Ever wondered about tank testing of the Flying Fifteen and computer simulation of the same??
Well, click here and take a look!
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Echoing completely what Ritchie has posted, one has to take the hoist seriously. Its not just the hoist but its attachment to wherever you hang it from and the strops you use.
I used a 1 Tonne Chain Hoist (Screwfix part number 46883). Electric hoists have a reputation for all happening too quickly – more like dropping the boat than lowering it. For strops and certified shackles, I got these from Load Straps and Slings http://www.lss1.co.uk/. The hoist is hung within the loft space above the garage on a specially constructed frame to spread the load over two rafters – I needed the extra height so that when lifting, the hoist hook doesn’t crunch up against the bottom of the chain hoist – also, so that the bit of chain you pull on leads outside the boat at a reasonable angle. Width of the strops is a compromise; obviously needs to be strong enough; narrow enough to get into the hooks and shackles; wide enough not to chafe on the boat
Its all worked well, nothing has collapsed. Keel has been taken off and returned; I’m not going to claim that job is easy but its all controlled with a decent hoist. Also, the hoist got used for turning the keel over onto its painting frame – there was a ‘moment’ doing this turn, but everything held together and no bones where broken – the shock-load of the ‘moment’ would surely have demolished an improvised arrangement.
Tips: you’d be surprised how much the boat blows around, even in the wind with the garage door open – needs stabiliser ropes. Get the strops the right length and when you’ve found the balance points, mark the hull so you can tie the strops back in position repeatably – strops need to be tied for and aft
Last point: for sorting dings in the keel, I prefer to jack the boat clear of the trailer and put blocks under the tail of the keel; that way is all stable to leave while fillers and paint dry
Martin Stainsby (3912)
To my surprise, one of the most frequently downloaded documents on the FF Blog is the one about Keel Refurbishment, written by Phil Tinsley, Commodore of Datchet. Setting aside Phil looking at it often, it was still downloaded 905 times in the last three years…..
Well, it’s a serious job as we all know. One of the problems is the handling of the keel once it is off the boat. At Datchet we have a frame in which the keel can sit, but it’s a bit Heath Robinson to tell the truth.
David Williamson has kindly sent in a couple of photos of the very neat keel support they used to mount the keel on his new boat. Very simple – needs to be tailored slightly for each trailer maybe, but very effective.
Following the recent article from John Hanson on packing for the Hong Kong Worlds, Adrian Simpson has kindly sent in these photos from the 2005 containerisation – photos from both Hayling and Kendal.
I see that the Army were persuaded to lend a hand that year…. boats and boys toys all in one weekend!!
This container had special built frames, I notice…
I’ve never actually seen the container packing happening, have you? John Hanson (Datchet Water SC), kindly sent these few photos in of the whole process.
It’s a big commitment for everyone involved too – a return container ticket for one boat is around £1,500.
Here’s how the Association stacks four in a container…..
1/ Put the Keels to bed for two boats
2/ Step two – get the top bunks loaded
3/ Get the first bottom “bunk”in place (nose to nose)
4/ Get all four aboard
5/ Seal up and ready to go
To load 4 boats to travel takes about two hours, John says.
Good luck in Hong Kong!!!
You will need to check with the guys in Cowes, but I’m fairly sure they milled a pattern with a CNC machine and used this to cast their keels. I also think they hang on to the pattern and keep it in their workshop which stops it being mistreated at the foundry.
I know Ovingtons get keels cast as well as Iron brothers, but don’t know if they all come off the same pattern.
Anyhow an iron keel ain’t that much of a precision instrument, I believe when the holes are drilled for the bolt holes they are just drilled any old how at he foundry. So all the art is in the finishing and putting the thing on straight! I think that’s worth paying money for!
The first person who mentioned CNC Milling of keels to me was Charles. I had to go and look it up!! “Computer Numerical Control” is what it stands for – and CNC milling is I guess a vertical milling machine that can reproduce a 3D object from a digitised image….
(Some reader is bound to correct me – but here is the wikipedia entry )
We’ve all heard stories in the bar about the old mould for our class producing twisted and overweight keels – and how they had to be worked by the craftsman’s hand to make them true. Then we will have all heard something like the mould for Aussie keel was imported here so that we could cast ‘true’ keels and get them to minimum weight easily. In fact, I think I might have had the first of these on 3934 in the autumn of 2008. Then have you seen the beautiful sculpted shapes and winglets that have been appearing too?? All this is basically an art form by artisans – so when is science going to arrive, you may wonder?? Well, I think the answer maybe “any moment now….”
As you will all know, we can now simulate drag, windage and all that stuff on a computer now, way before having to build anything in real life. The keels are still cast in sand, like the Romans did, and there is a tremendous labour content in casting and finishing our keels – did you know a new one costs about £1,500 by the time you get it under a hull? Well, the Blog has heard that P&B have two experimental CNC keels under wraps. They have digitised the shapes and are starting to try and figure out more systematically what the optimum might be. And we might actually get cheaper keels maybe?! In this case I think the CNC milling machines are used to create an acrylic plug, from which the lead keels would then be cast.
What might we expect?? Well nobody has ever been definitive about the best tapering bulb shape – and there must surely be an answer that’s not “forty two”!! The thing I recall Charles pointing out is that the flow line of the keel must bear some kind of relationship to the waterline of whatever hull it sits beneath. You would think for example that the central fore and aft line through the keel needs to be parallel to the waterline for example – well, who have we ever heard being definitive about that? Especially when we went from Mk 9 to Mk 10 hulls which float a bit differently. Hmmmmm …. well, hopefully, we are about to find out. And I bet it’s not forty two…..