Marine Alloy Catamarans versus Fibreglass Catamarans

Friday, 4 February 2022 9:58 am

This is a conundrum thats been around ever since marine grade alloys started to become popular over 50 years ago and I often get asked by many new operators now as to which is better to use for hulls on smaller passenger ferries.

It's well known fibreglass (GRP) vessels may offer more comfort due to their extra weight. Successful fibreglass designs from Shark Cat (now Noosa Cat), Power Cat and Cougar Catamarans were (and still are) very popular with recreational and commercial operators, then the alloy catamarans started to emerge in popularity as new efficient hull designs developed . 

Is there any advantage to catamarans being built in aluminium over fibreglass?

Aluminium catamaran pros :

*Lighter weight - translates to better fuel consumption and slightly smaller engines.

*Greater flexibility during collisions or groundings.

*Easier and quicker to repair should the plate actually split and not just dent.

*Does not mark as easily.

*Aluminium is a rising commodity over time and resale value is good on used alloy vessels.

*Long life expectancy with a little TLC

*Greater transparency of hull condition, as plate and extrusions are easy to inspect.

* Better wear and tear for beach landing vessels.

Aluminium cons :

*Needs a well designed earthing sytem on board to prevent stray current.

*Needs bilges maintained dry and clean to prevent electrolysis.

*A little more expensive to build.

*Can be noisier underway than fibreglass.

*Often needs fairing to obtain the exact look of fibreglass.

Fibreglass Pros:

*Quieter and softer ride.

*Often can establish a nicer looking finish on the end product.

*Quicker and cheaper to build due to hulls being moulded.

Fibreglass Cons:

Need to maintain gelcoat and prevent water ingress.

Subject to osmosis or delamination if not maintained.

Heavier, so increased fuel consumption.

Easier to scratch and longer repair time due to drying out prior to repair etc.

Not all class societies or flag states allow GRP vessels commercially.

As you can see there are advantages to both alloy and fibreglass and it depends on your daily usage, berthing and passenger disembarking arrangements.

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