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  1. buoy

    Reliability of prototype

    Since we are basically a R&D startup trying to develop a new technology, we have limited $$ and test time (and expertise). So we have identified some key components based on past failures and tested those. But our device is complex and there are many more components/assemblies that we can't test...
  2. buoy

    Reliability of prototype

    Not making things up, just not communicating the problem well (taking a component designed for controlled conditions and using it in a marine environment where you can get 'Perfect Storm' conditions).
  3. buoy

    Reliability of prototype

    "It uses off the shelf components in ways that differ from typical usage": for example, we are using parts not designed for a marine environment, one aspect of which is that waves produce variable rather than cyclic loading (i.e. amplitude and period are not constant). We just have an atypical...
  4. buoy

    Reliability of prototype

    We are developing a new product. It uses off the shelf components in ways that differ from typical usage, so it is hard to get accurate information about component life. Because the design is still being refined, we will not be building and testing multiples for a while. Is this too early in the...
  5. buoy

    Map of offshore oil & gas operations

    I am looking for a global map that shows the areas of world which have active offshore oil & gas operations, and that also indicates how much activity is going on. It just needs to communicate where oil & gas activities are taking place in the world ocean. If you could suggest a link or source...
  6. buoy

    How to estimate the period associated with the 100-year wave?

    I found the article 'Joint modelling of wave spectral parameters for extreme sea states' by P. Jonathan, J. Flynn, and K. Ewans, which discusses how to estimate extreme Hs and associated Tp. My method above should not be used. I will be trying to implement this using the tools in the WAFO...
  7. buoy

    How to estimate the period associated with the 100-year wave?

    I know how to estimate the 100-year wave height from a time series of wave measurements, but not how to estimate the wave period associated with the 100-year height. Let's say based on a 20-year time series of sea surface elevation measurements, the 100-year height is estimated to be Hs=15m, but...
  8. buoy

    C02 emissions from vessels using EPA's empirical relation

    I am trying to calculate the daily C02 emissions from a ship following this EPA report. Table 5-1 lists the C02 emission rate to be 44.1/(Fractional Load) + 648.6 in units of g/(kW-hr). Here are my questions, 1) What does the kW in the units represent? The ship engine's power output? My...
  9. buoy

    Directional width for swell vs. wind waves

    This question concerns a property of the directional wave spectrum, namely the one-sided directional width (sigma), which describes the amount of directional spreading of waves. Sigma is like a standard deviation of the wave direction. There are other ways to measure directional spread but sigma...
  10. buoy

    From engineer to manager

    Here are two useful articles that I dug up on this topic, Geek in the Lead Can a Good Engineer Make a Good Project Manager?
  11. buoy

    From engineer to manager

    Any thoughts on the fact that my team members will be smarter and more technically skilled in many areas than myself? I suppose I ask them for the big picture so I can make project decisions, and let them own the execution.
  12. buoy

    From engineer to manager

    I am about to transition from being an engineer to managing a small group of engineers. I would love recommendations for books, professional organizations, or other resources on managing an engineering team. I really liked this article. Presently I plan out and manage my own efforts, but soon...
  13. buoy

    Marine mammal guidelines for mooring design

    Can someone point me to a standard for mooring design that ensures that marine mammals do not become entangled? I am thinking specifically of a bridle or other "closed loop" in a mooring system, and want to know what loop diameter would be large enough that marine mammals cannot become entangled...
  14. buoy

    How to tell if a return period value is a good estimate?

    You are exactly right. I have been working through 'An introduction to statistical modeling of extreme values' by Stuart Coles - highly recommended. On p. 57, 'estimates and their measures of precision (i.e. the confidence interval that I was looking at) are based on an assumption that the model...
  15. buoy

    How to tell if a return period value is a good estimate?

    What I want is some metric indicating the fit is poor, and that metric is *not* the confidence bounds, I think. Instead I think the confidence bound is a measure of how noisy the fitted data is. So perhaps a better measure of fit goodness is the RMS value of the difference between the fitted and...
  16. buoy

    How to tell if a return period value is a good estimate?

    I am using the helpful package WAFO to estimate a survival load for a structure, but I am having trouble interpreting the results. Background:I have a measured time series of the load, and I identify peak values using the "peaks over threshold" method. The identified peaks are then fit to an...
  17. buoy

    Wave Energy Project

    Similar to offshore oil and gas, using 100-year wave, wind, and current conditions seem to be common. DNV gives nice guidelines on this.
  18. buoy

    Why is 3 hours sufficient for extreme statistics?

    In thread311-297005, I asked about the standard use of a 3-hour return period to determine the maximum load occurring in a 100-year storm (e.g. Hs=15m). The underlying assumption is that when a 100-year storm occurs, you want your structure to survive the worst load expected to occur if the...
  19. buoy

    What are the units of mechanical wear?

    I found a nice overview of cumulative damage theory at the link below. http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CCAQFjAA&url=http%3A%2F%2Fwww.dtic.mil%2Fcgi-bin%2FGetTRDoc%3FAD%3DAD0758414&ei=5nZPUMbjO8qmrAeX64DAAQ&usg=AFQjCNGt3izvQ472agqe8bAbtnhnycYcFQ
  20. buoy

    What are the units of mechanical wear?

    ...doubling the load reduces the life to 1/8, and the wear is applied over the total distance the bearing moves, which leads to units of [Newtons^3]*[Meters]. I will try to get better oriented and repost once I have the big picture. But I still don't "like" these units since I can't relate them...

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