Tracking down and repairing leak in aluminum hull (starcraft islander)

[acarleson]

Hello all,
I have an old starcraft islander 22 and it has a pretty bad leak. I had it out for about 2 hours the other day and when I pulled it in and pulled the plug it drained for probably a solid 10 minutes. I don't know how much water was in there but I'd guess at least 50 gallons, if not more. The thing is, I can't track down the leak. I've filled it with water pretty far and I can see a few little leaks but nothing that looks like it should be letting in 50+ gallons over a couple of hours. So I have a few questions:

1) what's the best way to track down leaks? My worry is that my leak might be below the water line when in the water, but above where I'd want to fill the boat with water.

2) What is the best way to repair a leak on these old aluminum hulls? Is there some product that works well? I've tried gluvit but I don't think it really seems to penetrate into the seams, it seems like it just sits on top and eventually flakes off.

Thank you all!

 

[briangcc]

IF it were me, I'd dunk the boat and open the engine hatch. Can leave it sitting on your trailer on a non-busy day. Check to see if water is coming in. Then start the motor and check again.

Assuming you have an I/O given the length correct? If so, when were the bellows last done???

Given the amount of water you had/estimated...I'd wager bellows or transom, provided there are no other glaring issues.

 

[acarleson]

@briangcc thanks. I actually just had the bellows professionally done, so maybe you're right? The timing lines up for sure. I always get some water in there, but this seemed like more than I was expecting. A bellows issue would be pretty obvious, I would think, and they seem to look good. And I asked a ton of questions about the transom and while they didn't test it, they said it looks totally fine.

Like I said, I definitely have some water leaking in through the seams, but it just doesn't feel like that's enough to be letting in 50+ gallons of water in a couple of hours. But maybe I'm wrong and maybe seam leaks are actually way worse than I'm imagining? Like, maybe filling it with water pushes water out the seams at X rate, but when you're actually out on a body of water, with the seam submerged, it lets water in 5x faster or something?

Either way, I'm confident that I can track down the leak. My big question is how to fix it, especially if the leak is on a seam that's, like, all the way in the middle of my boat. Is gluvit still the best option? Do I need to rip my floor up or will applying out the outside be sufficient? I've had bad luck with gluvit but maybe there's something better out there? Open to any and all options for fixing this (like, I'd rather not pull up my floor but I will if I have to). thank you

 

[Bondo]

My big question is how to fix it,

Ayuh,..... It depends on where it is,......

I ran an Islander for over 20 years, 'n leaks happened,.....
I found a couple of ways to find 'em,.....

One was, in the water, open every hatch, locker, etc, to look, 'n listen,.....
The other was to crawl under it on the wagon, 'n closely examine every sq. inch of the hull,.....
Most times, it was a missin' rivet, which I just replaced with closed end pop-rivets,....

 

[acarleson]

@Bondo thanks. I think the problem for me is that I have zero access to most of the interior of the hull. I have those hatches in the bow, and the doghouse, but zero other hatches. And there is wood right behind the engine, so I can access from the transom to the engine bay, and under those bow hatches, but that's it. I have no access to 80% of the hull.

In your experience, if it's something larger than a missing rivet, like in my case where there's a whole leaky seam.... what's the best fix? Is it still gluvit? And then, I'm still wondering how I can gluvit my hull when I can't access 80% of it. Can I put it on the outside, or is gluvit really only effective on the inside of the hull? Thanks!

 

[Scott Danforth]

any water leaking in is a leak. the leaks you found in post #1 can push a lot of water into the hull when you are on plane

additionally, if the engine is leaking, that will add water to the bilge.

yes, a missing rivet can leak a lot of water. damaged keel sealing can leak.

to seal with gluvit or other, you have to remove the engine, interior, and deck to get to the inside of the hull

 

[Bondo]

and I can see a few little leaks but

Ayuh,.... Where, Exactly did you find the leaks,..??

As Scott alludes too,.... There really ain't anything that fixes leaks when smeared on the outside,.....
Some sealants, like 5200 might help,... or not,....
Generally speakin' ya remove whatevers in yer way, 'n work from the inside for serious issues that might require weldin' or whatever,....

