1971 16' Starcraft Super Sport leaks

[looserivet]

As the title says, I have this boat and its developed a ton of leaks all of a sudden. I've owned it for four years, it was garage kept and freshwater run before I got it. The last time out I drained out about 40 gallons of water after a day on the water, event though the bilge pump was working. It ran about every 15 minutes that day. I filled the bilge up with clean water and found about 40 leaks, about half of them are rivets leaking, the other half are pinholes in the hull. Four rivets have popped off, the rest are just leaking but don't seem to be loose. The biggest leaks are the pin holes, it looked like it was raining under the boat when I put about 30 gallons into the lower hull. All the leaks are below the deck, all the leaks and loose rivets are near the keel, each of the rivets that leak are the last or lowest pairs on each rib, and all the perforations are near the leaking rivets.
The boat has loose foam flotation, I can see some of it at the back edge of the deck. The deck plywood and vinyl is original, and is in decent shape yet. There are no soft spots on the floor.

Its never seen saltwater, it lived its whole life on a lake in PA. I brought it here four years ago.

My question is, do I write off the hull for corrosion or attempt to fix this? Loose or missing rivets are no big deal to me, but the sudden number of pin holes tells me something ugly is going on below the deck corrosion wise.
I've owned dozens of Starcraft aluminum boats and have never seen one with corrosion holes like this, especially without any other signs of corrosion on the hull. If it were electrolysis I'd see it on the bare aluminum bits or around the water line, those areas are clean. The corrosion holes are all midship, basically right below the console on the starboard side only. The rivets that leak are in the same area, also on the starboard side. There are four rivets leaking at the stern, the last four along both sides of the keel strip. These were likely just bumped loose over time, there is no corrosion there.

I went around the whole boat with a plastic chisel and tapped on each rivet to see if any were loose or ready to pop and found none, I find it odd that only a certain few rivets and certain area is affected.

 

[BWR1953]

Welcome to the Starmada! :welcome:

Sounds like pretty routine stuff for a 47 year old Starcraft tinny. I have a couple of 42 y.o. SC boats myself and am working on one of them right now.

It's likely that the original foam is water logged and trapping water next to the hull skin. And since the boat is in PA, (where?) it's also likely that some of that trapped water froze, causing additional issues.

Time for a deep inspection and possible refurbishment! C'mon over to the iboats Starcraft subforum and join the tinsanity!

 

[looserivet]

The boat came from North Eastern PA area, I brought it to Jersey in 2015.
The boat lived its whole life under a roof, either in a boat house at the lake or in the garage next to the guys 1973 Ford wagon he towed it with. The boat hadn't bee in the water for 10 years when I took ownership of it.

I can't imagine how freshwater could corrode the hull like this? There's an area about a foot square under the drivers seat that's got about 14 holes eaten through the outer skin. All the holes are between rivets, where I can't get at the hole from the inside. The one hole is nearly 1/4" after poking it with a pencil, the rest are less than 1/8" but there are some blisters in the paint in that area too. I can poke a pencil through the hull at each of those tiny rough areas. I also noticed that the chrome on the side rub rail ends in all pitted on the starboard side only. The trailer doesn't contact the hull anywhere around that area, the only electric in the boat is the starter and running lamps. All of which are factory.
The hull doesn't seem water logged, its super light, three guys can lift the whole boat minus the motor. (Three senior citizens lived this thing off the trailer last summer so I could paint the trailer), so its not likely holding much water. I lifted the bow myself, and it wasn't much of a strain to lift it.

Its never seen rain and never had a leak before this. I don't think I've ever had anything come out of the drain plug before when I parked it. It shouldn't need a rehab, its not had much use over the years. The only thing not original is the seats, I removed the back to back seats in favor of single seats for more room in the boat. The deck is completely covered in Nautolex vinyl, as are the sides, Can I buy the same stuff if I have to tear into the deck? The wood is fine, I see no reason to replace what's not bad. The deck is 1/2" plywood under the vinyl.
When I got it, I removed the rear sliding doors and track, this let me put a modern gas tank in that area longways, I swapped out the seats, and I removed both Starcraft emblems on both sides because they were at the level that would hit the dock where I launch the boat, I didn't want them to get broken or lost.

The motor is a 1973 Mercury 500, which it came with when new. The guy that had this ran it maybe a half dozen times a year on a local lake up in PA, when it wasn't there it was in his garage. His family had a boat house and a boat lift they didn't use, so he'd keep the boat hoisted above the water when it was there for the summer. I considered maybe that the boat lift could have contacted the boat there but its too low on the hull. The lift was manual, with a huge wheel you cranked to lift the boat. It was suspended by the surrounding docks or pilings that supported the boat house. The motor is mint, not so much as a speck of corrosion on it.

