I've grew up with a fiberglass boat but have enjoyed using aluminum boats these past ten years on the Columbia river. For their length, aluminum boats are generally much lighter than fiberglass, therefore they require less horsepower to push them than a similar hull shape of glass. They also weigh less on the trailer, requiring less horsepower and braking ability to tow them there too. Aluminum dents rather than cracks and aluminum boats can bounce on the beach, along a dock, into other boats (while anchored at a hogline) or over logs and even rocks with no harm and very little cosmetic effect. The same can't be said for fiberglass. Managing an aluminum boat at a dock in choppy water is much easier too, because they weigh so much less, it is easy for one person to nudge it here or there, the boat responds quickly and you aren't likely to strain anything or get a foot pinched if the gunwale comes down on it. Likewise, they load onto trailers much easier and winching them on is cake.
I met Ernie Duckworth in the 70s back when he had two good eyes and was one of the first in the industry to put a big block V-8 into a shallow deadrise jetsled and run Hells Canyon in the class 4 rapids (upstream from Asotin, WA 190 miles roundtrip -- in one day -- an awesome ride I'd suggest to any boating fan with views of the world's deepest gorge, desert country, Rocky Mtn. bighorn sheep, deer, golden eagles etc.). For high speed performance in turbulent, shallow water, nothing can touch them. My large 23' boat that can comfortably seat 8 and is rated for 10 passengers has a 6" draft when on plane, my last boat 4". They can launch at the mere suggestion of a beach or ramp. There aren't two layers to the hull where water can accumulate, rot is never a problem. The quality of the welds has taken on a level of expertise that is as artistically beautiful as it is hammer-like functional (at a boatshow, compare North River, Thunderjet or Duckworth boats to Alumiweld, Raider, Lund or Smokercraft and you'll see what I mean). People with aluminum hulls don't spend time or money maintaining them, and that has significant charm. They can be bottom painted for salt water too.
So why am I switching to a fiberglass boat?
Kalama is a "hot" marina and I moor there year-round. It is fresh water but there is lots of electrical current in the water and yes, I can see some pitting on the jetpump from electrolysis. I have zincs. The hull is unaffected. This condition would be accelerated in salt water. I am jealous of the fiberglass boats with outboards that can be lifted 100% out of the water. Fiberglass is a poor conductor compared to aluminum.
Hull detail: aluminum used for boat hulls comes in flat sheets. They bend it, they cut it and weld it together in an amazing variety, but the strakes are not as sharp, crisp or numerous (again, as beautiful as an Estwing 40 oz. hammer). Here fiberglass has less compromise. From the ground up, glass can be molded/shaped with fewer limitations and much more detail, allowing for a more hydrodynamically influenced design. It is more elegant and finessed.
I realized that I am more interested in fishing and boating in the deeper water (that means deeper than 5 ft) - to include ocean and mainstem Columbia river than I am interested in fishing both deep water and also the shallower Cowlitz and Lewis Rivers where a shallow draft sled is required. I also want to get away from the big block V-8, its maintainence, and don't need a jet and its performance and accompanying fuel consumption. A propeller has better low speed control, making docking a breeze. Aluminum is also much louder than fiberglass. You hear the water through the hull more and generally, that is not a good thing, especially when you are trying to sleep. We also want a more cruising-friendly boat than we have with a galley and sink & sleeping quarters that can remain in place during use.
There are more and more aluminum boats designed for salt water. If the wiring is done right (not grounded to hull) and if the motors are well zinced, there aren't too many problems. C.W.