Thankyou Chris, that was great. Thats the kind of informed comments I like.
The lack of floatation/foam fill is interesting.
Could it be
1/ its added later
2/ not added at all
3/ its a danger when welding
Foam filling has advantages in that the whole structure becomes a form of sandwitch. Increasing the strength and making for a quieter hull.
Not sure about what floatation level you would achieve.
It’s good to see input/posts from respected Manufacturers and designers/N.Arch’s – to put a few things in perspective. Plus, it’s also always nice to see the ‘innards’ of any boat, be it glass, tin, cat/mono whatever… well I think anyway
Regarding the two main subjects discussed in this thread; i.e. what constitutes a 'true' plate boat, and, does market dominance sway the quantity of ‘bad product experiences’ being reported etc, both have been debated many times over the last 10 yrs +/- on here, that I can remember anyway. Do a search and I’m sure you will probably find many hours, maybe days of reading – and many differences of opinion!!
I have always thought the most appropriate term for these types of tinnys has been ‘hybrid’. They aren’t built like the ‘traditional’ pressed tinny, where 3mm thickness was ‘traditionally’ the max for the bottom ‘sheet’, and 1.6 then 2mm for the sides were used as the boats got bigger. Nor are they built like a ‘real plate’ boat. Of course the hybrid boats are a bit bigger than the traditional tinny too
In the late 90’s, 4mm started to be used for the bottom sheets of ‘pressed tinnys’ from ~5.5m or so, and this was when the bottom sheets started to be stitch welded to the ribs.
In the pressed boat world, the transverse ‘structure/members’, running across the boat are commonly called gussets, and these are stitch welded to the ribs. Rib extrusions lie against the hull bottom/bottom sheets. The combination of longitudinal pressings in the bottom sheet(s), and the transverse ribs and gussets, help give the hull its strength & rigidity.
Rib extrusions also changed from common top-hat section to box section, and rib tape was no longer used when the ribs were welded to the bottom sheet – for obvious reasons.
In my mind, this welding of the bottom sheet to the ribs was the birth of the ‘hybrid’, or whatever you want to call them.
This also relaxed one of the critical requirements of 'traditional pressed tinny' construction - that being the need for positive contact between the ribs and bottom sheet - at all times, to avoid fatigue cracks.
To achieve this (without them being welded together), typically the bottom sheet pressing 'die design', and how the flat sheet was physically pressed, resulted in a slightly concave sheet. This, combined with the convex shaped ribs (opposite profile) are what created the positive contact. Gaps between the bottom sheets and ribs were/are a big problem.
Of course the convex ribs (round bilge type hull) meant that the ride was pretty ordinary, especially when too much speed was involved, so only low HP was required.
When 5mm bottom sheet started to be used around 2002/3 (6m + boats, still with pressed strakes for stiffness), the building process ‘morphed’ further away from the traditional pressed tinny construction technique, with greater deadrise and 3mm sides (still with clinkers). One sales term being used at the time was 'pressed plate'!
At this time the max HP rating also increased, and quite dramatically over a few years – basically because the market demanded it, and many manufacturers reacted accordingly. Everyone wanted/wants to get there in a hurry. More HP = more speed (= more potential problems/stress related failures).
However, I have been berated once or twice on here over the years for stating these types of boats are not ‘real’ plate boats, and that ‘there is a difference’ between the boats (mostly by one or two Trailcraft owners if I recall
I used to be heavily involved in building them too (pressed tinnys/hybrids etc) – and I had no problem saying there was a difference then either.
Is there a place for them (hybrids)? Yes, definitely, just look at how many are sold by a number of manufacturers. Have I owned one? Yes, for 4 years with no issues. Would I own another? Yes, depending on the make, size and the intended use. If I wanted to use ‘the tinny’ like I use my current glass boat, I would probably buy a real plate boat (if I could afford it)… they cost a lot more, and you can’t get more man-hours and more material for nothing – because that’s what a real plate boat takes to build, a lot more time, more aluminium, more welding consumables etc.
Would I really need a true plate boat? Probably not, given my current usage, but I would still want one. What I want/like, others might not – for many reasons. Everyone’s different!
For those that think market dominance doesn’t sway/increase the number of ‘bad product experiences’ being reported etc, think again. It is impossible for it not to be affected. For those that think Telwater does not have a huge market dominance, also think again.
During the boom time of the early-mid 2000’s, I remember reading an article about the state of the boating industry in Australia, based on BIA and Transport Authority data I think (boat registrations), over a certain period. It covered the big boy’s boats through to trailer boats, but it was the Telwater numbers which blew me away, and stuck in my mind (well I am pretty confident I remember the figures correctly). During this period Telwater only made/owned the Quintrex and Stacer brands, and of the ‘trailerable’ sized boats sold in Australia the figures quoted had them at 80% market share of all aluminium boats built/sold, and 50% of all trailerable boats built/sold (ally, glass, plastic etc). That is a huge dominance, and that was when Trailcraft were alive and making a lot of boats too.
That means they sold 4 times as many ‘trailerable’ tin boats (say between 2.4m – 6.5m) than the rest of Australia’s tinny manufacturers combined! Do you think we wouldn’t hear about more problems with their boats given these numbers?
We all know how the GFC affected the industry, and I am sure for those manufacturers that actually survived, all were affected by the same % sales drop or near enough. Telwater have since bought Savage, added a Savage glass boat range, bought and subsequently closed down Ally Craft, and make the Yelowfin product. I doubt their market dominance has dropped much, if at all. The sheer numbers dictate that, assuming they build a boat ‘no better or worse’ than everyone else, we will hear 4 times as many complaints as every other tinny manufacturer combined - all things being equal.
