22' starcraft islander, crack(s) in hull -- aluminum repair options?

[jimmwaller]

Hi all, I have been trying to track down a leak in my 22' starcraft islander for a while, and today I think I finally found it. That's the good news, that bad news is that it seems to be coming from a crack in the hull. These boats are aluminum, so I'm looking for advice on options for aluminum hull repair.

I'll do my best to describe it and the photos should help, but essentially, there are two cracks (might just be one long crack?) in the hull. It's almost exactly halfway between the bow and the stern, on the port side. My boat has a moderate V bottom and a line of rivets right where the bottom meets the "walls" of the hull (where it starts to turn vertical)... it's almost a 90-degree angle at that point. The crack(s) are on the "bottom" side (so, not on the vertical walls).

I think there are two cracks, one about 8 inches long and one about 5" long. It's a little hard to tell because the crack goes into the seam (where the walls of the boat meet the bottom) and so I can't tell how far that crack extends. The other crack is about 4 inches away, so they may be the same crack. However, just looking, I think they are two different cracks. I'm guessing there was an impact of some kind.

What are my repair options? I've been using this boat as-is for a few years and have just been dealing with the leak, so it's not too annoying. But now that I found it, I'd like to repair it. I'm guessing this isn't something gluvit can handle (maybe I'm wrong?)? Should I just shove some JB weld in there> My worry is that it might flex too much. Or do I need to have this welded? Or can I try one of those torch weld sticks or something? I'm not sure if this is a structural issue or if it's getting any bigger, but they're still pretty small so I'm guessing they're not growing fast, if at all.

Really looking for options. Happy to explain anything better if I did a bad job, but hopefully the photos help!

Photos:

Here's where they are located:


They're on the "bottom" side, so the side that's facing the ground. This is the port side, so the bow is to the left and the stern is to the right. The longer one is closer to the bow.

Here's a photo of the longer crack (so, I am on the ground, looking up):


There was some paint and some gluvit/epoxy (and something that looked like JB weld, maybe) there, so there are a lot of things that look like cracks, but the actual crack in the metal is the one that winds through the two bare rivets (which, once the paint was off, are clearly damaged). This crack is about 8" long.

And here's a photo of the other crack. This one is maybe 5" long:


Again, lots of paint and epoxy, but the crack is winding between those two top rivets.

I'll spend some time over the next few days sanding off all the paint/epoxy/etc, but I'm anticipating that I have one crack of about 8" and another of about 5". Looking for any and all advice about the best way to deal with this, and how to know whether they are on highly structural components of the hull, etc.

Happy to answer any other questions, if I left stuff out it's because I didn't know that there was other relevant information so will gladly provide any missing info!

Thanks in advance

 

[racerone]

Someone tried to repair it before.-----Time to find an expert to put a proper repair plate on the inside of hull.-----Perhaps an airport in your area with a shop that can deal with this.-----Any way to get to this area from the inside ??-----Any other spots on the hull with this patch work repair.

 

[jimmwaller]

Someone tried to repair it before.-----Time to find an expert to put a proper repair plate on the inside of hull.-----Perhaps an airport in your area with a shop that can deal with this.-----Any way to get to this area from the inside ??-----Any other spots on the hull with this patch work repair.

Thanks. I don't see any other spots, but also, I looked for this leak (albeit kind of halfheartedly) for months and only just now noticed this one, so...

wow, welding in a whole plate seems like a lot more than I was expecting. So this isn't a candidate for either an expoy-based repair (gluvit or JB or something), or some kind of outside-the-hull welding (like one of the aluminum repair rods, or just tig welding the crack from the outside)? Why would, for example, just tig welding it from the outside not work?

 

[racerone]

Hurry to your local welding shop.-----See if they will take on this simple welding ( from outside ) repair job.

 

[jimmwaller]

I mean, I have friends who weld aluminum, I'm just not sure about whether or not this is a good idea so I'm asking the experts here. So just to confirm, you're saying that it's a good repair to weld it from the outside, and I'm not putting myself in any danger? I want to repair it right, I just don't know what my options are.

Thanks!

 

[Wildey]

Any way to get to this area from the inside ??

I'll ask this again ... ^

Why would, for example, just tig welding it from the outside not work?

Looks like just a little too much corrosion there for an effective weld.

