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Jeff H · 11-09-2003, 08:16

This does seem to be an issue of faith with you. To me it is a simple matter of engineering and understanding the materials involved. I do think that this is a good forum to have this discussion, where it can benefit more than just you and I and where others can provide substanative input into the discussion. From the email that I have recieved we are not the only ones reading and learning from this. That said, I am also open to exchanging email if you would prefer. My email address is burr.halpern@annapolis.net

To reply to your comments:

The thicknesses that I quoted come from the websites that you mentioned, literature from Hartley that describes their building process and are consistent with ferrocement design manuals.

Few marine surveyors have an engineering background. It is easy to mistake a thicker hull for a stronger hull. In recent years there have been increasing interest in the aging fleet of early FRP boats. These articles seem to universally conclude that these early laminates are decreasing in strength as the resins, which started out brittle continue to become increasingly less ductile and the reinforcements which also were less resilient show signs of fatigue. The insurance industry reports that this increased weakness is resulting in more expensive damage in comparatively minor impacts on older boats which is partially why you see more insurance companies declining insurance on older boats. I and my surveryor friends repectfully disagree with your survey. Some of these papers and articles are available on line.

As a former member of SNAME (Society of Naval Architects and Marine Engineers), I understand what it means to belong to SNAME and therefore be permitted to put SNAME after your name. I am not in disagreement with much of what I have seen quoted from Mr. Brookes. They seem to completely correspond to the points that I have made in this disscussion.

In any event, I think this has been a good discussion of Ferrocement. I think that it is helpful to understand the strengths and weaknesses of the various material options. I do not advocate that there is a universally right, one size fits all boat building material that will work for all sailors. (Heck depending on how you count them I have had boats built using 7 or 8 different techniques and materials so their wasn't even a universally right, one size fits all boat building material for even this one sailor.)

I am certainly open for any substantive information that you or anyone might wish to add to this discussion. I think that I learn a lot from this kind of discourse.

Respectfully,
Jeff (not Jay)

11-09-2003, 08:16	#17
Jeff H Senior Cruiser Join Date: May 2003 Location: Annapolis, Maryland Boat: Farr 11.6 (AKA Farr 38) Synergy Posts: 542	This does seem to be an issue of faith with you. To me it is a simple matter of engineering and understanding the materials involved. I do think that this is a good forum to have this discussion, where it can benefit more than just you and I and where others can provide substanative input into the discussion. From the email that I have recieved we are not the only ones reading and learning from this. That said, I am also open to exchanging email if you would prefer. My email address is burr.halpern@annapolis.net To reply to your comments: The thicknesses that I quoted come from the websites that you mentioned, literature from Hartley that describes their building process and are consistent with ferrocement design manuals. Few marine surveyors have an engineering background. It is easy to mistake a thicker hull for a stronger hull. In recent years there have been increasing interest in the aging fleet of early FRP boats. These articles seem to universally conclude that these early laminates are decreasing in strength as the resins, which started out brittle continue to become increasingly less ductile and the reinforcements which also were less resilient show signs of fatigue. The insurance industry reports that this increased weakness is resulting in more expensive damage in comparatively minor impacts on older boats which is partially why you see more insurance companies declining insurance on older boats. I and my surveryor friends repectfully disagree with your survey. Some of these papers and articles are available on line. As a former member of SNAME (Society of Naval Architects and Marine Engineers), I understand what it means to belong to SNAME and therefore be permitted to put SNAME after your name. I am not in disagreement with much of what I have seen quoted from Mr. Brookes. They seem to completely correspond to the points that I have made in this disscussion. In any event, I think this has been a good discussion of Ferrocement. I think that it is helpful to understand the strengths and weaknesses of the various material options. I do not advocate that there is a universally right, one size fits all boat building material that will work for all sailors. (Heck depending on how you count them I have had boats built using 7 or 8 different techniques and materials so their wasn't even a universally right, one size fits all boat building material for even this one sailor.) I am certainly open for any substantive information that you or anyone might wish to add to this discussion. I think that I learn a lot from this kind of discourse. Respectfully, Jeff (not Jay)