More pictures and notes from Tahiti on the Courage Winter family and their 55′ +- cruising cat.   Durakore and epoxy.  Again,

See https://share.delorme.com/CourageWinter

and http://tahiti-moorea-sailing-rdv.com/

and https://www.facebook.com/pages/Sailing-with-Lil-Explorers-Catamaran-and-Crew/281505708649584

An updated picture of the demountable tube cat 30.

I thought I had posted this many months ago but a search does not show it. So if I did, here again.

http://earth.nullschool.net/#current/wind/isobaric/1000hPa/orthographic=-111.27,11.83,405

CSR just got this box of goodies. Solid carbon fiber AC45 foils. They go on Chaak? I told Tim they should fold up some quick CM plywood/epoxy cat hulls, with as much carbon as they can afford, and build a drag racer.

Now I know why the my friends at CSR Marine always seem so motivated. When they done painting boats, they paint each other. Solstice parade.

I have been thinking more about my meeting with Roger Hatfield. One take-away that stands out is that despite an increasingly competitive market, he is sticking with epoxy resin. I have seen many builders switch to vinylester or even (I can’t believe this, but it happens) polyester. Roger told me that it makes life on the shop floor so much simpler. As I have said before, “you can be almost brain-dead and get epoxy right.” Recall that to get good strength numbers, the catalyst and initiator ratios must not only be very accurate, but must change with every temperature change. I expect that when Roger tests laminate samples, he gets consistently high numbers, unlike the ester builders, I am guessing. Maybe that is why designers who favor polyester also dislike sample testing.

When I used to work for Wickie at Wrights Marine, while in college, they used to make most of the money from servicing outdrives and sail drives.  To quote Latitude 38   “Knowing how often sail drives need servicing, it might be wise to invest in an air-filled lift bag like this one.” 
Photo Courtesy Escapade
© 2014 Latitude 38 Publishing, LLC

While in Vancouver, BC, I got to meet with the transplanted Russian catamaran building group. Here is Sergey, building a very modified Grainger. I might be working with others on a project.

I sometimes forget that not everybody knows what I and SM are.  They are the basic language of the strength and stiffness of a beam or tube of any kind.  Any beam should satisfy deflection, bending strength and shear strength.  In a very long span, deflection will govern.  Medium length, bending will govern, and with something short, like a chainplate, shear will govern.

When I specify an extrusion like a bow tube, I typically call out the moment of inertia it must have.  The “I”.  That is a language that any mast builder understands.  I see that Richard Woods has called me lazy for doing that.  I guess in lieu of declaring an actual section size.  I prefer to call out moments instead so people can have some freedom in picking a section.  Many might actually do the job.

With a round tube, this information in an Excel spreadsheet might do the trick.  When I have more time I will post the spreadsheet.  I can only do that from the laptop.

Ok, now for SM paste in =(0.098168*((E3^4)-(E4^4)))/E3

with the sizes in the E column.  Substitute these equations  into the bold above.

For I, paste in, =0.04908*((E3^4)-(E4^4))

For area, for shear, paste, =(6.2832)*(E3/2)*(E5)

I have used these for so many years that I forget where I got them.

In the previous last issue of Popular Science, someone asked if a spaceship could be built of wood. Daniel, the resident expert answered with the boat in mind built of heavy timber and old methods. I sent him the following note. No response at all.

Daniel,

I saw your article about if it is possible to build a spaceship out of wood in the June 14 issue. It didn’t sound very promising.
You were however only looking at old paradigm wood boats.
In my design office, we design catamarans out of plywood, but way different. www.multihulldesigns.com
We use wood as an engineering material. It is always encapsulated with epoxy, and often used in conjunction with carbon fiber. Carbon fiber and plywood have very similar stretch to failure rates so work well together.
All joints are done with both epoxy and fiberglass bonds. Out of plane loads like pressure, are resisted with core materials between the plywood faces.
The epoxy coating goes everywhere so there is no water evaporation. The epoxy is self-extinguishing as we have found in tests for the USCG.
I say that used as an engineering material, plywood could be used to build a credible spaceship. In fact I am building one, albeit it will never move. it is an R-3 permitted dwelling. It is done using entirely modern epoxy boatbuilding methods; like we do on the catamarans.
See http://lunarlanderdwelling.tumblr.com/ and www.themarsoutpost.com

Kurt Hughes