Am doing this very simple 40’+ dive catamaran. Mostly flat panel construction, except the bilge. Probably no core on hulls, with stringers instead.  As simple and cost effective as possible.  And an exploded view of the flat panels.

I keep hearing R2AK talk again.  Probably if you not already into it, it’s too late to start building. 

I am impressed with how many weird, pointless efforts I am seeing.  Nobody learned any lessons from last year?  After a bit of Juan de Fuca, it is mostly threading through the islands.  Shifty wind, kelp beds,  crazy tides, short tacking.  Then a last blast to the finish. 

Assuming the islands are most of the trip,  that says at least a 25 to 30 foot trimaran, with kick-up rudders, and oars in case.  And enough accomodation to last the several days out.  Maybe a bit more rocker in the main hull to help short tacking, and big amas in case there is a bit of wind from a good direction outside.  In the islands a taller rig always helps.

It doesn’t require a weird 60s  AYRS creature.  a trimaran with the above will win.

I found them.  The Google shoreline mapping drones.  Oh oh, they could be candidates for stuff done wrong.  Probably some code geeks bought what they had seen at a marina without understanding what was needed.  Even a couple of A class cat hulls would have given much flatter ride, less drag and less weight and greater range.  Shoveling after the parade again.  Google, call me.

At IBEX last September I noticed that there were more electric outboard vendors. I especially talked to the Torqueedo guys as I had used those on the oceanography drone catamarans I designed a year ago.  http://multihullblog.com/2015/02/oceanography-drone-on-youtube/

They told me that Google had been using their units to do coastal mapping now.  I decided to look that up.   Meanwhile I also found

Parsun www.parsun.biz and www.parsun.co.cn Chinese outboards, including electric units.  And

Elco www.elcomotoryachts.com  And don’t forget the Torquedo units. www.torqueedo.com

The octogenarians over at steamradio, a multihull forum, usually only worship Kelsall and swap stories, but once in a while something great leaks through. This time a Tom Speer paper. Tom sailed with me on the Geko once. It was gusting to one knot and glassy calm water. He did have all his man overboard gear on at all times. Unlike someone else.

http://www.tspeer.com/Wingmasts/teardropPaper.htm

Thank goodness for the Intracoastal Waterway.

The Precourt rigging style as seen with composite rigging is not that new. The USS Constitution when I visited it in Boston Harbor.

Colm, building one of my 31′ trimarans, came up with two sources of thick wall stainless ruddershaft suppliers.

“I bought my 304 rudder shaft from tube service co: www.tubeservice.com.  It was 299 for 6′ of 1.5 od with 0.375 wall.  Recently I was quoted the same tube in 316 from penn stainless: www.pennstainless.com   Quote was 380.

Jim Dory has brought to my attention that my standby sources for thick walled stainless steel pipe or tubing, have vanished.
Both Tubesales and Kilsby/Roberts phones have been disconnected. They once sold thickwall rudder shaft material. Typically a pair of shafts costed as much as a new Pygmy Kayak, but you could still get them.

For other things I have been using Online Metals, www.onlinemetals.com   and

Metalshorts,  www.metalshorts.com

The problem is neither of them have pipe heavier than Sch 80.  Usually I would specify XX thick.    Typically my rudders are higher aspect ratio than most, so the loads are higher.  I recall seeing a note  last year that Kelsall specified an 1/8″ wall thickness in a rudder shaft for a multi of around 40′.  I noted that such a shaft would survive for a few minutes on one of my boats.  I forget what he replied.

Another choice is to use high strength stainless Aquamet prop shaft cutoffs.  They are heavier being solid, but with such high properties the shaft diameter can be smaller.  I can run E x I spreadsheets for anyone needing that.

This does make carbon tubes more attractive, though cruisers will still find the less fragile nature of stainless better.  And stainless does have almost 3 times the deflection resistance or modulus of carbon.  I recall after multihull guru Mark Evans did a 90 degree sudden turn on the Geko, at about 25 knots, we were still fine.  I later discovered that the shaft had deflected so much that the glass halves of the rudder skin had sheared against each other,  on the trailing edge of the rudder.  The carbon shaft had no problems.

On the big boats I got a surprise that I did not expect.  A rudder shaft on one of the 65′ daycharter cats was 3-1/2″ diameter with 3/4″ thick walls.  It passed all the calculations for years of service.  However, when the rudders were turned, a blast from the props being pushed by a pair of 550 hp Cat engines pasted them back.  I did not see that coming.

So, in summary, if anyone knows of a source for thick wall stainless tube or pipe, let me know and I will post here.

It is boatshow season in the Pacific Northwest again.  Not as useful as the so called Fishexpo, but worth a look at new gear.

Portland.  Jan. 13-17 www.otshows.com

Vancouver BC.  Jan. 20-24  www.vancouverboatshow.ca

Seattle. Jan 29-Feb 6.  www.seattleboatshow.com