Skeg - Winter Project

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Hi everyone.Being as I was the one piloting my in-laws boat and am the maintenance man on it anyway......... now I have a new one. Long story short. Apparently the responsible parties don't reposition the bouys when the lake levels drop. 30 yards away from the markey bouy and found the rock pile anyway. Thankfully, only low idle cruise around the lake.So now when we turn into the land of 10,000 icebergs I'll have to get some experience in skeg repair. The prop will be subbed out.Being as stupid questions make more sense than stupid mistakes. MIG or TIG? Equipment I own to do this: OLD Airco (Miller 320AB/P). Primarily setup for TIG but I picked up an old (NOS Army surplus) Airco MiGet with controller, 5356 - 3/64 wire, contact tips yadda, yadda.TIG starting suggestions would be good. I'm thinking 3/32" pure electrode, 4043 at 3/32" filler, Argon at around 160 amps. Short runs to keep the heat saturation to a minimum.Input greatly appreciated. Thanks. Attached ImagesLast edited by millrat; 09-15-2012 at 03:15 PM.Reason: Forgot pics
Reply:Hopefully SundownIII will chime in for u.  He is the resident marine expert on the board.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:I think prop-doctor here has posted up a few of these repairs in the past. I'm thinking tig, but I'd have to search the old threads to be sure..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Pull and strip the lower unit. As close as that break is, you will cook the seals, the heat will temporarily loosen the bearing fits, possibly allowing them to move.4043 rod is compatible to A356 AL cast material, 5000 series rods are not.Using a higher end inverter tig helps cut the time required by 80%, since the heat can be focused and ramped uporders above what a transformer machine can do; via the AC frequency-set at minimum,torch is 10% EN--for max. penetration, with sharp point, 2% ceriated tungsten.(Air and porosity in the casting breaks initially makes for very dirty welding, most of which is taken back outwith carbide burr/grinder, then go at it again, and again, and again. The initial welding technique is akinto 'bump' welding of anodized stock: heat until seeing some wet/softness, jam the rod in, fuse, stop, cool.IOW--this type of repair is not a 10 minute job, if full pen weld and skeg alignment is desired forservice. That's 'why?' most 'professional' shops never do a full pen weld and 'why?' the crooked skeg breaksoff--again.)Blackbird
Reply:Thanks for the replies. The plan would be to trace on cboard the break line and transfer to the replacement skeg and cut it down. I don't plan on removing any more of the original casting than I have to. Bevel both, align and weld in short runs to keep the heat to a minimum within the housing (I'll have all winter for it).Don't know how much impurities will be there but I can't imagine there will be anywhere near what I find in those Onan oil pans! Lots of crap in those. Lot of work. Pure T seems to work best in this machine.A new machine would be nice but there a long way from the $500(delivered) I paid for the old boy I have. Used Syncros are going for over $2K around here. Wife would have a fit. Course, if I was talking a ring for her I'm sure she'd be all in.
Reply:Tig all the way.Done several of these.
Reply:Thanks.BTW. The machine. Circa 1957/1958. Doesn't look like much but it WELDS. Still has the original Miller cooler. Attached Images
Reply:Not trying to be a smartazz, but if you have to ask whether to go with mig or tig, you're NOT READY to take on this repair.It's really NOT a difficult job, IF you have experience welding aluminum.Lots of practice with aluminum samples is in order before you even consider taking on the "real job".  Very easy to damage the casing with too much heat.As mentioned, the welder (machine) is not ideal, but will do the job in experienced hands.I'd keep as much of the original skeg as possible.  Will help to keep the heat away from the housing (where the seals are).  Also recommend "venting" the fill hole to prevent pressure build up in the housing (and blowing the seals).  There's a kit available where a fitting screws into the fill/drain hole (used for filling the housing thru the drain plug).  That will allow the oil to remain in the housing (for a heat sink) but not be under pressure as the temp goes up.Don't get "in a hurry".  Allow to cool between welds.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Oops.  Double post.Last edited by SundownIII; 09-18-2012 at 12:48 PM.Reason: Double postSyncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Originally Posted by SundownIIINot trying to be a smartazz, but if you have to ask whether to go with mig or tig, you're NOT READY to take on this repair.It's really NOT a difficult job, IF you have experience welding aluminum.Lots of practice with aluminum samples is in order before you even consider taking on the "real job".  Very easy to damage the casing with too much heat.As mentioned, the welder (machine) is not ideal, but will do the job in experienced hands.I'd keep as much of the original skeg as possible.  Will help to keep the heat away from the housing (where the seals are).  Also recommend "venting" the fill hole to prevent pressure build up in the housing (and blowing the seals).  There's a kit available where a fitting screws into the fill/drain hole (used for filling the housing thru the drain plug).  That will allow the oil to remain in the housing (for a heat sink) but not be under pressure as the temp goes up.Don't get "in a hurry".  Allow to cool between welds.
