New, to me, Boat; convert from work to fishing; stop corrosion

[rocky_taco]

I picked up a new, to me, boat. It's a 16' and 3/16" 5086 aluminum. It’s an interesting boat with high sides and a modified V of 12 or 13 degree. It has a tow bit and outboard guards. I think these will get in the way of landing fish, so I’ll probably cut them off. It has a welded in deck that looks like it could have been made self bailing. But, the boat has a welded in pocket from deck to the hull at the transom. There is a drain plug that seals off the deck and then another drain plug at the transom. The plug that goes to the sealed deck area has some foam in there and seems dry. So, hopefully, I don’t have any issues with corrosion in there. With the welded floor, taking it out to remove foam is a bigger job than I would want to mess with.

Overall, there is little/no corrosion, with the exception of where the bottom of the boat is coated/painted. The boat was used in salt water and there is corrosion under the bottom coating. It looks to be mostly confined to the area between water line and above to where the paint stops. I believe the bottom is coated with coaltar. I picked up a few scotchbrite pads to try removing the coating. One is very coarse, but specifically for removing coatings/paint from metal. I was able to remove the paint in a test spot and it seemed to work well. There are still pits in the aluminum, but I would classify them as smallish. I've no intention of leaving the boat in water at a marina. I will trailer to and from the lake when I use it. There may be a rare occasion when camping or something where it might stay for 5 days in the water. But, this would be really rare. The boat will be used in fresh water for 80% or more fishing, mostly trolling. My thoughts are to strip the coating off the bottom of the boat where it’s corroding, cut the tow bit out, cut the motor guards off, acid etch the boat, and not repaint the bottom.

Anything else I should be thinking about before I get started to ensure a quality end result? Should the cutting/sanding discs be brand new never used on other material? Are there special kinds of cutting wheels, sanding discs, etc. specifically for aluminum? Is sanding/acid etching sufficient for the pitting, or should more be done? Any other advise on what I should be doing or not doing?

Thanks

http://s152.photobucket.com/user/rocky_ ... 9702226555

[kmorin]

rocky_t, not sure what's with my system but I can't get to the photo/pic.

Might have some reply? but can't see the image- likely my old system but still can't see it.

Cheers,
Kevin Morin
Kenai, AK

[Chaps]

I can see the pics, Kevin you might need a photobucket registration to see them.

Those are stout boats (Workskiffs). What you are doing will work, make sure none of your discs or wire wheels have ever been used on steel or other ferrous metals. The pitting is very minor especially on a hull that thick, not to worry. Pull the engine, take out the tow bit and flip it over, it will be a lot easier to work on bottomside up. Acid etching after you get all the old coatings off would give things an overall pleasing look if you can get the metal really clean.

[rocky_taco]

Kevin,

I sent you 3 emails with the pictures attached. Sorry, I can't figure out how to get them to post directly into the body of the post.

[kmorin]

rocky_taco, I got the pictures and that made me go back to the link and experiment. I needed to turn off the add-blocker software to display the site's images. I turned mine off and was able to see them, but thanks for sending.

My take is the corrosion is shallow and not long term damaging if you can stop the cells from expanding. So sanding the tops off the cells as the test strip is a good step. Next by acid etching the boat you'll flood those cells with acid and most will clean out, but all important is to rinse the acid off while its wet, not to let it dry and become acidic again from rain or even dew. So diluting the wet acid with a pressure washer or high jet from the garden hose is good to help clean out the residue in those pits.

If they're cleaned and rinsed and left to dry the covering that made them possible is gone and oxygen inside the pit will allow the aluminum to form oxide and stop the acid corrosion that caused them. Taking off the paint, everywhere is fine if you'll be in fresh water and on the trailer most of the time. Leaving a week here and there in the water is not too likely to grow much grass on your hull in fresh water.

I'd look for cutting tools instead of grinding tools to do the metal work- grinders tend to get into jambs unless you remember to take strokes of material away and not use the tool with its hard disk as a saw. Flap disks are good for clean up of residual welds, and if used with care so you don't gouge a flat surface can even leave a decent coarse finish of weld removal. There are two types- you show the face cutting tool so make sure you don't try to use it on the edges or tipped up like an edge grinding hard wheel. The round edge flap sander is used on its outer edge and leaves a fairly nice cupped fillet when used with some care.

Hard wheels just for aluminum are much softer than steel wheels and will not load up and become coated with melted aluminum but steel grinding wheel will coat with melted aluminum and soon you're just rubbing aluminum on aluminum at high speeds. The plastic abrasive pads come in several grits, from the 36-40-50 you show to polishing levels but the one you show looks like its taking off the paint and corrosion residues well.

Someone gave the topsides a nice turned pattern buff job so when its etched I'd expect it to look nice, especially if you're able to find a disk that size to match the previous patterns?

Looks like a nice shape, sure strong enough is 3/16' in 16'.

