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Jackett

Member Since 27 Mar 2011
Offline Last Active Today, 07:20 PM
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Posts I've Made

In Topic: This looks bad...

01 December 2015 - 08:09 PM

Come on you guys, lets be real here. Do you really believe that there wasn't an engineering study here? Of course there was.
Loads from the keel can be carried in part by the skin, but equally it's possible to design the structure so most of the load is taken by the structural frame, with the skin doing little other than keeping the water out.
Not saying the design isn't wrong. Something almost certainly went wrong with either design or construction. But after a lifetime as a marine engineer the one thing I've learned is that try as you might, occasionally mistakes happen. Most of us are lucky and our mistakes happen in a non spectacular way (and yes, that is just luck). If you're unlucky, things happen in a spectacular way, and worst case is someone dies. But any good designer who's honest with himself knows its an element of luck (plus the conservative nature of design codes) that has prevented this kind of thing happening to them, as much as technical ability.
Oysters response seems spot on. Why speculate until you know all the facts? As for not expressing sympathy with the crew and owner, that will be the lawyers. Sadly in this day and age, expressing sympathy can be taken as an admission of guilt in court (if someone steps in front of your car and you hit them, don't ask if they're ok - s far as the law is concerned if you do you've as good as admitted guilt)

In Topic: Cool 30-footer

30 November 2015 - 12:48 PM

Ignore Verboaten. Tell us more.


In Topic: My newest project

17 November 2015 - 12:56 PM

Bob,

 

Apologies if this has been answered elsewhere, but with 3510 posts to trawl through, hopefully you can forgive me.

 

Why does the backstay come down to a point on deck some way forward of the transom? Bringing it down to the transom would give a slightly better angle for tensioning the forestay, and would allow a bit more roach on the main (a bit more area on what is a smallish main for a heavy boat is always useful downwind). I know you'll have your reasons, I just can't work out what they are. 


In Topic: seabins

02 November 2015 - 01:06 PM

That's a huge volume of water that has to be pumped through for every bit of rubbish collected - even in a heavily littered area of water, think how much water their is for each item of litter. So that's a lot of energy required to power the pump for each piece of litter removed. 

 

Furthermore, it can only remove rubbish that is floating high on the water, with little draught (you'll note that they demonstrate it with an empty drinks can, that hasn't yet started filling up with water). Anything with a bit more draught won't get collected, and worse than that, will get held around the bin by the general inflowing current and once enough of this deeper draught litter (or even seaweed) has built up around the bin, it will block the lighter stuff from getting sucked in.

 

I've spent a good chunk of my engineering career either doing the engineering for 'green' companies, or assessing their proposals on behalf of potential funders. While all are well intentioned, unfortunately the vast majority are fundamentally flawed. While I'm going to give them the benefit of doubt, having not looked into the details of their proposals, I suspect that this is one that falls into the 'flawed' category.