Aluminium SailBoats VS Fiberglass SailBoats

[Joh.Ghurt]

Originally Posted by smj

Catamarans don’t fall over on the hard.

True, but catamarans get hit by floating pallets just as much as monohulls. Recently I heard a very loud bang while underway and then saw in my wake some pallet debris.

At anchor I checked what happened, and except a few scratches in the antifouling, nothing in the aluminium hull. Not even a dent. Would a fibreglass boat have had as little damage or would it be time to break out the epoxy and the glass-mats?

[smj]

Originally Posted by Joh.Ghurt

True, but catamarans get hit by floating pallets just as much as monohulls. Recently I heard a very loud bang while underway and then saw in my wake some pallet debris.

At anchor I checked what happened, and except a few scratches in the antifouling, nothing in the aluminium hull. Not even a dent. Would a fibreglass boat have had as little damage or would it be time to break out the epoxy and the glass-mats?

I’m guessing the aluminum would be harder to hole. I’m also guessing if holed the aluminum catamaran would probably be headed for the bottom while a fiberglass catamaran not. That is a disadvantage for aluminum when considered for a multihull.
I would also feel more at ease worrying about fiberglass blisters rather than electrolysis in aluminum as that is another can of worms. But that’s just me.

[JPA Cate]

It is hard to get bottom paint that works to retard biofouling for aluminum boats. Our woman singlehander friend had to dive to clean her boat's bottom S. of 40 deg. due to excessive biofouling, cold and scary.

Ann

[Joh.Ghurt]

Originally Posted by JPA Cate

It is hard to get bottom paint that works to retard biofouling for aluminum boats. Our woman singlehander friend had to dive to clean her boat's bottom S. of 40 deg. due to excessive biofouling, cold and scary.

I can vouch for this. The choice of antifouling systems is smaller (I use some Hempel product) and a good bottom-scrub is necessary from time to time. However, I can't really say whether I have to do it more often than with a fibreglass boat. Going by how it feels compared to the previous boat, I'd say it's roughly the same.

[Jim Cate]

^^^^
Our friends and acquaintances with alloy boats all seem to need antifoul renewal every year, whilst others with non-aluminum boats can use paints that last at least two years.

Depending on your usage and your location, this can be a significant issue.

Jim

[Panope]

As much as I enjoyed building out my aluminum boat (twice!), I do not enjoy maintenance, so the question of low maintenance is almost always a top consideration of mine.

Given my sensibilities and tax bracket (I cannot afford to pay for maintenance), I believe the lowest maintenance common HULL material is fiberglass and the lowest maintenance common DECK/HOUSE material is aluminum.

If I lost Panope, I would build a new hybrid boat of the above materials. Would be an interesting experiment and with any luck, might result in a nice boat.

I do not use any antifouling paint on Panope. Scrub (vigorously) once a month when not on the hard.

Steve
(playing with same aluminum boat for 46 years)

[Cheechako]

Some aluminum boats have degrading corrosion fast. it can be difficult to maintain.
The French use aluminum a lot and seem to be better at it.
You can't delay getting the sacrificial anodes changed etc and must be careful about bottom paint.

My cruising friends had a 48 ft custom built aluminum boat, built by a premier yard in the NE USA. She was a beauty.
They couldn't keep paint on it though.
It was repainted in an expensive US yard prior to leaving Florida.
It was repainted 3 years later in Trinidad.
It was repainted again in Columbia.
All in all the boat was painted 3 times in less than 10 years.

[Jim Cate]

Given my sensibilities and tax bracket (I cannot afford to pay for maintenance), I believe the lowest maintenance common HULL material is fiberglass and the lowest maintenance common DECK/HOUSE material is aluminum.

Steve, it is interesting to note that the Allures yachts are built in exactly the opposite way: alloy hulls and glass deck and house. Our friends with an A-44 love the boat but have had ongoing issues with leaking hull to deck joints FWIW.

Jim

[Breaking Waves]

Originally Posted by Jim Cate

alloy hulls and glass deck and house.

When we were building our aluminum boat, there were some interesting designs being built with steel hulls and aluminum decks - you can buy flat bar that is bi-metal, steel and aluminum explosion welded together, so you weld the steel hull to one side and the aluminum to the other for an integral join. The explosion welding bonds at the molecular level and they were claiming that it did not corrode (i have never seen any specific follow-up on that claim). This produced that bulletproof steel hull with lighter superstructure for better stability and sailing - but ofc steel hull maintenance. (edit: there are other suppliers now, but back when I was involved in it Du Pont I think had a patent on the process to make these - might be wrong about that but that's what I vaguely remember).

I used to offshore race on a boat with aluminum hull and wood decks - was relatively common back in the '70's. Seemed to work so long as maintenance was kept up.

As with everything else in this discussion, they all have trade-offs. Good designed and builders can make a great boat from any of these methods and bad designers and bad builders can make a **** boat.

Each to his own preferences - I personally always thought a monocoque structure of all one type of material was preferred - less complicated, less to go wrong.

[Panope]

Originally Posted by Jim Cate

Steve, it is interesting to note that the Allures yachts are built in exactly the opposite way: alloy hulls and glass deck and house. Our friends with an A-44 love the boat but have had ongoing issues with leaking hull to deck joints FWIW.

Jim

Yes, the Allures folks certainly have priories that are different than mine. No question their solution is lighter for a given strength/weight and also much more conducive to having naked people lounging around (few people want their bare butt on an unpainted aluminum deck).

