Post a pic that makes you LOL

[boatgeek]

I guess it’s an excuse to over engineer everything.

Yes and no. You add a little more margin on power and resistance estimates. Where the boat has room to be heavier, you tend to add a little more structure or a little more fuel capacity. I do sometimes us engineering psychology (this foundation plate could be 1/4" steel, but the operators are less likely to cut out structure if I make it a little heavier, so I'll make it 1/2"). Of course, every pound of steel means one less pound of useful capacity, so you can't go overboard. It gets more difficult on high-speed boats which are more towards the aviation end of the scale where pounds really matter.

A very wise professor of mine said that "Engineering is the science of good enough." Meaning that you do your analysis, and you don't get too tripped up by not knowing every detail if you have sufficient margins and factors of safety. Of course, "sufficient margin" varies by what you're doing. For example, on a project of mine that is about to get launched, I'll be happy if the final as built weight is within 1% (~35 tons) of my weight estimate. That would be a totally unacceptable level of uncertainty in an aircraft or spacecraft. On a barge, it's fine.

 

[jqavins]

I guess it’s an excuse to over engineer everything.

It's the reason not to ask customers open ended questions. The question to ask is "What are the requirements?" If they respond with a shrug of the shoulders, then you can ask questions like these, tell them to go away and think about it, and come back with requirements. They ought to either have enough experience to answer or hire a consultant who does.

Of course, that goes for lots of engineering, but I don't know about naval architecture.

For example, on a project of mine that is about to get launched, I'll be happy if the final as built weight is within 1% (~35 tons) of my weight estimate. That would be a totally unacceptable level of uncertainty in an aircraft or spacecraft. On a barge, it's fine.

Depends on what kind of spacecraft; you might be surprised. For the comsats I used to work on, the mass, CG, and moments of inertia were followed month by month as the design and integration matured, with margin left for balance weights at the end. Fuel is loaded to use all available mass capacity, but before the fuel goes on and after the balance weights, 1% off prediction would not be bad. (We always remembered to load unused memory in the on board computer with zeros to save a little weight. )

 

[NTP2]

For example, on a project of mine that is about to get launched, I'll be happy if the final as built weight is within 1% (~35 tons) of my weight estimate. That would be a totally unacceptable level of uncertainty in an aircraft or spacecraft. On a barge, it's fine.

So what you’re saying is that you’re a bad engineer who can’t do mass margins right?

Ps this is a joke!!!

 

[brockrwood]

Mutant accessible bathroom.

 

[Sandy H.]

Yes and no. You add a little more margin on power and resistance estimates. Where the boat has room to be heavier, you tend to add a little more structure or a little more fuel capacity. I do sometimes us engineering psychology (this foundation plate could be 1/4" steel, but the operators are less likely to cut out structure if I make it a little heavier, so I'll make it 1/2"). Of course, every pound of steel means one less pound of useful capacity, so you can't go overboard. It gets more difficult on high-speed boats which are more towards the aviation end of the scale where pounds really matter.

A very wise professor of mine said that "Engineering is the science of good enough." Meaning that you do your analysis, and you don't get too tripped up by not knowing every detail if you have sufficient margins and factors of safety. Of course, "sufficient margin" varies by what you're doing. For example, on a project of mine that is about to get launched, I'll be happy if the final as built weight is within 1% (~35 tons) of my weight estimate. That would be a totally unacceptable level of uncertainty in an aircraft or spacecraft. On a barge, it's fine.

In the first industry I worked in, there was a rule that you had to justify the use of any bolt smaller than 5/8", as the thought was basically that even a big guy couldn't break a 5/8" diameter bolt. Obviously there were tons of places on the machine where smaller bolts were approved, but it was just a rule of thumb. I think typical plate thickness were in the 3/4"-1 1/4" mild steel range.

At my last job, there was no rule of thumb for bolt sizes, as they were so gigantic that there was zero changes for a big guy with a 10ft bar breaking them just due to the loads we were working with. 2" bolts were common. Plate thickness on that job were often in the 4-10" thick steel range and at times way thicker and alloy instead of just mild steel.

Crazy the things you get used to. . .

I think the reason I got the job was that when asked how big should the fillet weld be to join a 2"-ish plate to a 4"-ish plate, I said I have no idea, I've never done that. But it better be a multi-process bevel weld per whatever the book says finished with whatever the book says the fillet should be, a plain fillet weld is wrong for that implementation. The guy interviewing me laughed. I think he had heard the answer 2" way too many times because of rules of thumb that don't scale well. . .

 

[Cape Byron]

 

[Knundrm]

 

[Knundrm]

 

[Knundrm]

 

[Knundrm]

 

[boatgeek]

It's the reason not to ask customers open ended questions. The question to ask is "What are the requirements?" If they respond with a shrug of the shoulders, then you can ask questions like these, tell them to go away and think about it, and come back with requirements. They ought to either have enough experience to answer or hire a consultant who does.

For new design, we'll typically ask questions like "How much fuel capacity do you need" and "How much cargo capacity do you want" rather than the questions above. However, for a single trip stability letter (giving instructions for safe loading of the boat until the final stability instructions are approved), we often need to ask questions like that to try to bound the range of possible loadings, and we often get vague answers like the above. We will typically drill down to try to clarify, but it's often hard to extract the needed information. It's also frustrating how much vagueness there can be on what they're carrying two days before departure. Are you putting the owner's new truck on the boat to save paying freight, or not?!

Of course, that goes for lots of engineering, but I don't know about naval architecture.

The hardest thing to deal with is the uncertainty of the sea, particularly the North Pacific, Gulf of Alaska, and Bering Sea where most of our customers operate. There is a lot that we can design in but a lot also depends on the seamanship of the captain and crew.

