Sealing and preping sand blasted aluminum hull for bottom paint.

[waitingforthetide]

Hey fellow boaters,

Looking for some ideas for what to do next. I had my Spectrum aluminum boat sand blasted to remove the left over barnicle pads left behind from all the scraping and power washing. Its now sitting and waiting for bottom paint. After the blasting I noticed some minor pitting on the hull. So far doesn't look like anything has gone throught. But I will be filling the boat with water to check for leaks before painting.

As for the pits, I've heard JB weld should fill them, Cool or Not Cool?

And I'm thinking of trying to reseal the seams from the outside of the hull while its all clean, with Gluvit, Cool or Not Cool?

Once it's all sealed up and pit free I'll primer and paint the bottom so there no more barnicles.

Any thought on a electric anti corosion device I can install?

Thanks and safe boating

 

[Mi duckdown]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

Not a Fan of filling the boat with water. Dunk it and see if you have water intrusion. If not Paint it. My .02
Pics would Help.

 

[jbcurt00]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

JB Weld for pits inside or out. Etch, fill, sand/fair as needed....

Gluvit (or equal) is 'normally' applied to the interior only, all seams & rivets, it may make it difficult to sand & fair if applied to the exterior.

Gluvit is temperature sensitive, so in BC you're working in a well insulated & heated space, correct? In adequate temps, gluvit may take 72hrs+ to cure.

IMHO, paint is not an exterior leak preventative. Float test w/ a normal & distributed weight load can be better then filling the hull w/ water, but either test can be used... Some rivets may need to be replaced, some may be re-bucked which will re-seal them.

Paint prep of an aluminum hull, esp a bare hull, needs to be thorough & well done. Any bare aluminum needs ZC (zinc chromate) or SE (self etching) primer, then metal primer, then finish coats. With light sanding & thorough cleaning between steps.

Read some of the tin boat rebuilds, most include paint details. There's an advanced search feature from the resto forum homepage:

Try: paint aluminum

It is a well covered topic. As are the steps to give the bare aluminum a mild acid wash before ZC or SC is applied.

Prep
prep
prep
Can't ever have too much prep, including research

 

[Pmccraney]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

JB Weld for pits inside or out. Etch, fill, sand/fair as needed....

Gluvit (or equal) is 'normally' applied to the interior only, all seams & rivets, it may make it difficult to sand & fair if applied to the exterior.

Gluvit is temperature sensitive, so in BC you're working in a well insulated & heated space, correct? In adequate temps, gluvit may take 72hrs+ to cure.

IMHO, paint is not an exterior leak preventative. Float test w/ a normal & distributed weight load can be better then filling the hull w/ water, but either test can be used... Some rivets may need to be replaced, some may be re-bucked which will re-seal them.

Paint prep of an aluminum hull, esp a bare hull, needs to be thorough & well done. Any bare aluminum needs ZC (zinc chromate) or SE (self etching) primer, then metal primer, then finish coats. With light sanding & thorough cleaning between steps.

Read some of the tin boat rebuilds, most include paint details. There's an advanced search feature from the resto forum homepage:

Try: paint aluminum

It is a well covered topic. As are the steps to give the bare aluminum a mild acid wash before ZC or SC is applied.

Prep
prep
prep
Can't ever have too much prep, including research

Yep...This ^^^

 

[waitingforthetide]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

Thanks everyone for the great info. The pits are on the exterior of the hull. Ya its cold up here so I bring it into the heated shop when working on it. Looks like I have some man hours to put it before the summer.

Any thoughts regarding Anti Corosion methods, she sits the ocean all summer and on the sand bar when the tide goes out.

 

[jbcurt00]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

Sorry, I have never nor plan to ever, leave a boat moored long enough to need additional anti-fouling bottom paint/anti-corrosion devices..

Make sure you aren't grounding the battery to the boat's hull or structure.

 

[1FASTLASER]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

Prep
prep
prep
Can't ever have too much prep, including research

Words of wisdom that should be adhered to STRICTLY. A project can only turn out as good as the prep work is done.

 

[jasoutside]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

she sits the ocean all summer and on the sand bar when the tide goes out.

Have you considered going fiberglass?

