I found a 8.5 inch stress crack in my Tracker, and also several leaking rivets.  My neighbor is a truck driver, and turned me on to a product called quik steel.  He used it to plug a hole bigger than a quarter in one of his fuel tanks.  He made that repair 2 months ago, and there isnt any seeping at all.  Solid as can be.  Anyhow I used some on my boat, and it worked great.  Comes in stick form, pinch off a piece and knead it, apply within 2 minutes and solid in 10.  can be applied even to wet surfaces.  

This is the only product I have ever found that actually works, so I thought I would share it with you guys.

It is made by CarGO.

Recon

I think you will find there is a big difference in the gas tank and your boat. Your boat has flex and twist and I have found that most of the putty type products break and pop off.

Where is the crack at?

The only sure ( well not SURE and you will read why) fix is to have it welded. If it is a jon style it will not be a problem. If it is a "bass" style boat you will have a real hard time finding anyone to do it without stripping the interior. Someone had welded my boat. The second year I owned it, it started leaking...THE WELDS were leaking. I took it to a friend of mine who has an industrial welding service and he said that they probably did not strip the boat when they did it and...being worried about starting the foam/interior on fire...they tried to cool the welds or cooled them too quickly. This left the welds pourous and they cracked and started leaking.

Depending on the boat, it age, and its value...you can try the putty. I did it two years ago and so far it is okay.

I actually used a scotch3M aluminum 2 part epoxy/adhesive. I think it was the 5200 but would have to look back to remember for sure.

The surface prep will kill you. It took me a long time...lying on my back under the boat with a grinder...getting the metal clean and preped as it did to put the expoxy on. Took two days to prep and maybe two hours to put the putty on. The metal has to be CLEAN! you have to get it down to fresh unstained and undamaged aluminum.

I went a step further and painted the bottom ( except where the bunk boards on the trailer go) of the boat with truck bed liner to seal the rivets. I only wanted to do this once...and was worried I would patch the leaks and have more show up in a year or two. It did the trick...but it is a messy, terrible job. I would wear a rain suit cause the bedliner soak through everything and completely ruins any fabric it comes across. Even the white tyvec suits do not work.

The prep on this is the same...alot of work...you have to get the whole bottom CLEAN CLEAN CLEAN ( more time on your back with a grinder)...then paint it with a Sherwin Williams primer...then put on the bed liner ( the bed liner will not stick to aluminum)

If it is a Jon boat style...the best solution I have seen was the truck bed liner...but on the inside.

If I were to work out an hourly wage...( my time is worth X amount of dollars)...I would have been better off spending the $1500 on the same boat ( Tracker Pro Team 175) that was for sale around the corner from me.

Pretty windy today I took the boat out and well....beat the snot out of it.  The Quik steel held without problem.  

guess time will tell how good this stuff really is.

On the tank repiar by the way, the fuel knocker, which caused the problem in the first place, is still hammering away on the patch, and it is holding firm also.  

For the record I have never had any luck with any of the pinch and knead type patches before....this stuff seems pretty good.