 

[Renderwurx]

Galvanic corrosion is likely the culprit. Either dissimilar metals or people using the boat hull as a ground for their electrical stuff. I understand that some bodies of water have high electrical activity as well... but maybe more of a rare case.

I think many will recommend drilling/riveting the pinholes with closed end rivets and using gluvit to seal everything. I had a goof bit of galvanic corrosion in my boat, but luckily it didn't result in pinholes just pitting. Mine also was along where the stringers had been reinstalled with stainless screws. But I also found a wire or two that was grounded to the hull.

 

[boedekerj]

I would ++ to what BWR1953 said. I'm dealing with corroded aluminum, but in a different way. I have an 5052 aluminum tank in a fiberglass boat that was foamed in place, in the hull. (So, the aluminum was never actually IN the water. The foam got soaked, and in-turn held the water on the tank, causing it to severely corrode. From what I've read (here and elsewhere) Aluminum, when it oxidizes DOES create its own corrosion protective layer (aluminum oxide) but it only does so when it's allowed to dry after being submerged. So, it either needs to stay dry, or there MUST be air movement sufficient to dry it. To me, one tell tale sign here might be the appearance of the pinholes. When viewed from the outside, if the pitting surrounding them appears to be nowhere near deep enough to penetrate through the hull,outside corrosion would be consistently shallow. If these pinholes are not at the bottom of any valleys of significant patches of corrosion, it would indicate that the corrosion is coming from the other/under side (as BWR1953 said) probably from foam or something else holding the water there. Good luck, brother!

 

[boedekerj]

...the underside might look like this, when you pull 'er apart: http://nautechmarine.co.nz/wp-content/uploads/2014/08/Aluminium-Corrosion1.jpg

 

[Bondo]

Ayuh,..... My guess is,....

Somebody over the last 47 years, used the hull as a electrical Ground path, insteada runnin' Ground wires for whatever it was they were wirin',....

 

[GA_Boater]

From your description of the pin holes, ya know the deck will need to be removed to see how bad it is. Repair from the outside will fix the obvious leaks, but it won't stop the holes that are about to open up. You will be fixing leaks until the hull is clean and the corrosion is stopped by doing it right the first time.

Not sure what you have for flotation foam, but if it's the Styrofoam blocks, they suck up water and never dry out. The wet foam adds to the possibility of more corrosion down the line. It never stops until you do something about it.

Yes, new Nautolex vinyl is available.

Welcome to the forum and good luck fixing up another survivor.

 

[looserivet]

The only electric in the boat is the bow and stern lights, and the starter. Evertything appears to be factory and wired without any grounds to the hull.
The boat is very basic, just a motor and two lights, the starter is through the control box. The battery is mounted in a plastic box above deck at the rear on the port side.
The corrosion holes, 7 in all are between rivets on the starboard side near the keel . All of the holes go through to the lips of the ribs between the last two rivets on the stringers directly under the drivers console. There is no foam in that area, the middle of the deck between the stringers doesn't appear to have had any foam? The only foam I see is in the bow and along the outsides of the aluminum stringers. The holes are irregularly shaped. They appear as black dots on the painted surface.
The one missing rivet head is at the stern 3" before the transom, Its the second from the last rivet that holds the keel strip in place down the center. None of the transom seal rivets are damaged nor are any of the other rivets I can see. It looks like someone dragged the rear of the boat over something and knocked off the rivet head. The rivet is smeared toward the rear of the boat and sheered off. Oddly enough, it don't leak there.

I cut a hole through the floor above where the corrosion is, and the metal i can see is clean and shiny, there's no sign of corrosion on the inside but I'd have to remove the stringer to get at the inside of the hole.
I'm thinking about just neutralizing any corrosion, sanding and dimpling the holes from the outside and filling them in with epoxy. I intend to coat the inside with Gluvit anyway. The floor was rock solid, no rot at all, I cut a clean 18" x 12" hole, I'll patch the hole with metal I suppose when I'm done. I had to get a look at the inside but the repair will have to be made from the outside.
My big concern is why and are there any other little spots ready to 'pop' open at anytime. The area around the holes is rough, like sandpaper with small pits or blisters popping through the paint, but the rest of the hull feels smooth. The affected area is about 8" square and only on the outside. One hole was larger than the rest, the others are smaller than the point of a sharp pencil. The larges hold is maybe 1/8" wide and L shaped.
I sanded the paint off the other bumps in the paint but none of the others are deep corrosion, the pitted area under the paint sanded smooth easily.

 

[Tnstratofam]

How about the trailer? Have any of the bunks been replaced with pressure treated wood by chance?

Also are all the wires in good condition? Not frayed or missing insulation allowing the wire to ground to the hull?

