Roger and Epoxy

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.

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Sail Drives

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

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36′ Daycharter Cat Price Reduced Again

OK, several people have inquired but nobody bought it yet.
Its now priced down to $80K.  Building a new one would probably cost three times this price.

It comes with with USCG stamped plans to carry 24 passengers out to 20 miles. This 36′ x 24′ daycharter cat is for sale. Owner hopes to sell soon. Get it now and have it working by Labor Day.
Built using CM plywood epoxy construction with cored decks.
It has a pair of new Honda 15 hp high thrust with 20 hours each. Electric tilt.
Lefiel mast, boom and bowtube
Teleflex steering
Harken hardware
Staaf sails
Kick-up rudders
Portabote tender
KED lights
Life Sling Lifelines 2 Bruce anchors
It is demountable and does all fit into one container except the mast. Is here in Washington state but can be shipped anywhere. Contact me at 206-284-6346 or at khughes@multihulldesigns.com

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Moment of Inertia – Section Modulus of Tubes

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.

SECTION PROPERTIES OF TUBES
enter O.D. in inches 3.50 or mm.
enter I.D in inches 3.00 or mm.
thickness in inches 0.25
SM= 1.937065 inches to third power
I= 3.389588 inches to fourth power
area 2.7489 square inches

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.

New 20′ Tri Launch

I just got these pictures of Al’s new KHSD 20′ Spitfire trimaran launching on Vancouver Island. It looks great.  Am pretty sure those are beach cat amas, but except for the detailing, they could also be developed ply.  The work looks really clean.

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Spaceship out of Wood

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

RIP Prof. Thiel

Godspeed to Philip Thiel. He died last month at age 93. He was my professor at architecture school. Originally he got his degree in naval architecture at Web. I got to keep in touch with him through the Small Boat & Yacht Designers Group. Was brilliant professor. I had not realized he also recently combined tiny house with boats. http://tinyhousetalk.com/pedaling-afloat-with-phil-thiels-tiny-houseboats/

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Back when I lived on the yellow trimaran, he used to pedal up on his pedal boat and we would talk.

PayPal Final Update

I just got word that a bank in Greece decided in favor of my Greek customer, GEORGIOS ANAGNOSTOU.  They decided that he can have his powercat plans for free.  It turns out that anyone can use this method to get things for free.  And I am not allowed to know the name of the bank nor of any contact person there.  I did submit proof that he he got his plans, and Paypal agreed with me. It turns out however that any local bank anywhere can have the final word.   I was curious what their threshold was as I provided proof that he got the plans.  What else would it have taken to have gone my way?  No way to know as the bank is secret.  You would think if you get robbed, they can at least let me know who the accomplice is.

Paypal leaves designers and other merchants completely unprotected. Many of you have given me suggestions about what hard-case methods other designers use. I hoped it would not come to that. Paypal told me the only possible recourse I have is Small Claims Court. I assume he would laugh at the judgement against him.  Again I urge people not to use Paypal on the website for now.

Carbon Hinge

Here is a carbon fiber hinge, built by Russ Brown, that I got to touch. It must weigh a couple of ounces, and be at least 4 times stronger than A36 steel. Of course it makes no sense as carbon is most useful for deflection driven parts. But you can prove that you are one of the cool kids with these. These are like the chocolate chai caramel vanilla hazelnut white mocha caramel sauce classic syrup mocha cookie crumble frappuccino of coffee drinks.  These are the definition of yuppie.  What do you suppose they cost?  $100 each?  $500? I wish I had some.

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Catching Up with Roger

I got to catch up with old friend and boat building legend Roger Hatfield today.  I had one insight before the meeting.  I often am critical of shoddy designs and/or shoddy engineering.  I have heard it put up to resentment or something else.

Be clear, I have probably lost more jobs to Roger than anybody else.  But he does great work.  I have never seen anything to be critical of. Thats the difference.  He is in town working out the build of a new Bieker 50′ something cat.  The design fee will be at least $100,000.  And I hear so much whinging about my design fees.

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