I’m going to jump out of one of the threads below and offer some thoughts on engineering from the perspective of one who has spent his adult life designing the kind of things most of us here entrust our live to when we cast off the lines.
I’m not a trained engineer, having gotten sort of accidentally into naval architecture, but I’ve done a lot of engineering. Having to do it with simpler mathematical tools than most has forced me to often look deeper, or at least differently, at many problems. I did the research on sailing vessel stability that was a primary source for the establishment of regulations for sailing school vessels and developed the basic methodology of modifications to the existing passenger vessel rules. While meeting with USCG naval architects, it became apparent that graduates of some of the best marine engineering schools in the country did not actually have a clear idea what the numbers we were working with actually meant in terms of real wind striking real sails at sea. Their understanding ended with the number at the end of a complex calculation and how it compared to another number. It was illuminating and frustrating.
I’m sure some of you think I’ve been beating around the bush in my postings about one of the recent accidents for fear of being sued. There is the wonderful freedom of the layman in being able to come right out and say the obvious but that’s not what is at work here. It is a more nuanced perspective on what engineering and vessel design involves.
Someday, if there is a web page of my famous quotations, it will say right under, “Eggs don’t cause chickens.”, “Good engineers understand that numbers are only a guide to their judgment; poor engineers believe the numbers.”
Was the keel of that boat strong enough? Well, it sailed many miles and survived numerous (according to reports) groundings. Clearly, it was strong enough for something. It’s the “something” part of that equation that is the essential factor in designing things like boats but the emphasis is almost always on the other part.
Bridges are different. You can post a sign saying “No trucks over 10 tons.” If someone tries to sneak a 40 ton truck over and it breaks, you can blame them. With boats, you are designing bridges where a truck of almost any weight can come down the road. It becomes very statistical and “strong enough” becomes much less of a computational question than is commonly realized.
Often, the true nature of a structure isn’t revealed until it fails which is why testing to destruction is an essential part of may engineering development programs. If your vessel was rolled by a large storm sea, you wouldn’t necessarily expect to come up with the rig intact. You could well expect the mast column to buckle, stays to break, rigging pins to sheer. You might feel very differently however if the boat came up with all that stuff intact and big chunks of the deck torn out with the chainplates. It might be more critical than just your feelings since, in the former case, you would have something water tight and a base for erecting a jury rig. In the latter, you might well sink before you could stabilize the situation.
These relative relationships between the strengths of various components are often more critical to life and death than the absolute strength of a single component such as keel bolts.
I’m not a trained engineer, having gotten sort of accidentally into naval architecture, but I’ve done a lot of engineering. Having to do it with simpler mathematical tools than most has forced me to often look deeper, or at least differently, at many problems. I did the research on sailing vessel stability that was a primary source for the establishment of regulations for sailing school vessels and developed the basic methodology of modifications to the existing passenger vessel rules. While meeting with USCG naval architects, it became apparent that graduates of some of the best marine engineering schools in the country did not actually have a clear idea what the numbers we were working with actually meant in terms of real wind striking real sails at sea. Their understanding ended with the number at the end of a complex calculation and how it compared to another number. It was illuminating and frustrating.
I’m sure some of you think I’ve been beating around the bush in my postings about one of the recent accidents for fear of being sued. There is the wonderful freedom of the layman in being able to come right out and say the obvious but that’s not what is at work here. It is a more nuanced perspective on what engineering and vessel design involves.
Someday, if there is a web page of my famous quotations, it will say right under, “Eggs don’t cause chickens.”, “Good engineers understand that numbers are only a guide to their judgment; poor engineers believe the numbers.”
Was the keel of that boat strong enough? Well, it sailed many miles and survived numerous (according to reports) groundings. Clearly, it was strong enough for something. It’s the “something” part of that equation that is the essential factor in designing things like boats but the emphasis is almost always on the other part.
Bridges are different. You can post a sign saying “No trucks over 10 tons.” If someone tries to sneak a 40 ton truck over and it breaks, you can blame them. With boats, you are designing bridges where a truck of almost any weight can come down the road. It becomes very statistical and “strong enough” becomes much less of a computational question than is commonly realized.
Often, the true nature of a structure isn’t revealed until it fails which is why testing to destruction is an essential part of may engineering development programs. If your vessel was rolled by a large storm sea, you wouldn’t necessarily expect to come up with the rig intact. You could well expect the mast column to buckle, stays to break, rigging pins to sheer. You might feel very differently however if the boat came up with all that stuff intact and big chunks of the deck torn out with the chainplates. It might be more critical than just your feelings since, in the former case, you would have something water tight and a base for erecting a jury rig. In the latter, you might well sink before you could stabilize the situation.
These relative relationships between the strengths of various components are often more critical to life and death than the absolute strength of a single component such as keel bolts.
Carbon fiber makes a lot more sense for highly loaded areas where the deck stiffness and strength need to be increase.