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Andymac View Drop Down
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Post Options Post Options   Quote Andymac Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 12 at 10:09pm
Originally posted by G.R.F.


The factory I recently visited sits adjacent to the Bonneville Hydro electric plant on the Columbia river the electricity is free.
 
Yep, I guess it is, but I bet the dam cost a few $$$ to build, and a few more to maintain.
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tickler View Drop Down
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Post Options Post Options   Quote tickler Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 12 at 11:23pm
And while you were all arguing ...I was  sailing..........
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Post Options Post Options   Quote tryinghard Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 12 at 11:30pm
Me too ........ Smile
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Chris 249 View Drop Down
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Post Options Post Options   Quote Chris 249 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 12 at 12:06pm
Originally posted by G.R.F.

Abuse given to Australians is legal - fact.
At no time is an Englishman expected to back any comment he may have made to an Australian, the Australian should simply accept the wiser and superior words of the Englishman and be humble, in fact be happy he is even being acknowledged as anything other than a convicted felon or a bush dwelling aborigine.

Don't knock my ancestors! Big smile

This is the Law.

So now to the facts.

The factory I recently visited sits adjacent to the Bonneville Hydro electric plant on the Columbia river the electricity is free.

The resin I told you of's formula is secret it is being kept in the US to protect their intellectual property from thieving Chinese (and Australians).

The wood used in blank construction as well as Bamboo is from managed forests from within a 50 mile radius.

The Sports that like light stuff as well as Windsurfing, which no longer has the sun filled uplands of a better tomorrow in which to bask in the fires of progressive innovation, are SUP ( a hollow race board), kite twintip and surf boards and wake boards capable of being both light yet capable of sustaining punishment in cable parks. I've no doubt that somewhere along the Gorge folk are using similar stuff to build sailboats and all manner of stuff, but those are the instances that have prompted my latests rants.

You may now go to your room and reconsider your position.

Actually, you haven't gone to any facts. Windsurfers are not significantly lighter than racing dinghies once adjustments are made for the fact that dinghies are bigger. Only those completely devoid of logic would ignore the fact that boards are smaller and a bit of basic maths indicates how much of their weight advantage is down to that.

Ignoring size factors is like saying that lead is lighter than air because 1 cubic centimetre of lead is lighter than 10 cubic metres of air. Kiteboards are smaller than a lot of centreboards, of course they are lighter than an entire boat.

I did check kiteboard weights - same thing, they are around 80L volume (raceboard) and weigharound 5kg. That's much heavier, size for size, than at least some dinghies. Amusingly, the first kite site I came across boasted how in this year's model "Full carbon sandwich construction replaces 2011 bamboo sandwich construction increasing rigidity while reducing 1kg of weight".

So instead of kiters leading the way, they are actually switching to a material used by dinghies for years. Ooops..... Hollow SUP boards? Again, they have no rig loads and anyone who has installed chainplates and foils knows that those are the heavy bits so it's natural than craft without them are lighter. Although, of course, those accursed dinghy sailors are actually turning out boats LIGHTER than SUPs if you account for the size. Of course, you don't which is like saying that a steel kiddy's bike is more high-tech than a F1 car because it's lighter.

It's nice to see that one company is using hydro power. Pity they have to use fossils to ship the stuff around the world. And it's hardly likely to be cleaner than actually cherishing the boats we

Once again, you are back to abuse instead of facts. It's quite clear you are just trolling so I'll bail out.


Edited by Chris 249 - 07 Jun 12 at 12:17pm
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Post Options Post Options   Quote alstorer Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 12 at 1:00pm
Originally posted by Chris 249


Yes, bamboo's tensile strength is impressive but then again kevlar's tensile strength is very high and it's largely been abandoned in boatbuilding.  I've got no engineering knowledge but as I understand it, bamboo has major problems in variability and flex strength. Comparison of tensile strength with carbon is not necessarily valuable as carbon has fairly moderate tensile strength (lower than even E glass AFAIK) but it is valuable because of its compressive strength etc, which is a problem with bamboo. So we are back to the issue that you are giving out abuse, not facts.
Carbon can be made to have very high tensile strength, but that comes at a sacrifice of tensile modulus (usually)- the push in development is to improve both strength and modulus at the same time- this is the path being taken by the higher and higher "Intermediate Modulus" fibres, with some IM grades pushing into both high strength and high modulus performance (my own employer, Hexcel, has one called IM10 that is especially high performance). Compression strength meanwhile is very much resin dominated.
 