Reply:Thought I'd follow up now that it's done.I made a plate for the lower unit so I could fill it with water as a heat sink and mounted it on an engine stand so I could rotate it around. That gave me complete immersion of the gear case so I didn't have to take it apart. Short weld time to where the water just got warm and then drained and refilled. I also used a brass backer for a heat sink and stiffener/positioner.The replacement skeg is a POS. More crap in that casting than an old oil impregnated Onan oil pan. The out drive casting was really nice, but the skeg would boil, puke and spit crap out for about 3/4 of the length of the weld. It was so bad the crap in it actually caused a crack to take off perpendicular to the weld joint.   It was a struggle with the new skeg, but it's done. Attached Images
Reply:More pics. Attached Images
Reply:Thanks for the update - it was instructional.  Nicely done too. Your airco beats mine on age, mine is only a 1963.  Welds excellent   Btw, about how many amps did it take?Dave J.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Dave,I don't recall exactly. I think I wrote it down and it's somewhere in the pile of notes on my desk. I'm thinking somewhere between 200 and 220, pedal "kill" to start puddle and then feathered the pedal (I think that's "pulse" now), fill about 3/4" and stop. I can't do long runs up there anyway with a 60A breaker.100% Argon at 15 on a dial face reg and 3/32 Pure tungsten and #7 or #8 cup. Short runs to keep the heat off the housing bore and seals and alternating sides (after tack up) with the heat sink and welds and checking the water in the housing for temp. The base housing and skeg material was 3/8" thick. Beveled both pieces to about 1/8" flat in the center.We were on the water this weekend and so far so good, but then again, we didn't hit anything. So that's a good day on the water.: laughIF it happens again (ya right), it was still better than taking it to the local marine dealer who charges $395 minimum to start a skeg repair.
Reply:Nice repair. Now here is a stupid question from someone who has LOADS of aluminum TIG time and has done cast. Did the replacement piece you welded in have to be cast? Looks to me like a piece of plate.Can extruded aluminum be welded to cast? I don't think I have ever tried. I have used 4043 to build back parts like ears on transmissions and such. I think I may have patched the bottom of a oil pan with a piece of plate once, but cant remember if it worked or not.If you cant fix it with a hammer, it must be an electrical problem."Boy, everyone starts with a full bag of luck and an empty bag of experience. The trick is to fill the bag of experience before the bag of luck is empty."-Grandad circa 1990ish
Reply:Larphead,I learned a long time ago that seemingly stupid questions make more sense than stupid mistakes. Apparently it doesn't have to be cast. I talked to the guy that repairs my props and he just welds a piece of plate on and then grinds/sands the contours of the skeg. Given the cast quality or the replacement skeg, that's what I'll do next time. It'll be faster than trying to repair that crapped up casting.I would think extruded would be the same as plate, channel, etc other than possibly being anodized. I don't know what the alloy would be on extruded but that may vary as well depending on application. Then again, I've never tried either.Might have to visit my prop guy for some info and drops. He's been building the structural for extruded/anodized decking planks. I don't recall if the planking is bolted directly to the framework or if he's welding mount tabs to the stuff.
Reply:Originally Posted by millratDave,I don't recall exactly. I think I wrote it down and it's somewhere in the pile of notes on my desk. I'm thinking somewhere between 200 and 220, pedal "kill" to start puddle and then feathered the pedal (I think that's "pulse" now), fill about 3/4" and stop. I can't do long runs up there anyway with a 60A breaker.100% Argon at 15 on a dial face reg and 3/32 Pure tungsten and #7 or #8 cup. Short runs to keep the heat off the housing bore and seals and alternating sides (after tack up) with the heat sink and welds and checking the water in the housing for temp. The base housing and skeg material was 3/8" thick. Beveled both pieces to about 1/8" flat in the center.IF it happens again (ya right), it was still better than taking it to the local marine dealer who charges $395 minimum to start a skeg repair.
Reply:I repaired my Uncles 15 horse Johnson skeg with a piece of extruded aluminum and 4043 filler. Much smaller (about and inch and a half long by 1/8th inch thick) compared to this one, but welded surprisingly well.Late to bed, and early to rise. Fish like hell so I don't have to make up lies. Syncrowave 200MM211 & Spoolmate 100
Reply:Originally Posted by MinnesotaDaveI had a feeling it was fairly thick.  Your memory sounds right for amps. Alternating sides sounds like a good plan as well.$395 to start the job?  You really saved money on this one Good post to remember - thanks Dave J.