Duet’s Mast Refurbishment 2014

March 12, 2015 at 12:12 pm

If you’ve been with us a while you might remember that my re-launch last summer was delayed due to some issues with the mast and rig .  I documented all this starting here, but basically the rigging was a bit of a mess as there had been corrosion on the bottom of the mast so the previous owner had had the bottom 2 inches cut off the mast, and then rather than re-adjust the rigging, a professional(!) yard shortened the chainplates, except they couldn’t do the forestay due to the roller reefing so she was left with dreadful mast rake.  I stepped the mast myself, and then found that the yard didn’t have a crane or any means of re-stepping the mast, so I spoke to a local rigger who took one look at my rig and condemned the lot (even though, unbeknown to him, the standing rigging was 5 years old and had barely been to sea) …So to cut a long story medium length, although at one stage it had looked like I might be able to procure a second hand 1 year old mast from a salvaged Newbridge Navigator, in the end the rigger was too busy to be able to fit in my work in a time frame that I was happy with so I have ended up doing Duet’s mast work myself, and re-stepping the original mast myself using an A frame.

But do you know what? It wasn’t actually that difficult in the end… And I know I saved myself a lot of money.

1) After lowering the mast from the deck to the ground (with help from some other boat owners in the yard!) I took off all the standing rigging and removed the brittle plastic sheathing before washing it all in a solution of oxalic acid, and then I rinsed it clean so that I could take a close look at it and make sure that there was no corrosion or broken strands.

2) To start with, after checking all the rigging over for loose strands, I decided to have some new cap shrouds made up with proper swaged fittings and new bottle screws.  The bottle screws on Duet are of unknown vintage as I know they were not replaced last time the rigging wire was replaced (in 2009).  The cap shrouds are pretty vital for the integrity of the mast and were only talurit spliced, and I wasn’t happy with the quality of the splice on one side, so in a rationalisation of peace of mind versus finances I decided to replace the caps this year with a swage fitting, with a view to perhaps replacing more next year. These were given to Bussells who made up some new ones to their length.

Old Cap Shroud, and dodgy looking crimp on the talurit splice.  See the gap in the wire?

Old Cap Shroud, and dodgy looking crimp on the talurit splice. See the gap in the wire?

3) With the mast on the ground I discovered that the mast cap was rather disconcertingly wobbly.  I wasn’t sure if it was supposed to be like that and so a made a video and posted it to the Hurley Owner’s Association Yahoo Group to get some advice. Here it is:

As I hoped, I got some great advice…  No it wasn’t supposed to be that wobbly… It was recommended that I remove the bolt, replace it if it looked at all suspect, clean up the corrosion around the hole and have some steel plates made if the hole was cracked. They also recommended that I replaced the mast head light with an LED tricolour to save power, which was a great idea.

Now I could have a close look, it turned out that the mast cap was wobbly because a wind vane had been bolted on the cap, preventing it from sitting squarely.  Once that was off it all fitted back together securely and the wobble was gone!

Hurley 22 Mast Head

The offending nut on the windvane. The rivets have been drilled out and the mast cap is on its way off.

4) I fitted a new NASA LED Tricolour bracket, rivetting it on and using sikaflex to seal between.  Both the mast cap and the bracket for the light are made from aluminium so there should be no issues with corrosion like you get with aluminium and stainless steel. But I used some sikaflex to create a barrier anyway.

Hurley 22 Mast Head Light

5) Now to the shroud (the wires that run each side of the boat to the top of the mast) fittings.  On a Hurley 22 original mast like mine, the fastenings are held by a bolt that passes through the mast. This bolt, and the fastenings are made from stainless steel, where as the mast is made from aluminium and you get a problem called ‘galvanic corrosion’ between the 2 metals where they touch, assisted by the salty nature of their environment. Galvanic corrosion causes problems with the aluminium as it is softer. In this picture below you can see the white powderyness around the hole that the bolt goes through.  The picture on the right shows it after I’ve cleaned it off with a brillo pad and some water.  The gold anodised finish had corroded through and the aluminium mast is pitted.  But it was not cracked and I was confident it didn’t need patching, as the forces of the shrouds are across the bolt.

Cap Shroud Fastenings

However, I did replace the bolt, and also added some big penny washers. There are 2 grades of stainless steel found in bolts:  A2 (or 304 grade), and then A4 (or 318 grade) which is stronger and is more resistant to corrosion so is better in a marine environment (and is more expensive).  I made sure that the new bolt was A4 as it’s going to be at the top of the mast and I wouldn’t be able to keep an eye on it. I also bedded both sides to the mast with a good pad of Sikaflex to insulate the stainless steel and create a barrier to hopefully prevent any more galvanic corrosion.

Cap Shroud Fastenings

6) Turning to the foot of the mast, which had been shortened but wasn’t in the shoe squarely and was also only secured by two A2 bolts, with no nuts on the back (as a note I actually have the receipt from a professional yard for over £300 for this bodge!). It was a fairly straightforward task to undo the bolts, jimmy the shoe off, clean up the corrosion and make the cut straighter with the help of a dremmel so it would sit better on the shoe. As I was in the middle of epoxy coating the hull, I had some epoxy paint left over and used that to paint around where there was a little corrosion, again to prevent any further contact between the metals and therefore any further corrosion.  I used aluminium rivets to refasten the shoe (after a great deal of consideration on where to position them… there’s getting to be alot of holes at the bottom of my mast.) Again it is better to use rivets than stainless steel bolts or self-tappers on a mast as they are made from aluminium alloy and are less corrosive as the metals are the same.

Mast Foot Repairs

7) Then the spreaders, made from simple aluminium tubing were very corroded, especially at the ends.  I have been told that the spreaders are very important in the stability of the rig. Their purpose is to increase the angle of the cap shrouds to the top of the mast, increasing its stability.  They clearly needed replacing as they’d obviously been weakened by corrosion, especially at the ends where the stainless steel wires are in contact with the aluminium tubing. Luckily they are a standard gauge aluminium tubing and I found a local fabricator to make some new ones for me (they cost  £36!)

Spreader Corrosion

However I’d been hoping to be able to use the old plastic cap ends to secure the shrouds in the end, but they disintegrated. I have done a bodge with some cable ties but I want to check that in particular before the start of this season. (The yellow stuff is Duralac, a compound that is supposed to help prevent corrosion)

Spreader Shroud Fittings

I also had some plastic ‘over caps’ to help hold it all in position.

New Spreader

8) Lastly, I rewired the mast with a new power cable for the light, as the old one was un-tinned and very black looking.  While I was at it I replaced the VHF cable too… Pretty straightforward to do with a mousing line:

Mousing the Mast Cables

Mousing the Mast Cables

So there we have it… one much tidier mast! And all for about £250 (the biggest outlay were the shrouds which were £120, then the NASA LED light which was £52, then some cable, and some rivets and a new bolt for the shrouds).  I dread to think what it would have cost in a yard…

Before and After

Before and After

Now it’s 2015 though, I do want to get it down and look it over before I head out into the Western Approaches… And I’ll put new bottle screws on the remaining lowers and the back stay as well.  I don’t know how old they are but I have see that some of the nuts are broken.