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Thanks Robert. Yes a lot of time, effort and experience goes into each part of the design and we contract the services of a very good composite engineer with a background in composite aircraft and the amazing Spitfire" http://marine.bdg.com.au/spitfire_gallery.html so he knows how to design light and strong.
At the moment we are developing a new way of building the beams. The way I built the beams for both the Maine boat ( http://www.harryproa.com/building_hg/buildinghg_wk7.htm ) and the present Visionarry ( http://www.harryproa.com/building_Vis/building_Vis_4.htm ) is very time consuming and ends up heavier than we would like. It also makes adding fittings or inspection holes difficult because all the carbon uni reinforcing laminates cover most of the beam. The new method will use carbon 'bars' in the corners only with foam walls between. This works out lighter, cheaper and is easier to build. The booms will also use this method. One of the advantages of building our designs ourselves is it enables us to improve the building methods.
We use rectangular sections on most of our beam designs. As well as being good in torsion and bending it is also most practical for fitting bow rollers, tramp fittings, stanchions, walkway brackets etc. and can be walked on easily. Also, a round or oval beam of the same duty is significantly bigger.
Just out of interest for those following the Visionarry progress, we painted our final coat of highbuild undercoat on Friday. Next week we will give everything a final light sand before spraying the top coat. The owner is heading overseas for six weeks so the boat will be put aside while we start on the new Elementarry. This will be built using the new 'one shot' glassing method. This involves making a cheap female mould and vacuum bagging a foam sandwich hull shell with glass on both sides at once. We are very excited about this boat.
Rob will be staying here (Bellingen, East coat of Australia) for a couple of weeks. For those who don't realise, Rob lives on the west coast of Australia while I live on the east coast, about 3200km.
Horses for courses. It is hard to beat bamboo for ability to take loads and torque from all directions but if the bamboo was constrained with the load more in one direction I would imagine it would end up more oval. If there is no problem with torque go for an I beam. My idea for a folding beam is based on an I beam, allowing easier load transfer when partly folded, with judicious addition of fairing to provide resistance to torque and fore and aft bending moment. It is tempting to just buy some of those composite beams used in the building industry as a start For simplicity in building and reasonably close to optimum I would go for a ring framed wooden box section reinforced on the corners with carbon tow. This way the web can also act as a flange. Fibreglass in the same circumstances would be less useful as it stretches too much and the timber goes past its limit long before the fibreglass takes up the strain. There may have to be some cloth reinforcement around the beam to prevent the carbon tow from delaminating from the timber.
I have been closely observing the Harry construction and I am most impressed with the engineering. It seems to be based on years of sea time and knowing what breaks, and mathematical and material analysis on how to best achieve the strength required with building techniques within the ability and cost of the low volume builder. I certainly wouldn't stray from the specs. This is what you're paying the money for.
--- In harryproa@..., "Tony Richardson" <atrichardson@b...> wrote: > > ----- Original Message ----- > You wrote > - You have to make a box section, nothing else is remotely > comparable. > > I dissagree > I'm no engineer but I do have a tri with round beams > Rob and I built them in a female mould mostly of uni's > It flies two hulls and has no seastays/wires etc > They have a degree of flex in them though > The beams weigh 5kg each bare. > The boat is only 16ft but it is 15ft wide > Rgs > Tony
Robert Don,t worry about the math because I think Ray is an engineer and may have done it already. I thought they might be weak torsionally but because there...
Thanks Robert. Yes a lot of time, effort and experience goes into each part of the design and we contract the services of a very good composite engineer with a...
Mark, Is the Elementarry building method similar to the Farrier vertical foam stripping building method? (http://www.f-boat.com/pages/construction/index.html) ...
Andrew Dickson
andrew@...
Jun 5, 2004 7:53 am
MessageNo, Ian uses form frames and glasses one side only which then requires the outside surface to be fully faired after glassing. We will be making a female...
Hi DOug The reason is I didn't want seastays They cause lots of drag when underwater, add weight, cost of fittings etc, take more time to initially fit up,...
To Tony, I've forgotten which reply I was making to you, but I remember talking about anything hollow meaning a box as opposed to something solid. I really...
Doug, The latest design of the Harry beams based on four carbon rods on the corners gives plenty of stiffness for the driving hull effect (See Marks comments)....
Gidday Doug We were talking about sections of beams Just a question but isn't a triangle section beam the lightest possible construction design type? I like...
Tony, The extended bunk version is also my choice. Add to the list 'able to be transported relatively easily'. I plan to leave mine on the hard on my block...
Tony, What do you mean you were talking about sections of beams? It sounded like a solid slab of timber - as in the '60's hartley plan! Weighed beam 1 today...
... (perpedicular ) strength except some glass in these photos as it seems kiri + carbon longditudinal? Doug, That much Kiri, prevented from buckling or being...
Dear Robert, This is coming from a student remember - but I think you are talking about vertical shear which yes is not much. I'm talking about longitudinal...
Doug, I am not the engineer, merely someone who has a background in maths and physics and has followed the engineering of the Harry fairly closely. The...
Doug , I went back to my books and did the arithmetic. Apologies, There is a fair bit sheer and I don't know how much Kiri can handle. I recall when I was...
Hi, Thanks for the understanding replies. DOug Robert <cateran1949@...> wrote: Doug , I went back to my books and did the arithmetic. Apologies, There...
Hi Doug, You are correct in saying there is significant longitudinal shear at the midpoint of the shear webs. I'm afraid the engineers we used at the time the ...
G'day, The Visionarry in the pictures is being built by Mark and his team in Coffs Harbour. I have just got back from there and it looks fantastic. The...
I tend to favor the ballestron rig for reasons I have pointed out previously one less mast to build simplicity ease of handling etc The only disadvantage I see...
I must admit I like the idea of the single lightly loaded sheet of the Ballestron when the jib is up but when reefing do you put on a smaller jib for balance...
... possible construction design type? ... but I cant think of one offhand. I worked on a crane with a boom based on a triangular section truss. Also many...
... possible construction design type? I think the basic concept with the triangular beam is to come up with an I-joist type truss that will carry the major...
Robert wrote ... the Ballestron when the jib is up There are very few boats where one lightly loaded sheet is possible ... smaller jib for balance or have a...
... not a fan of this. ... Even with Jack-stays, or are compression loads a problem? ... out ... the ... bigger ... on ... the ... not ... be ... 25 sq ... ...
I think Rob wants to use a Kite and just put the rest in the I'll think about that when I have a bit of time basket. I talked with him once about it and the...
I've been racking my brains as to how to shunt with a kite without tangling the lines in the mast. I've been thinking it might be possible to lift the kite...
Trusses and beams are very different in the way that stresses are distributed because for one thing, the material is distributed very differently. ... From:...
... distributed because for one thing, the material is distributed very differently. Agreed the material is distributed differently but a box section can be...
G'day, Been away, and missed part of this thread. First, we can supply carbon uni in tow form for $30/kg, which, for given strength and stiffness may be...
G'day Rob, Hope you enjoyed your trip. What sort of size is a small roll of carbon - 5kg? Can this work on chain plates? Also I'm having trouble wetting out...
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