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.

Some More Thoughts on Aluminum

 At least once or twice a week I am approached by someone who wants to have one of my composite cats done in aluminum. Usually they don’t care that the result will be up to 50% heavier, have more complicated interior, and have no insulation, compared to a composite one.
They like the idea that they can hit a rock and presumably not have to stop. There are a couple of assumptions in the mix that are usually not noted.
For whatever reason, alum. cats are usually done by fishboat builders. Fair and smooth is not even a concept, compared to what efficient catamarans must have. I recall hearing that Atlantic Fury was up to 3/4″ out in places.

 furyimages

For fishboats, that’s no big. They just pile on the horsepower to make up for it. With a rough bottom like that, driving around with rock damage is not an issue.  If the boat didn’t sink, nobody cares.  Until they have to pay for the fuel.

Again, for any cat to move well, it must not only be light, but also be extremely fair and smooth.  It doesn’t matter if it’s composite or aluminum, a gouge will slow the boat down and require more fuel.  And any unrepaired gouge will attract marine growth and further slow it down.  And again, the fishboat guys don’t care about efficiency.  We do.  The word catamaran means something very different to a fishboat builder, compared to a design that moves well.  The work-around for fishboat builders is to basically bog up a composite hull on the outside of the aluminum hull to make it fair enough.  But even with that is done, if the idea is that you can crash aluminum and not have to repair it is followed, you will be reducing that efficiency.

And always I wonder, if you have an aluminum cat with an added composite hull outside, and basically a composite hull inside to insulate it,  why the alumimum again?

In summary, smooth and fair are important for catamarans, but are often forgotten in building aluminum ones.  And don’t forget that there have been big advances in impact resistance of composite hulls compared to the polyester ones of 30 years ago.

Back!

I wasn’t gone. All last week, in fact since the last post, every time I tried to log onto this blog I got the message “access denied”. I see it’s finally fixed. I will have some posts shortly. I do have a couple of USCG emergencies today and tomorrow.

We Lost Henk from Zeevonk

I just got word of the passing of Henk Bijl. Cancer claimed him April 21. Henk and Joke lived their dream. They built one of my 45′ cruising cats in 1999, I think it was, and have been offering clothing optional ocean cruises in the Caribbean ever since. I never met them, but they were delightful to work with. Zeevonk is for sale, with Allan Veth of Evecom.  www.multihull.nl

bemanning1

Epoxy Weather

It looks like a couple more days of good epoxy weather here in Seattle. I will update all the comments here in a couple of days when the rain comes back. The parts are too big already to fit in the shed so I’m working outside. Materials are stored in shed.

Time Moves Along

Friend Steve Vogel retired from CSR Marine last Tuesday.  I realized its end of an era. I first met Steve when we both were livaboards at Kelly’s Landing some 33 years ago. Our two boats couldn’t have been more different.  He had a very traditional single hull wooden cruiser.   I had the lightweight trimaran.  He was often game (or crazy enough) to do races with me on my old tri Smoholla the Shaman. More than once he found himself crewing with me at Point No Point, after midnight, with a gale shrieking, as the boat is fully out of the water slugging to windward.
Or the day he ran me up my mast in a late December evening snowstorm, went back to his warm boat, and forgot about me. NPR was riveting. the mast was covered with ice and it was getting darker. I really had no options. I tried yelling. The snowfall got so heavy, all sound was absorbed. He remembered an hour later. He still laughs about that.
He will be cycling in France. Have good one Steve.

Trikala Update

During the last trip I did pretty much finish up the new 2013 Trikala plans. Will take a week or two to get around to updating the website. Until the update hits, I will offer the new set at the old set price. New price will be more. I keep hearing that my sets are less cost than most. Maybe that hurts me overall.  Have to fix that. 

You can probably already tell that you can push this much harder than the Searail.   And you can bring non-sailors along on this tri.  Can’t imagine Auntie aboard a Searail in a blow.

And if I may, this new T19 looks a lot less frumpy than the Astus.  Even if they did copy the sliding system.

trikalailustrate