Metric

Virtually all new work is done in metric now. The work is created real world size and then plotted at some scale, metric or not. However there are some exceptions. I recall that some 15 years or so ago the US Coast Guard declared that all work submitted to them for review must be in metric. Within a month or so, the plans reviewers had told me that any plans submitted in metric would be returned without any action.

So, on the chance that a plan set is different than you prefer, I propose buying a dual format tape measure and this website, http://www.hocltd.com/metricalc.html
Again, most of the new work is metric and most of it has dual dimensions.

Latest

Between rush deadlines and supporting some 50 ongoing projects, the blog has fallen behind. As soon as I can surface for air, some of the topics will be:
Revisiting Post-Apocalyptic Boat Building.
Always new projects submitted.
Latest on sealing the vacuum bag.
Looking into PET foam.
The greater Seattle area has about a dozen relatively exotic KHSD multis building and sailing- lets look.
The cat projects in Africa and Estonia are ongoing.
I should catch up soon.

Plywood/Glass strength Comparison

How strong is glass compared to plywood? Here is a table comparing strengths with out of plane loads (like water pressure).

Plywood/Glass Thickness Conversion comparing bending strength. (Assumed 60,000 psi bending strength for glass and 10,000 for plywood)
Assumed that triaxial amount is on both sides of a core

Ply thickness Triaxial thickness Core

3mm ply equals     (12 oz)  400 gsm w/12 mm core

4mm ply equals     (17 oz) 600 gsm w/12 mm core

6mm ply equals      (22 oz ) 750 gsm w/12 mm core

9mm ply equals      (34 oz)   1150 gsm w/19 mm core

12mm ply equals   (2) (22 oz ) 1500 gsm w/19 mm core

USCG certification

I understand that the USCG stability rules are catching up with the increasing girth of Americans. The official passenger weight for COI boats is to go up from 160 lbs to 180 lbs as I understand it. For monohulls, that can be a crisis. For catamarans, it will not actually change the stability at all. I expect that everybody will need to revise their stabilty calculations and stability letters. I have spreadsheets ready and can do that for everyone who needs it.
Related, I can’t believe that with all the budget cuts, a plans submittal and inspections for a COI vessel is still free. Where else can you get a building permit for free? I can’t imagine it will be free for long. Submit those COI plans soon.

A little hull layup…

Upgraded the video on this a bit: The layup on a 68′ cylinder molded hull currently under construction in Roatan: it’s speeded up quite a bit, this is about 25 minutes of real time. the half hull panels are approximately 11′ x 71′ – 4 layers of 3mm plywood and 33 gallons of epoxy.

[flashvideo file=”http://multihullblog.com/wp-content/uploads/flash-hull.flv” /]

Sailing on Sarabi

I got to go sailing with Barry and Karen, the owners of Sarabi earlier this month. Sarabi is a KHSD 56 catamaran with an Aerorig. See http://www.multihulldesigns.com/designs_other/56aerocat.htm for more pictures. Its a fast, safe cruising machine. I enjoyed their stories about sailing in “aquarium mode” through green waves, or closing on monohull friends so fast at night that they were mistaken for pirates. She looked great for having done most of a lap around the Pacific.  Thanks you two. It was a fun sail.

beautiful day
tempered, double curved safety glass

CSR at Northlake is Gone

CSR Marine on Northlake Ave here in Seattle will be gone by the first of November. CSR has been a fixture there for some 25 years. They were not only the best, but they hauled out multihulls. And they owned the legendary trimaran CHAAK. Its almost like the space needle moving.  They will have their two smaller locations near the locks and at Des Moines.
I have heard from several sources that the Puget Sound Waterkeepers threatened them and many other waterfront businesses with ongoing lawsuits unless they left. Or, I heard, they could pay protection money and stay. I will be finding out the other side later thi

s week.
I have worked in and with many boatyards over the years. I have never seen a more contentious boatyard with the environment.
I support the Greenpeace and all, but this seems wrong to me. I will get to bottom of this soon.  CHAAK's last haulout below.

the yard is bare as they move out
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Kurt Hughes on Catamarans, Trimarans, and Boat Design