We prefer to avoid fastenings (cost, weight, leaks, localised loads) and have largely managed to do so using carbon tow and rod to make fittings.
Infused laminate is 65% glass which is far tougher than say a csm laminate which is only 25% glass or a hand laid one which is 50%, the rest being relatively soft resin. And if the laminate is solid (ie, no core), wearing it away will take a lot of beach dragging, and is easily fixed by adding more glass. Varying the laminate in this way (core/no core/solid glass) is easy with Intelligent Infusion.
One of the potential problems with the cargo ferry is that, on some routes it may occasionally and inadvertently bounce across coral reefs and have to land on rocky beaches. One of the solutions we are looking at is a solid glass hull bottom, and accepting that repairs will be required. Another option is adding a 1mm thick stainless steel cover to the bottom of the hulls. Adds about 500 kgs to the weight but would make it pretty much scratch proof.
Including alloy plates in laminates is fine until they are drilled, tapped and bolts inserted. This is a possible point of ingress for salt water and the resulting corrosion causes the alloy to expand and blow it all apart. Mast manufacturers found this out the hard way with bolted on tracks. Better is to use either solid glass or filled epoxy annuluses in the core and bond the bolts in. However, this can cause crevice corrosion in the bolts if they are oxygen starved. Hence my preference for tow.
On a dinghy, a rebate in the laminate for a piece fo screwed on plastic is another option, but it gets scruffy pretty quick.
On Mon, Jun 18, 2018 at 4:12 AM, StoneTool owly@ttc-cmc.net [harryproa] <harryproa@yahoogroups.com.au> wrote:
Every boat requires some if not quite a few "hard points" where
something bolts through. Obviously the core must be something other
than foam here, and more layers of glass must be used to spread the load
over a large area. A dense wood would work well, but would present rod
opportunities. What's the best material to replace foam where there is
compression load combined with jerking and tugging, such as where an
anchor or drogue, or even dock lines must connect?
H.W.
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Posted by: Rob Denney <harryproa@gmail.com>
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