You're pretty much spot on with the big problem with using non-refined natural products such as bamboo. With heavily refined or entirely synthetic products you can relatively easily produce exactly the same material time after time after time. When your material's properties are heavily dependent upon that month's weather, you've got a real problem- so what if it grows fast if you get entire harvests that are next to uselsss. I'm also sceptical about " tensile strength or weight to strength being not far off carbon"- good E-glass isn't far off low grade carbon and is very cheap.
 
As for the mystery resin, other than guessing it's likely some sort vinyl ester (it surely wouldn't hurt to mention the commerical trade name of the resin- could probably tell you much more about it this way as a fair bit will be public) I can't really comment.
 
 
-_
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Post Options Post Options   Quote Steve Clark Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 12 at 5:07pm
I did some test samples with bamboo cloth that was being sold for organic surfboard construction.  Pretty unimpressive really.  Just a blotter to hold plenty of resin in place.  I sourced one or two other styles with similarly unimpressive results.
As a surface laminate or laminate bulker it's probably fine, but as a structural skin, it does not compete with any of the standard reinforcements.  The process of turning it into yarn and then weaving that yarn probably damages the bamboo fiber so it really is no better than cotton or hemp.  The cloth I tested was for garments,so it's really not surprising that it didn't perform well as a plastic reinforcement.  There is more to getting this right than running down to the fabric shop.
Bamboo as a structural wood has many fine qualities, but stripped up into veneer and glued together into sheet goods isn't one of the obvious choices.  A small stand will provide home grown tiller extensions and ski poles, which can be very green.
And to pile on: surface area is the biggest driver in weight. With modern materials, you quite quickly get to the limit of what can be regarded as watertight and strong enough. This is something in the order of 200 g/m^2 carbon cloth on either side of 55 kg/m^3 foam. Depending on the thickness of the foam, you can predict that the best you is about 1 kg/m^2 of surface area. This goes up as you add bulkheads , local reinforcements, trunks and everything else that takes a flat sheet and turns it into something you can use. If you want a robust boat and capable of being slammed around in waves and getting mishandled a bit,  the weight goes up.  There are advances in fibers, nano toughened resins and processing because reinforced plastics is a fast moving technology with and a dynamic market. For a long time boat building was about 10 years behind aerospace. However in the recent past, the marine industry developed techniques for building larger pre-preg composite parts than was thought possible by aerospace..... so it's possible for industrially significant developments to come from our little leisure sector.
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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 12 at 5:28pm
Originally posted by Steve Clark

..... surface area is the biggest driver in weight. With modern materials, you quite quickly get to the limit of what can be regarded as watertight and strong enough. This is something in the order of 200 g/m^2 carbon cloth on either side of 55 kg/m^3 foam. Depending on the thickness of the foam, you can predict that the best you is about 1 kg/m^2 of surface area. .....
SHC


Taking an RS400 size boat as being around 2m by 4.5m, You might guess at 10sqm in the hull skin, say another 5 in foredeck and side decks, allow another 5kg for a rig bulkhead and board case, it looks like radical weight saving could be possible?
Even allowing for local reinforcement.
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Post Options Post Options   Quote DaveT Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 12 at 5:57pm
I'd such high hope such as esteemed handbag retailer could revolution dinghy design, bad times 
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Post Options Post Options   Quote aardvark_issues Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 12 at 7:25pm
Originally posted by RS400atC



Taking an RS400 size boat as being around 2m by 4.5m, You might guess at 10sqm in the hull skin, say another 5 in foredeck and side decks, allow another 5kg for a rig bulkhead and board case, it looks like radical weight saving could be possible?
Even allowing for local reinforcement.


A 400 is probably more like 11 or 12 M for the hull - if you look at the mouldings for the cockpit the insides will be more again! Don't forget to add a few hundred g per M2 for the gelcoat though. If you painted a 400 you could drop loads of weight out of it, but add a couple of Łk to the finished price...
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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 12 at 7:47pm
I was thinking about what a similar size boat could be built down to, not looking to build a light 400.
You could lose most of the double floor.
Taking 12 sqm and adding decks etc say 20sqm times 1.5kg/sqm
30kg for a shell.
Looks like 40kg bare hull ought to be possible.
There are some kg to be lost from the ali rig.
Would it be strong enough?
Would it be going faster and hitting the water harder?
How different would it feel to sail?

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