All posts by kurt

Bottom Siders

I wanted to find some ethafoam mats for the lounging pit on the lunar lander project (a house built like a modern boat). I imagined something like the wrestling mats that I recalled from high school would be great. And would be good to work with local company. http://www.bottomsiders.com/
It turned out each 15 square foot cushion would be $1265.00 before tax. That’s $84 per square foot. Yeow. All six cushions would cost as much as a new Hyundai. I have to keep looking.

Trimaran Ferry

Thursday’s job was to create some updated renderings of the 149′ passenger ferry design. They never real till they real, but this one might go. Interesting irony that it might start in Africa first.

I recall that Richard’s excellent presentation on it was soundly rejected by Washington State Ferries some 25 years ago with the words “If it ain’t steel, we ain’t doin it.” Its foam/glass. Aiming for 40+ knots and 2500 hp. 149 seats.

model6PSP2G

 

model6PSP3G

 

Silverthane

I got to use System 3’s Silverthane polyurethane sealant this weekend, in place of 5200. http://www.systemthree.com/store/pc/SilverThane-SA-2100-c58.htm
It is a 2 part product so that seems to solve my two main complaints about 5200; that my $17 tube hardened in just a few weeks, and after seems like days, the part I sealed was still wet.
I lose 5200 tubes after they opened even though I try to seal them up.
The two part poly self-mixes in a special nozzle. I’m guessing each use ruins the nozzle, so get several if you work like I do, with several small jobs. And my job was functionally cured the next morning, which was the soonest I tried it.

Only comes in white at this time.  So I still have to bear with 5200 for black jobs.

Captain’s Nautical Bookstore

I finally tracked down the book I needed to verify the design rules for the 149′ passenger trimaran. It’s the IMO HSC Code 2000. I faced the expense and the month wait for it to be posted from UK. Then I saw on the IMO website that their publications are also available at Captain’s here in Seattle. www.captainsnautical.com  I had forgotten that they have everything to do with boats there. They are now carrying my Design Book also. (and at less cost as there is no shipping cost)

Carbon/Glass and Rule of Mixtures

 

Maybe once a week I hear a suggestion that someone wants to slightly punch up a glass laminate with a bit of carbon. Or even a bit of Kevlar. I have even seen laminates on a roll with a small bit of carbon mixed in with the largely glass roll.  It is seen like a vitamin I guess.
Bad news,  it doesn’t work that way. The problem is the difference between each material’s stretch to failure percentage. E-glass is around 6%. Carbon is typically around1%. So, for example, if you had half of each in a laminate, when the carbon started to fail, the e-glass would be only contributing some 17% of its possible strength. Another way I have heard to visualize this is to imagine two boards several feet apart. A steel wire, and a rubber band connect them to each other. Imagine that each will fail at 100 lbs pull. The rubber band is doing nothing yet, as the steel fails and breaks.

E-glass can be laminated with carbon, if they are not both oriented in the zero degree axis for example.  The carbon could be on the 0 degree and e-glass could be on the off axis.  The off axis will contribute almost nothing to the strength, but will help keep the zeros in column and add some shock absorbing ability to the laminate.

More Bagging Seal

Just back from Home Depot where I tried to find something called Roofers Sticky Tape. No joy. They had never heard of it and did not have it. I find it on a note from last IBEX, maybe from Jim Gardiner? By the name, it sounds ideal. I imagined some nasty, black, cheap, industrial sealer on a roll.
I did get some Scotch Indoor Mounting Tape for $10. 350 inches. So far nothing seems to beat Liquid Nails Projects, at under $2 a tube. Most baggings take just over one tube and the excess in the opened tube keeps until next time.
Anybody has any more on the Roofers Sticky Tape, let me know.

They Didn’t….Did They?

The new ProBoat Drawing Board picked a first design right out of Stuff Done Wrong. Yikes!
http://www.proboat.com/proboat-drawing-board
A 36’+ powercat that is only 12.6 feet wide overall. It takes me right back to the Florida cat rolling over in the relatively small beam-on wave and killing someone. Yikes. http://multihullblog.com/2013/02/catamarans-and-waves/

And it seems to be over 20,000 lbs. in lightship condition.  For a 36′ powercat.  Yikes. No wonder it needs so much horsepower. We are supposed to be improving these things.