One way to display images in your posts:
go to Photobucket and click on our image, and when it shows up by itself as a full page image, right click up comes the dialog box with "View Image and Copy Image and (3rd choice down) "Copy Image Location" when you click on that the image's URL address (link) is copied onto your clipboard. Click back to the AAB.com Forum tab in your browser, and type Cntl V and a string will print on the text box. Now just type bracket [ img ]closed bracket(no spaces in the final version) in front of the string from Photobucket. At the back end of the string (URL Link ot the image) type the same bracket [ then forward slash / them img followed by another closed bracket ]

I have to mess up the typing to show this as the sites display software wont' show the real deal- it will show a picture if typed correctly.

[ img]http://i383.photobucket.com/albums/oo27 ... edux_a.jpg[/ img]
There is a space after the first closed bracket so the entire string of information is not 'processed' or read by the site. And at the right end there's another space after the slash that stops the site from reading this correctly. Below I'll take both spaces out so the link is typed correctly. You won't see text any more just the picture of the old Alaskan fishermen. I'm pretty sure this is all done automatically in the tool bar (above) with the "mountain and sun" icon -9th icon from left- upper icon tray beginning with Bold icon? but I do it as I've shown.





Cheers,
Kevin Morin

[rocky_taco]

I got to spend a bit of time on the boat this weekend and got the motor guards off. I used fiber cutting disks. Worked okay, but I can see how a cutting tool would be better. I’m not wanting to try cutting disks on the tow bit, as I really want to get the whole plate out so the deck is back to just the diamond plate and doesn’t have another thickness or two of plates higher than the deck. But, there’s 6 foot of weld that needs to be cut out for this. I’m thinking of just going at it with a circular saw and setting the depth right at the plate thickness. Is there a better cutting tool for this that is somewhat readily available?

How many gallons of zep-a-lume should I order to acid etch the whole boat? Due to shipping costs, I’d rather have too much than not enough. But, don’t want to end up with a lot of extra after I’m done. Also, how clean do the welds need to be of paint before I acid etch?

[kmorin]

rock
the type of controlled cutting is best done with this in an electric die grinder - slower than skill saw but a little more control.

The skill saw will work but I'd want to set shallower than deeper to leave a tiny film of weld. No telling what that root looks like so the deck under it is most important preserve.

I'm expecting so see some crevice corrosion under that doubler plate and not sure if any items reach through? I'd say it was worth the time to go slowly into that weld and maybe two cuts with the saw set to score would be the safest. The die grinder bit is fluted coarse for aluminum and you use it with pan spray to keep it from building up ( I do it that way) and the cuts are done in tiny strokes not hogging away the weld.

the grinder can get after the surrounding deck just as easily as the saw so... its a "feel deal" either way to make sure your cuts stay above the final deck surface. If you use a disk in this operation the tendency is to sand down a fairly wide path all around the weld you're trying to remove- a low angle cut will sand the adjoining deck. However, a high angle cut with a hard wheel will risk going through the deck so... that's why the skill saw or die grinder are better choices.

There is a counter rotating saw out there now, and some counter rotating free hand cutters, also we have had some discussions of a "meat axe" here, for just such work as you show.


Yes, this is a grinder motor with three non-ferrous 4" blades stacked on the spindle- yes this is not what the manufacturer suggests and it can be dangerous. But I have found that two or three blades provides a very shallow cut, very controllable and very very stable -no grabbing - so this tool would have that weld out, with very little removal of the deck and it would remaing safely in MY control all the time.

[AAB.com Forum only shows this for educational purposes- they do not advocate you rig this up and use it. I rigged it up- I welded the extra guard extensions and I find it safe in My work- posting it here is not in any way a suggestion by the site that you should follow my example. If for any reason you should mount a single saw blade on a 4" grinder motor shaft; that is potentially a very dangerous modification to the tooling- use with extreme caution.]

So those are the main choices, die grinder- slowest and shallowest cuts; skill saw- as long as the table and items to be removed can be arranged- fine; and the meat axe with 2 or more blades that will combine the previous two tools' cutting effects.

Hope this helps your decisions and planning.

Cheers,
Kevin Morin
Kenai, AK

[rocky_taco]

the tow bit is cut out. There were holes in the tow bit bottom plate where, I assume, it was screwed into another boat. Those had been sealed with silicone or some such caulk. But, there was still water between the plates. But, the corrosion wasn't bad and pitted like under the bottom paint. Still, glad I got it cut out. Kevin had some thoughts on the acid forming due to the gap that he will hopefully share. I was just happy there wasn't any pitting.

I'm pretty happy with how it turned out, with the exception of a deep cut on one side where I got confined and couldn’t hold the meat axe like I wanted to. But, I didn’t cut any meat, so all good. The center blade did load with aluminum shavings between a couple teeth on the middle blade. I should have tried only 2 blades instead of 3 to see if it would shed more shavings. But, I was more afraid of kick back than cleaning teeth. So, I never tried this. If I have to cut anything else out, I will though. The 4-3/8” blades I was using were 40 tooth and didn’t seem to have as much space between them to shed shavings as the pictures of Kevin’s 3 stack meat axe.

sorry, keep getting an error that I can't load an image over 1280 pixels high..... So, back to the old photobucket link.

http://s152.photobucket.com/user/rocky_ ... 7856515588

[rocky_taco]

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[Chaps]

Wow, what a transformation Rocky, well done