'74 Starcraft 16SS Body Work

[wrmdunker]

I have a few holes and rough spots to fill in the aluminum gunwales and side panels from old rod holders, step pads, etc. I have filled bolt holes with JB Weld in the past and painted with OK results. This time I have spots that are deformed, dented and slightly oxidized and think I will be happier with a Bondo type repair. Something that wont show thru the finish paint.

So is Bondo the product? This is all well above the water line. Do I need to sand to bare aluminum or just sound paint? Should I prime the aluminum with ZC primer or Bondo right to the Al? Any thought?

At 42 years old the boat has seen better days but if I'm going to do something I'd rather do it right.

WD

 

[jbcurt00]

MarineTex is similar to JB Weld but easier to sand. I'm guessing the JB was so hard to sand the spots werent sanded/feathered smooth, so the spots of it are showing thru the paint on the other holes you filled w JB.

Larger holes can be filled by putting a larger then the hole backer plate behind the hole, well buttered w JB Weld. Then fill the hole after the backer plate is cured.

A good sanding/prep is critical to a good paint job. I wouldnt use Bondo on a boat, even above the waterline.

 

[Drewmanselle]

if the holes are small enough you could use a very hot torch and brazing rod. I did this to holes in the bottom of an old aluminum boat and then took an angle grinder to smooth out the braised area and painted over it. It takes a lot of heat and a little bit of technique but there are you-tube videos out there that show you how.

 

[harleyman1975]

You could epoxy prime the area and then epoxy and cloth if a larger hole or epoxy and cabosil for smaller screw holes. Tap the holes in a little so you can fill them and then just do your body work. Make your fairing compound with epoxy and cabosil.

 

[wrmdunker]

I think I need to post some pics........Perhaps the carbosil silica is the way to go. I have some 3:1 epoxy made by US Composites that I used to epoxy the wood panels and floor I replaced. Can I make a fairing compound out of these materials? Carbosil is pretty cheap. Marine Tex is $15 for 2 ounces.

 

[classiccat]

if they're that bad, have you considered replacing those sections of aluminum with fresh pieces?

 

[Watermann]

Yeah so the fiberglass stuff I can see it being a problem getting that mix of the 2 materials right. I think a pint of this 3M marine filler is 11 bucks. They have other fillers for below the waterline.

3M Marine Filler is a creamy formula that achieves great adhesion to aluminum, fiberglass, wood, resin, gelcoat, SMC, cured epoxy, urethane and primers. Hardener included. Intended for above the waterline use.

 

[wrmdunker]

Here are some pics. Always seem to help clarify the issues. This is the cross piece at the front of the splashwell. Not huge areas to warrant total replacements. Small snap screw holes Ive done with JB Weld and my high build primer likely covered well. The 3M looked good price wise but its appears to be single use filler and hardner pack for a one shot application.

I appreciate the inputs thusfar.

 

[Watermann]

I hate to say this but that's nothing! Here's a look at the Swiss cheese gunnels of my Chief, over 70 some odd holes in each gunnel I had to repair, repaired and then primed.

 

[wrmdunker]

No offense taken Watermann. I know its minor but sometimes its only a little more effort to do it right and avoid the loss of a bad repair and starting over. So you repaired them rather than replace. Did you use the 3M? I might try mixing 50% at a time. Take it down to bare metal and rough it up for a good bond.

What ive done for small holes is back them with aluminum held in place with Gorilla Tape. Then patch with JB Weld and force enough through to mushroom out on the back side and they have held up. I later remove the tape. Just no experiece with anything bigger than 1/4 inch holes.

 

[Watermann]

No offense taken, it takes way more than an internet forum to offend me and everyone has their opinion. :lol: I try to only listen to the guys who've actually done it not just read about it. I thought you were wanting to fill a a larger area not just smaller holes like in your pic. On big holes you need a backer plate to help support the repair.

For smaller holes it's easy but for large areas of mauled AL you would have to use some sort of filler, personally I've only used marine tex to fill larger areas rather than the 3M filler. I filled a crease in the bow of my Chief. But on all those holes I used JB water weld 2 part epoxy sticks. Made a wad filled the hole so it would form a mushroom on the inside and then once set up sand it smooth. The mushroom and thicker stick JB means no need for a backer plate to keep the gooey stuff where you want it.

Some day if I have the need I do want to try using the 3M filler, but hope I never need it.