I just got this picture of one of my 37′ trimaran designs from the old days. It must have been the third or fourth design I ever did. August 1986. Hand drawing days. I’m struck by how good it looks to me at the first telling glance. Cylinder molded plywood epoxy. I hear that it also may be for sale soon.
I got these pictures of one of my cats from Australia’s gold coast. I was told it is about 45 feet and open bridgedeck. I would have guessed is Paul’s Quemarla or however is spelled. Anyone know more about it? I see is named Gato.
I see that Owen has discovered a huge amount of great stuff and will dribble in in this week. I have had some unexpected parent health issues so has been demands on my time last week or two.
Five years ago. Still one of the best sailing videos I’ve ever seen. Simmo Kook did such great editing and sound track. And still one of the best examples that the earth is flat. Simmo from near Genoa, Italy picked a Bakersfield punk-folk garage band as soundtrack. http://www.youtube.com/watch?v=9u6UepbaCKo
I think I forgot to note this when it arrived in April.
ESET is again downloading antivirus definitions so computer is too slow to use to search. It hogs the CPU.
If you want a copy, email me and I can forward the PDF. NVIC 02-16 is 50 pages.
These are the bikes parked out front while the hearty are inside getting painted up. A big enclosed shed and right on the parade route. I know it’s past Solstice. I been scrambling. As before http://multihullblog.com/2014/06/csr-painting/
Long time east Florida catamaran builders Offshore Catamarans has been ramping up. “We now have six builders on payroll not counting me. The shop we are in is rented (80′ clear span} with bigger space available. We build the parts here and do our final assembly at Seminole Boatyard where we can travel lift in cats to 25′ beam and hire a crane for wider.”
This Hughes 36 Day Charter Catamaran USCG Inspected for 24 passengers. This Cat is demountable and can be shipped anywhere in the world. For more information, please visit http://www.offshorecatamarans.com/hughes-36.html Michael Bell 561-714-9045
I recently had to review the complete process of designing a catamaran bow tube with MSC (Marine Safety Center) at the USCG.
The boat in question had a Gold Coast style timber space frame bow tube that had failed.
Usually the GC units are pinned to the hulls to allow movement, but in this case it was bonded, and(or) bolted to the deck. It had cracked, water got in, and it began to rot.
As everybody at MSC is new now, the design assumptions that we have used in the past are no longer valid. In the past I used an aluminum tube section and A frame wires that matched the mast section and shroud diameter. That sounded like voodoo to the new MSC. I had to come up with complete calculations.
I assumed the span for the Eulers column bucking calculations to be between the forestay and the hull; half the overall length.
MSC disagreed. I had to use the whole length and assume no support. I argued that the A frame restrained upward buckling, and the forestay restrained it from downward buckling. I finally convinced them. I also noted that as far as I know, not one of my COI cats using my stock bow tube arrangement has ever failed. They were barely impressed.
I was surprised how close the calcs were though. And again, there had never been a failure. I expected generous safety factors.
I realized that several other things help us out.
If the tube was to deflect, it would have to pull the hulls inward. The hulls have huge section properties. The tube is restrained by that.
The load that MSC used was the breaking strength of the forestay. Load cell studies that Roger Hatfield did showed that the forestay is loaded less than the shrouds are. Typically they are the same diameter.
The tube itself resists bending some.
And finally, the weight of the tube, fittings and wires helps resist the forestay load. Not much but some.
All these compensating factors are hard to calculate easily however. But the evidence is that none have failed.
Then I remembered that there was a bow tube on one of my cats that fails regularly, though so far, not catastrophically. It was designed back in the hand drawing days and has a welded moment connection. The welds give out.
It might have still worked except for one thing. The builder freestyled the main beam.
Before designing it, I had just come back from my first MACM composites conference where Dr. Reichard had presented a paper on the structural design of the catamaran Fury. I had used that information to design a main beam that resisted twisting and polar loads also. The fairing I designed flowed into the sides of the hull. It would have been a strong and stiff moment connection.
The builder had heard that Fleury had broken up and he assumed it was the same boat. He told everyone that my design was thus flawed.
A guy wandering by the shop who had seen a Crowther cat in Australia a decade earlier was chosen to design the main beam. It had no twisting nor polar load resistance. So the bows were able to move way too much. And they keep welding it, to this day I assume.
Again, back. I however see that no email will go out today. I’m most of the way through the 500 emails, but after seeing the morning news, I backed up everything before logging on.
That put me into ther time where the Eset anti-virus began uploading anti virus definitions. It slams the CPU up to 100% and it has stayed there since noon today. Nothing else is really possible until it decides it is finished. The email just keeps eternal hourglass going on. They say that you can pause it but it never actually does.
All the email will have to wait until tomorrow.
Out of office next week, 8th through 12th. I will have the workstation with me and it’s squirrel mail. Or text me 206 719 4893.