Lagoon Cat smashed in Thailand

[socaldmax]

Originally Posted by noelex 77

Thanks for the detail.

One bit of information missing from the above description is the type of resin used. I presume ortho polyester with a bit of vinyl ester in gel coat ?

This is just the sort of data that is needed so we can compare similar sized boats. Even if we don't understand the detail there are plenty of people that will "translate" for us on CF.

I cannot understand people buying a boat without these particulars. This is the fundamental structure of the boat. A cruising boat is subject to a lot of unexpected stresses such as colliding with floating objects.

.

Exactly.

Yet in another thread when I questioned boat design, I was chided by a member who had been here for a long time, he stated something like boat owners could "tell it was right just by looking at the lines of the hull."

I realize a lot of people make their decisions based on aesthetics, but I'm interested in safety first, and looks second. The two characteristics aren't necessarily mutually exclusive. It just takes a little more than looking at it for it's lines.

[barnakiel]

As one man who laminates this world's toughest hulls said:

only as much resin as it takes to perfectly glue the fibers together and NOT a drop more

Now depending on matrix fibers and resins used this may oscillate in 60/40 to 40/60 range easily and beyond that too.

So please stop claiming old hand laid hulls "can be better" as we all know many of them had way too much resin and this situation actually detracts from optimum weight/strength ratio. A thinner, well scrimped or vacuumed, laminate will be stronger than a heavier oversaturated one. Caeteris paribus.

It is all said on the web no need to create alternative realities.

b.

[a64pilot]

Originally Posted by Cadence

I believe he specified mat and roving and the weights. Nothing exotic? Just old school probably hand laid and the MFG stated 60/40. Why don't you post the lamination of your hull? We may all learn something.

I did publish what IP said my layup is, I think I was the first to do so

[barnakiel]

Originally Posted by noelex 77

(...)

I cannot understand people buying a boat without these particulars. This is the fundamental structure of the boat. A cruising boat is subject to a lot of unexpected stresses such as colliding with floating objects.

.

They also buy cars without knowing their fundamental structure.

Why should boats be anything different than all other goods?

b.

[weavis]

Originally Posted by barnakiel

As one man who laminates this world's toughest hulls said:

only as much resin as it takes to perfectly glue the fibers together and NOT a drop more

Now depending on matrix fibers and resins used this may oscillate in 60/40 to 40/60 range easily and beyond that too.

So please stop claiming old hand laid hulls "can be better" as we all know many of them had way too much resin and this situation actually detracts from optimum weight/strength ratio. A thinner, well scrimped or vacuumed, laminate will be stronger than a heavier oversaturated one. Caeteris paribus.

It is all said on the web no need to create alternative realities.

b.

I was talking to a friend who has some involvement with Seawind in their new factory in Vietnam, and he was extolling the benefits of the vacuum system.

Said much more even saturation and a stronger product for less work.

[a64pilot]

Strongest layup I've seen was pre-preg, but of course that requires an autoclave.
I believe the original jet-skis were made this way, they were tiny hulls and II'm sure they came out like pop corn the production rate was so high.
Most main rotor blade skins of modern helicopters are pre-preg, very strong, flexible and light.
Are Gunboats really pre-preg?

[Cadence]

Originally Posted by socaldmax

Exactly.

Yet in another thread when I questioned boat design, I was chided by a member who had been here for a long time, he stated something like boat owners could "tell it was right just by looking at the lines of the hull."

I realize a lot of people make their decisions based on aesthetics, but I'm interested in safety first, and looks second. The two characteristics aren't necessarily mutually exclusive. It just takes a little more than looking at it for it's lines.

Maybe if he had been around he was referring the boats lines not necessarily the aesthetics. Just a thought. You can go into all types of things eg, prismatic coefficient but I'd stake my bet on some old salt and his eye.

[minaret]

Originally Posted by colemj

He told you - 3408 triax is 34oz stitched fabric (unidirectional fibers oriented and stitched in three directions) with an 8oz layer of mat. So 43oz total in one fabric layer.

4 layers of this with a 50% resin ration will be 0.28" thick.

Mark

3408= .077 per lam. We'll call it .08. Four plies then equals .32, or almost exactly 1/3 of an inch. This will be the thickness at the sheer. The entire boat is certainly not built of only four plies of 3408. They will spray gel in the mold, skin coat it with matt, apply the quoted four plies of 3408, probably by infusion, and this will build a part. By the time the two hull halves are joined, and extra layers are added down low, the hull thickness will taper from 1/3" at the sheer (if we don't allow an 1/8" for gel and skin coat, which we should), to 3/4" or more at the turn of the bilge. An email saying your boat is built from four plies of 3408 might as well say "please go away, we have no time to answer your question with an actual laminate schedule". No boat is built with the same thickness everywhere. This should look a lot more like the lam schedule neilpride posted, but here they have only given the "main" plies.


Fiberglass Thickness + Weight Fabric Sorter

[Sand crab]

Originally Posted by a64pilot

Are Gunboats really pre-preg?

