I got a "coaching session" with Shane from Southport Yacht Club.
Really all I needed was a rescue boat to recover a broken boat or a broken me but a coaching ses was the best option.
He managed to get a few great photos at the same time.
He says he was trying to catch the crash, but each time was a bit pre-emptive, capturing these photos. They clearly show the boat about to fail, but to the untrained eye they are quite impressive. Especially this one below with the leward wing tip out of the water.
In the above photo I think I was trying to round up out of a crash. Amazing how sensitive the tiller is when out of the water.
I don't think the rudder was lifting enough. As the boat would rise up, it maintained a large attitude followed by a large crash. Didn't manage to make the boat fly level yet. I think part of the trouble is once it was in the air I got excited and didn't know what to do next.
The gantry needed a fairing. The roosters tail is evident in the above photo. Huge drag thingy. Not that that matters now.
I swapped with Shane. He after one crash he had it flying straight and level for around five seconds before the gantry declared itself not quite leet enuf.
It broke right on the point where the inserted single skin stops. Before anyone else says "you should have tapered the single skin insert out" I didn't see the need, as the unis should have been so much stiffer than the E glass mulsh inserted for bearing strength.
What is really interesting is how double bias just self destructs when it fails. Looking at the way he double bias has delaminated between it's uni plys demonstrates why people still build with woven cloths, atleast failure doesn't progate as rapidly/catestropically - Not that that would have saved this. Time to weld up a thin walled stainless gantry I think.
I have Alan's old gantry which came with the foils. I think I will have a go at hacking them up to suit this weekend, and may make it onto the water on sunday. Failing that I have booked another coaching ses. for next wednesday.
Go the thin walled rostfrei gantry! Much easier than alu! Please post tubing dimensions!
ReplyDeleteBoner Pirate looks awesome on the water. Well done. With the boat getting too high the first thing you need to do is put some more lift on the rudder to get it flying level. Once you have level flight you might find that you need a shorter wand (if you can make it adjustable length on the water it’s easiest to find a good length – but this will also vary with conditions).
ReplyDeleteRegarding the gantry failure you may have been ok if you had wrapped the edges of the panels with some cloth at 45. a 30mm x 5mm bit of 80kg foam doesn’t have much shear strength. Might be for the best anyway, the photo whilst low riding it looks like your dragging a bucket around behind you.
I hope you get something sorted for the weekend.
Cheers
The fix for the drag bucket would have been easy, just put a thin panel across the two triangles. Or wrap tape around it, closing off the top as well as the bottom.
ReplyDeleteIf I get a pipe one welded up I think I will put a flat plate across the bottom tube to deflect the water down.
The ritual sinking was sadly a floating
ReplyDeleteI know how you feel having broken 5 Gantry's over the last 3 months.
ReplyDeleteI think BR have it right with an alloy gantry. I just had one made for me and it I have to say that it so alot stiffer than the Fastercraft tube gantry and the laminated foam gantry I made much the same as yours.
The torque produced by the rudder when it is off centre is much more than anyone ever thinks, and that's where most of mu failures have happened.
If you need any help with this, I'm more than willing to help with my experiences.
Out of all of my options I think alloy tube is at the top of my list.
ReplyDeleteYes, I would like to email you, mostly to discuss fabrication details and supplier.
could you please ping mr.markla at gmail . com and I will be in touch