The pro's and cons of steel boat building

[prv]

Embarrassingly i spanked into a pillar buoy couple years ago coming down a river, sun low down dead ahead and head in a mobile phone trying ti get first emails for a few days. Big bang, which would very likely have meant fairly major grp work on a plastic boat instead of some sandpaper and a load of coats of epoxy. So if you don't look forward much get something strong

I've been on board a GRP boat that did something similar - even less excuse as it was a clear morning in the western Solent . I disclaim all responsibility since I wasn't skipper or mate and was down below making the tea at the time

The skipper had set the autopilot on a "go to" one of the big steel port-hand channel markers, and it did as it was told with unerring accuracy. I'm not sure whether nobody was looking out at all or if it came from behind the jib or what, but we crashed right into the thing at full speed and probably with the tide under us too.

The main result was a big embarrassing red paint streak, and the owner had someone come to refinish the gelcoat the following week, but as far as I'm aware there was no structural damage at all.

This was an early-2000s Halberg-Rassy so on the solid side of modern GRP building.

Pete

 

[lpdsn]

This was an early-2000s Halberg-Rassy so on the solid side of modern GRP building.

I was on board an ULDB racer that whacked a big metal can full on at about 8 to 9 Kts after gear failure caused us to round up into it. It was as lightly built a GRP boat as you're ever likely to encounter. There was a hole in the bow but a half-filled bucket out of the companionway every minute or so kept up with it till we made it to the hoist.

Plastic boats are not as flimsy as they look.

 

[solent clown]

our only accident was ramming the bow into the pontoon at full engine speed when the morse fell off. the front of the Trident climbed right up on the deck before sliding back down. very heavy and embarassing impact, only sign of damage was some light scratching. If it is cold this winter might try a bit of icebreaking with the old battleaxe. they don't make 'em like they used to!

 

[prv]

our only accident was ramming the bow into the pontoon at full engine speed when the morse fell off. the front of the Trident climbed right up on the deck before sliding back down.

Hah! I did exactly the same (while, according to my crew, holding up the detached handle with a stupid look on my face ) on a chartered Sadler 32.

Pete

 

[[70521]]

Get a big sledgehammer and go do some testing.....

Sorry that does not answer my question.

 

[GHA]

Sorry that does not answer my question.

Answers all you need to know in the real world

 

[prv]

Answers all you need to know in the real world

It doesn't address his actual question, which was "how is Brent measuring strength?". But if you want some good sledgehammer action, the start of the Crash Test Boat hole-plugging video is quite fun:

https://www.youtube.com/watch?v=bRhcXBtmPQs

Notice that even before starting to hit the boat with a hammer they knew they'd have to weaken it substantially with an angle grinder.

After the belting with a hammer and before trying the chisel, the video skips over them adding to the single cut line with two additional crossing cuts, visible when they zoom in on the red-handled masonry bolster.

Then at 1:24 he has another go with the grinder.

When he finally smashes through with the stock of a solid metal mobo rudder (presumably the heaviest object lying around the yard, the tools they brought having proved inadequate), notice that all the fibreglass edges we see in the hole are clean-cut, with the grinder, not torn as they would be by impact. He didn't actually puncture the hull with his various battering implements at all, just bent back the jagged tips around a cut that was in fact made by an angle grinder. Confirming this, at the start of the shot inside the forepeak, the straight angle-grinder cut lines are visible on the inside of the hull - they were cut right through and all the battering was just to fold the edges back a bit.

This same process would have had exactly the same effect on steel - cut through the shell plating with a grinder and beat the edges back to look jagged, and you have a hole.

Of course, if you go to heavier impacts than a man with a hammer, steel will bend and stay watertight after GRP would crack and leak. Despite Brent's army of imaginary straw men, nobody here is saying any different.

Just saying that a mere sledgehammer ain't going to cut it if you want to demonstrate the "flimsiness" of a GRP hull.

(The boat in question was a bog-standard Jeanneau bought cheap in order to be destroyed.)

Pete

 

[bbg]

Answers all you need to know in the real world

In the real world, there is more to sailing than hitting reefs (or hitting hulls with sledgehammers).

 

[GHA]

It doesn't address his actual question, which was "how is Brent measuring strength?". But if you want some good sledgehammer action, the start of the Crash Test Boat hole-plugging video is quite fun:

https://www.youtube.com/watch?v=bRhcXBtmPQs

Notice that even before starting to hit the boat with a hammer they knew they'd have to weaken it substantially with an angle grinder.

