Also I see the pictures showing nice curved mast, so supposedly more awero dynamically shaped.  The shot up wards is giving plenty of bend aft, particularily above the forestay it bends a lot. Is this managed to be done on a straight laid up mast? So there was no pre3 bend put into the laying up in moulds during manufacture of it. What gives that shape most? The leech pulling above the position of the foretsya?   So That should be possible to acheive with mine too?   Doug --- On Mon, 21/12/09, Doug Haines <doha720@yahoo.co.uk> wrote: From: Doug Haines <doha720@yahoo.co.uk> Subject: [harryproa] ballestron booms To: harryproa@yahoogroups.com.au Date: Monday, 21 December, 2009, 18:34   Hello folks,   Do we not need to use some vangs for the balletrson booms (espoecially the jib boom)? With my clearance from the boom down to the deck now being so large I would make good use of a wire or solid tension rod froom the base of the mast (at deck height) out to the boom ends (or in a bit from the ends). Mostly the jib boom with its forestay tensio could use the vang.   I know thee will be more compression on the mast, but compression is not a big load problem. It would not get in the way either.   DOug.   Merry Christmas. Looking at new plans to go south about around March /April, rather than North this summer. --- On Wed, 16/12/09, Doug Haines <doha720@yahoo. co.uk> wrote: From: Doug Haines <doha720@yahoo. co.uk> Subject: Re: [harryproa] Re: ruddershaft construction To: harryproa@yahoogrou ps.com.au Date: Wednesday, 16 December, 2009, 19:02   i am sorting out keeping the tillers horizontal when in use - because now the tillers are hinged for the way the rudders swing up - so i am putting a fence to stop tiller falling down. otherwise seems ok. went around riverbend last hot easterly and used a windsurfer rig and the outboard. ran out of petrol, then seabreeze brought me back to              the yard.   what sort of tension is the forestay going to need?   Doug --- On Wed, 16/12/09, Doug Haines <doha720@yahoo. co.uk> wrote: From: Doug Haines <doha720@yahoo. co.uk> Subject: Re: [harryproa] Re: ruddershaft construction To: harryproa@yahoogrou ps.com.au Date: Wednesday, 16 December, 2009, 18:32   What style rudder are you doing Robert? --- On Wed, 16/12/09, robert <cateran1949@ yahoo.co. uk> wrote: From: robert <cateran1949@ yahoo.co. uk> Subject: [harryproa] Re: ruddershaft construction To: harryproa@yahoogrou ps.com.au Date: Wednesday, 16 December, 2009, 15:25   The bag blew because I forgot to replace the endplate of the mould when putting things back together for the fifth time. Sticking to knitted cloth would definitely make it easier. Some of it came out very nicely but there are a couple of sections where the tow slumped a bit in the stuff ups so there are some weak spots. The bits that worked are very strong and light, and I may be able to reinforce the weak face and use the rod for something like props to hold up the cockpit roof. I feel reasonably confident about getting the next one right. I will try making the Harriette shafts again and if I get it right have a go at the Harry shafts. Dealing with such thick walls will be some more learning. I can see what you mean by the differing forces if using carbon and glass for cross linking. The glass ends up not doing much and all the stress goes onto the carbon --- In harryproa@yahoogrou ps.com.au, Rob Denney <harryproa@. ..> wrote: > > Carbon cloth should not be any different to glass cloth, but both are more > difficult than (most) knitted double bias or biax. > > Not a problem on the little ones, but balance the laminate > (glass/uni/glass/ uni/glass etc) on the bigger ones or the laminate may twist > or warp when curing and will impart weird forces under load. > > Using carbon for the off axis loads is a pretty expensive way to save a few > kgs. On Rare Bird's mast, glass off axis added 18 kgs (mostly down low), > saved a couple of grand. > > Surprising the bag blew part way through the job. Could be caused by heat > from the laminate and a small bridge formed as the laminate settled into > position. Not much you can do about this except try to ensure there are no > possible bridges. > > The rest of the lessons are ones everyone learns when using bags. The trick > is to only learn them once! > > regards, > > rob > > On Tue, Dec 15, 2009 at 6:33 PM, robert <cateran1949@ ...> wrote: > > > > > > > Today I tried pressure moulding some Harriette rudder shafts. I learnt: > > that carbon cloth is a lot more difficult to handle than glass cloth; after > > setting up the pressure bag it is not a good idea to try and unseal it to > > let out a bit of air when one's hands have got some talcum powder from the > > gloves as it makes it very hard to reseal; also if things get sticky with > > resin the tacky tape doesnt stick as well; when taking apart the mould to > > re-seal the bag and then putting it together again, it is important to make > > sure the end plates are put back in before repressuring. . I managed to hold > > about two atmospheres for a while before the bag blew, so hopefully it will > > be good enough for a Harriette rudder shaft. If not, it was worth it for > > learning the mistakes before the Harry shaft. > > Things that went well: the wet out machine worked a treat, though only a > > couple of pieces of tow at a time to be able to pull through the guides with > > enough pressure to keep the resin ratio down ; the kitchen scales made it > > easy to get accurate mixing; the mould worked well and with different > > inserts can be used for a number of different sections including Harry > > rudder shafts, beam corner rods, and mini beams. Larger sections would > > probably be easier as there would be a better match between the pressure bag > > and the mould and there would be more space to work. In the larger sections > > I am thinking that the outside and inside cross fibres in glass would make > > it easier to control and just have the inner cross fibres in carbon. > > > > > > >