Any manufacturer even half this big, is going to be heard about more, whether it's good or bad news. The real test is, with any company - big or small - how they handle the 'bad news'/warranty situations.
My 2c.
Cheers & Happy boating.
Brendon
An old post, to save more bloody iPhone typing...
Originally Posted by gofishin
The Aluminium Association class below .25" as sheet, over is plate.
http://www.aluminum.org/industries/p...ng/sheet-plate
What is the engineers measurement for the Alloy "plate" over "sheet" ?
I know where there is one with over 1,500 hours, and an original Archer (before they called them Stacer) that is on its second motor, the main area of debate here is when is a pressed boat become a plate boat, and what exactly is a plate boat, to some, what it is made out of defines it as being "plate" to others, it is the bulkhead setup, then to others in is only a plate boat if it has a certain construction method.
That's how i know it, the old fashioned 1/4", as that is how the suppliers specified it. Can't say/recall if they all specifiy on this same criteria though.
Does it really matter? You might find different terms used in different industries, although all could use the exact same product. What is important (in my mind) is the actual 'material specification', i.e. the physical properties of the aluminium material provided; grade/strength/hardness/temper etc etc.
This might typically be 5083 H32 for the hull skin material (???, PB/Chris can confirm), and be supplied in a size say 7m x 1.5m x 6mm thick to make a bottom side of the 'hull skin' for a 6-7m 'real platey'. Whether its called plate, sheet, or 'extremely thick foil' ... is irrelevant to me. Material specification and how it is used (how the boat is built) is important to me.
Think of the type of boat classification another way; if the hull skin of the boat is built first, welded up, turned over and leak tested in a tank (as they are, a floppy hull skin that is 'hopefully' watertight), and the internal structure is added after - it is a pressed or hybrid (whatever you want to call it) boat, regardless if it has flat sides and/or bottom, or not.
If the hull skin is added after the hull internal matrix structure is built - it is a true plate boat (in my mind).
Be interesting to hear PB's/Chris's views on this, and what they call the 'material' before it is transformed into boats. Me personally, I would like to know if the material specification changes whether the 'material/member' is structural or not - in one of your plate boats.
Cheers
Brendon
Gday Brendon.
When we order material for our boats it is ordered as 5083 H321 Plate we typical nest our parts onto a 9m x 2.2m Plates for CNC cutting this ranges from 4mm up 8mm depending on the size of the vessel, all components including the transverse frames, stringers, keelson, sole, bottoms, top sides, transom ect ect. 3mm 5083 is also available but we don't use it in any of our boats as it is more difficult to work with.
the next grade down is 5052 Plate, still a marine grade plate but designed with bending in mind, we will sometimes use 5052 if we have to do some non structural tight radius bends for shelving or storage cabinets., but the vast majority of the hull is built with 5083 H321
Any material not specified as 5083 or 5052 is classed as sheet but it's not recommended nor would I ever build an entire hull from 5052 as it just does not have the yield or tensile strength of 5083.
Its interesting to look at the allowable stresses
Ultimate tensile strength
5083 (H321 or H116) = 305-385 MPa. <-- this is what most Aussie plate boat builder's use
5052 (H32) = 200-250 MPa
Yield strength
5083 (H321 or H116) = 215 MPa.
5052 (H32) = 160 MPa
well i guess you dont have to be a engineer to figure out which material spec you would like the structural components of your alloy plate boat built from - construction methodology being essentially similar
cheers
I guess it is nights like these ...
... when the weather is a little worse than predicted [emoji15] ...
that you are happy you have one of these tinnys under you ...
... when you are out off Moreton and not home in bed
Hope no one is actually out there in a trailer boat, regardless of what type and what it is made of!
Off topic, but I just this morning hopped off a cruise ship in New York, yesterday and the night before that we hit some bad weather coming back from the Caribbean in the Atlantic. A good 18 hours of sustained winds over 50 knots, highest I saw was 65knots for an hour or so.I guess it is nights like these ...
... when the weather is a little worse than predicted [emoji15] ...
that you are happy you have one of these tinnys under you ...
... when you are out off Moreton and not home in bed
Hope no one is actually out there in a trailer boat, regardless of what type and what it is made of!
From my quite comfortable vantage point on deck 10 I can say how horrible ocean looked even from that somewhat distorted, elevated position. I couldn't imagine being down in it in even a 100 footer, the boat I was on was alright at 350m and with the waves being more wind chop then swell it was far more comfortable than the 10ish foot swell we had the day before, albeit the chop would have been a good 12 foot on its own.
After bearing witness to what I did, I reckon If you got hit with 50 knots in any type of trailer boat I don't reckon it would matter how they built it
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So does anyone know what grade alloy telewater use in their plate range
"It's just a bit of chop - right skip" LOL.Off topic, but I just this morning hopped off a cruise ship in New York, yesterday and the night before that we hit some bad weather coming back from the Caribbean in the Atlantic. A good 18 hours of sustained winds over 50 knots, highest I saw was 65knots for an hour or so.
From my quite comfortable vantage point on deck 10 I can say how horrible ocean looked even from that somewhat distorted, elevated position. I couldn't imagine being down in it in even a 100 footer, the boat I was on was alright at 350m and with the waves being more wind chop then swell it was far more comfortable than the 10ish foot swell we had the day before, albeit the chop would have been a good 12 foot on its own.
After bearing witness to what I did, I reckon If you got hit with 50 knots in any type of trailer boat I don't reckon it would matter how they built it
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Haha pretty much, never backed off, punched into it at 20knots the whole time.
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