Aluminium trailer-boat or a fibreglass trailer-boat up to 7 meters,what are the key differences & which is a better boat to own?
Here are some of the major differences as I've seen them from my experience with both types of boats.
Generally,fibreglass boats are sleeker & more curvy & can be made in a variety of smooth seamless finishes with complex curves & the colour impregnated into the gel-coat or fibreglass but aluminium can only be shaped or bent so far & generally is limited to variations of plate or flat or pressed & rolled finishes which can be painted.
An aluminium boat is much lighter than a fibreglass boat of equivalent size & so aluminium boats require less horse-power to push it through the water so you get fuel savings as well as not having to have a much larger engine to buy or run.
Alloy boats are also lighter to tow than a fibreglass boat so you probably won't need a big 4WD or light truck as a tow vehicle.
Aluminium boats generally have a flatter deadrise or bottom than the deep V of a fibreglass boat which makes the alloy boat stable at rest but can be a little rough riding & noisey in sharp choppy waves,fibreglass boats are heavier so are smoother riding & quieter in the chop but can be prone to being un-stable at rest because they have a very deep V hull as they need to displace more water because they are much heavier,so fishing two or three blokes from the corner of the transom might be something to avoid in some deep V trailerable fibreglass hull's,test it's stability at rest in the water at the boat ramp before you buy rather than at anchor at an isolated reef or seal colony while trying to burley up sharks with 1 meter high dorsal fins.
Blind Freddy can see a fatigue crack in an aluminium boat but rot (dry or wet) in the structural timber frame of a fibreglass boat and osmosis or water penetration where the gel coat gets damaged causing seperation in the fibreglass layers themselves can be hard to detect,even harder or near impossible to fix in the worst cases.
In the 1970's and 1980's before marine grade aluminium sheet was designed and became widely available and used in boat building, makers used standard aluminium sheet which was subject to electrolytic corrosion in water so it's very common for old & even newer aluminium boats that have spent years moored (ex-commercial) or in the water alot to have electrolysis affected aluminium,the hull & even the frame can be affected and severely weakened,it is hard to detect unless you look for it and is usually wide spread & fatal....scrap metal value only for those boats...but most of them aren't sold for scrap... they regularly come up for sale with a fresh coat of paint or fibreglass laid over the aluminium temporarily sealing the thousands of pin prick (or larger) leaks.
Be extremely wary of an old alloy boat with any riveted construction or any that lack several working zinc anodes's or had its hull painted below the waterline as electrolytic corrosion attacks the areas of the hull and motor in direct contact with water and differing metals in contact with each other and if you can't remove the inspection covers in the floor to visually inspect the inside the hull's under-floor area lowest points for evidence of water getting in and pooling &/or electrolytic corrosion/pitting on the topside of the sheet as well as the internal frame and keel area...forget that boat...keep looking.
Aluminium boats can be welded or modified pretty easily & cheaply except for an aluminium boat that been fatally corroded by electrolysis but a fibreglass & particularly an old fibreglass boat can have more major faults that are un-seen or bogged up & painted over & can have dramatic consequences like a transom & motor suddenly falling off while underway...buy newer not older in any boat.
Aluminium in aluminium boats "work hardens" with use & cracks from movement or stress or lots of trailering on rough roads particularly on the bottom of the hull around where wobble rollers or the slides sit and around the transom & engine mounts and around the cab structure from side-ways movement & shocks.
So whats better,neither one really,both have major differences so it's up to you what you choose but I now have a strong preference for aluminium boats after all I seen over the years owning,working on & using both types over 25 years.
Feel free to contact me via the eBay system if you want to ask a question.