DiSCO Design Review Notes P. McGill 3Apr19 Present: Alana Sherman Dale Graves Paul McGill Jim Barry Chris Lovera Paul Roberts Ken Smith Brett Hobson Knute Brekke Andrew McKee * Knute - Why not pan in addition to tilt? Dale - Cost and complexity. * Paul R. - What about occluded objects? Jim - We'll choose our sites carefully, so it shouldn't be a problem. * ? - Will laser be bright enough? ? - We'll see. * Ken - Will you pick the best time during the tidal cycle to deploy? Jim - Good idea. * Knute - Tripod will never be level. Jim - That's okay, it's a pretty flat area adjacent to the rocks. Some tilt won't matter. Ken - Have you thought about making legs telescoping? Dale - Not for this first go. We'll address that if we have problems. * Ken - Why a SINGLE, NEW acoustic release instead of dual, proven releases? Jim - We're not worried, it's a shallow dive if there's a problem, and we need to save money. Andrew - Don't you have an "extra" Benthos release? Could you put one of each on? Jim - It's not really extra, we'll go with one for now because it's a shallow site. Chris L. - We may get more releases next year. * Knute - Why round flotation? Dale - It's cheaper! * Knute - Is there an ROV pull pin? Dale - Yes Knute - How do we recover the 300 lb weights? Nobody ever addresses this. Dale - That's up to you. Jim needs to answer this question (Jim had stepped out). Jim - Only if it's practical to recover, as stated in the Sanctuary rules. We could make multiple linked weights that could be brought up separately. Chris - Could we lower with a wire? Andrew - No, it's too light. Adding a depressor weight to the wire doesn't really help, either. Chris - Could you add weight after it's on bottom to add stability? Jim and Dale - Maybe, if needed. * Paul M. - What's your policy on diving with glass spheres? Knute - We don't have one. It's not a problem. * Knute - Eliminate float from recovery line. It causes problems. Dale - Okay. Andrew - Use a 3/4 braided line, 5 m long. Make sure frame doesn't come up TOO fast, as that causes problems when line surfaces second. Andrew - Can we have pressure release let the recovery line go when near surface? Brent - May still have problems with that, may still tangle. Dale - We'll consider this for version 2. Knute - Recovery line is big, and there's a lot of it. You might make a UHMW snap-in holder to organize the wraps. Dale - I can do that. Jim - can we add a safety safety line to be released on the surface. * Alana to Andrew - Is frame height okay? Andrew - It has to be less than Smith tripod, which barely fits. Dale - Why can't we use port crane? Andrew - It's more dangerous, less control, and crane operator doesn't have good visibility. I'll give you the vertical under-block clearance, which I think is 14 ft, but it depends on the shape of the tripod and how the feet catch on the edge of the deck. All - We don't think it'll be a problem. * Alana - Hard Nautilus connection between ROV and tripod is a risk. Knute - We've dealt with that before, and have designs to deal with that so connector will unplug if ROV goes dead. I can work with Dale on this. * Dale - Can we eliminate lift ring on top to save height? Andrew - Yes, possibly. Also remember that on recovery, you gain height because quick release isn't in line. Knute - You might want to keep the ring in case we have to add flotation for emergency recovery. * Paul R. - Will you want to do photogrammetry? You might want a scale or color standard in the field of view. Jim - Good idea, we'll talk.