Be me, I'd break a piece of aluminum sheet of the proper gauge and length to seal and rivet a patch on the outside. Being familiar with airplane construction/repair and comfortable drilling all of the necessary rivets out and bucking in new ones. IF you can access the inside of the hull in that area.

 

[Wildey]

I want to repair it right, I just don't know what my options are.

Actually, that area should have stood out like a sore thumb, even for an untrained eye. I would firstly go all around the boat at every seam and junction to verify how extensive the compromised areas might be, if there are more.
Look for more of that cat krap smeared around and on the rivets. That crack you found, by the look of the rivet pattern, is at the end of a rib maybe. There could be more. Could be a can of worms. Worms do occasionally come in aluminum cans.
Good luck to ya,
W

 

[jimmwaller]

I'll ask this again ... ^

Looks like just a little too much corrosion there for an effective weld.

Be me, I'd break a piece of aluminum sheet of the proper gauge and length to seal and rivet a patch on the outside. Being familiar with airplane construction/repair and comfortable drilling all of the necessary rivets out and bucking in new ones. IF you can access the inside of the hull in that area.

Oh, my fault for glassing over that question! The answer is... it's not immediately accessible. I'd have to, at the very least, cut an access port into my interior sidewall, if not remove the 14'-ish long sidewall entire.

That said, I'm not opposed to doing either of those things, I'm just trying to get a handle on my options. If doing it "right" means cutting out my sidewall and having an airport weld in a patch from the inside, that might be what I have to do.

I'm just trying to make a calculated decision. If the "right" way will last for 40 years with a 3% chance of failure but requires dismantling my boat, but the "wrong" way will last for 35 years with a 4% chance of failure but is just slapping some jb weld in there (which also implies that, even if it fails after 35 years, all I'd have to do is just slap some more JB weld in)... I'd like to know this context so I can make a good decision.

I'm not opposed to patching the outside, but if I'm going to get access to the inside somehow, I may as well have a plate welded in. Is there some reason why blind rivets are a no-go for a sheet repair?

Thanks!

 

[jimmwaller]

Actually, that area should have stood out like a sore thumb, even for an untrained eye. I would firstly go all around the boat at every seam and junction to verify how extensive the compromised areas might be, if there are more.
Look for more of that cat krap smeared around and on the rivets. That crack you found, by the look of the rivet pattern, is at the end of a rib maybe. There could be more. Could be a can of worms. Worms do occasionally come in aluminum cans.
Good luck to ya,
W

Yeah... it should have. I knocked a bunch of the gluvit and paint off for these photos, but before I did that, it blended in pretty well (looks like it was painted over and the gluvit was put on over the paint, so all I could see was a crack in the paint that looked a LITTLE too deep). But yeah, once I noticed it, it was like... how did I not see this before?

I'll go over it all again... hope it's not terrible. Thanks

 

[Wildey]

What is the year and history of the boat ?
If it spent a lot of time in rough water, those type of cracks are common, look closely. Be safe above all.

 

[BWR1953]

Welding doesn't work well. There's original sealant between the layers of aluminum at that location and it will burn off or leak out or otherwise contaminate the weld. And it will also likely cause more gaps between the layers, which in turn can cause still more leaks.

The "right way" is to patch it using aluminum on the outside, back-buttered with 3M 5200 sealant.

Many such fixes have been done in the Starcraft sub-forum. I'm about to do one myself.

 

[jimmwaller]

What is the year and history of the boat ?
If it spent a lot of time in rough water, those type of cracks are common, look closely. Be safe above all.

Late 60's, and I've only owned for about 5 years so... lots of unknowns. Recognizing that I am apparently bad at spotting cracks, is it safe to assume that if no water is getting in, there are no cracks? Do these cracks tend to cause catastrophic failures, or more gradual? Like, so long as I keep a close eye on leaks and inspect the hull pretty well before going out, will a failure be more "oh, a new crack opened up so I have a minor to moderate, I need to fix that" or "well, my boat ripped in half 10 miles from shore, this is bad"?

 

[jimmwaller]

Welding doesn't work well. There's original sealant between the layers of aluminum at that location and it will burn off or leak out or otherwise contaminate the weld. And it will also likely cause more gaps between the layers, which in turn can cause still more leaks.

The "right way" is to patch it using aluminum on the outside, back-buttered with 3M 5200 sealant.

Many such fixes have been done in the Starcraft sub-forum. I'm about to do one myself.

