On a catamaran, you simply measure centerline to centerline front and back, and you’re there.
On a trimaran, if the amas have no angle, or if the sheer line is parallel to the water, the same.
But who wants amas with no angle and no shape on the sheer? On these, if you match centerline forward with centerline aft, your hulls will not be parallel. This slightly ancient graphic shows why. The CM Construction Manual has this and the new Composites Manual underway now will have a newer graphic of the same thing.
We had the only two sunny days in weeks this last Friday and today. I took advantage. Forecast is again rain for as far as we can see. The lunar lander panels were taking over the shop. They had to be epoxied and glassed so they could be moved outside. The dozen panels were arrayed in the sun all over the yard outside as they were glassed. Laying glass did give me ideas for topics here. Not as Zen as sailing, but close. Back in the office tomorrow catching up on designs again.
As I face the prospect of disassembling my trimaran, I am reminded about the most important thing to do with installing any hardware with epoxy. And I hope to find out that I kept this in mind when I built Geko. MOLD RELEASE
Every fastener set into epoxy should have already had mold release was rubbed into it and buffed. Or even green soap. New builders don’t believe it, but much of your hardware will move or be replaced over the years. And I will admit perfidy on this. The evidence is when is forced to use the battery and jumper cables to heat the fastener. Mold release!
Ok I’m still mumbling about the top level house on my 65′ plywood/epoxy passenger ferry being more like would be found on an 85′ cat, but I’m impressed. It sits well on the water and looks to move well. I can start breathing normally again. It should be the first of 10 vessels. Rob is a visionary.
See http://www.earthwiseventures.com/The_Ferry_Project.html
Amani side viewI like this with the freighter. The old and new.
I now have the kind of information that the USCG needs to accept unstayed masts. FEA studies like this are great. Of course every boat needs its own study, unless the righting moment is similar.
I took a deposit on my boat. Will miss the zen of single-handing at 25 knots. Or passing F boats. When the prime directive becomes “don’t break anything”, the racing becomes less fun. New chapter, if it goes ahead.at the guest dock after a race
I was stumbling around looking for photos for the new composite construction manual. Found this picture from 1980. My first boat. 31′ then. Tim Ryan steering and Dennis Hough on sheet. Hat Island race. Courtesy John Marples.1980
I always have the notion that I am the only person who ever reads this blog. Matthew tells me however that it is gaining about 20% every month. And it just got a nice write-up in the French Multihulls World magazine! Thanks everybody. I have a list of interesting upcoming topics that I will do.
This new 20/21 foot shuttle cat has begun production at Zuhai, China (near Macao). It is especially intended as a chase boat for rowing teams or as a mini shuttle. Unit #1 has a bit taller cabin than designed.
