Is this hull too far gone?

[Peterwd]

Hi All,

I am new to this forum but have been reading for hours searching previous posts and threads and finding out way more information than I knew existed. The knowledge here is unparalleled. 

I wanted to post a picture of my boat. I just got this boat as a trade and they said there were "minor" corrosion issues. I think the fact that the last zink rotted off 4 years ago and was never checked since might have something to do with this.. Needless to say, this boat was in the water up until last summer and I'm not sure how it didn't sink. I guess barnacles are a good filler?

I couldn't find a soda-blasting facility anywhere remotely close to my home on central Vancouver Island so I opted to get it sand-blasted just to see what I was dealing with.. Pictures attached. I removed the motor and plan on flipping the boat over and doing an acid wash/etch to really get it clean. After that, I'm not sure what the best route is to get this boat back on the water. Thoughts? 

I think the bottom plate material is 3/8" thick. It is a very heavy boat build by Eagle Craft (Diagle Marine)

Thanks in advance and sorry if there is already a similar post I just couldn't find a case similar to this in my searches. 

Peter 

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[kmorin]

Peterwd,
Yes, I'd say the boat was too far gone to bother repairing - unless you remove the entire bottom and re-plate?  The reason for my pessimism is the uniformity of the corrosion- as though the boat's electrical system was delivering stray current to the hull or the bottom paint was copper based.

The forefoot bottom plate at the bow and the transom submerged areas seem to show uniformity of corrosion bow to stern. The detailed photos show a depth of penetration coupled with a close proximity of corrosion sites making any repair wasted money IMO.

I have repaired boats with pitting, by gouging out the pits and TIG welding in replacement aluminum.  However, I wouldn't even offer to consider that in this hull's condition. Time for recycling IMO.

Cheers,
Kevin Morin
Kenai, AK

 

[Peterwd]

Thank you for your response! 

[IronwoodIsland]

Kevin and other Al boat building experts:

Would it be feasible to salvage this valuable hull by "strip planking" a new skin over the old plating in the corroded area below the waterline?

Given that the structural framework is like unaffected by the pitting that occurred to the plating, could a person MIG buttweld a series of 3" 3/16 strips of aluminum over the existing hull (with periodic plug welds to secure the strips to the existing plating).

The strips would be relatively easy to conform to the hull with a soft blow hammer ( if planked in the same direction that a wooden boat would be constructed).

The result would likely be serviceable, but not perfect, and would certainly add weight (at 2.7 lbs/sq ft x 8 ft beam x 20 feet = about 450 lbs) - but the weight would be low.

A major drawback would be the crevices created between layers that would result in future corrosion of the new plating.

Just thinking out loud - there is so much value in the rest of the boat it seems a shame to scrap it.

[kmorin]

Ironwood,

Would it be feasible to salvage this valuable hull by "strip planking" a new skin over the old plating in the corroded area below the waterline?


 

 I find several reasons that argue against this idea.  1. What's to weld too?  2. Burying existing corrosion cells? 3. labor & welding?

1.  There's so much widespread corrosion shown, I question what could be used to anchor or attach the planks?  The seams between planks would be long and many... what will back them up? Will the planks float?  I'd want them welded to the hull but welding over the mess shown is a fool's errand.

2. IF any cell is still active and not excavated via blasting w soft media then a cell could remain reactive so the planking idea would just cover up a time bomb, rendering the planks an extremely expensive but short period 'solution'.

3. If the hull were inverted and blocked keel up- then redoing the bottom may have some future gain. However, if the project were proposed while keel down (?) it would be very expensive in labor and welding to get planked. 

If the hull has enough worth to redo the bottom the only realistic method of work in my experience would be to invert the hull, cut off the entire bottom at the chines, turning loose all transverse framing stitch welds including bulkheads' seal welds (!!) and replating the entire bottom. This would be worth a great deal more than the boat looks worth in existing condition.

Note the un-etched transom showing overall mill scale corrosion? What does the bilge of a boat this poorly maintained look like? I'm guessing not too sound? Overall, I can't see a final hull that justifies the money to recover the massive bottom deterioration? 

I'd ask; what could you resell this boat for if you completely recover the entire bottom from chine to chine? IMO you can't find a recovery of the money and value of time it will take to revive this level of corrosion/neglect.

Cheers,
Kevin Morin
Kenai, AK