tonyquoll Posted May 11, 2008 Report Share Posted May 11, 2008 Hi, The aluminium box rudders on my Paper Tiger would be OK, if the system of pulling the blade up & down worked. The current design has an over-centre level pulling a stainless steel cable, which is attached to eh wooden blade with a screw. When it's run aground, the screw rips out of the wood and the aluminium gets bent, as there's no give in the system. After repairing it four times, (because hitting jellyfish at speed also breaks it), I'm looking to improve the design. At the state titles I inspected all the rudder systems, and vote Trent Godfrey's rudders on 3042 as the coolest. These transfer the pull-down rope to the boat's deck via a special fitting on the boat's transom. The rope then has 2:1 purchase, with a stretchy O-ring at one end and cam cleat on the rear cross beam at the other. Elastic pulls the blade up. (photos available; cant seem to attach them here) Some other PT's had similarly ingenious designs, some even moving the pull-up rope to the front cross-bar. Is the transom fitting an off-the-shelf product or custom made? Does anyone recommend an alternative system? Regards Tony Hastings tonyquoll@yahoo.com 0427 534 548 Link to comment Share on other sites More sharing options...
h20melon Posted May 11, 2008 Report Share Posted May 11, 2008 Hi Tony, The first things I will say is to stop running aground! This will solve most of the problem. I cannot remember how Trent's rudders are setup exactly, but mine are like his. The fittings at the pintle isn't totally off the shelf. You will have to do a fair bit of manual work to make/modify existing fittings, etc.. If you would like more info, please let me know, I can write the process, and supply photos if you like. Neil NSWPTCA Link to comment Share on other sites More sharing options...
tonyquoll Posted May 12, 2008 Author Report Share Posted May 12, 2008 Thanks for the info. I have photos to work from, so will make custom fittings. The rudder system I designed & built for "Why Worry" has a massive elastic pull-up, lots of timber-on-timber friction & works a treat, but is a bit heavier than the aluminium boxes I'm now looking at. Y'no why I love the Paper Tiger? Keeping a hull flying, the mainsheet held tight, using the rudder to keep it balanced; push to round up in gusts and pull to bear off in lulls. Rising and falling with the wind, soaring like a pelican, at one with nature. awesome. [This message has been edited by tonyquoll (edited 20 November 2008).] Link to comment Share on other sites More sharing options...
h20melon Posted May 12, 2008 Report Share Posted May 12, 2008 Ah that explains it Well, if they break by just hitting a jelly fish then they definitely need fixing. Where I sail (Koonawarra Bay Sailing Club, Lake Illawarra, NSW), there's plenty of jelly fish, and some of them ain't small. The rope system works well. You just need to make sure you put a rubber ring in the system somewhere to take the shock of hitting something - I use a rubber ring from an exhaust system - they guys looked at me weird when I went into an auto place and told them I didn't need for a car. Neil Link to comment Share on other sites More sharing options...
tonyquoll Posted May 18, 2008 Author Report Share Posted May 18, 2008 Have decided on a simple and hopefully effective option: - nylon blocks (white breadboard) mounted between the stainless rudder gudgeon and the boats transom. These have a grove cut through which the rudder pull-down rope will slide through, and be guided onto the deck. More friction than pulleys, but friction here is OK; helps hold the blade in place. - micro-blocks on the ends of the pull-down ropes, providing 2:1 purchase - a rope with knot inside rear cross beam, through micro-block, tied to heavy-duty shock-cord elastic, about 500mm long tied into a loop. To operate, the shock-cord loop is pulled, the blade swings down, and the loop is attached to a hook on the end of the rear cross-beam. When fitting the rudder boxes, I might touch up the rudder pins with a mallet to align them in a single vertical axis (as the top one is now 12mm further back from the transom). Hopefully this touch up wont be necessary, as there is enough gap in the rudder fittings. Compared to using the car exhaust rubber donut for 'give' on impact: - the longer length of shock cord maintains gradually increasing force over about 200mm stretch. This should allow the blade to rotate backwards about 45 degrees, with about 300mm added clearance at the bottom of the blade. The elastic force is in the range of 10kg increasing to 20kg, which will be doubled by the 2:1, with some friction helping hold the blade in place. With that much stretch, a cam-cleat seemed unnecessary if the lengths are tied correctly. However, operation will require reaching back much further to the transom than the cleat system. - a rubber donut stretches about 80mm maximum, with force greatly increasing with stretch. This seems likely it would only allow about 10 degree blade rotation, with not much gain in clearance at the blade's tip. If there's anyone with an old 'tiger looking to upgrade to this type of thing, I can send photos once the system is fully installed and tested. Tony Hastings tonyquoll@yahoo.com Link to comment Share on other sites More sharing options...
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