Aluminum boat repair question/advice

admin

I have a potential odd job for this weekend.  Older boat - owner will not want to spend much cash.Standard Lund 16 foot boat - it's been backed into while on the trailer.  Personally I would just turn it in to insurance.For the crack - one option I thought of is stuffing a piece of .060" aluminum behind the crack and rivet another over the crack. (it's what I have in the shop)I would also straighten the bent pieces as good as possible.Not sure I would really try to TIG the crack due to the wood inside.The bent pieces will likely crack on straightening - I'm thinking they will be weldable.Any suggestions or options I've overlooked?Dave J. Attached ImagesDave 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:
Reply:We already calculated 5 rolls would do it 1 roll for no leaks4 more for strength 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:I had a similar repair on a aluminum duck boat. I just pop-riveted a piece of aluminum over it, then covered the whole mess with fiberglass cloth, epoxy and paint.
Reply:I think I would replace or ad angle to the top, I am sure the plywood is broken as well and the motor will flex the transom back and forth and weaken it further,  other than that sounds good the boats are riveted from the factoryMy .02Last edited by JPS; 05-14-2013 at 08:25 PM.
Reply:Those Lund Aluminum boats are almost always 7075-T6 aluminum.  Not weldable.  That's why Lund rivets the boats.  Weld it and you'll reduce the strength by at least half and you'll have cracking issues too (if it is 7075).   Before I'd weld it I'd at least talk to Lund and maybe show them the pictures.  At least find out what the aluminum alloy is before you weld it.
Reply:All posts so far are true. Btw the lakes are still frozen Talked to him and he agreed to my original plan. I thought I remembered it was not weldable - glad you guys could confirm - thanks! I will post pics of the repair once his wife approves 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:If I were to attempt it, it would be a whole new transomDynasty 200DXPassport plus w/ spoolmate 100victor 315c oxy/(act and prop)Miller digital elitemilwaukee power tools
Reply:Put a large plate across the whole rear end, with rivets or screws. It both covers the damage, and adds strength to the engine mount. Seal with polyurethane sealer (using silicone is one of the deadly sins).
Reply:What about low heat aluminum welding rod to fill ing the crack and add a backing plate to it for strengthLincoln Power Arc 4000 Thermal Arc Fabricator 252 iThermal arc 186Thermal Arc 26 tigTweeko 200 amp spool gunHobart AirForce 400WP-17V-12R
Reply:I put new transoms on our rental boats a lot.  I would weld it up, put a cover plate on, weld or rivet it.  I have no idea about the 7075 comment, thats a new one to me.  If it is 7075, is that not weldable? I have welded 7075 before, but never noticed problems, but don't know.  I thought that was an alloy mainly for sprockets etc. Sometimes you have to put a new brace to handle motor torque.  I use "Sikaflex urethane" same thing they glue windshields in with.
Reply:So far it looks like using a plate is what he wants.  He wants it to look like it's just an extra plate for a trolling motor.I like the idea of welding it to seal it and then using the plate over it.  I will still slip one behind it as wellI'll call our local Lund dealer and see what they say about welding.  I will use the Sikaflex, or local equivalent, in either case.Thanks for the excellent suggestions so far 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:I took a tour of that Lund Boat plant in New York Mills, MN.  Quite impressive.  While I was down there we asked them about repairing boats.  They do it.  Took my dad's old lund boat (1970's) down there a few weeks later.  When they were done (in a few weeks) the damn thing looked brand new.  I bet they could replace that transom no problem and it would be as good as new.  Might cost a bit more that what you are proposing to do but (no offense intended) I think it might help the resale value more than what you are thinking about.  Then again if the guy is never going to sell it, the resale value doesn't matter.  They even retighten every single rivet in that hull when they do the repair too, just as a matter of course.  They even repaint it if that's what you want.
