Fibreglass vs Aluminium Impact Strength

[Mr B]

Whether its F/G or Ally all cabinetry would have to be removed inside for repair, requiring clear access,
I would suggest that the cabinetry would be screwed in on the ally boat. making it easy to remove.

To resheet the full side of that boat and grind the welds smooth and repair any bent frames inside, would take me personally just over a week working full time on it, two weeks at most,

Paint by others, I have no idea on,

[Eric50]

Hi everybody,

There are no "good" or "bad" material, but rather bad designs or bad workmanship.

The video shown in example is clearly made by a GRP enthusiast who wants to highlight the advantage of the GRp over the aluminium...

When the guy says that the GRP has only surface damage, is still intact and kept its integrity after the puncture test, he is, to my opinion, not saying the truth at all.

Everybody can see that the sample has been as damage (if not more...) as the aluminium, that the de-lamination has occured both side and that the whole thickness of the sample is impacted. there is not leak test to even ensure that the sample was not punctured at all.

On the aluminium sample, the size of the hole make it easy to plug or to repair on the opposite.

On the repair point of view, it is not obvious to me that the GRP is soooo easier to repair.

First of all, you need to have the repair kit onboard, wich is not always the case on GRP boats I met.

I can also have some repair kit and tool for the aluminium and for emergency situation, a rivet tool, some rivets, some square inches of aluminium plate, hammer, a hand drilling tool and some sealant, nothing costly or not easy to store and that is most of the time already in everyone tool box.

Secondly in the case of the OVNI accident, the damages of such extent, and length, on a GRP boat would require so much repair material, that it would have been impossible to repair the boat on site, in order to keep it afloat, and reach the next shipyard to perform a proper and final repair.

The aluminium boat, not being leaking,was able to reach its next shipyard, without any major repair and stayed afloat.

Of course I am an aluminium boat owner, so I can not be considered as totally fair towards other materials, but, again, to me, trying to proove that one material is over the other ones is totally non sense.

I am working in the oil and gas industry and the quality control area and always found out that any material is OK for a particular application, proven it has been well chosen, well sized, well manufactured and can never be compared to a different one as there is always differences and advantages.

There is a point where the choice has to be made, and for the same application in all extent, you may have to choose a different material than the previous one, simply because the previous one is not available, not authorized and so on...

The most important to me in the choice of your boat's material is how much are you familiar with the material and how much can you repair it and survey it by yourself ?

This is the main criteria to me (regardless the cost criteria of course, but quality boats of any kind of material are more or less in the same range of prices usually).

[europaflyer]

Yachting Monthly's Crash Test Boat is holed Part 1 - YouTube

(Yet another) unscientific video of holes being made in stuff. This time, punching a hole in a Gin Fizz, and trying to block it. A good series of videos, by the way, if you happen to have the time.

An aside - a point I took from the video is that the furniture would have formed a watertight compartment if they hadn't intentionally holed it. Useful.

[Panope]

So here is a "Fiberglass Attack" video to go along with my previous "Metal Attack" video. Again, these are totally unscientific demonstrations and it was probably dumb of me to include ANY verbal analysis other than my personal belief that either material is great one for boat building.

Steve

metal test - YouTube

Fiberglass Test 1 - YouTube

[silverp40]

Steve, your videos are appreciated...Great workout also, wonder if any neighbors saw that and what they thought.....

Please do not pull those loose glass strands with your bare fingers though - they are sharp and FG shards hard to get out of the skin. If you already have them, rub some thick hand lotion on then wipe it off. Repeat 2 or 3 times to get them out.

Cheers
Ovi

[Panope]

Originally Posted by silverp40

Steve, your videos are appreciated...Great workout also, wonder if any neighbors saw that and what they thought.....

Please do not pull those loose glass strands with your bare fingers though - they are sharp and FG shards hard to get out of the skin. If you already have them, rub some thick hand lotion on then wipe it off. Repeat 2 or 3 times to get them out.

