17.5' 1998 Tracker (tin boat) lost part of bottom support/rail strips

[old school]

1st - great forum - been able to DIY our bilge, pour a new transom, fix the OB and now ....

When we bought the boat I noticed that one of the rail strips on the bottom had been repaired - someone spot welded on top of a loose rivet - I thought it looked strange so I even snapped a couple pics at the time - it also had some other little spot welds on the hull on either side of the rail (you can see them in the pics) - I figured they had a problem with the fuel tank brackets and needed to do some welding - our boat has a 5' long, 24" wide, 8" high plastic fuel tank that lays flat under the floor

We were out the other day - nothing irregular (although my wife did hit some other boater's wakes rather hard) - get back to the house, hosing underneath and WOAH! WTH!

QUESTION - is there another way of installing the broken piece of rail? (other than welding). I still have the foot long piece as it was hanging on by a sliver. The piece broke off right where the rivets were drilled on both LH and RH sides. The LH rail piece that is still on the boat is SUPER HARD to push and lay flat against the hull (maybe why it fatigued in the 1st place??). The RH rail is easy to push and lay flat against the hull.

Can another piece of aluminum just be cut and laid on top and then riveted? Or is it best to have all this welded?

Thanks!

 

[ianat182]

No expert on metal working but looks as though ordinary pop rivets may have been used hence the spot weld to fill the pop rivet holes.
As the piece you have is the right length to fit back again a tongue of shaped wood could be inserted bridging the gap and extending beneath each of the fixed ends. The wooden insert should have sealant between it and the hull and screws from the inside to the wood to retain it in place; then fit the original strip and drill say 8 holes, and countersink lightlythe outer holes
Screw through the strip to secure it to the timber both ahead of the join and after the joins, fill any gaps with filler and fair off. Use countersink stainless screws outside, and domeheaded screws for the inside to the wood with sealant beneath each domehead.
Some pop rivets have a plastic insert that must be fitted to keep water out ,I guess that those used previously did not.

Have fun!

 

[alan17]

Ally strips

You say "tin boat" I assume that this is a general term for metal and really the hull is aluminium as are the rails.

There is going to be considerable force on these rails when going through waves or making a high speed turn. If you want the rails to be secure they are going to have to be welded and done by a competent welder. Pop riveting even with marine grade monel rivets is bound to lead to weakening the rails and there will be some movement between hull and rail resulting in elongated holes which will further weaken the rails. Continuous seam welding is the only way to go imho.

 

[old school]

thanks mates - here is what we have done so far ...

An autobody repair guy/friend inspected the rail - what caused the failure were little stress (flex) cracks that started around the rivets in the outside and thinnest part of the rail -there are actually 2 more tiny cracks by the next set of rivets as you head back along the rail towards the transom (again, right at the rivets)

We are assuming the front piece of rail failed by the rivets and then it peeled back to the next set of rivets (luckily I didn't lose the 12" piece of rail)

My friend's brother had an aluminum welding machine and tacked and welded the piece back in - he also put a couple tack/blob welds on top of the other 2 rivets/cracks - it doesn't look pretty but for 2 hours on his back at night (after working all day) it is pretty OK with me - I will post pictures

To ensure that more of the rail (there are 4 rails total running the length of the boat - 2 each side) do not fail - we are planning to add a few more rivets (they are currently spaced every 12" and we want to split that to 6" mainly upfront where the evidence of flexing is greatest - (since the hull is an older 1998 and the integrity is questionable we have decided against spot welding the rail to the hull instead of riveting) - there is also a 20 gallon fuel tank laying in the hull (please don't ask if we took it out before we welded - lets just say I had a lot of water blasting down the hull inspection/access compartment last night)

QUESTION - for the 32 rivets we will add (8 per rail for the 1st 4' of each rail) can we use just regular aluminum rivets or should we order that new Bull Frog Rivet kit? (that has epoxy you put on each rivet) - I am not that concerned with minor rivet leaks as the boat has a good bilge pump (boat was taking on about a 3/4 gallon every 45 minutes which was no big deal)

 

[ianat182]

As you are going the rivetting route you could have a look on the 'net' for 'Blind Rivets' and the appropriate air gun for the job(about $56 for the gun).
I thought that the rails were keel strips but they are obviously spray rails.
ianat182

 

[old school]

final solution - not going to rivet ...

just going to leave it spot welded.

After much consultation with other tin boat owners it looks like the rail failed because the hull was flexing (maybe previous owner hit large waves or wakes on a regular basis). When the hull flexes small stress cracks develop around the rivet holes. After a while it is just like bending a pop can back and forth - finally cracks in half (just like the rail).

Rather than weaken the rail, and put more holes in the hull, we are leaving it spot welded. As you can see it was not a pretty job but welding it upside down caused the weld to drip down and not into the holes - so it was a lot of spot/blob welding and grinding. I have since smoothed on some Marine Tex (epoxy) on any forward facing weld to help sheer the water off.

We are going to inspect all rivets on a more regular basis and when one starts cracking just spot weld that particular rivet/hole.

Thank you everyone and I hope this helps someone else having problems.