Sorry, but I don't know what back-buttered means. Does that mean more like put aluminum on the back of the outside patch, or that I need to access the inside of the crack and butter the "back" of the crack with 5200?

Does this patch need to be riveted in? Also, should I be doing anything like drilling out the cracks to stop spreading, or will the patch do that?

Thanks

 

[jbcurt00]

Paging
@classiccat
@Watermann
to the dry dock STAT

Wouldn't recommend welding immediately adjacent to the chine seam

 

[jimmwaller]

Paging
@classiccat
@Watermann
to the dry dock STAT

Wouldn't recommend welding immediately adjacent to the chine seam

Thanks... do you mean welding, at all? Like even having an airport shop weld a panel in the back?

@jbcurt00 what is your recommended fix, something closer to an aluminum plate with 5200 on either the inside or outside?

Thanks

 

[Wildey]

........ is it safe to assume that if no water is getting in, there are no cracks? Do these cracks tend to cause catastrophic failures, or more gradual?

Nope. Well, maybe if you stay in knee deep water.
You never know, depends on the event/situation.
An airplane with those indicators should not leave the ground without a thorough and comprehensive inspection with necessary repairs made.
Inflight failures tend to be very unforgiving. Offshore boating failures are as well.
I respect my boats as I do my plane.

 

[Wildey]

The 'buttering" refers to applying the sealer to the patch (or outer hull) at assembly.
Like buttering a ceramic tile to a wall .... or laying a brick in mortar.

 

[Rasdiir]

Sorry, but I don't know what back-buttered means. Does that mean more like put aluminum on the back of the outside patch, or that I need to access the inside of the crack and butter the "back" of the crack with 5200?

Does this patch need to be riveted in? Also, should I be doing anything like drilling out the cracks to stop spreading, or will the patch do that?

Thanks

I'm a boat new guy, but I have spent years reading the Starcraft restorations on this site. The vast majority of people in there who are patching a crack will drill stop holes at the ends of the cracks to prevent it cracking further, remove the old rivets (if applicable), make and form an aluminum patch that extends a bit larger than the crack, then coat the inside of the patch in 5200, put it on, and rivet it down. Some also fill in the crack and any pitting with marine tex before putting the patch on just to make sure that there are no gaps between the hull surface level and the patch. I think 1/16 aluminum is thick enough, apparently old road signs are a good thickness and aluminum type. Because of the extra layer you will need longer rivets.

Some examples are these threads:
https://forums.iboats.com/threads/1972-starcraft-nova.744078/post-5763915
https://forums.iboats.com/threads/1...shment-splashed-july-2019.687763/post-5163904

 

[jimmwaller]

Thanks all. Riveting a patch down from the outside seems like the agreed-upon best fix, so I'll likely do something like that (but will continue to get advice for a few days while I mull it over).

I think the big outstanding questions for me are:

1) How do you "form" it to the hull? Do you mean just like rough forming it, or how precisely does this need to be done? Are we talking... making a cast of the hull and having a patch custom made, or something more like just getting the angles pretty close and then riveting it down?

2) What kind of rivets? Are blind rivets good here?

3) Does the patch get... I guess "treated" at all? The way I'm imagining it, the edges of this patch will catch a lot of water and take a lot of force. Do people.... i dunno, Bondo over it or something just to make that leading edge more hydrodynamic?

Thanks!!

 

[jimmwaller]

also, thanks for the threads, @Rasdiir they were really helpful. Those patches look really nice, I'd be psyched for an outcome like that.

Three more quick questions to add to my list, above.

4) Given that I have what seems to be two cracks that are about 4-5 inches apart, is it better to do two patches, or one longer patch?

5) Either way, I have a ton of rivets that I'll have to take out it looks like... I'll probably have to remove all the rivets on the "side wall" part of the chine and then a few others. Is the goal simply to take out all the rivets that would naturally end up under the patch, and then replace only those rivets? Or should I replace all those rivets but then add additional rivets as necessary to create a tighter seam around the perimeter of the patch?

And I guess the follow up question: Do I need to take out the rivets that are under the patch, too, or just the ones around the perimeter? Any tricks for mapping the rivet holes onto the aluminum?

6) How can I tell if there's a rib in there? One of the threads noted that, when all the rivets are pulled from a rib, the rib pops up so you can't rivet it down without holding it back in place. If I have ribs, and they're under the floor, this seems like worst-case scenario. How can I tell if there's a rib, and what do I do if there is?

Thanks!