Major repair on riveted aluminum boatn

[Flynn18]

i recently purchased for $550 a boat that i do not know much about: the previous owner told me that its a 1986 mirrocraft musky(or mister musky) with a 1986 johnson 75hp outboard (according to the model number(E70ELCRD) i believe its a 70hp from 84)

He was selling it saying that the boat was free and i was paying for the motor and trailer, the hull has a large dent(~1.5ft dia) on the bow just above the waterline, i do not know what caused the dent but it is about 3in deflected at the deepest point, the dent is right over a riveted seam and has caused a + shaped crack about 2in by 2in about 5in below that seam. I have heard that Mirrocraft is a lower quality boat so i am seeking advice on whether or not it is worth it to repair or have this repaired.

i do some welding(steel only) and fabrication out of my garage so i will do any prep work that i can to minimize shop time/cost
if i bring it to a marine shop i would like to have it fully stripped and ready to be welded

I have a friend that is an experienced aluminum welder and would help me out, but i am worried about the aluminum becoming work hardened and brittle from stretching(denting) and then being forced back to its original shape, i have thought about cutting a large X or + into the dent, then bending it to shape and having it welded and reinforced like that but that will be a lot of welding and heat and may heat treat the metal and make it brittle. is this something that must be performed or at least looked at by a marine repair specialist or am i overthinking it?

so my question is should i:

a)hammer or jack the dent out and have the crack welded and reinforce the area(if this is a good option, should i do this with or without heat?)

b)cut an X or + into the dent and bend it to shape then have the cuts and the crack welded and reinforced

c)scrap this hull and find another

should i attempt to do this repair with my friend welding it or should i leave it to a marine welder?

Please note that this does not need to look pretty inside or out, i haven't had it on the water yet but judging by how much sealer is on the boat I'm sure it has many leaking rivets, the previous owner told me he'd kept using the boat even with the dent and crack because the bilge could pump water out much faster than it was coming in, especially when lightly loaded.

I would also like to know what you guys think the boat/trailer/motor are worth, and if you think it will hold up to being in the Long Island Sound or if i should only take it to greenwood lake

Please let me know what you think

 

[Flynn18]

I am trying to post pictures so you guys will see what i am working with but am having little success

 

[Flynn18]

I made my avatar a picture of the dent, it doesn't show a whole lot but its the best i can do right now, if any one is feeling generous please give me some guidance on how to post pictures or i can email somebody the pictures and they can post them if its a new member restriction

thanks in advance

 

[GA_Boater]

Welcome aboard, Flynn.

Now that you have made 3 posts, the new member restriction, try posting the pics again. It should work this time. The avatar pic is too small and we can't see the damage.

Click on the Forum Help link in the sig below and look at the Photo Attachment Tutorial to assist adding the pics to your posts.

 

[Scott Danforth]

big hammer and a block of wood will take out the dent. a patch of aluminum, some 3M 5200 and some rivets will take care of the leaking crack.

 

[ezmobee]

Since you don't really have much to lose, I'd bang it out and then patch any resulting damage.

 

[jbcurt00]

Pix tutorial GA suggested
http://forums.iboats.com/forum/forum...pload-tutorial

If the Mirro is a 1986, it will have a HIN stamped into the hull on the top right corner of the transom, from the back.

The seam will certainly complicate the repair no matter how you attempt it. Go slow and it may take a little hammering, some jacking or other typical dent pulling methods used in sheet metal repair. Give it a try and see what works. As a rivetted boat, near a seam, I'd probably avoid welding, for the reasons you mentioned, and used rivets.

As the seam is already open (PO said it leaked there), I'd even consider removing the rivets in the seam at the dent befoee trying to pound out the dent.

Just be careful to not make it worse while pounding, whether or not you remove any of the seam rivets

 

[fishin98]

With out pictures it's hard to give really good advice. That being said, MirroCraft boats are worthy of trying to repair. My thoughts...work from outside of the dent with a wide body hammer and a backing piece,use a heat gun and SLOWLY work the metal back into place. When finished use 3M 5200 SLOW CURE in the seam after you warmed it up with the heat gun. Then rebuck the rivets in the near by areas.

 

[Watermann]

Welcome aboard Flynn :wave:

Sounds to me like you've already done your research on the repair. One thing I would add is to stop drill the ends of the crack in the AL before starting the repairs.

 

[Bondo]

but i am worried about the aluminum becoming work hardened and brittle from stretching(denting) and then being forced back to its original shape,

Ayuh,.... Welcome Aboard,... Aluminum is Easy to anneal for further hammerin' it straight,...
It also work-hardens very quickly,....

To anneal the area, wipe the back-side with a fairly oily rag, leavin' a film of oil,.....
Heat the opposite side with a torch, propane is plenty hot enough, keep movin' the heat 'round, til the oil on the back-side evaporates,...
Then let cool to touch,.... it's annealed, 'n ready for Beatin',....

When yer poundin' on it, use a Heavy hammer, 'n Big Wacks,.....
If ya could bend it back in a single blow, That's the Best, less annealin' to do,....
Usin' tiny hammer taps, still hardens the metal, 'n stretches it more than less heavier blows,...

Weldin' it back up shouldn't be a problem for yer Bud,...
Any issues might be cleanin' any seams enough,... ole sealants can be a problem,...
Aluminum has to be clean, Clean, freshly gone over with a ssteel wire-brush on an angle grinder Clean,...

 

[Flynn18]

thank you guys for the advice, ill be pounding it straight as soon as i can find the time, the photo files are all too large to upload but ill try to condense them

 

[GA_Boater]

Try using a photo hosting service like Photobucket, then use Option 3 from the link jbcurt00 provided the link for.

 

[Flynn18]

No Title

 

[Flynn18]

finally got the pics uploaded, what do you guys think after seeing the damage?
what would you say it is worth(I was happy paying $550, won't be offended if you say its crap), looks like the skeg was broken off and welded back on and the corrosion near the prop in the last picture worries me a bit. are these signs of an abused motor?
the steering cable seems to be seized, the carpet needs to be replaced or glued/stapled/pinned back in place, could use new wood and switch panel for the console, and I'm not sure if the gauges work, has a lot of sealer on many rivets
the gunwales also seem a bit flimsy, I'm not sure if this is normal to lower end riveted boats or not, for all i know this thing may have been designed with benches of make a live well up front that kept it supported
when on the trailer if i climb into the boat by the gunwale it will flex outward an inch or so

please let me know your opinions on the worth/repair of the boat

Thanks,
Ryan

 

[ezmobee]

Actually I think it looks even more pound-out-able than I thought it would. Obviously you'll have some crack repair to do but I think it'll come out fine. That lower unit is junk though and will need a replacement.

 

[Flynn18]

thanks for the input, what downside is there to running this lower unit for a while?

 

[Watermann]

Yeah so that is a substantial dent you have there but it can be made less noticeable and the boat can be made seaworthy again easily. The seam will make it a very difficult repair but you have to give it your best try.

Oh and the LU on the motor, as long as it's not leaking run it.

 

[Flynn18]

Thanks, ill post pics of the repair and let yo guys know how it turns out when i get around to it