But, for the stated goal of the original poster (cheap maintenance) I think my glass hull/aluminum deck idea is better as long as (as you mentioned) the hull/deck joint is/stays perfect.......and that is the big challenge. A challenge that is most attractive to me!

Steve

[Panope]

Originally Posted by Breaking Waves

When we were building our aluminum boat, there were some interesting designs being built with steel hulls and aluminum decks - you can buy flat bar that is bi-metal, steel and aluminum explosion welded together, so you weld the steel hull to one side and the aluminum to the other for an integral join. The explosion welding bonds at the molecular level and they were claiming that it did not corrode (i have never seen any specific follow-up on that claim). This produced that bulletproof steel hull with lighter superstructure for better stability and sailing - but ofc steel hull maintenance. (edit: there are other suppliers now, but back when I was involved in it Du Pont I think had a patent on the process to make these - might be wrong about that but that's what I vaguely remember).

According to a friend with long history of metal yacht design, the Steel/Aluminum Bi-metal bars work well. He says the trick is to ensure the paint overlaps the margin for at least an inch or so onto the aluminum, inside and out. No corrosion even if the rest of the aluminum is unpainted.

I used to offshore race on a boat with aluminum hull and wood decks - was relatively common back in the '70's. Seemed to work so long as maintenance was kept up.

I work at a firm that builds a line of sailing yachts with (solid) glass hulls and wooden deck/houses. The early boats are now over 40 years old and the refitting of these is becoming a larger and larger percent of our business.

Typically, these hulls need nothing more than new thru hulls, and bottom job. The decks on the other hand, often need considerable rebuilding.

As with everything else in this discussion, they all have trade-offs. Good designed and builders can make a great boat from any of these methods and bad designers and bad builders can make a **** boat.

Each to his own preferences - I personally always thought a monocoque structure of all one type of material was preferred - less complicated, less to go wrong.

Monocoque is certainly enticing.

Il'l note that the PNW wooden fishing fleet typically replaces original wooden bulwarks with aluminum. Nothing like a large diameter unpainted aluminum pipe for dragging all manner of gear across.

Close friends eventually replaced the wooded decks of their glass hulled gillnetter with aluminum. It was awesome. Worry free, thick glass hull. Decks that could withstand tremendous wear and tear.

Steve

[seandepagnier]

Originally Posted by Stewie12

I lived on an aluminium yacht for 5 years and I have also lived on a GRP yacht. The big difference is if you hit a rock the fibreglass will probably shatter and the hull will leak.

But I hit lots of rocks on my fiberglass boat and it didnt' leak. It did make cracks you could stick your fingers in, but the hull was 1 inch thick there and just did not crack all the way through. Also with an encapsulated keel it wont leak.


Aluminum is toxic to humans. So living on a boat made of it, is unavoidable you end up breathing it, you end up eating bits of it. This cant be good for you but no one knows how bad

[CdS2 Roland]

Hello,
I bought a used blue water SV, build in 1985, 12 years ago.
In my life I owned first a plywood one and later fiberglass.
I'am very happy and would not go back to other material.
Once we hit the rudder and went ashore during a nightthunderstorm in Panama (ancor dragging) . Layed 2 days in 1 meter of water before we were towed in deep water. Damages : broken steering chain and antifouling like sanded on the keel. Only minor damaged I could repair by my self. Hit on the rudder was particularly violent. When the rudder came to the stop, end steering chain broke. With hanging rudder on modern fiberglass SV it could be an other story.
I think with a fiberglass you have a nice limousine and with an aluminium one you are "driving" a truck. Choosing between fiberglass and aluminium should not be a economical choice or you will be desapointed.

[redneckrob]

It's probably worth putting to bed what appears to be a common misperception that aluminum doesn't suffer from corrosion unless you have wiring or dissimilar metal issues. I spent many years running maintenance programs for our Coast Guard helicopters and airplanes, all made of aluminum at least for the structural members. Every Coast Guard aircraft goes through a depot level overhaul every 4 years where it's essentially stripped to the ribs almost entirely to remediate corrosion. And this isn't corrosion on the thin skin, these are often large stringers and beams sometimes with a significant percentage corroded or cracking with corrosion. And these are aircraft that get washed with fresh deionized water every day they fly and have a corrosion prevention team at the air station whose only job is to remediate corrosion as soon as they see it.

Certainly aluminum boats are far more overbuilt than aircraft, so they can withstand far more corrosion. But make no mistake, that blistering paint you hear aluminum boat owners complain about has nothing to do with the paint, its the aluminum under it corroding. And under that high density foam insulation? If well taken care of an aluminum boat has lots of benefits as owners have described here. But it certainly isn't maintenance free in the way fiberglass is and while blisters generally have no impact on structural integrity, corrosion certainly can. So bottom line, if you're interested in an aluminum boat just be aware that there could be significant corrosion issues in the boat you're looking at and that you'll need to be careful to properly care for the boat once you own it.

[noelex 77]

Originally Posted by redneckrob

It's probably worth putting to bed what appears to be a common misperception that aluminum doesn't suffer from corrosion unless you have wiring or dissimilar metal issues. I spent many years running maintenance programs for our Coast Guard helicopters and airplanes, all made of aluminum at least for the structural members.

Aluminium has very different properties depending on what other metals are added to the pure alumnium . For aircraft manufacture typically the highest strength aluminium alloys are selected to reduce weight as much as possible. Unfortunately the trade off with these is that they have very poor corrosion resistance (especially the 7 series such as 7075). Aluminium boats are are constructed from one of the five series such as 5083.