I believe so.

Composite construction of vacuum-bagged, infused post-cured epoxy resins

Gunboat 60


And you pay for that.

[44'cruisingcat]

This thread is becoming laughable. Nobody seems to know exactly what happened with this boat, how severe the conditions were, what kind of bottom it was run into, and yet they're all happy to jump in and say the boat was underbuilt, or poorly built, or built to a price. (What boat isn't built to a price, and who could afford one?)

And of course a monohull would have done better.

[minaret]

Originally Posted by a64pilot

Strongest layup I've seen was pre-preg, but of course that requires an autoclave.
I believe the original jet-skis were made this way, they were tiny hulls and II'm sure they came out like pop corn the production rate was so high.
Most main rotor blade skins of modern helicopters are pre-preg, very strong, flexible and light.
Are Gunboats really pre-preg?

Pre preg is fairly common in high end boat building. But a custom built wet out machine which rolls wet laminate onto cassettes is much more common. Pre preg does not require the process materials of traditional bagging, as the ratio is theoretically already correct. But it sucks to work with, many types must be kept in a freezer. Every time you pull a roll and cut material, you must record exposure time. This is because newer prep regs autoclave at much lower temps, meaning you no longer need an oven. You just build a big plastic tent over the hull and hook a Tuco duct to it, ramp up slow for two days to temp, then cook it for two more, depending on resin system. Personally, I don't like working with it. Too finicky. Much prefer traditional bagging. I think there may be some confusion here as to bagging methods. A pre preg bag is strictly to create a lam with zero voids. When working in carbon, the layup is black and hence opaque as opposed to the clear layup you get with normal glass. This means you can't see air bubbles/voids, and a bag is required for a quality layup. In traditional bagging, the layup is done by hand as normal, resulting in a laminate with hand layup ratios. The bag is applied while the layup is still fully wet, and excess resin is sucked through the perf and into the bleeder material, which soaks it up and is disposed of after cure. This is why perf pattern is so important to resin ratio. In infusion, the entire layup is applied dry. The bag is applied while the layup is still totally dry, and vacuum applied. When the operator is happy with the lay of the glass, he catalyzes enough resin for the entire layup. It is then sucked (or poured) into the bottom of the mold, with vacuum running at the flange. The operator sprinkles baby powder on the bag to "lube" it, and uses a rubber squeegee to help work the resin from the insertion point towards the vacuum point. Excess resin is sucked out through the vacuum line. However, in this case, there are no process materials (other than a mesh bleeder). Therefore, resin ratio is controlled almost exclusively by the skill of the squeegee operator. There is no perf, and no blanket bleeder. For this reason, infused laminates will actually come out slightly richer than a quality hand laminate, if both are well done. And there is great potential for a rich layup due to mistakes/laziness as well.

[weavis]

Originally Posted by 44'cruisingcat

This thread is becoming laughable. Nobody seems to know exactly what happened with this boat, how severe the conditions were, what kind of bottom it was run into, and yet they're all happy to jump in and say the boat was underbuilt, or poorly built, or built to a price. (What boat isn't built to a price, and who could afford one?)

And of course a monohull would have done better.

Hi 44
As is wont with a forum thread, the discussions will wander from the main topic to different facets of the original posting.

Its the way chat boards work.

I think we are all learning a lot about fibreglass construction, well at least I am.

With what I learned from here, Im pretty sure a similarly constructed monohull would not have fared any better.

[Goosebumps]

Originally Posted by weavis

Hi 44

As is wont with a forum thread, the discussions will wander from the main topic to different facets of the original posting.



Its the way chat boards work.



I think we are all learning a lot about fibreglass construction, well at least I am.



With what I learned from here, Im pretty sure a similarly constructed monohull would not have fared any better.

I cant help being tickled by monohull promotions, why do they even have to be promoted. Some enjoy the characteristics of mono or multihull, it is personal individual! I personally dont enjoy lots of movement while at anchor and hate habing to wait until
finished sailing to properly cook or even be able to put my coffee down. But I admit it is the cosy i teriors of monohulls below the waterline that enticed me to the sea.


Sent from my iPad using Cruisers Sailing Forum

[downunder]

Many vessels today are built using cores which gives a stronger construction.

Infusion/vacume bagging of cores certainly makes a lighter and stronger vessel.

some links

Controlled Vacuum Infusion

Vacuum Bagging Boat Construction

https://www.youtube.com/watch?v=mCrASxG_u48

https://www.youtube.com/watch?v=fD8kmx96khY

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

https://www.youtube.com/watch?v=Oz1rgpn8el0

[a64pilot]

Originally Posted by 44'cruisingcat

And of course a monohull would have done better.

I hadn't seen that at all, did I miss it? I don't see this thread really having anything at all to do with Cats really, but construction materials and techniques.

Of course the picture of the bridge deck on the beach is silly, I'm sure you can find similar pictures of steel freighter or any other type of boat, airplane whatever.

However, the pictures that were posted of the one with the bottom ripped off were sort of telling, weren't they?