cracks between rivets on aluminum starcraft islander

[tabletop]

hello,
I recently bought a starcraft islander with an aluminum hull and it leaks a little. Finally found the source of the leak and there are small cracks in between the rivets right along the port chine, on the bottom side. They mostly go from rivet to rivet, sometimes going up into the chine seam. Total, cracks are about 24" long. I have a few questions, photos are at the bottom.

Question #1: how bad are these cracks? it looks like the boat came down on some rocks as opposed to just falling apart or something. I've had it out a few times and it doesn't leak that much and the cracks aren't getting worse. It looked like the PO had smeared some JB weld on there, but it cracked again so I removed the JB weld with a wire brush.

Question #2: in terms of fixing them, what are my options? I know a patch with full buck rivets is the best option but I really don't have access to the inside of the boat (there is a whole cabinet system and carpet and seats and flooring and everything all in the way). Could I use blind rivets? Or just aluminum and sealant? Or is there something else I could do so I don't have to pull the whole boat apart? Or something I could try "first" and see how long it lasts, and do a more robust fix later if necessary?

Question #3: What about welding or brazing? These cracks are not near the gas tank, but there are right on the chine where two panels meet. I'm worried about melting whatever sealant is in the chine. I think these boats have sealant where two panels overlap, and these cracks are very close to a panel overlap.

Question #4: Any other options that I'm missing? Or things I'm not thinking about?

Thank you. Photos below.

 

[jbcurt00]

@classiccat to the SC dry dock, STAT
@Watermann too

Happens to old Starcrafts run hard and/or w compromised decks and side panels below the gunwale. Often prior owners remove the side panels. Either way, the chine gets worked as a hinge, which leads to cracking.

Pix of the inside of those cracks.

Already likely work hardened to crack, so I wouldn't recommend welding a chine, esp as it's a seam w some sort of sealer in close proximity to any welding.

Classiccat did extensive crack repair along the chine & hull bottom, w great graphics of the repairs to help explain what's also shown in pix

Adding Chine Bracing on a '75 18' Starcraft SS

Howdy Folks! I'm in the early stages of a Resto on a '75 18' Starcraft SS. My home water is a big tidal river (Hudson) that puts a beating on a hull; if there is a weak-point in the hull construction (chine cracks are pretty common), i guarantee that it will show after a season or 2...

forums.iboats.com

 

[silverbul]

first off, drill holes at the end of each crack, that will stop the crack from getting worse then patch as you see fit.

 

[tabletop]

first off, drill holes at the end of each crack, that will stop the crack from getting worse then patch as you see fit.

Thanks. I think they already naturally have holes at the ends... they all start and stop in rivet holes.

@classiccat to the SC dry dock, STAT
@Watermann too

Happens to old Starcrafts run hard and/or w compromised decks and side panels below the gunwale. Often prior owners remove the side panels. Either way, the chine gets worked as a hinge, which leads to cracking.

Pix of the inside of those cracks.

Already likely work hardened to crack, so I wouldn't recommend welding a chine, esp as it's a seam w some sort of sealer in close proximity to any welding.

Classiccat did extensive crack repair along the chine & hull bottom, w great graphics of the repairs to help explain what's also shown in pix

Adding Chine Bracing on a '75 18' Starcraft SS

Howdy Folks! I'm in the early stages of a Resto on a '75 18' Starcraft SS. My home water is a big tidal river (Hudson) that puts a beating on a hull; if there is a weak-point in the hull construction (chine cracks are pretty common), i guarantee that it will show after a season or 2...

forums.iboats.com

Thanks. Problem with pictures of the inside is, this is an islander so there's a big cabinet and seats and carpet and decks and side panels in the way. If I have to remove all of that I will, but that might take a looong time so I'm wondering if there's anything I can do before basically gutting my whole boat thanks!

 

[silverbul]

sorry but i would check everything, you can see what i can't. just saying.

 

[tabletop]

given the size of these cracks, would small tack welds done maybe every few inches just to stick them together run the risk of melting the sealant?
thanks

 

[Watermann]

Common issue with the older boats before SC figured it out and added rib end braces in the mid-late 70's. The answer to your question is nothing can be done to repair them permanently from just the outside. You have to patch over the cracks and add the braces to the inside for it to be properly repaired.

This is a pic of my 79 V5 SS with the braces factory installed under the ribs, over the chine.

 

[tabletop]

@Watermann thanks for the insights. Since this is a common problem, maybe someone knows the answer to the question of... how serious is this? It leaks a little but is this a "this needs to be fixed before it goes out on the water ever again" or more of a "this might get worse over time but it probably won't suddenly and catastrophically fail."

After reading some of the threads, my plan was to: put some tack welds in there with a tig machine just to add some strength. I'm hoping that if I just do tack welds every few inches, there won't be enough heat to melt the chine sealant or warp the metal or anything. Then, take some 3/8" aluminum sheeting and bend it around the chine from the outside. Smother the aluminum back with sealant and rivet it down using aluminum sealed blind rivets (from the outside). If that hold, great. If it starts leaking again, I'd go in and pull the flooring and do it right. I don't run my boat outside of bays so it doesn't take a beating or anything.

Terrible idea? Thanks

 

[BWR1953]

@Watermann thanks for the insights. Since this is a common problem, maybe someone knows the answer to the question of... how serious is this? It leaks a little but is this a "this needs to be fixed before it goes out on the water ever again" or more of a "this might get worse over time but it probably won't suddenly and catastrophically fail."

After reading some of the threads, my plan was to: put some tack welds in there with a tig machine just to add some strength. I'm hoping that if I just do tack welds every few inches, there won't be enough heat to melt the chine sealant or warp the metal or anything. Then, take some 3/8" aluminum sheeting and bend it around the chine from the outside. Smother the aluminum back with sealant and rivet it down using aluminum sealed blind rivets (from the outside). If that hold, great. If it starts leaking again, I'd go in and pull the flooring and do it right. I don't run my boat outside of bays so it doesn't take a beating or anything.

Terrible idea? Thanks

I think @Watermann has a catastrophic failure pic somewhere.

 

[Scott06]

Had a neighbor that had a ‘69 starcraft , had similar cracking in chine. Had it TIG welded and it held for the remaining ten or so years they had the boat (they had this boat over 40 years). If i recall the welder drilled holes in the end welded from outside in .

 

[Watermann]

I think @Watermann has a catastrophic failure pic somewhere.

Grandad had the longest pics of his Holiday with rib end cracks but his pics I'm afraid were a victim of potobuckets demise. The it's going to the bottom pics were of the side splitting down the spray rail chine.

 

[BWR1953]

Grandad had the longest pics of his Holiday with rib end cracks but his pics I'm afraid were a victim of potobuckets demise. The it's going to the bottom pics were of the side splitting down the spray rail chine.

Ah, good ol' photobucket.