover. The hull can be placed back where it started or anywhere else if desired. Stronger tempoary hull cross bracing would probably be required in two places where the lift straps wrap around the hull.

Keel cooler and wings

The keel base plate is on and the sun/rain tarps are up.

The 3mm thick keel cooler plates are around 5" wide in the garboard. Improves the hulls shape and  provides good surface area to dissipate engine coolant heat.

The keel cooler actually ends where the small vertical weld is about 18" back from the leading edge. (There is a 32mm galvanised coolant crossover pipe inside here). The leading (and trailing) edges of the cooler are actually sealed voids to make a faired in shape. welds are all ground flush with the hull to reduce any turbulence and drag, which should improve keel performance upwind.

For those interested in wylo winged keels heres a few pics, below is the frame up.

The wing plate is 3mm steel, templated and welded on. The triangular frames are visible.  A small modification to the winged keel design may be beneficial from a building perspective here. It probably would have been easier to make if the wing keel top and bottom plates meet each other edge to edge , and not tucked in 1/2 inch from outer edge as per design.

Welding the hull up - outside

Welding the hull is a big job and it can makes or break a steel boat. I followed the recommended books of G.Klingel and T.Colvin. Correspondence with Nick Skeates and the TAFE night welding course also were invaluable. Prior to full hull seam weld up, the entire hull is held together by tack welds at about 6" spacings. Full weld up begins on the outside. Once outside welding is done then the hull is rolled over for internal welding.

  

Good preparation of the weld seam is important. Beveling the plate edges and leaving a 1mm gap between plates/chine bars allows for good weld penetration and also stronger weld with no hairline cracking due to shrinkage (could occur if the plates are hard-pressed together)

 

3.2mm weld rod stubs were used as spacers between frames and chine bars or stringers (These were fitted at the framing stage befoe hull plating). They were knocked out as seam welding progressed past them and the hull began shrinking. In retrospet 5mm spacers would have been better, especially near frames 1 and 2 in the bow, where hull shrinkage was greater.

I used short weld runs around 2-4" long. The short welds are needed to prevent any unsightly distortion (buckling) of the plates occuring. After doing a short weld i moved to another location to allow the first weld time to cool down. Both sides of the hull are also welded symetrically to prevent the hull pulling out of shape. Full hull welding has the effect of shrinking the hulls size by about 5-10mm.

A welding pattern needs to be followed. This is to balance out all the shrinkage forces evenly. I began near the center of the hull in the garboards (keel meets hull joins) and worked outwards towards the ends of the hull. After several meters of weld were in the garboards, i started on the lower chines..when several meters were on the lower chines , i started on the upper chines.

When a longitudinal (sub-horrizontal) weld seam reached a tranverse (up and down) plate join then i started welding down the plate join. Small plate bolts and washers were knocked out before the weld seam reached them, otherwise they would be clamped in by hull shrinkage.

 

After a weld was done the slag is chipped off with a welders hammer and wirebrushed.  Then the angle grinder was used to prepare the end of the first welds to meet the next weld. If a pinhole was noticed, it was ground out and rewelded.

Power wire brush fitted to 4" angle grinder make weld cleaning fast and easier. A face sheild is needed to protect eyes from any wires that may fly off.

The soft chines of the wylo2 are a bit unusual. They are 2" flat bar laid flat which forms the hull skin and makes a gentler corner which helps give the apperance of being a rolled plate hull instead of a hard chine hull. But the problem i noticed during weld up is this is easier to distort than usual chine methods of a solid round rod or on-edge chine bar. So i tack welded  tempoary 1" flat bars on edge, on the outside, in the center of each 2" chine bar to prevent chine distortion (photo above).

Welding seams. The rubrail was added prior to weld up. It is a 40x20mm steel channel set about 6" below  (above in this pic) the gunwale. It acts as a very strong double external hull stringer. As designed, it is also more aesthetic, reducing any slab-sided effect of the topside plates.

