Aluminum stiffener

[fallguy1000]

6061 is welded to 5000 plate all the time. No issue with corrosion. Almost all extruded sections are 6061 or 6063. You can't extrude the 5000 series alum.

Bonding alum to alum is HARD. Not to do initially but to have the bond survive for years. Eventually moisture gets under the edges and weakens the bond.

Welding will leave a line but it won't be too bad on 3/16 if the welder is good. Easy enough to fair and paint.

You could also lay up some flat polyester/glass panels with a few foam stiffeners (from offcuts) on the underside of the panel.

Any thoughts on the stiffener idea?

Just foam verticals and then tape them on? Prep? Danny like.

[Evan_Gatehouse]

Are you talking about all glass panels now or some aluminium/foam/glass hybrid?

I was suggesting dropping the aluminium and just lay up some glass panels. Make them cored between the part that laps on to the beam recess or just a few shallow stiffeners.

Glassing foam stiffeners to aluminm plate will work for a few years until the epoxy bond fails.

I once got Lloyds Register to agree to a class approved fiberglass repair of a main bulkhead to the inside hull of a 60m aluminium mini cruise ship. The chemicals involved in the prepping were ugly and we all agreed it was only a temporary fix until the next drydocking, I.e. less than a year. Nobody believed the bond would last for more than a few years including the experts I consulted with.

[fallguy1000]

Are you talking about all glass panels now or some aluminium/foam/glass hybrid?

I was suggesting dropping the aluminium and just lay up some glass panels. Make them cored between the part that laps on to the beam recess or just a few shallow stiffeners.

Glassing foam stiffeners to aluminm plate will work for a few years until the epoxy bond fails.

I once got Lloyds Register to agree to a class approved fiberglass repair of a main bulkhead to the inside hull of a 60m aluminium mini cruise ship. The chemicals involved in the prepping were ugly and we all agreed it was only a temporary fix until the next drydocking, I.e. less than a year. Nobody believed the bond would last for more than a few years including the experts I consulted with.

I was thinking a glass stiffener glued with 5200. The plate is made. It is fine on the boat, but flimsy off. I figure the stiffener would also keep the thing from bending if an odd wave smashed it just right.

[fallguy1000]

Keeps waves from slamming up into the notch.

[narfi]

How is it attached? Is it bolted on? Because the fiberglass angles there should provide plenty of rigidity? If you wanted more and had the clearance on the inside, rivet on aluminum extruded angles?

[fallguy1000]

How is it attached? Is it bolted on? Because the fiberglass angles there should provide plenty of rigidity? If you wanted more and had the clearance on the inside, rivet on aluminum extruded angles?

I don't want rivets. I have them, but prefer no because it'll show like a blemish.

It is rigid bolted on. But remember, boat is demountable, so this piece is removed for mounting and it could get kinked taking it off.

[Jaysen]

What about a small break down the middle just to add rigidity?

[fallguy1000]

What about a small break down the middle just to add rigidity?

Already fitted. No changes to the plate dims allowed now. Part ofnthe reason I want to keep it safe is the nuts are all epoxied in and not accessible later. If I need to make a new one; big pita. The new one would require holing and rivnuts or something odd.

[narfi]

I don't want rivets. I have them, but prefer no because it'll show like a blemish.

It is rigid bolted on. But remember, boat is demountable, so this piece is removed for mounting and it could get kinked taking it off.

A good rivet pattern looks clean and nice. But thats subjective so if you don't like it, then don't do it (even though it's under where no one will see it.

You are over thinking it though, as long as you are careful you won't kink it, I've handled a lot thinner without kinking.

Honestly how many times a year you plan on trailering it? Thats not a small project. So if you do a couple times a year then I would just keep it like it is.