Center keel removal & repair – On a SALTwater tin

[DaleH]

Center keel removal & repair – On a SALTwater tin

Well, the title says it all ... a saltwater boat and salt WILL attack and corrode rivets, thus the boat will leak ‘someday’. That 'day' turned out to occur this year, but I do leave my boats out in the salt 24/7 at my boat club dock.

This is my old 14’ boat, as I had sold it to a kid ~5-years ago, and it wasn’t leaking when I sold it to him. He had completely stripped it and applied Steel-Flex, as he too used it in the salt, but we found out a crucial lesson. On this hull there is a hard domed or ‘V’-chine or rib that forms the keel going down the center of the boat. This is designed to be open and there are a few factory ‘weep’ holes in it, but he closed them all up with the Steel-Flex, doh – not a good thing to do! He bought a new boat this season and was so grateful that I had helped him out through the following years of his ownership (like tuning the motor or changing the impeller, even general boating & fishing advice) that he sold it back to me for about ½ what it was worth.

The rest of the hull is integral - no leaks anywhere. Thus ... with the small leak/weeping ... surgery has commenced! Look at the water weeping out of the keel section, so one can see it was getting trapped in there and not draining. My plan is to remove that keel section, clean it and the hull (also inside) up really well by mechanical sanding and white vinegar washing, then prime with 2-part self-etching epoxy-based tin primer, then reassemble and re-rivet it with closed rivets. I’ll use LifeCaulk or 3M 5200 as a sealant, with the piece held in place with Cleco fasteners as the re-riveting begins.

KEY Tips for the Repair – Most factory OEM rivets are 3/16” in diameter, but I don’t drill them out with that size drill, as I want my hole to remove them to be smaller. I drill the heads off with a smaller (like 9/64” or /32”) sized drill. Then is done so when I finally re-drill through for the new rivets, using a new cobalt 3/16” drill bit, a get a nice clean, sharp hole for the new solid rivet.

• Clean the rivet area well so you can see where you’re working; I used a sharp 3/8” wide chisel to cut through the Steel-Flex as shown – [Picture Step 1]
• Use a ‘prick punch’ (not a ‘center’ punch) to mark the center for the drill – [Picture Step 2]
• For this many rivets, only use sharp new drill bits, cobalt recommended, where a heavy feed and medium RPM cuts the best – do NOT burn out your drills. I also keep a catfood tin of cold water handy to dip the bit into.
• Drill through the rivet head only! Don’t try to drill the rivet out entirely! Again, I use a smaller than 3/16”drill bit to drill off the old rivets – [Picture Step 3]
• Sometimes, like 1 out of 3 on this repair, the rivet head sheers right off due to the drilling – you get lucky! – [Picture Step 4]
• Otherwise put that same chisel on a low angle and one solid punch should sheer the head right off

NOTE to above Step 3.
By partially drilling through the head, if your pin strike was off or the drill bit drilled off ... now you can “see it” well before you completely drill through the hull/rivet and now you can adjust your drill hole. Either re-punch the remaining rivet to get on-center, or tip the bit to drill through, targeting the center of the rivet.


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Stay tuned for more pictures as this repair progresses ...

 

[DaleH]

Update:

• All tin in the repair areas cleaned
• Then any 'bare' tin was vinegar etched
• Pieces primed, many multiple coats, but very thin coats for best adhesion
• Back-sides (inside hull) of corrosion 'weep' holes taped with adhesive HVAC tape (it sticks WELL to tin!) to prevent any epoxy dripping through
• Corrosion areas/holesfilled with G-Flex 650 flexible epoxy, sanded flush when dry
• All repair surfaces painted with special copper-free anti-fouling paint, especially that inside of the keel-chine piece
• Mating surfaces wetted w/more G-F 650
• Pieces re-riveted back together whilst the G-Flex was still wet, as applied in a putty-like consistency
• Once dry, all new rivet heads sealed in more G-Flex, 73 rivets in all, but amazingly still using the same $21 G-FLex kit, as that product really goes far!