Did I just say that out loud?

uke:

 

[jbcurt00]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

Have you considered going fiberglass?

He said GOING GLASS!

The significance of this statement makes it worthy of consideration :happy:

 

[jigngrub]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

. But I will be filling the boat with water to check for leaks before painting.

Posting pics of your boat will get you the best help when we can see what you have to work with.

This would be a lot better than putting it in saltwater to check for leaks, leaks are easier to find with water dripping out of a boat than trickling in too.

What's wrong with putting the Gluvit on the inside like it's supposed to be done?

If you're going to leave her sitting in saltwater all year I wouldn't skimp on the paint, I'd suggest multiple coats of a marine epoxy type paint... maybe look into steelflex paint.

 

[jasoutside]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

Hang on, I just got one more....

uke:

Ok, let me just...

:brushteeth:
...so we can talk.

The significance of this statement makes it worthy of consideration :happy:

Yup. I spread liquid alum on my toast in the morning and receive by monthly alum blood transfusions, just cus.

A trailered alum boat in salt is reasonable, sorta, pretty much, with maintenance.

An alum boat docked all summer long, in salt? No way. Wouldn't do it.

I'd have to go buy the nuclear fallout suit, and join by itchy brothern:tinfoil3::tinfoil3:






Now, I never said this, none of this ever happened!:anonymous:

 

[jbcurt00]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

Now, I never said this, none of this ever happened!:anonymous:

:spy:
nothing/nobody to see here, keep moving.... :tinfoil3:-anonymous......

 

[jigngrub]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

He said GOING GLASS!

I considered it an "outing" of sorts.

I've been suspicious of him ever since I caught him cross dressing by putting fiberglass tape in an aluminum boat.:faint2:

... of course he's going to say he only did it one or two times...

 

[jasoutside]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

Whatever.

I only did it like one or two times.

I didn't even like it.












Very much.

 

[RichBKK]

Re: Sealing and preping sand blasted aluminum hull for bottom paint.

Here's what I did (right or wrong), for what it's worth..

Bought a 1980 14' MirroCraft (semi-v hull).. I live in S.W. Florida on the Gulf.. The boat had previously been owned by a mullet fisherman.. Had a small deck up front that he'd put in, middle seat taken out and an aluminum frame made to hold a large igloo cooler was in it's place.. Needless to say, the boat was pretty "beat up" from the hard life she'd lead.. No barnacles as the guy had kept it on a trailer but, the time spent on flats and oyster bars was quite obvious.. In the bow, at the waterline, she'd been rammed into a concrete piling and had a gash that had been "filled and sealed" with JB Weld.. It leaked a little, nothing serious..

Well, one thing (read: project) led to another as they always do on boats.. Long story short, after palm sanding entire interior, all seams and rivets got 3 coats of Glu-Vit, then self-etching zinc primer, then 2 coats of Beher's oil-based semi-gloss paint.. Then flipped the boat and palm sanded the entire bottom as well with 80 grit sandpaper to take off and take down all of the nicks, scrapes from the oyster beds.. Filled any "large dings", nicks and bow gash with "Marine-Tex" epoxy (I'd removed the JB Weld patch that was leaking)..Then used 100 grit, finishing up with 120 grit to "smooth her out"..

I gave her 2 coats of Glu-Vit on all exterior seams and rivets, followed by 2 rolled out coats of Glu-Vit over the entire exterior of the boat, bow to stern, top to bottom.. Then lightly sanded with 160 grit paper and gave her 2 coats of Beher oil-based, semi-gloss paint..

Some will say it's wrong to use Glu-Vit on the exterior.. So far, I'd disagree with them.. It's been great and held up excellent.. It also really helped "stiffen up the hull".. No more "flexing or twisting" to her in big seas.. I go offshore, 10 miles out (just losing sight of land) in 1 to 3 foot seas.. If I had things to do over again, I would give 2 coats of Glu-Vit over the entire interior as well..

The paint has adhered excellently (I didn't primer over the exterior Glu-Vit, just paint) and no barnacles or growth on the bottom (she's living in the water a good 20 to 25 days a month).. Granted, the water temp is in the low 70's and do expect growth late spring, going into summer.. Easily taken care of while snorkeling..

Good luck and keep writing, letting us know how things are coming along..