Guest Posted January 3, 2013 Share Posted January 3, 2013 Any Ross 930 owners out there have an idea what the design loadings are for the mast compression structure. Mine just failed under average wind and sea conditions and I want to rebuild it. Helpful to know what sort of loading I need to engineer it for. My inclination is to fabricate in stainless versus wood because its what i know best but if anyone has an opinion I will be interested to hear it. Cheers J Link to post Share on other sites
Guest Posted January 3, 2013 Share Posted January 3, 2013 Give Tony Smith the owner of Fast Company a call Jon. His went 3-4 years ago and he replaced it with a big lump of wood. He will be able to steer you in the right direction. Tony runs Westhaven Marine Brokers. 0275 4 BOATS (0275 426287) Link to post Share on other sites
all fired up 6 Posted January 3, 2013 Share Posted January 3, 2013 Grant Jenkins of Kiwi Rigging is the 930 rig guru. He did some very effective work on the rig of my 930. He may be able to advise you on your question. He can be contacted on 027 493 1682. His website is http://www.kiwirigging.co.nz a.f.u Link to post Share on other sites
Guest Posted January 3, 2013 Share Posted January 3, 2013 I have a bit of 4x4 Oregon under my mast. Zero sign of anything bad happening with it. Link to post Share on other sites
Guest Posted January 3, 2013 Share Posted January 3, 2013 Is that vertically under the mast? Or for and aft between the bulkheads? Link to post Share on other sites
Kiteroa 8 Posted January 3, 2013 Share Posted January 3, 2013 I would imagine you'd see around 4500-5000kg of mast step compression in your usual upwind trim with runners applied. If you're using tight luffed code zero type sails up wind you'll see more than the designed compression loads for sure. Link to post Share on other sites
Guest Posted January 3, 2013 Share Posted January 3, 2013 I would imagine you'd see around 4500-5000kg of mast step compression in your usual upwind trim with runners applied. If you're using tight luffed code zero type sails up wind you'll see more than the designed compression loads for sure. Thanks for that I was thinking 5000Kg would get me in the ball park. It does make the existing structure look a bit inadequate but the boat has survived many sea miles over its life so it can't have been that marginal. j Link to post Share on other sites
Kiteroa 8 Posted January 4, 2013 Share Posted January 4, 2013 I would imagine you'd see around 4500-5000kg of mast step compression in your usual upwind trim with runners applied. If you're using tight luffed code zero type sails up wind you'll see more than the designed compression loads for sure. Thanks for that I was thinking 5000Kg would get me in the ball park. It does make the existing structure look a bit inadequate but the boat has survived many sea miles over its life so it can't have been that marginal. j You should get real numbers from someone who's done the calcs if possible. I'm just guessing from what Wild Thing is engineered for, and some other similar boats I've had involvement with. The 930 rigs were well under cooked in their first incarnation, so there's a chance the boats step structure could be on the limit also. See if you can get the designed numbers from Murray Ross, then compare them to someones numbers with a new rig. There might be a gap! Link to post Share on other sites
Guest Saturday Night Special Posted January 4, 2013 Share Posted January 4, 2013 Being deck steped as long as the post under the Cabintop has a longditudinal seat well glassed into the keelson of the boat it should carry most loads seen ,The problem generally with modern light displacment boats is point loading and no load distribution for and aft and athwart ships and they crack badly under the Mast step on the outside generally due to the boats beam closing up under rig loads Link to post Share on other sites
Guest Posted January 4, 2013 Share Posted January 4, 2013 Is that vertically under the mast? Or for and aft between the bulkheads? Vertical under the mast. Knot all boats have 2 bulkheads, or in the odd case any bulkheads at all in the region. My bulkheads wouldn't support the mast without work. The post isn't in the way nor a pain, in fact it's handy to hang dunny paper off and to hold onto if Otto is driving while you are 'unloading ballast', he is a rough bastard As noted by others above, yes mine does sit on plenty of meat. Link to post Share on other sites
Changed 10 Posted January 5, 2013 Share Posted January 5, 2013 Are 930s not keel stepped masts. Link to post Share on other sites
Guest Posted January 5, 2013 Share Posted January 5, 2013 Are 930s not keel stepped masts. As far as I know all are deck stepped with structure underneath Link to post Share on other sites
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