Marine spray foam, aluminum hull sealant, Keel guards

[Arcs&sparks]

I bought a 2nd “new to me” (basic, Riveted, Deep V aluminum) boat that will be modified.

 

 I am in the planning stage right now.  I’m hoping some of you might have some insight of what products to use in my situation.  I have used the search tool here, but couldn’t find much.

 

I’ve spent the last few nights after work doing research on other forums and watching YouTube videos on the subjects...in other words,  wasting 90% of time spent reading arguments and watching Joe Shmo soak foam in plastic tubs....

 

 

1.  The previous owner said that the boat does leak just a bit.  One product that was recommended for this on here and other forums;  

about $50 for the can,  and made for application from the outside of the aluminum hull over seams and rivets.

 

   

 

 2.  I haven’t decided if I’m going to go nuts and pull up the factory floor yet. (Flat deck, ~4” off bottom)  It feels solid but I haven’t dug into it yet.   If I do, I think I will want to spray foam under the floor,  unless someone will talk me out of it.  But in either case,  I will be using at least some canned foam to fill in voids and such when I build compartments.  I understand that high density closed cell foam is what you want for marine applications so it won’t absorb water or ~gasoline~ (please verify?)

 

The two products I’ve considered so far are;

 

 

~$20

 

 

 

 

Both products seem to be well suited for the job.

 

3. My boat is with a mechanic right now or I would take a picture,  but has anyone installed a Gator Guard KeelShield on a heavy gauge riveted keel?

 

 4.  I will also take hull paint brand recommendations. Probably black FYI

 

 

 

Any input on these products,  cheaper alternatives, or better alternatives, are highly appreciated!  I have a hectic work schedule during the summer, hardly any time to fish,  let alone spend hours and hours researching,  so I’m hoping for some help from you good folks.

 

Thanks!

 

This isn’t my first boat build, now that I’ve learned from the past, I would like to spend alittle more time with product selection instead of settling with what is available at the home improvement stores ? 

 

 

[Fishing Rhino]

Regarding the foam.  There are two types.  One does not expand, and the other does.  If you use the type that expands you'll need to cut some "vent holes" which will allow the excess foam to expand.

 

If you don't, the foam may lift the decks off their supports.

 

Gluvit is a good product.  So is 3M 5200, which is a marine adhesive.  Be careful with 5200.  Do not use it to seal through hull fittings, or anything else than you may need to change in the future.  

 

It is great for bonding and sealing the edges of plywood decking. 

[Catt]

Surface Preparation of Aluminum for Painting

 

Sand paper: 80-100 grit

Scotch-Brite Hand Pads: part # 7447

Conversion coating: acid etch primer/Alodine/Chemfilm

Paint: automotive or marine grade polyurethane

Paint & Coating Stripper: Eldorado Solutions' DoradoTM Industrial Products part # 2021 or 5051

 

Steps

010: Clean the aluminum surface with a good cleaner using Scotch-Brite Hand Pads to remove all dirt, old paint and oxide from the surface. When sanding I prefer 80-100 grit it gives better tooth and paint adhesion.  Sanding must be taken into the best previously adhered surface in order to have the new coat of paint hold properly. Start with an orbital sander; finish by hand with Scotch-Brite Hand Pads. Rinse thoroughly with clean water & let dry completely.

020: Apply a coat of acid etch primer following the mixing and application instructions to the letter.

030: Within 24 hours of applying the etch primer, apply the topcoat finish.

[TOXIC]

Without knowing what model boat you have, I can't tell you if the KeelShield will work.  It is a fantastic product with a lifetime guarantee.  Here is a tin compatibility list.  

 

Aluminum Boats:

• Alumacraft – Not compatible
• Crestliner
• Fisher
• G3- some models
• Lowe
• Lund – Not compatible
• Mirrocraft
• Monark
• Polar Kraft
• Princecraft
• Ranger
• Sea Ark – some models
• Smoker Craft – some models
• Starcraft
• Tracker
• Triton
• Weldcraft
• Xpress

 

 

 

[Arcs&sparks]

Thanks @TOXIC,  I did see that list,  but wasn’t convinced every model of each brand was a yes or no.  It’s a ‘76 Starcraft Holiday 14’;  I couldn’t find a good pic online,  but heres a similar boat;

 

 

 

 

 

@Catt  My other boat was bare aluminum,  so I did the whole sanding and etching primer thing.  This one has paint that is in pretty good shape.  Is it really a big No-No to use the existing paint as a primer (after a good scotchbrite and clean)?   

 

*I don’t intend for the boat to be a showroom resto,  just functional and a bit personalized. 

 

@Fishing Rhino  thanks,  I’ll check out that 5200

[TOXIC]

Looks like the KeelShield will fit that hull.  

[Catt]

42 minutes ago, Arcs&sparks said:

Is it really a big No-No to use the existing paint as a primer (after a good scotchbrite and clean)?

 

"best previously adhered surface"

 

If ya gotta take to bare metal take to bare metal.

 

If the "best previously adhered surface" is the paint, scuff it & paint it.

 

[Arcs&sparks]

4 minutes ago, Catt said:

 

"best previously adhered surface"

 

If ya gotta take to bare metal take to bare metal.

 

If the "best previously adhered surface" is the paint, scuff it & paint it.

 

??. The way it was worded I had some confusion.

 

Thanks for the clarification.