What Make???

Hightower · 18 June 2005, 00:13

http://cgi.ebay.co.uk/ws/eBayISAPI.d...556795532&rd=1

What make is this? And is kevlar really used in RIB construction?

Andy

benc · 18 June 2005, 02:08

The hull/cushions look very similar to mine, so if I was to guess I'd say its Tornado.

I'm sure i'll be told im wrong

codprawn · 18 June 2005, 03:50

Quote:

Originally Posted by Hightower

http://cgi.ebay.co.uk/ws/eBayISAPI.d...556795532&rd=1

What make is this? And is kevlar really used in RIB construction?

Andy

Kevlar is not as "hitech"as people think - some people do use it as stiffners/reinforcing in hulls etc etc

RIVA · 18 June 2005, 13:54

think its a cobra

Alan · 18 June 2005, 13:57

I agree with RIVA. Looks like a basic fit out Cobra.

slimtim · 18 June 2005, 16:34

It is a cobra I think as i seen it linked elsewhere.

Kevlar (or Aramid as its supposed to be called) is just a replacement for glass or carbon but with different properties. Its stronger and has a lower density than glass and carbon but does not have the stiffness of carbon. Its very good for resisting impacts which is why its often used for ballistic applications. Adam Younger's 6.5m demo RIB is made from Aramid. The main reason glass is used is because its cheap like the budgie.

Tim

Hightower · 18 June 2005, 21:26

Thanks guys for the replys, I'll have to investigate this kevlar use in RIBs a bit futher.

Andy

martini · 19 June 2005, 20:39

The hull shape and tubes remind me very much of a ribtec. white hull and that blue on the tubes is very ribtec as well!

jwalker · 19 June 2005, 21:23

Quote:

Originally Posted by slimtim

Its very good for resisting impacts which is why its often used for ballistic applications.

Not once it's encapsulated in resin. It delaminates easily on impact. It has good stretch resistance and tensile strength which makes for rigidity.

codprawn · 19 June 2005, 23:23

Quote:

Originally Posted by jwalker

Not once it's encapsulated in resin. It delaminates easily on impact. It has good stretch resistance and tensile strength which makes for rigidity.

Which is why aluminium is the preffered choice for a really heavy duty rib hull.

jwalker · 20 June 2005, 01:22

Quote:

Originally Posted by codprawn

Which is why aluminium is the preffered choice for a really heavy duty rib hull.

I presume you mean aluminium alloys since aluminium is particularly malleable and ductile.

Perhaps your preferred choice. Laminate up a cylinder. Roll up an aluminium cylinder the same diameter and wall thickness. Now hit them with a hammer. Come back and tell us your findings.

Cod, you do often appear to believe things to be true rather than know them to be true.

codprawn · 20 June 2005, 03:18

Quote:

Originally Posted by jwalker

I presume you mean aluminium alloys since aluminium is particularly malleable and ductile.

Perhaps your preferred choice. Laminate up a cylinder. Roll up an aluminium cylinder the same diameter and wall thickness. Now hit them with a hammer. Come back and tell us your findings.

Cod, you do often appear to believe things to be true rather than know them to be true.

So why do heavy duty workboats have steel or aluminium hulls????

simonnud · 20 June 2005, 08:50

Quote:

Originally Posted by martini

The hull shape and tubes remind me very much of a ribtec. white hull and that blue on the tubes is very ribtec as well!

I totaly agree i think it is also a Ribtec with the bow curling up like that.

Pete7 · 20 June 2005, 08:54

Quote:

Originally Posted by codprawn

Which is why aluminium is the preffered choice for a really heavy duty rib hull.

what a bit like Halmatics then ?

Its not a Ribtec although the tubes look similar so presumably it was tubed by Henshaws. Early Cobras had stringers laminated into the inside of the bow area that could be seen above the decks but this doesn't seem to have them. Hmm a mistery, perhaps someone should ask the vendor.

Pete

Daniel · 20 June 2005, 10:41

That Yammie v4 will be a thirsty beast (i know, i used to have one)

Hightower · 20 June 2005, 12:50

Quote:

Originally Posted by Daniel

That Yammie v4 will be a thirsty beast (i know, i used to have one)

Yeh and didn't she go well with it strapped to the back

.

RIB BOI · 20 June 2005, 16:41

Same boat but tells you the maker http://ribs.apolloduck.co.uk/display.phtml?aid=28049 wich is Picton Boats wich is cobra i think.

RIBBOI

slimtim · 20 June 2005, 17:24

Quote:

Originally Posted by jwalker

Not once it's encapsulated in resin. It delaminates easily on impact. It has good stretch resistance and tensile strength which makes for rigidity.

But then thats the same for all PMCs. With regards to material properties, the matrix system (in this case epoxy or perhaps polyester resin) dominates the delamination properties, not the reinforcement (unless you have a system of through stitching). Aramid has high specific strength, low compressive strength (ie it buckles easily) but has high toughness, therefore a composite made up of aramid and epoxy is much better at resisting impacts than a carbon composite (carbon has high stiffness but low toughness).

Glass is just generally pants

jwalker · 20 June 2005, 19:03

Slimtim, I got the impression you were justifying it's use in boat construction by comparing it's energy absorption properties in such things as anti-flack jackets.

Quote:

Originally Posted by slimtim

...the matrix system (in this case epoxy or perhaps polyester resin) dominates the delamination properties, not the reinforcement (unless you have a system of through stitching).

Yeh, I suppose that is generally the case but if the reinforcement material is hairy in texture there will be considerable reinforcement across the resin boundary. My experience of kevlar is that it is a slippery material and distinctly non-hairy. Whilst it is superior to glass cloth it does puncture. If you have the opportunity, take a couple of patches of kevlar and laminate them together, part their ends slightly to get a grip and you'll find you can just pull them apart by hand without a great effort. Even with the lowley CSM you would not be able to do this. Not very scientific I know but it gives an indication of how easy it would be to produce an inferior laminate without appreciating the material for what it is. Saying a matrial has toughness and strength is not sufficient information in its choice for a particular application.

jyasaki · 21 June 2005, 22:54

Seem to recall that the US Navy is using RIBs made with kevlar (rather than a polyester) as the base material for the polyurethane fabric. Don't recall where I heard that, though.

As to the Aluminum vs glas debate, see how many hammer blows it takes to hole that glas tube vs aluminum. Then, see how tough it'll be to repair.

Aluminum alloy has better holing resistance than glas, has less upkeep (no gelcoat to chip, peel, or whatever), and can easily be cut and re-welded. A hole or tear in an aluminum hull can be drilled and saber-sawed out, and a patch welded in.

[Hmm. Can you tell I bought Aluminum?]

jky