 

[looserivet]

It didn't have a trailer until I bought it, I put it on a brand new Load Rite roller trailer. The lights are wired from the factory, no rollers or supports are anywhere near the bad spots. Even when it was on the boat lift's bunks, this area was free from any contact. The closest hole to the keel is 2" away, the farthest is 5" up the side from the keel. Its not near anything that would have touched it and the paint is origina and still shiny. Its as if the corrosion started below the paint.
The upper trim has been getting pitted up since its been here but everything rusts or pits around here for some reason. I'm not near saltwater though. The nearest saltwater is a 40 mile ride. Chrome on cars pits and fades fast here for some reason, the chrome bits on this boat were mint when I brought it here but have gotten pitted over the past year, even though its garage kept. Bits like the chrome end caps on the side bumper rail, the front rail, and light assemblies have pitted badly since its been here. Its only been on the water maybe a half dozen times so far here. When I park it, I remove the battery for charging and it does double duty in my car trailer. So its never sitting with electricity in or around it.
I think if it were galvanic corrosion, it would look different, not just all in one spot.

The wiring in the boat consists of a single lead from the switch to the battery, and another lead from the bow light back to the switch, and a lead up to the stern light. There's a small 3 circuit fuse box behind the dash. No grounds, no stray current. I don't even think I've ever used the lights, but they do work. The motor is connected to the battery via two power cables, and the other wires run directly into the control box. There is no connection to the hull. My guess is that everything in this boat is as it was from the factory.

Regardless of its past, now I've got to patch the holes. I'm leaning toward just dimpling in each hole a bit, then filling them with JB Weld, sanding, and touching up the paint there.
If another hole opens up again, I'll patch it and sell it.

 

[Tnstratofam]

How close do you live to any factories? Or trash incinerators?

I know that in Kingsport Tn ( 30 minutes down the road from me ) people who live near the Eastman Chemical plant have had issues with corrosion on vehicle chrome. It is thought to be caused by stuff released into the air from the plants waste stacks.

 

[looserivet]

There aren't any factories anymore, just about everything has closed up over the years. I am a mile from a power generating station but that runs on natural gas. I also border a power substation and the high tension lines pass over the houses here.
The substation has a combination of overhead and underground wires, the incoming power from the generating station come in underground, the outgoing power leaves overhead.
But if any of that shorted, I wouldn't be here typing this today. One of the feed conduits shorted years ago and it sounded like an explosion every time the cable shorted to ground. It killed all the grass in the surrounding acre and you could see the blue arcing across the surface of the wet ground. They went around door to door making sure no one wandered close to it.

I have always had issues with trailer parts rusting too, but mostly on galvanized trailers. The painted trailers don't seem to have any issues. On the galvanized trailers, the hardware rusts away to the point you can't get a wrench on the nuts and bolts in three years, but on painted trailers it's never affected. I just figured it was sacrificing the hardware due to the galvanized coating.

I have a painted trailer I bought in 1979 for my 1979 Mirrocraft and its as rust free as the day I got it and it sits outdoors all year here. Yet my four year old car lost nearly all its chrome off the belt line moldings and window trim in the garage.
The spring shackles rusted off my one truck twice now, and that truck has never launched a boat. The springs or frame are never affected. Garden tools don't seem to rust but plumbing fixtures here don't last long at all. I go through Moen faucets every four years. The finish gets eaten away and the trim gets pitted pretty bad but I always just figured that was due to the chlorine in the water.

 

[reelfishin]

If it were an electrolysis issue, I would think that the bare metal parts would be attacked first, or the motor. Not a specific area of painted metal. If the inside of the hull is clean and shiny, I'd all but eliminate it being from bilge water or foam.
Most of those hulls had foam in the middle of the stringers, but not all. I've seen a few that seemed to be 'prepped' to have a ski locker added but I've not had an older model like yours apart yet.
From your description, it sounds like a paint issue that's taken years to show up. The fact that the pits are only along the stingers may be a clue as well.

 

[looserivet]

I ended up tapping the holes in a bit with a ball peen hammer, sanding down to bare aluminum there and filling each spot in with JB weld. After the JB Weld cured, I shot the area with some self etching primer and a coat of white paint. I would call it about 80% invisible, and since its below the water line, and you can't see it unless you crawl under the trailer, all is good.

I cut a few 2x4's made up a patch for the floor where I cut through it, I left a lip and cut an insert to fit the hole. I then made up an aluminum frame with thin aluminum angle iron to trim the edges. I wrapped the patch in the piece of rubber flooring I removed and trimmed it in aluminum as well. Instant storage locker, battery hole, anything. That was Thursday night.

I listed the boat for sale on a bulletin board at work Friday morning and it has a new owner now. A salesman who was visiting bought it and its on its way to WV as I type this. I showed him where the fix was, he didn't much care about it so long as it wasn't visible in the water.

I'll find something else by summer that I don't have to worry about.
I liked that boat but don't have time for to deal with the unknown.