mrblenny Posted March 17, 2010 Report Share Posted March 17, 2010 Hi again, Just when I thought a good weekend of sailing might be coming up a cyclone comes off the QLD coast! So I thought I should finally fix a minor leak on the Hydra, in particular the bottom rudder hinge point on both hulls eg http://picasaweb.google.com/mrblenny/March#5449339713552403730 You can see the cracks forming from the constant motion the hinge is under and I have no doubt a bit of liquid is coming in at that point. However I have no idea on the best way to fix. A previous owner just put silicone around the metal (it had perished so I just pulled it off) which makes me think it is harder then unscrewing it. Does anyone know if it is standard design to have some sort of metal backplate and a locking nut on the inside, or is just coarse screws straight into the fibreglass? I suspect there might be locking nuts as one screw turns loose but does not move in or out, in which case silicone around might be an option as opening up the hull sounds complicated for someone of my limited skills Cheers, Damo Link to comment Share on other sites More sharing options...
tonyquoll Posted March 17, 2010 Report Share Posted March 17, 2010 Typical is to have 1/4" stainless bolts with the biggest washers you can get on the inside, with nylocs. You might need to drill the holes through pintle larger to fit them (if they only have 3/16). You're right these take a huge amount of force, which has caused all that cracking and leaking. Ideally you'd replace the fitting with one that has a larger footprint, to distribute the load better. Not sure why parts manufacturers dont seem to make decent gear for this. A carbon fibre unit that include both top & bottom pintles would be ideal. On an old cat some strong-wind sailing ripped the entire lower pintle off the boat, leaving a fist sized hole in the transom. Watch out for that one if your's is weakened! To repair it I made aluminium plates that reinforced the inside, from top to bottom pintle, and patched in some ply to replace the missing fibreglass foam. To 'open up the hull', hopefully there are hatch covers on the deck that you can just unscrew and reach in. If not you'd have to fit some. http://www.binksonline.com.au/store/prod646.htm Something like; trace a circle with marker, drill a hole, cut the circle with jigsaw, glue fitting in with "Sikaflex" & dont use any screws. If anyone has other ideas please jump in; maybe I can improve my methods too. Good luck with it! [This message has been edited by tonyquoll (edited 17 March 2010).] Link to comment Share on other sites More sharing options...
Slowpoke Posted March 17, 2010 Report Share Posted March 17, 2010 Damo, Looking at your photo, I think you might want to check the alignment of the holes in your rudder pintles. If they are not in alignment with each other (verticle) it will put undue pressure on the fittings and could be causing the cracking. As far as the glass repair procedures I will leave that to someone with more experience. Gary Link to comment Share on other sites More sharing options...
Loose Change Posted March 17, 2010 Report Share Posted March 17, 2010 Originally posted by mrblenny: Hi again, Just when I thought a good weekend of sailing might be coming up a cyclone comes off the QLD coast! So I thought I should finally fix a minor leak on the Hydra, in particular the bottom rudder hinge point on both hulls eg http://picasaweb.google.com/mrblenny/March#5449339713552403730 You can see the cracks forming from the constant motion the hinge is under and I have no doubt a bit of liquid is coming in at that point. However I have no idea on the best way to fix. A previous owner just put silicone around the metal (it had perished so I just pulled it off) which makes me think it is harder then unscrewing it. Does anyone know if it is standard design to have some sort of metal backplate and a locking nut on the inside, or is just coarse screws straight into the fibreglass? I suspect there might be locking nuts as one screw turns loose but does not move in or out, in which case silicone around might be an option as opening up the hull sounds complicated for someone of my limited skills Cheers, Damo Hi Damo, I also would be inclined to put an inspection port in the boat as Tony has suggested, but I would be more inclined to mount it on the inboard side several inches forward of the transom rather than on top, it will be easier to seal on the side due to being flat and I would use screws as well as the Sikaflex. Lastly I would place a piece of marine ply about .5 inch thick on the inside of the transom and make it big enough to cover both and extend beyond both top and botton pintles. Clean the inside as good as you can with rough sand paper and epoxy the ply in place, holding it with the pintle bolts and has been pointed out, using the biggest washers you can find, even to the point of making your own, keeping in mind if you make your own and of course you are using stainless steel and need to drill holes drill at the slowest possible speed and plenty of lubricant. Use the pintle pin to align the top and bottom holes accurately. After that is done then you can think about repairing the outside. You will of course need to take the bottom pintle off again to effect a good repair. Link to comment Share on other sites More sharing options...
madboutcats Posted March 17, 2010 Report Share Posted March 17, 2010 I think the ports will work better on top if you want one, they'll probably suck water and make resistance with waves on the side. Aluminium backing plate will work better than ply as the ply will compress over time and soak up water causing slack in the pintles, stainless would be even better as it wont react with your stainless bolts. You'll have to sand off the gelcoat where the cracks are and fill that surface level with proper cloth and resin or the pintle wont hold the rudder straight, when your using the resin you can fill the bolt holes and redrill holes that hold your rudders perfectly balanced in line with your centreboards if you have them. If you don't want ports just cut a hole on top at an angle do your job then resin the top back in. Link to comment Share on other sites More sharing options...
QB2 Posted March 17, 2010 Report Share Posted March 17, 2010 Use an aluminum backing plate and glass it in. The average drill bit is not tough enough to get through stainless steel in one go,(Not unless you are prepared to resharpen the damn things constantly, etc or buy a heap of excy super sharp new ones). Some perfectionists would run a thread tap into the aluminum but it is easier to drill a hole and push a SS bolt through. Glass over the backing plate so you have the washers and bolts contacting glass/resin and not the aluminum. You will still get some electrolytic corrosion but only on the bolt thread running through the plate. Some marine grease will help out there. Link to comment Share on other sites More sharing options...
mrblenny Posted March 17, 2010 Author Report Share Posted March 17, 2010 Ah, thank you everyone for your replies. Looking at my hulls it seems there might be a panel that can come off if I cut away the sikaflex (?) bead. You can just make out one line in the top right of the photo. There is already a nice hatch (with attached compartment to keep things away from hull) but it is sitting forward of the dolphin striker. The job seems reasonably simple so I will give it a go when the maintenance season comes along in the winter months. Thanks again, Damo Link to comment Share on other sites More sharing options...
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