Impact resistance ??
Impact resistance ??
To anyone with a good technical knowledge of Ferro boats- I am in the market for a SAFE sailboat 35-45 ft suitable for long-term cruising. I currently prefer Steel or Aluminum construction for it's strength. I am, however, enticed by the very low prices of many ferro boats. Unfortunately I have heard bad things about the impact resistance of ferro hulls. Everything from simple groundings and reef/other collisions that resulted in sinkings. Normal cement has very little elasticity and is brittle, thus the above results. Is there something in the construction of ferro boats that is done to mitigate this? Have I been misinformed? Can someone please compare the technical merits only (i.e. exclude ease of construction, etc. I am only interested in the strength and safety issues) of ferro to steel/aluminum as well as GRP? I am looking for sound technical numbers, evidence, and experience. Any help will be greatly appreciated. Please copy me on your response by email. Thanks.
Kevin Bennett...keven_bennett@ams.com
As with all forms of construction used in boat building, the impact resistance of the finished hull is not only set by the type of material used but also by the size and shape of the hull. I have no intention of using the help and advice forum to begin a comparison debate. The figures for all mediums from many tests are well documented from considerable research. As an example..a 35ft typical hull built the Hartley method (averaging 3/4" thickness and 30lb steel content per cuft), will approximate 8,000 lb per sqin in 14 days moving to 11,000 in 28 and establishing around 19,000 after 90 days. Only an acceptable thickness of solid steel plate can match it. Under certain conditions, all hulls can be damaged by impact regardless of what materials are used. Regards
Colin Brookes...colb@xtra.co.nz