Now if it EVER dries up here in the Nor'East US, the bottom of the hull will have another full coat of the copper-free A-F paint applied, as the boat is left in the water, saltwater to boot ... hence all the epoxy precautions.

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[508]

I'm always impressed with how meticulous your work is. And I feel you about the weather, it's been brutal!

 

[onthewater102]

Did you get into the bow section at all with this? My brother has a 14' alumacraft but the bow section appears to be 2 sheets that terminate and are joined by that keel section. I was thinking he should just G-flex it without the re-rivet effort as it seems more like the seams are weeping than the rivets leaking, but if it's possible to set it 100% right without gooping the outside up then that might be a better option.

 

[DaleH]

I'm always impressed with how meticulous your work is.

Well, thank you for the kind words, but it is honestly MORE driven by the 'need' to do these steps right for saltwater boat use, especially those immersed for 7-months of the year.

Did you get into the bow section at all with this?

... seems more like the seams are weeping than the rivets leaking

I did not get into the bow seam. The panel under where I was working was a solid sheet. But one of the West System's G-Flex 650 tutorials I've posted before, talks about using heat, after applying the epoxy, to allow it to weep into seams.

Whereas G-Flex remains flexible, and something like Gluvit doesn't, it sounds like the G-F product is just the ticket for your brother's use!

 

[DaleH]

FYI - Here is a graphic photo showing how 'salt' ATTACKS unprotected tin!

I guess I shudda added this photo up above in sequence of effecting the repair ... but at least the area is all cleaned up and fixed now!

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[gogittum]

I like your idea of using a smaller bit to drill them out, then shearing the heads. I removed a seat in my 16' Starcraft when installing the folding grab bar and I did get a couple of oval-ed holes due to drill bit walking. I did use a snap punch to mark centers and started with a 3/32 bit, followed by a 3/16 but it's often hard for old eyes to see exactly where the thing is going, with paint on parts, shadows, etc. Fortunately, all were inside the boat. The ones attaching braces to hull drilled out fine.

I became "very" familiar with clecos when building a small airplane 20 years ago, so ordered a new set and pliers when planning this job. Disappointed - the gap in the jaw of the pliers was too wide and the clecos cocked sideways when under pressure. It worked, but was an awkward PIA. Bought them from Aircraft Spruce, whom I dealt with extensively 20 yrs ago, but they ignored my complaint on this. Disappointing.

They were just cheap castings from China with rough shaping/grinding and I'm very aware of what usually happens when bending....trying to bend....cast parts. $7 pliers, WTH, give 'er a go, so heated the jaw carefully with propane torch, then when barely red, took a small modelers hammer and tapped the side of the jaw against an anvil. It only had to move 1/16" and it worked. Phew. Now the thing is a pleasure to use.

 

[gogittum]

I like your idea of using a smaller bit to drill them out, then shearing the heads. I removed a seat in my 16' Starcraft when installing the folding grab bar and I did get a couple of oval-ed holes due to drill bit walking. I did use a snap punch to mark centers and started with a 3/32 bit, followed by a 3/16 but it's often hard for old eyes to see exactly where the thing is going, with paint on parts, shadows, etc. Fortunately, all were inside the boat. The ones attaching braces to hull drilled out fine.

I became "very" familiar with clecos when building a small airplane 20 years ago, so ordered a new set and pliers when planning this job. Disappointed - the gap in the jaw of the pliers was too wide and the clecos cocked sideways when under pressure. It worked, but was an awkward PIA. Bought them from Aircraft Spruce, whom I dealt with extensively 20 yrs ago, but they ignored my complaint on this. Disappointing.

They were just cheap castings from China with rough shaping/grinding and I'm very aware of what usually happens when bending....trying to bend....cast parts. $7 pliers, WTH, give 'er a go, so heated the jaw carefully with propane torch, then when barely red, took a small modelers hammer and tapped the side of the jaw against an anvil. It only had to move 1/16" and it worked. Phew. Now the thing is a pleasure to use.

 

[DaleH]

YIPPEE! Rode it hard through some boat wakes on purpose - NO LEAKS!

 

[LDUBS]

Well Done Mr DH