I forget now how many gallons will flow through a 3/16" hole per hour, but the number is unbelievably high,.....

 

[acarleson]

@Bondo great questions on where I found the leaks, and maybe I need to rethink what's happening here. I went down to look everything over today and I don't *think* I have any missing rivets. Some of them were covered by the bunks, so I couldn't really see what was going on there. (any advice on how to inspect under the bunks?)

But I took a closer look at where I marked the leaks, and noticed that a lot of them were right on the bottom strakes. And looking closer at the strakes, I see that they have holes in them, I assume for draining... which means that the strakes can fill with water. So now I'm not sure if the leaks that I saw were actually through-hull leaks, or just the strakes draining. In which case... I have no clue how the water is getting in.

I think I might just have to take the boat down to the wash station and drop a hose in there and fill her up until I see leaks. Any concerns with doing this? My guess is that there's a point at which the boat gets too heavy, but I would think that a few gallons of water might not be too awful.

Thank you

 

[Bondo]

I think I might just have to take the boat down to the wash station and drop a hose in there and fill her up until I see leaks. Any concerns with doing this? My guess is that there's a point at which the boat gets too heavy, but I would think that a few gallons of water might not be too awful.

Ayuh,...... In my mind, that's the worst test there is,.....

Water gets real heavy, way before the outside waterline when the boat is floatin',......

What I always did was launch it, tie up, 'n go crawlin' through the bilges cavities,.....
Look under, 'n behind everything,.....
A good flashlight, 'n digital camera or phone, you'll be surpised what you can see,....

'n Ya, the strakes are wet, both sides,..... inside hull skin runs from the outer strake, to the same on the far side,.... no seam,.... only in the bow,....

When ya put the boat back on the wagon, load it a couple inches to a side,.... bunks in a different spot,.....

 

[acarleson]

@Bondo yeah unfortunately I just don't have access to most of the hull. the PO put boards basically right behind the doghouse, so I can't even see anything between the engine and the very front bow hatch... soooo I have a view of ~2 feet of the bow and ~2 feet of the stern But who knows, maybe that's where the leak is! I'll give that a try first

 

[havoc_squad]

At the rate being mentioned of water intrusion, either transom hole leak or somewhere under the floor.

If its under floor, all of the floor has to come out.

Need to either invest in fixing the core issue or sell it to someone who will do the work. No sitting on the fence.

First though you need to 100% rule out leak through transom outdrive hole.

You put the boat in the water for a leak test, do not pour water in it.

 

[acarleson]

@havoc_squad thanks. what do you mean, the transom outdrive hole? is that a general statement about the transom leaking through one of the bellows or the drain hole or something, or are you specifically suggesting a leak around the transom cutout for the outdrive? thanks

 

[acarleson]

Ok so... it's an outdrive leak in some capacity. The water appears to be coming from the exact middle of the outdrive cutout, but I can't tell exactly what's happening. I pulled it out and checked the bellows from the outside and all the bellows look good, and like I mentioned, I just had them professionally done. So I guess my question now is: does this mean that the bellows are definitely the issue, or is there anything else that could cause a leak besides the bellows? Like, I guess I'm wondering... if I have a leak coming from the middle of the outdrive hole, is that definitely the bellows (so that having the bellows redone will fix the issue) or are there other things that could be causing this? Thanks

 

[Bondo]

Ok so... it's an outdrive leak in some capacity. The water appears to be coming from the exact middle of the outdrive cutout, but I can't tell exactly what's happening. I pulled it out and checked the bellows from the outside and all the bellows look good, and like I mentioned, I just had them professionally done. So I guess my question now is: does this mean that the bellows are definitely the issue, or is there anything else that could cause a leak besides the bellows? Like, I guess I'm wondering... if I have a leak coming from the middle of the outdrive hole, is that definitely the bellows (so that having the bellows redone will fix the issue) or are there other things that could be causing this? Thanks

Ayuh,..... Dead center, is the drive shaft,.....

So what are you calling exact middle,..??