Aluminum and salt water

Most yachts over 130' are all aluminum hulled (some steel as well on displacement ones). Westport was the first yacht builder to start making yachts over 100' in fiberglass. Prior to that pretty much anything over 75' or so was aluminum. It takes a huge commitment ($$$) to build a fiberglass mold and you have to sell several just to pay for the tooling costs. Aluminum allows you to build a totally different yacht each time. They have special primers and paint inside and out. Some use an epoxy coating on the inside. You still get corrossion bubbles on the exterior under the paint after 5+ years on the paint job that need to be sanded down and fixed.

Some? A lot, along with a lot of workboats and even CG vessels. I'm not aware of issues with salt water.

No, it's too heavy for a lot of designs. Steel hulls are the strongest when built properly. However, on a lot of motoryachts, they find steel too heavy. Some builders use a steel hull and aluminum superstructure. I'd say the majority of yachts over 100' are aluminum. Steel is not without it's corrossion issues either.

Eh, you're joking right?..... Salt an aluminum are an easy recipe for corrosion and need to be kept separated at great effort and expense. No to mention the problems with dissimilar metals and galvanic action. Slacking on any of that is a death sentence. Notice you don't see a lot of old shaggy aluminum boats.

I have seen and run a few aluminum crew boats from the 1950's,1960's, and 1970's, and when I tell you they were run hard and put away wet, they were. They were still in pretty good condition and useful in a commercial setting.

Learned something new. 1950's? I've run them built in the 60's and up, and yes they're run hard and keep coming back for more. The big problems with aluminum hulls wasn't salt water corrosion, but electrolysis from dissimilar metals and finding bottom paint that worked and held to the surface. Aluminum is used in boats for the same reason it's used in planes. It's light and requires very little maintenance. Aluminum, steel and fiberglass all have their good points and bad and different materials they need to be pared with.

Our company has an entire aluminum shipbuilding division. Lots of boats and ships that are 100% aluminum. Some get painted, some do not. You just have to use the correct type of aluminum. Also, thousands (probably millions) of small aluminum boats out there. Builders like North River, Armstrong, weldbuilt, etc - all 100% aluminum.

Marine grade aluminum holds up well in saltwater as long as maintained properly. Maintaining a yacht finish if you want to show off at the dock requires regular attention. In commercial use aesthetics is not always a priority, actually you don't have paint it above the waterline. There are a lot of old aluminum boats still floating. One of my favorite SF boats designs is the Strikers. All welded construction eliminating fasteners, caulking, laminate coring, blisters, no delamination, not to mention fire resistance and strength is appealing.

I had a 1965 48 foot aluminum Chris Craft Roamer that I had a capac unit on to prevent corrosion of the hull it worked very well.

https://www.evoqua.com/en/evoqua/pr...mpressed-current-cathodic-protection-systems/

That 70 is a big ship. If I switch back to a SF I'd consider the Striker 62. Actually, I have thought about it, still hanging on to my tackle...

Oh Strikers still had blisters! We had one two boats ago. It was a tank.

OK, I sit corrected. I actually have an 80's 24' Starcraft sitting in my back yard. It's a project which will need to go down to bare hull..... in my copious spare time. Hull is in very good shape. It was a Great Lakes boat.