Some builders make the rubrail coincident with the gunwale (Klingel-Colvin method) fitting a 40-50mm preferably galvanised pipe instead of the designs 1" flat bar gunwale. This then requires an extra internal 1" flat bar stringer to be fitted to maintain hull stiffness around where the design rubrail would have been. A gunwale rubrail takes all the bumps well but it does make the hull appear to be a bit stockier aesthetically than the wylo2 design rubrail method.

I did  the hulls chines and garboards with a traditional 180 amp stick welder with 3.2mm rods and about 110-130 amps set. It takes 15 amp AC input. The 3mm hull plate joins needed 2.5mm rods with ~90 amps set. It may be better to "back-step" these joins, weld upwards starting  2" down from the previous weld.

Arond this stage i bought a 130 amp MIG (metal inert gas) welder with 10 amp AC input for thin 3mm hull plates. It  produced far less distortion than the better-penetrating 180 amp stick welder. The MIG was set at around 90-110 amps and a continuous wire feed from a spool activated by a trigger is easier to weld too. The MIG can be run gasless with flux coated wire or with an Nitrogen bottle attached by regulator and hose. The inert nitrogen gas of the MIG makes a gas sheild over the molten weld keeping out oxygen and making for a good weld without slag etc. My MIG prefered downhand welding (weld gun above weld). On overhead welds the MIGs gas sheild cowl got quickly filled up with weld spatter, never a problem with the arc welder.

The MIG has a big box, almost the same size as the arc welder, but with only 8 feet of flexible cable to the weld gun (no "traveller" as in expensive MIG welders). so moving the MIG with nitrogen bottle around was more difficult than the simpler 180amp arc welder with its long 10m cable. For me the MIGs welding advantages for 3mm plate outweighed its mobility disadvantages. (It wasn't powerfull enough for the thicker plates or chines so both welders were good for their particular uses)

Keel base plate

The keel base plate is made from a solid piece of 12mm thick steel about 6 meters long and around 40cm wide, it weighed hundreds of kilos so was moved with chain block and rollers etc.

The photos show keel base plate preparation work. Making sure the bottom of the keel is leveled off for the plate to fit on top, so the welding gap is correct all the way around.

 Moved up to large oxy-acetylene tanks for cutting steel hull plates (small ok in the frame building stage). The 12mm base plate cutting needed large cutting tips and alot of gas. It may be possible to provide a full-size template to a steel fabrication shop and they could plasma cut the keel base to shape.

This photo shows the keel profile shape. It is a NACA designed foil section. A 4" hollow pipe on a raked back angle forms a nice oval leading edge shape horrizontally. The keel has 6 compartments with 5mm plate bulkheads. These bulkheads extend to floor level inside the hull making the keel very well braced for extreme sideways forces. Moving front to rear the first 3 compartments house the ballast. The 4th and 5th are water tanks and i made the final thin compartment a sealed void (others use it as a tank, its a stove-kerosene tank in Nicks plans). The first 2 ballast bulheads have 45 degree cutouts on the corners, it should elliminate the chance of metal fatigue cracking where 2.2 tons of ballast gets thrown around by the sea. The 2 separate water tanks (25 gallons and 45 gallons) are fully sealed at the corners.

Sorry no photos of the plate making or raising. But i used a standard masonite template as the other plates were done. The keel base plate was about 10mm wider than the keel sides, sits ontop with  T joins to the keel sides. This join is probably strongest and is per design. 

(Also it allows the optional keel winglets could be attached..that a story in itself - to cut a long story short, i started building the 5" winglets, got the lower side in place on both sides but after awhile realized it was all too much time and work, and decided to "keep it simple" so oxy-cut them off and reground the ragged base plate edge smooth again. If you want to win the Ammerica's cup or something like that then build the winglets, i don't think they'll be necessary on the 4'3" draft keel version, (useful on the 3'9" draft keel version though, eg wylo35 Mahina ))

So the base plate was cut out and edges ground with the 9" grinder. (sorry cant remember peening it, if i did it would need a sledge hammer).  A strong angle steel was welded to one side of the hull and braced to take the 1/2 ton chain block, then it was raised into position and tack welded on. Shade cloths went back up. Final edge measuring, scribing and grinding followed.