Didn't take much, did it? Little lump hammer.

That video makes me feel even more secure offshore, all is not lost getting rammed by a ferry or running into a ton of floating debris full speed

 

[prv]

Didn't take much, did it? Little lump hammer.

Did you actually read my post?

Pete

 

[GHA]

Did you actually read my post?

Pete

Yes. They used a very low force to punch a hole compared with what's a more likely scenario in the real world hitting heavy floating debris or getting rammed by a ferry.

 

[Tranona]

Didn't take much, did it? Little lump hammer.

That video makes me feel even more secure offshore, all is not lost getting rammed by a ferry or running into a ton of floating debris full speed

See the posts where people have actually hit something big and hard with a GRP boat - plus as prv says watch the vid and see what they actually had to do to create a hole! Then imagine if they had a newer Jeanneau where that part of the hull is Kevlar reinforced.

Would be interesting if you could gather together some solid evidence that GRP boats have been hit and holed by floating debris. You will struggle if you have the same difficulties as YM did a few years ago when they tried. Given how many hundreds of thousands of GRP boats there are sailing in the world how few founder for any reason at all, let alone from hitting debris or coral reefs.

 

[Tranona]

Yes. They used a very low force to punch a hole compared with what's a more likely scenario in the real world hitting heavy floating debris or getting rammed by a ferry.

They cut it with an angle grinder because just hitting it did nothing. Don't see many angle grinders in the sea waiting for yachts to come along.

 

[GHA]

Would be interesting if you could gather together some solid evidence that GRP boats have been hit and holed by floating debris. You will struggle if you have the same difficulties as YM did a few years ago when they tried. Given how many hundreds of thousands of GRP boats there are sailing in the world how few founder for any reason at all, let alone from hitting debris or coral reefs.

Can think of 3 straight away hit by ferrys, the steel one had bent bowsprit, one other was laid up for an entire year getting structural GRP sorted on insurance. Another boat along the coast not so long ago had it's hull punched through with a pad when a fishing boat made a big wake while the sled was getting pulled up.

Bearing in mind we're talking long distance long term cruisers here who tend to go for heavy boats with thick hulls despite what you keep saying about lightweight plastic being the norm. Maybe on a one off arc.

This has been done over and over already, of the beaten track long term, long distance steel really comes into it's own and is a popular choice of hull material.

 

[prv]

Yes. They used a very low force to punch a hole

No, they did not.

They attempted to punch a hole, and failed.

Then they cut a hole right through the hull using an angle grinder, and finally hit it a bit to rough up the edges.

a more likely scenario in the real world hitting heavy floating debris or getting rammed by a ferry.

Sure - maybe you didn't read my last couple of paragraphs either. Heavy floating debris and ferries are not sledgehammers.

Pete

 

[[70521]]

Answers all you need to know in the real world

It doesn't address his actual question, which was "how is Brent measuring strength?".

Thanks Pete.

Direction of force, type of force, what you hit and how you hit it is all part of the equation.

If I give any hull a thump with a lump hammer it just bounces off, if I introduce the hull to a big flat object and apply pressure it will compress and split along any line weakness. Other examples can be given.

From an engineering perspective, I am trying to ask Brent how he is measuring stuff. Understanding how he is measuring stuff will either support or disprove his theories.

I can get hold of some mechanical engineers if you want the detail.

 

[Tranona]

Can think of 3 straight away hit by ferrys, the steel one had bent bowsprit, one other was laid up for an entire year getting structural GRP sorted on insurance. Another boat along the coast not so long ago had it's hull punched through with a pad when a fishing boat made a big wake while the sled was getting pulled up.

Bearing in mind we're talking long distance long term cruisers here who tend to go for heavy boats with thick hulls despite what you keep saying about lightweight plastic being the norm. Maybe on a one off arc.

This has been done over and over already, of the beaten track long term, long distance steel really comes into it's own and is a popular choice of hull material.

Again, this "thick" hulls bit is overplayed - the Jeanneau is not of that type.

Then on the one had you talk coastal accidents (one on shore) but claim that it is only long term off the beaten track steel comes into its own. Where is the evidence that GRP boats do not survive long term off the beaten track, or the evidence that the REAL risk (rather than the imagined) of collision is any greater?
There are always individual examples available to illustrate what you want to, but as seen above this can apply both ways. Individual examples of GRP boats surviving collisions with minimal or no damage are just as valid as your examples.