Depends on what kind of spacecraft; you might be surprised. For the comsats I used to work on, the mass, CG, and moments of inertia were followed month by month as the design and integration matured, with margin left for balance weights at the end. Fuel is loaded to use all available mass capacity, but before the fuel goes on and after the balance weights, 1% off prediction would not be bad. (We always remembered to load unused memory in the on board computer with zeros to save a little weight. )

The unused zeroes is a big deal. It's also important to keep the fax paper tightly rolled so it fits through the wire.

So this project basically has three check-in points on weight. At the start of the project in late 2022, we used the weight of the previous version, which is exactly-the-same-except-different in a few relatively minor ways. About two months ago, we got final model weights by module (~24 modules) for structure. That's based on the 3D model that was used to develop the laser cut files. We added a few outfitting things not included in the model, plus margins for rolling (the steel mill usually gives you a tiny bit more steel than you paid for), welding, and paint to get the final estimated weight. The day after the barge is launched in early March, we'll use Archimedes to determine the actual weight. That should be within 1% of our final estimate.

For many projects, we use parametric weight estimates early and are happy to be within 5% error when we get to the end.

 

[Knundrm]

Regrettable tattoos ...

 

[Tyeeking]

View attachment 626944

We have lots of Blue Herons here at the lake and actually call them pterodactyls.

 

[boatgeek]

We have lots of Blue Herons here at the lake and actually call them pterodactyls.

I'll see your blue heron and raise you a pelican.

 

[Banzai88]

We have lots of Blue Herons here at the lake and actually call them pterodactyls.

Same here

 

[KenECoyote]

We have lots of Blue Herons here at the lake and actually call them pterodactyls.

I have a few that frequent my backyard dock in NY and once I was jogging and suddenly one flew out of the treetops! I wasn't aware that they roosted in trees.

They definitely remind me of a pterodactyl when they're flying!

 

[KenECoyote]

I believe a Blue Heron did this when it was flying over my car parked in my driveway...

About 2 years later I saw the same mess under a tree on the other side of my lake.

 

[boatgeek]

I believe a Blue Heron did this when it was flying over my car parked in my driveway...
View attachment 627075
About 2 years later I saw the same mess under a tree on the other side of my lake.

You can find the local heron nests out here by the smell. They often dump waste right after taking off, so if they were roosting on your roof, they'll make a mess of your car. It was seagulls, not herons, but my old office on the saltwater waterfront had a couple of parking spots we called the splash zone. Nobody parked there because at the end of the day the car would look about like yours above. Or worse.

 

[KenECoyote]

You can find the local heron nests out here by the smell. They often dump waste right after taking off, so if they were roosting on your roof, they'll make a mess of your car. It was seagulls, not herons, but my old office on the saltwater waterfront had a couple of parking spots we called the splash zone. Nobody parked there because at the end of the day the car would look about like yours above. Or worse.

The mess made was actually spread over maybe 20' x 30'. It got my front deck and even the door. No trees anywhere nearby either. When I first posted the pic of the mess no one could believe it was a single bird.

"Terror-shat-all"!

 

[Tyeeking]

I'll see your blue heron and raise you a pelican.
View attachment 627072

View attachment 627073

We seasonally (spring and fall) get migrating Pelicans as well. They’re fun to watch and love to travel together. Very majestic. The Blue Herons, however even sound like what I would imagine a pterodactyl sounds like.

 

[Tyeeking]

You can find the local heron nests out here by the smell. They often dump waste right after taking off, so if they were roosting on your roof, they'll make a mess of your car. It was seagulls, not herons, but my old office on the saltwater waterfront had a couple of parking spots we called the splash zone. Nobody parked there because at the end of the day the car would look about like yours above. Or worse.

Oh man that is so true. Sometimes they will roost on the covered dock. When they take off they make an incredible mess and must be a couple of pounds lighter.

 

[Hobie1dog]

I believe a Blue Heron did this when it was flying over my car parked in my driveway...

Okay someone explain why all bird poop is white...... instead of the brown normal color.

 

[jsdemar]

Okay someone explain why all bird poop is white...... instead of the brown normal color.

https://www.audubon.org/news/what-makes-bird-poop-white
Birdie birdie in the sky,
Why'd you do that in my eye!
Aren't you glad cows don't fly?
-Henry Gibson

 

[boatgeek]

https://www.audubon.org/news/what-makes-bird-poop-white
Birdie birdie in the sky,
Why'd you do that in my eye!
Aren't you glad cows don't fly?
-Henry Gibson

 

[OverTheTop]

Okay someone explain why all bird poop is white...... instead of the brown normal color.

I believe it is because of the urine mixed in with it.

Fun fact: Lizards and birds have similar digestive systems. You can tell the difference by the size of the splat .

 

[dr wogz]

It's the reason not to ask customers open ended questions. The question to ask is "What are the requirements?" If they respond with a shrug of the shoulders, then you can ask questions like these, tell them to go away and think about it, and come back with requirements. They ought to either have enough experience to answer or hire a consultant who does.

For me / us, it's always been "what does the competition do / meet / require?".. and we do 'just a little bit better'.. price / cost not included. (But it is a bonus to meet or undermine them with a slight performance / benefit..)

 

[les]

A very wise professor of mine said that "Engineering is the science of good enough." Meaning that you do your analysis, and you don't get too tripped up by not knowing every detail if you have sufficient margins and factors of safety

Another way to look at it is per the old saying (not necessarily PC, but .....)

In every project, there come the time to shoot the Engineer and begin production"

 

[dr wogz]

 

[kuririn]

 

[Cape Byron]