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Old 03-12-2012, 15:54   #136
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Originally Posted by noelex 77
Have a look at the Ovni range. The largest maker of production aluminium cruising yachts.

Which is why very few aluminium cruising yachts use this paint type. There are plenty of alternatives.
Yet the Dutch routinely paint aluminium. Also as far as I see Ovni do finish the aluminium, it has a swirl type pattern finish.

Using Ovni as a guide to what aluminium boats do is a bit misleading

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Old 03-12-2012, 15:58   #137
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Originally Posted by minaret

Not so. Beneteau just bonds in a hull liner and other structural members with Plexus. No tabbing. Of course they delaminted in an impact, and of course a lot of trouble had to be gone to to access the area. It's a function of their poor design.
Beneteau have argued elsewhere that there construction method is stronger then outdated older methods. Tabbing is outdated. Virtually all builders with any volume have gone to liners or partial liners.

To suggest one of most successful builders of all time is a function of poor design is elitist claptrap. Beneteaus have circumnavigated before during and after your life span on this planet.

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Old 03-12-2012, 16:49   #138
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Re: Fibreglass vs Aluminium Impact Strength

The video that I posted previously does not play properly on some computers. Here is a link to a YouTube version.

Steve

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Old 03-12-2012, 17:40   #139
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Re: Fibreglass vs Aluminium Impact Strength

Great video Steve.
Custom done for CF wow!
I think you might of silenced some of the aluminium critics.

That was 4.7mm aluminium. My boats bottom is 12mm and most of the strength of any metal boat is not in this plating but the framework of the ribs and stringers.
I will certainly shout you a beer on my boat, after that effort, as long as leave the splitting maul behind

BTW do you know the aluminium grade it was 5052 or the stronger 5086 /5083 or something else?
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Old 03-12-2012, 17:45   #140
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Originally Posted by noelex 77
Great video Steve.
Custom done for CF wow!
I think you might of silenced some of the aluminium critics.

That was 4.7mm aluminium. My boats bottom is 12mm.
I will certainly shout you a beer on my boat, after that effort, as long as leave the splitting maul behind

BTW do you know the aluminium grade it was 5052 or the stronger 5086 /5083 or something else?
What does it prove. Utterly non scientific.
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Old 03-12-2012, 17:47   #141
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Re: Fibreglass vs Aluminium Impact Strength

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The video that I posted previously does not play properly on some computers. Here is a link to a YouTube version.
As a test - not very convincing. It shows the lawn is durable as that is where all the energy is absorbed.

Is not 3/16" plate on the heavy side for a small boat?

For surviving impacts with an axe wielding boatbuilder I would definitely go with aluminum or steel. For sailing around in sleek fast durable boats I am going to stick with composites.
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Old 03-12-2012, 18:33   #142
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Re: Fibreglass vs Aluminium Impact Strength

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Originally Posted by noelex 77 View Post
Great video Steve.
Custom done for CF wow!
I think you might of silenced some of the aluminium critics.

That was 4.7mm aluminium. My boats bottom is 12mm and most of the strength of any metal boat is not in this plating but the framework of the ribs and stringers.
I will certainly shout you a beer on my boat, after that effort, as long as leave the splitting maul behind

BTW do you know the aluminium grade it was 5052 or the stronger 5086 /5083 or something else?

Your boats bottom or it's keel is 12mm? Big difference.
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Old 03-12-2012, 18:36   #143
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Re: Fibreglass vs Aluminium Impact Strength

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As a test - not very convincing. It shows the lawn is durable as that is where all the energy is absorbed.

Is not 3/16" plate on the heavy side for a small boat?

For surviving impacts with an axe wielding boatbuilder I would definitely go with aluminum or steel. For sailing around in sleek fast durable boats I am going to stick with composites.
Couldn't agree more. For the next video test, clamp a piece of the plate in a beefy horizontal bench vise. Then strike it right next to the clamp. This represents what happens when an impact occurs on an alloy hull right next to a frame or stringer. The frame is stiff and doesn't give, the hull plating flexes. The result can be failure. I've seen plenty of discussion of boats plated in 3 and 4 mm on this forum. Try using some of that instead, especially if we will be comparing only to Beneteau's. It was an impressive workout though, I may have to take up beating the ground as a form of exercise...
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Old 03-12-2012, 18:45   #144
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Re: Fibreglass vs Aluminium Impact Strength

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Originally Posted by noelex 77 View Post
Great video Steve.
Custom done for CF wow!
I think you might of silenced some of the aluminium critics.

