Nasty rash!
Printed From: Yachts and Yachting Online
Category: General
Forum Name: Repair & maintenance
Forum Discription: Questions & tips on the subject
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=4136
Printed Date: 14 May 25 at 6:59am
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com
Topic: Nasty rash!
Posted By: Femto
Subject: Nasty rash!
Date Posted: 09 Apr 08 at 10:39am
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Ok you lot, this ain't pretty - I've got a nasty rash around me hounds..... Seeing as there were some pretty insightful and informed comments on the painting a boat thread, has anyone seen this before? The lacquer on the mast is smooth and sound apart from around the spreaders and hounds where it looks 'orrible! Not only is it flaking but it feels as though it has crystals growing in it. Someone told me it was 'carbon mite'- not sure to believe them. Any advice? Is it just that the previous owner used the wrong stuff and it isn't flexible enough around the high load points? Current plan is to strip it all back and re-do with two-pack.   ------------- RS600 717, RS400 870 Netley SC Kerr 11.3 (Pier View YC) |
Replies:
Posted By: alstorer
Date Posted: 09 Apr 08 at 12:51pm
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Are there any rivets in that joint? Looks like there's a couple towards the back of the mast in that top picture? if so, I'd be worried that they aren't properly insulated, and you've got some 'orrible galvinic effect going on there. Whatever the cause, you're going to need to strip back to redo it. be careful doing this, you need to avoid damaging the fibres. If you're stripping back and you do reach the fibres, and the resin still looks like that, then, um, that's a very bad thing. |
Posted By: Femto
Date Posted: 09 Apr 08 at 1:13pm
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Another pic showing the hounds below if its any help. I was also wondering about the galvinic effects of stainless bits into a carbon mast- as far as i know its a standard off the shelf RS800 mast so hoped such things would have been sorted at manufacture. The fibre layup below the lacquer looks fine and its had good ragging in 25knots recently so can't be that bad!! Anyone know the best way to strip the existing stuff off as i suspect sanding might be rather tiresome? Also any method to tell if it will react to two-pack over the top of any reminants? Cheers  ------------- RS600 717, RS400 870 Netley SC Kerr 11.3 (Pier View YC) |
Posted By: alstorer
Date Posted: 09 Apr 08 at 1:30pm
| That's pretty ugly, how old is it? That last phto clearly shows the problem extending along the fibre twills, which could be a cause of concern. |
Posted By: JimC
Date Posted: 09 Apr 08 at 1:30pm
Tell that to owners of the early RS600 masts... Ye canna ignore the laws of physics Captain... In theory there should be anti galvanic zinc paste under the fittings, but presumably that doesn't last for ever - it can't do if its going to work. In practice it has been known for people to forget. Carbon should erode the metals though as I understand it. I have seen rivets with the ordinary steel pins left in. You can usually tell by rust stains. Good to push those through if there are any.
I'd probably use a mixture of sandpaper and a stanley knife blade held at 90 degrees to the surface as a scraper for the very loose stuff. If its not loose you don't really need to remove it.... To test reactions - apply a small amount of vanish/paint and leave for 48 hours... |
Posted By: Femto
Date Posted: 09 Apr 08 at 1:47pm
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The boat is a fairly early one - 873, not sure if the mast is original,
it was refinished about a year ago by the previous owner. Been sailing 600s for several years now, so have seen and heard all about the problems with metal sleaves in the angel masts. I'm just wondering if all the effort of stripping back and reapplying is wise without sorting the problem- Any ideas how much someone like Ashdown marine would charge to strip, re-rivet and re-finish the mast? ------------- RS600 717, RS400 870 Netley SC Kerr 11.3 (Pier View YC) |
Posted By: JimC
Date Posted: 09 Apr 08 at 3:02pm
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The trouble is that replacing rivets, even if done well, is best avoided too... rivets and carbon masts don't really mix very well, even though there's often no choice.
The real fix is to have no metal fittings in the mast at all, which is impractical, and even reducing the number gets seriously expensive. This is why you see flash bonded carbon spreader brackets and all the rest of it on the development boats which aren't built down to a price so much. |
Posted By: Femto
Date Posted: 09 Apr 08 at 4:18pm
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Ok so whats the best fix here? - Get it professionally stripped and re-riveted? - Strip the flakey areas and re-lacquer? - Don't look up!? (would an insurer consider this lack of maintainace if the mast were to break?) Thanks for the advice so far! ------------- RS600 717, RS400 870 Netley SC Kerr 11.3 (Pier View YC) |
Posted By: JimC
Date Posted: 09 Apr 08 at 4:57pm
| I'd strip and revarnish. If the class rules are OK with it I'd paint the mast rather than varnish because I think its protects the spar better. |
Posted By: craiggo
Date Posted: 09 Apr 08 at 6:13pm
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It looks like the badly effected areas are near joins in the spars, and areas with fittings. It looks like the area may not have been properly prepared last time is was re-laquered and subsequently moisture has got in at the joins and fittings. The moisture will run along the fibres and when it freezes will expand lifting the local lacquer off of the carbon. Once warmed the ice will melt and it will carry on running along the fibres. As Jim says the corrosion usually occurs on the metal fittings not on the carbon.
The fix is to scrape off the old stuff and re varnish with International two-pot varnish. When you scrape and sand the old stuff off take it down until all the current coating goes a milky white colour, clean it up with a bit of acetone and then apply your new coating. The trick is to get right into the corners of fitting as this is where the problem has arisen. Slapping an extra thick coat on in these areas may look good initially but wont help the underlying problem, so make sure you prepare it well. Paul |
Posted By: SetSail
Date Posted: 10 Apr 08 at 12:21am
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off on a tangent slightly.....you should see my mast. the carbon has gone furry around the gooseneck and below. if im honest, the mast is a mess! original as well. came in not the best nick anyway, just waiting for it to give in! despite this, its still going strong and has had some stiff breezes to deal with  ------------- RS821 - Now for sale, PM for details |
Posted By: JimC
Date Posted: 10 Apr 08 at 8:22am
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I reckon Paul's got it. Something going wrong with the replacement finish was in my mind too and I reckon he's right, especially as to finishing.
Setsail, your mast could last for years yet and if you want to sell the boat first you'll be stuffed. Even if it goes you'll be unable to sail for several weeks while another one comes. Some preventative maintenance would make a lot more sense. I'd probably dampen the fibres with epoxy resin then squash them all down with parcel tape and finally revarnish or paint the entire mast as Paul describes. |