These events are random and occur in coastal waters and offshore. The risk may be higher in certain parts of the world where there are more hard things to hit or more dense debris, but these things are known, and as said many times avoiding the risks is a sound policy.

This is not meant as a criticism of steel as a choice. The physical properties are proven, although it is not easy to exploit these and make a practical and durable boat. However, there is no need to slag off GRP and claim that it has negative properties which it simply does not, or at least the so called deficiencies don't lead to the negative outcomes claimed.

All of this does not explain why the vast majority of sailors are quite happy sailing their GRP boats in exactly the same way as the tiny minority who choose steel.

 

[Brent Swain]

Little bumps?

You are making a fool of yourself again. They were sailing at hull speed and repeatedly hitting steel barges and rocks. Perhaps this is why people sailing GRP boats don’t worry as much as you think they ought to and there’s no history of people disappearing at sea through their GRP hulls failing on impacting a semi submerged object?

You keep citing extraordinary situations where a steel yacht was ‘pounded for weeks’ etc but most of us (even those of us who have sailed all over the world and across oceans) don’t have such poor seamanship that we get our boats into those situations. In fact my reaction is not, “Wow, what a strong hull and design!” but, “What idiot allowed themselves to get their boat stuck there?”

YOU are making a fool of yourself again, suggesting that little thing, is the equivalent of a full sized barge, tied solidly to a dock, or that little toothpick is the equivalent of a meter diameter, first growth fir log 14 meters long, in a swell, or suggesting that plastic boats never hit anything. Any builder can show off, by building the bow of a plastic boat 100mm thick, then making sure all videos are of the boat hitting that spot only ,or implying that plastic boats can't hit something on a dark, moonless or foggy night, if the skipper is "Plastic boat infallible." as you imply all are.
I remember meeting Patrick in Tahiti in 73, on 'Trismus" a copy of Berrnard's "Joshua" a 39ft steel boat.I later heard he dragged on to Rangiroa in a hurricane , and abandoned her when she filled thru a vent. Ten years later the locals refloated her and beagn using her to move coconuts around .
What became of Patrick? He was lost without a trace, while crossing the Atlantic in a plastic boat!

 

[Brent Swain]

Again, this "thick" hulls bit is overplayed - the Jeanneau is not of that type.

Then on the one had you talk coastal accidents (one on shore) but claim that it is only long term off the beaten track steel comes into its own. Where is the evidence that GRP boats do not survive long term off the beaten track, or the evidence that the REAL risk (rather than the imagined) of collision is any greater?
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Our coast is littered with plastic boats which did not survive.
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avoiding the risks is a sound policy.
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Yes, and a steel hull is the easiest, and wisest way of avoiding the risk of holing and sinking.
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This is not meant as a criticism of steel as a choice. The physical properties are proven, although it is not easy to exploit these and make a practical and durable boat.
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I found it damned easy, far easier than building or paying for a new plastic boat, by many years.
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However, there is no need to slag off GRP and claim that it has negative properties which it simply does not, or at least the so called deficiencies don't lead to the negative outcomes claimed.

All of this does not explain why the vast majority of sailors are quite happy sailing their GRP boats in exactly the same way as the tiny minority who choose steel.

Because plastic is extremely heavily promoted ,giving the impression that it is one's only option, and because steel options are based on grossly outdated building methods, making them prohibitively expensive to buy or build ,and because conclusions about steel are based on poorly built, painted, maintained or designed boats, not on the better ones.

 

[Brent Swain]

Thanks Pete.

Direction of force, type of force, what you hit and how you hit it is all part of the equation.

If I give any hull a thump with a lump hammer it just bounces off, if I introduce the hull to a big flat object and apply pressure it will compress and split along any line weakness. Other examples can be given.

From an engineering perspective, I am trying to ask Brent how he is measuring stuff. Understanding how he is measuring stuff will either support or disprove his theories.

I can get hold of some mechanical engineers if you want the detail.

By what they have already survived. Try a steel pickaxe on a piece of standard 12 meter plastic hull , then try a fibreglass pickaxe on a piece of 3/16th steel plate.
A 303 British will shoot thru 23 inches of douglas fir ,but barely make it thru 3/8th steel plate. Haven't tried the fibreglass comparison. Give it a try, and give us the results. Should be interesting .