Cheers
Ovi

Thanks Silver. The neighbors are totally acclimated to my various industrial activities that include the use of hammers, grinders, chainsaws, winches, torches and welders. I am sure they thought it was normal.

Hands are fine. Guess I have thick skin.

Steve

[glenn.225]

Steve, I’m most impressed with those videos. I know they aren't very “scientific”, but I've never seen an accurate side by side test of a boat on rocks either. They do leave me in some doubt now, I'm pretty familiar with steel and thought steel or aluminium would make the better boat. Now I'm not sure based on solid layup, non-cored hull. More food for thought.

[europaflyer]

Another great video Steve!!

You say the aluminium had 39 hits, and I counted 44 for the GRP.

What does this prove? As you say, nothing!! Utterly unscientific, but utterly entertaining. I agree with you - they are both great materials. I have to say I was surprised at how well the GRP stood up to the pounding, but on the water? Who knows. I don't want to say too much, or I'll probably get torn apart.

Maybe this is the start of something great though... perhaps one day aluminium will be listed as having a Steve Attack Factor of 39, and GRP with a SAF of 44!

As per silverp40, careful with the hands! If you do get glass fibre shards in them, it itches like HELL. But then again I have (fairly) soft hands.

Once again, thanks. Love having videos specially made for the forum!

[europaflyer]

Originally Posted by glenn.225

They do leave me in some doubt now, I'm pretty familiar with steel and thought steel or aluminium would make the better boat. Now I'm not sure based on solid layup, non-cored hull. More food for thought.

OK, you were brave enough to say it... the metal boat crowd will be along soon! Let's just say I hope this thread might have provided the odd poke at some old assumptions.

[Kettlewell]

Interesting, but not realistic. Panels would need to be suspended with nothing behind them like the ground in the videos. Big difference in how much impact something can take not being backed up by the earth.

[europaflyer]

Originally Posted by Kettlewell

Interesting, but not realistic. Panels would need to be suspended with nothing behind them like the ground in the videos. Big difference in how much impact something can take not being backed up by the earth.

I think everyone agrees they aren't realistic...

[minaret]

I think that the pistol video and the fiberglass attack video both prove my point about failure modes quite well.

[malbert73]

Perhaps you get an advantage in aluminum/metal in abrasion resistance- ie if you wash up on a reef or rocks with mild/moderate impact, and are just sitting there rubbing on the surface- in that case metal will hold up better to prolonged abrasion without holing.
On the other hand, a well built and tabbed FG boat may do better with point loaded moderate/severe impact due to elasticity- less likely to hole from such impact than metal.

Now, if someone can make a realistic case why one scenario is more important to plan for while cruising, I want to know on which page of the west marine catalog you bought your crystal ball....

[boatsail]

Originally Posted by malbert73

Perhaps you get an advantage in aluminum/metal in abrasion resistance- ie if you wash up on a reef or rocks with mild/moderate impact, and are just sitting there rubbing on the surface- in that case metal will hold up better to prolonged abrasion without holing.
On the other hand, a well built and tabbed FG boat may do better with point loaded moderate/severe impact due to elasticity- less likely to hole from such impact than metal.

Now, if someone can make a realistic case why one scenario is more important to plan for while cruising, I want to know on which page of the west marine catalog you bought your crystal ball....

Abrasion happens on or close to land... sink and live

Hole happens off shore... sink and die

I'm typing on a tiny screen, so can't elaborate, but abrasion arty Sea is not a worry for either hull.

So we then talk about hole. Fiberglass wins????

[noelex 77]

Great video Steve
I think that's the first time someone has produced a video to answer a question on CF. Well done.
Very accurate chopping. I think you might have split a few logs in your time.

The fibreglass certainly stood up to your abuse better than I expected. Boats washed up on rocks get holes very quickly and seemingly easily. It shows the forces must be very high in a grounding accident.