Reply:Poptm - good advice and that is what he should do.  But he won't - it's an old boat 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 am not sure what ever you do is going to restore that transom to it original strength.  If I remember right I think that particular model boat takes a 40  hp motor max (maybe even a 50 hp) .  Thats a bit of stress on that transom on a bad day (although at the moment it looks like he's got a 25 hp Johnson on it).  Does he tow anything with that boat off the handles on the transom (kids on tubes, smaller kids on water ski's, stranded boaters/boats)?  I know we used to do stuff like that a whole lot.  Especially, draging the anchor(s) we used to have tied to each of the handles on the transom.  Trailering that boat around won't be good on the repair either, especially if the guy isn't using a transom saver.  If he trailers it alot that's may turn out to be an issue in the long run.What's he gonna do, if he feels you didn't do the repair properly?  Will he try to hold you liable?  What if the damn thing sinks while he's out in the middle of Winnie?  Does he go out in the middle of Mille Lacs (or any of your other large lakes) with it? Think he tried to say it was your fault and sue you?  If it's the right time of year up there and it sinks he'll be dead in minutes if help isn't right next to him.  What will his next of kin say about your repair if that happens?The more I think about it the less I think I would want anything to do with the repair.  Good Luck with whatever you decide to do with it.
Reply:Sandwich the break between 2 stiff sheets of aluninum or just use 1 good stiffener using plenty of rivets & plenty of 3M 5200 between the layers.
Reply:Yep, two sheets is definitely the plan so far.  The adhesive is still open to local availability.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:I have done a couple of these kind of repairs. Here's what I did. Remove top capRemove both corner gussets(if required)Straighten back as good as u canCut a piece of 3/16 5052 as a back stiffener. Make it as big as you can an bend a 90 degree top to it to replace the existing top cap you have removedThis will keep the transom straightUsed sika flex ,lots of it ,to adhere it to back of boat. Clamp it on and bolt it right through with 1/4 -20 stainless bolts. Sealant in the bolt holes. Then repair interior transom shelfReinstall corner gussets ( if required)If you pm me your email I could send pics of my repairsDan
Reply:My advice is not to do work for tight wads.
Reply:Originally Posted by Showdog75My advice is not to do work for tight wads.
Reply:Poptum, are those for sure 7075 al?
Reply:Finished the boat up - is there a specific reason I seem to use 3 times as many tools as I think I will? I used some left over 3" tall Z aluminum inside and outside the transom.  The long legs are overlapping each other over the top of the transom.1/4" stainless bolts press them together.I used Sikaflex, as suggested, on the patch and related areas that needed sealing.Made only two welds - just to lengthen the scraps.The original top cap and the corners had to be removed.  Then I hammered the bent sections of transom as straight as possible (it was stretched by the impact pretty good).Thanks for the suggestions Dave J.(I brushed that weld after the pic to take the shine off it) Attached ImagesDave 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:I don't see the tape.Great job.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Originally Posted by Drf255I don't see the tape.Great job.
Reply:The warning sign here is "the owner does not want to spend much" He wants a good job for very little money and will never let you forget if he thinks you over charged him or if the repair fails. Tell him to take it somewhere else or to do it himself.Cheap boat repair sounds like someones gonna have a wet azzLooks like a nicely executed repair sir.
Reply:Originally Posted by vwguy3Cheap boat repair sounds like someones gonna have a wet azzLooks like a nicely executed repair sir.
Reply:That turned out rather nice.  Don't think he'll have any problem with it staying a float.  From the original pictures the transom looked cracked from the top to dang near the bottom.  From the repair pictures it didn't look like you had to do any welding to it.  Sounds like it was only bent and you beat it back flat.  Is that correct?
Reply:Thanks The crack was bad, but the weep line made it look longer.  I refrained from welding the transom.I beat the metal kinda flat, the bolted Z braces brought it the rest of the way.Now I'm actually replacing all the wooded seats - they were rotting and he decided to have me fix it....again, a little outside my norm - but hey, that's why I have so many tools right? 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:what ever you do don't put a smooth finish on the seats.  When the seats in my dad's boat (just like the ones in that boat you're working on) were refinished, a smooth finish was used.  Everyone and anyone sitting on those seats would slide all over the place when the boat was coming up out of the hole.  Was kind of irritating.  Took awhile before the seats became weathered enough for the sliding to stop.
Reply:Good advice, I just finished the seats and no worries on being too smooth Customer requested treated plywood with routered edges - I left the tops alone.Too smooth sucks sometimes - my uncle's garage floor will about kill a guy every time it snows...FYI for anyone that gets suckered into replacing plywood seats - took me six hours start to finish.  Thought I could do it in four - must be getting slow. Almost every cut has an angle on it.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.