7819RE: [Bulk] RE: [Bulk] [Weta-Trimarans] Re: Standing rigging, shrouds, side stays
- Aug 22, 2014
I’m sure you are correct. The “staining” I am seeing could be typical of having a barrier treatment and what you see is surface and not imbedded corrosion. With no barrier treatment, what you have experienced with imbedded corrosion is probably the norm. Guess this just reinforces to be vigilant and have some Tuff Gel and plastic washers in your repair and parts kit. If I do a thorough job with the washers and Tuff Gel, I typically see the fastener remain “clean”.
Regarding pivot bolts for rudders and tillers, I found that you want the pivot/working portion of the fastener to not be threaded but to be smooth shank. I’ve had rudders supplied with fully threaded bolts as pivots bolts and they broken while sailing (and your steering suddenly gets very weird). On my A-Class rudders, I have seen 10-24 fasteners used as pivot bolts and break. Upgrading to ¼-20 with the smooth shank in the pivot/working area is pretty bulletproof. That will probably one of the first things I look at on my new boat and possibly change if needed based on past experience.
From the evidence of the corrosion on my boat, I'd argue that galvanic corrosion between carbon and stainless steel is more than just on the surface.For example, one of the screws that fixes the tiller extension to the tiller sheered off completely at the point where it entered the carbon - although possibly not helped by the Weta Mk 1 method of attaching the flat universal joint to the round tiller without the Ronstan RF3136 "Round Tiller Adapter" to spread the load.
Also the pivot bolt for the tiller was so badly pitted and worn that I was pleased when cracks appeared in the rudder stock so that I had a reason to get a complete replacement. I do endorse putting a barrier material between then where possible.
Interesting article on Stainless Steel and corrosion here http://www.bosunsupplies.com/Corrosion/
On my 2005 Corsair tri, I’ve had to deal with a lot of galvanic corrosion issues where stainless and aluminum were bolted together with no barrier treatment. New Corsairs coming out of Vietnam seem to have a better QC program for this than the waning days in the California location (the new owners/management of Corsair are really on top of quality from what I have seen in the boats especially the new Sprints and Dashs). On carbon-stainless interfaces, the corrosion is more a surface staining of the stainless steel and I don’t believe the structural integrity of the metal is really compromised (other than it looks like s#&t). If I screw or bolt into stainless steel, I use thin plastic washers underneath a stainless steel washer at the mating surfaces and coat the threads of the fasteners with Tuff Gel. Tuff Gel is an excellent barrier treatment and seems to last longer than LanaKote.
I also bought a second hand boat from 2009 and I've often heard the Punggggggggggg noise which I've now identified as being from the T-balls not being properly seated in the slot - you can solve this by taping them in place before you hoist the mast - or leave a loop of bungee wrapped around the mast above the T-ball slots (put the halyards over it) and just bring it down over the stays to keep the T-ball in place while raising the mast - it will move up out of the way when you tighten them.I have had to replace one stay after one of the threads broke and another is looking a bit dodgy so probably worth replacing on a regular basis.
Anywhere where you have stainless-steel next to carbon should be washed with fresh water after sailing in seawater as the two materials create galvanic corrosion in the steel.
This is particularly prevelent in the pivot for the rudder blade, the stainless fittings on the tiller and the screws which attach the tiller extension fitting to the tiller (they have a plastic cover over them and so you can't see any corrosion but remove and replace annualy, I'd suggest). The fittings attached to the mast are also prone to the same corrosion.
Hope this helps
- << Previous post in topic Next post in topic >>