well, its one of the remaining files i promised with the design package. and maybe i am feeling a bit compulsive.
but it does show some interesting things. the centre of gravity is futher aft and lower than i would have expected as shown in the graphic below (note it excludes skipper weight)
the weight calcs result in the following numbers:
hull, paint, gantry = 11.87 kg
wings (alloy), tramps = 9.89 kg
foils, tiller = 8.50 kg
rigging, standing, running, control, mast, sail = 13.06kg
Total = 43.33 kg
This distribution is illustrated below.
this is clearly 6 or so kg overweight. as I have noted previously, changing the wings to carbon would save around 3 kg. changing to dacron tramps (rather than trampoline material) would save some too. and I need to change to carbon spreaders.
the remainder i think would need to come out of the hull. my construction method of laminating the seams of prefab panels results in a lot more bonding than a moulded boat (2kg i would estimate).
how else to save weight? maybe less hull, particulary in the foredeck. or if you were confident in your boat handling maybe a lighter panel laminate, like nomex and prepreg.
that rigging component is still a large piece of the pie. easy to see how a wing is viable from a weight point of view.
Chinchillazilla boys used a similar technique to make a female mold, then sealed the joints and bagged the hulls.
ReplyDeleteThose hulls and the Hungry Beaver hulls are wet layup over Nomex. A bit harder to make watertight than foam. They are plenty durable.
I am not sure the tramp material is heavier. I have both types so will weigh the old dacron when it comes off in favor of the polypro version. Kirk just replaced his and the polypro came out the same I think. Durability wise it is a no-brainer: lifetime vs. annual replacement?
Thanks for the numbers.
I don't think your hull is expecially heavy. Yeah you can build them lighter, but I think you'd find the production boats are in the 10-12kg region anyway. I'd say your wings and rig are the place to start...
ReplyDeleteCookie,
ReplyDeletemodern production hulls are around 8kg. Mark's rig is a bit heavy too, skinny mast is about 2.3kg, sail 3.5, boom 1.5kg and about 1kg for spreaders and stays. Carbon wings are around 5kg (you can check the numbers on the CST Composites web site), it all adds up.
I'm going to have to find someone happy to take a boat apart and weigh the bits now!
ReplyDeleteI was making 8 kilo Ninja hulls and noticing the difference when I picked up boats from 'other' manufacturers. Now I'm making 10 kilo hulls and making them chuffin' stiff instead! I suspect my wings are quite a bit lighter than the others as they are loads smaller though. Maybe I'll just knuckle down and take my boat apart...
PS - Yours is still lighter than a Bladerider RX!
ReplyDeletehttp://bristol-moths.blogspot.com/2010/01/weight-weenie-part-2.html
My weights are here:
ReplyDeletehttp://madmothist.blogspot.com/2011/11/try-foil-weights.html