That was 4.7mm aluminium. My boats bottom is 12mm and most of the strength of any metal boat is not in this plating but the framework of the ribs and stringers.
I will certainly shout you a beer on my boat, after that effort, as long as leave the splitting maul behind

BTW do you know the aluminium grade it was 5052 or the stronger 5086 /5083 or something else?
Thanks Noelex, It was definitely not my intention to silence anyone in this interesting debate - only to add something however crude or unscientific. Although I have an aluminum boat that I love, I am not sure that the material offers any real world hull pucture advantage over a well built FG boat. I sure wish I could find a similar weight FG panel to go to "work" on with my maul! My suspicion is that I will again become very tired before the panel is holed.

I do not know witch 5000 series my test panel is.

Steve
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Old 03-12-2012, 18:47   #145
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Re: Fibreglass vs Aluminium Impact Strength

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What does it prove. Utterly non scientific.
Agreed, Utterly non scientific

Steve
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Old 03-12-2012, 18:53   #146
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Re: Fibreglass vs Aluminium Impact Strength

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Originally Posted by silverp40 View Post
Quote:

sailing up the great barrier reef nr cape york we sailed past a steel yacht up on one of the many reefs in the area,who we had met before in bundaberg.

at the time there were fairly strong trade winds and we could see waves breaking on the yacht,so you could imagine our surprise when he turned up in darwin a few weeks later.


Some steel boats do not make it like your friends....This one was not so lucky
Unless you were told, You would not know what that boat was built from,

While it was sitting there on the reef,they could have packed all the holes with sails, bedding, towels, clothing etc, made it pretty water tite for when it lifted off with the next tide,

Having a hole in your boat and not supported by a reef, if you cant pack the holes quickly enough, yes, your going to sink, No matter what its made from,
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Old 03-12-2012, 18:54   #147
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Re: Fibreglass vs Aluminium Impact Strength

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Originally Posted by Panope View Post
Thanks Noelex, It was definitely not my intention to silence anyone in this interesting debate - only to add something however crude or unscientific. Although I have an aluminum boat that I love, I am not sure that the material offers any real world hull pucture advantage over a well built FG boat. I sure wish I could find a similar weight FG panel to go to "work" on with my maul! My suspicion is that I will again become very tired before the panel is holed.

I do not know witch 5000 series my test panel is.

Steve

I agree with your suspicion. And again I will say, the video was not about ultimate impact strength, but failure modes. If you HAD been able to penetrate the panel with your serial killer maul attack, it would have made a hole, no? If you did the same to a glass panel it wouldn't, instead it would shatter and fracture but still remain mostly watertight. Though high point loading like a maul instead of a sledge hammer might be the exception to that rule, unless there's some Kevlar in the lam. I'll try to make an equivalent video with some hand laminated 3/4" polyester flat stock I have kicking around. It doesn't have enough rovings for it to be an accurate test, but I bet I will need the shop hydraulic press to break it. And 3/4" is a small boat layup.
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Old 03-12-2012, 18:59   #148
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Re: Fibreglass vs Aluminium Impact Strength

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Your boats bottom or it's keel is 12mm? Big difference.
The bottom plating is 12mm. The keelson is 20mm.
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Old 03-12-2012, 19:02   #149
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Re: Fibreglass vs Aluminium Impact Strength

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As a test - not very convincing. It shows the lawn is durable as that is where all the energy is absorbed.

Is not 3/16" plate on the heavy side for a small boat?

For surviving impacts with an axe wielding boatbuilder I would definitely go with aluminum or steel. For sailing around in sleek fast durable boats I am going to stick with composites.
Perhaps I should not have labeled this video as a "Test". Maybe it is more like a demonstration. I was not trying to convince anyone of anything. Only to add something (however primitive) to the discussion.

Panope is 34 feet long and weighs about 15,000 pounds. Ballast is 5,000. I believe most would consider this to be a "medium displacement" boat. A West sail 32 for example weighs about 20,000 pounds. Most of the Saugeen Witch fleet are built in 1/8" Steel and at the same displacement as mine may only use about 3,500 pounds of ballast. I do not consider 3/16 aluminum to be heavy for this size of boat.

I agree that the "axe test" is somewhat irrelevant to the real boating world - much like the test video that started this thread.

Steve
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Old 03-12-2012, 19:04   #150
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Re: Fibreglass vs Aluminium Impact Strength

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Originally Posted by Panope View Post
I could find a similar weight FG panel to go to "work" on with my maul!
Quote:
Originally Posted by minaret View Post
I'll try to make an equivalent video with some hand laminated 3/4" polyester flat stock I have kicking around. It doesn't have enough rovings for it to be an accurate test, but I bet I will need the shop hydraulic press to break it. And 3/4" is a small boat layup.
I would love to see a video the same sort of attack on fiberglass.
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