Nobody should build a boat outdoors. Do what I say, not what I do, or have done.
As in the picture, and its not really a boat, just built like one, notice the bog is dark. I use the slowest hardner in hot weather, but add graphite powder to make it dark grey or even black. That enhances a solar cure so I can be sure it will be sandable the next day. That also helps on cold days with a heat lamp.
Notice how the bog bits get darker as I get closer to completion.
Back at the 1986 Marine Applications of Composites conference in Melbourne, FL, the chairman, Ron Reichard took some of us on an after-hours tour of the materials testing lab.
The most visually informative samples that he had were a series of cored panels of about 2′ by 2′ dimension. They all had the same laminate; probably two layers of 34 oz triaxial each face. They all had the same thickness of core, 1″ as I recall.
Each of these had a bowling ball dropped onto it from maybe 18 feet?
The balsa one was made of contour core squares and had the little squares blasted out the far side of the panel. The impact side was destroyed.
The crosslinked PVC one (Divinycel) had its core sheared apart but the face skins were mostly intact.
The linear PVC (Airex, and later would be like Corecel) had a slight delamination in a small impact spot, only on the impact face.
For me that was a powerful visual comparison. As Prof. Thiel used to tell us, “Compare simultaneous alternatives.”
As designer, I liked the previous one better. And they sailing reefed when sailing at all. Guess they have to use the big Cat engines more. USCG certified for 100 passengers as I recall.
http://youtu.be/FcxD_4hzLVQ?list=UUjigikzWFcXr1OQWsg7vqqQ
I came across some pictures of a design that I did back in late 80s or early 90s. It is a 40′ cat that I understand is seen often in Mexico. Pantera was the first project where, at Bob Smith’s urging, I combined the hull deck into the hull lines as one entity. That took Prolines software to its limit of chords and made the section lines a bit chunky, but it was a big step forward. And Prolines also upgraded as a result.
Bob convinced me that he was starving boatscum so real construction drawings were never budgeted. It was strictly freehand work except for the lines. Even the laminate design. I learned later he is very comfortable. So the only plans are on flimsey paper, if I still have them.
Foam/glass construction.
Designing for impact has many rules, but just as many exceptions. Here is one. Typically plywood/epoxy is thought of as very poor in resisting impact. And I agree, but here, as with many things, you have to sort out what the goals are.
Here is a picture of the 55′ Sierra Cloud after a jetski impacted it. The kid leaped off early. The jetski was taken out through the hatch. This is clearly a poor impact resistance. Or is it? Larry did the repair quite easily with a 4 sided scarph replacement piece. The damage was little larger than the front profile of the jetski.
Consider that if the boat had been built of an impact resisting material such as foam/glass, the jetski probably would not have broken the surface and would have bounced off of it.
But, I am sure the delamination area would have been at least a meter or two in each direction. That would have been a huge repair. Since the cats can’t sink, breaching the hull is not the worst thing possible. More on this topic later.
Talo is taking his beautiful D-32 trimaran out exploring the islands in what looks like the summer Baltic.
Another nice view of the 65′ Adventure Cat 2 sailing under Golden Gate Bridge.
Rotating Mast Hounds-An Evolution
“we agree that every rotating mast has a single axis of rotation yes?”
For me the conceptual lodestar of rotating masts has been to imagine the wire from the shrouds and forestay morphing into strands at the mast that then spread out onto the mast.
When multis started using tripod rigs and rotating masts it profoundly improved performance and ease of sail handling. Mega roachy mains were now possible without some of the crazy workarounds that we saw in the 80s such as dropping the main down for every tack or jibe, or massive double running backstays and type A runner apes.
The earliest rotating hounds that I know of were Gougeon designs. They consisted of a chunk of aluminum, a beak, bolted inside of the mast. They were fixed. I used this system in my extrusion mast on my 31’ tri Smoholla and it worked very well. I could get 110 degrees of rotation each side of centerline. The rotation was provided by a toggle between the rig plate and the beak, and another at the wire terminal. Rotation was allowed by the slop between these.
My boat was less than 35 feet long and not used everyday. We found that the charter cats that went out every day were wearing through the aluminum beaks pretty quickly. The next step was to move to stainless steel beaks and to get them to rotate instead of being fixed. On the boats under 45 feet or so that worked pretty well. The bigger boats had two problems. First, the main toggle that holds the rigging plate to the mast took a lot of abuse. Standard stainless ones wore out very quickly. We had to go to high strength stainless. Next, on the big boats, the whole assembly was getting heavier, and starting to cost as much as a Subaru. Especially the fixed part base became crazy to build. Imagine taking a half inch thick piece of stainless and bending it to fit the curve of the mast. Then welding the ears on and drilling dozens of holes for fasteners.
I have seen some solutions where the rotating beak and its base are pushed through the front of the mast. The base is then fastened to the mast. That does reduce the large bolted plate, but I worry that the leverage of the base is so much smaller; like 20 times smaller, that the fastener holes elongate and fail. Also, the rotator base parts must be cantilevered out that much farther. Up top there, every millimeter counts, as I see it.
About the same time, people started building composite chainplates. I decided to try them on composite masts. They worked great and were relatively easy to do and at very low cost. They made especially good sense to do it your selfers.
Next I decided to try composite hound bases on aluminum masts. Of course I was worried about the bond between the composite and the aluminum. The technique of an acid wash and alodyne, plus coating the contact area with epoxy and sanding it seems to work. The wet epoxy blocks the oxygen from getting to the aluminum, and the sanding exposes new, unoxidized surface. Additionally, the very large contact area and the wrap-around shape ensure that the composite hound base cannot move.
To solve the problem of three wires coming into a single beak, the Gougeon masts had used a rhomboid stainless steel plate that we called the batwing. Each shroud side of it was bent back to fairlead to that shroud. Again on multis under 40 feet or so, it worked well and lasted a long time. The big boats wore through not the batwing, but the master toggle between the batwing and the rotating beak. I had been insisting on high strength toggles such as Reikman or other 17-5 stainless ones.
A client of mine, Geoff Strange (had a 60’ tri and is building 49’ cat now) came up with a very simple solution. No more batwing. The beak does have to be a bit larger.
My friend and competitor Roger Hatfield has probably built as many rotating masts as anybody. The last time I talked to him, he had dialed back the rotation on his workboats. He used to use an enormous galvanized shackle up there that all three wires were loosely toggled to. He has since started using three toggles, one for each of the wires, but with loose shrouds. He says he gets only about 30 degrees rotation each way from centerline now, but he feels the simplicity is so much better.
My customers with synthetic rigging do about the same thing as the rigging has more stretch. I could see a time where the forestay line spreads out onto the mast, like in my original imagining, and is epoxied onto the mast; all as one piece.
Almost there for James Grinsell
https://www.facebook.com/photo.php?v=10203358114606206&set=vb.1011402351&type=2&theater
“Having fun against two F18 after work in a stormy day (with 1 reef at main)…speed looks pretty close ”
It only lives on Face now, but he thinks he can get a Utubes version soon.
