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.
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.
I’m off to Fish Expo today. Fortified myself with sardine lunch. They have upscaled the name to Pacific Marine Expo, http://www.pacificmarineexpo.com/10/public/enter.aspx but we still know it as Fish Expo. Its a serious boat show, especially for Alaska fishermen. I ran into Steve Sheidler there once and he put it perfectly. He said “If these guys have equipment failure, people die.”
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
This plywood/epoxy CM catamaran has been carrying passengers for more than 20 years there on Lake Tahoe. It was always one of my favorites. And its a demountable boat.
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.
The first Earthwise ferry is nearing launch at Lake Victoria. See http://ewventures.wordpress.com/ I worry about the weight and crossarm revisions, but its almost wet. It is cylinder molded plywood/epoxy vacuum bag design, though KHSD is never noted as designer.
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.
