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.

The evolving riddle of Duet’s mast rake – Part 4

July 18, 2014 at 2:10 pm

See Part 3 here

So by this time, I had lowered the mast on the tabernacle but at was pretty precariously balanced on the coach roof.  We had propped it up and lashed it as left to its own devices the weight of it dented the coach roof. Also, it seemed that the yard I was in had no capability to restep the mast as they only have a travel hoist and not a crane, but suggested I make contact with a local rigger who had a pneumatic lift thing (!)

So the rigger arrived and together we took the mast off the tabernacle and moved it forward on the deck so it was resting on the pushput and the pulpit, and lashed it down again safely.

He also looked over my rigging for me, and although it had been replaced in 2009 (and 2011 for the back stay) he deemed that it was of poor quality and needed replacing really…

Duet’s mast is supported by 4 wires to the top of the mast.  The one from the top of the mast to the front of the boat is called the forestay, and the one to the back of the boat is called the back stay.  The wires running to each side of the boat are called ‘shrouds’.  The cap shrouds run each side from the top of the mast to the deck, and then there are what are called ‘lowers’ which run from just under the cross trees to the deck, with one forward and one aft, giving you what are called the the forward and aft lowers.

Basically, the forestay is used to control the rake of the mast (which is why I have shortened mine to correct Duet’s mast rake).  The cap shrouds (from the top of the mast down the sides of the boat) run through the cross trees and are really important in supporting the mast laterally.  The lowers are important for supporting the bottom half of the mast and keeping it rigid.

The rigger wasn’t happy with the quality of Duet’s rigging as although the fore and back stays had been made with swage fittings (where the wire is fed into a proper eye fitting and compressed), the cap shrouds and lowers had what are called talurit splices (where the loop at each end is made using a compressed copper band).  Ideally, a boat my size and above would use swage fittings all round as they are stronger.

Rigging Splices

We also took the spreaders off and found them to be really heavily corroded, especially at the ends where the cap shrouds run through them.  He suggested that I have some new ones made up by a local fabrication company and as they were just aluminium tube they shouldn’t cost much.  In fact, in the end they cost £26.

Corroded Spreaders Hurley 22

Duet’s corroded aluminium spreaders

The rigger looked at the bottom of the mast, where the work had previously been done by a professional yard to remove the corrosion and he also said that this was of poor quality.  The mast was not sited squarely in the shoe and A2 bolts had been used to secure it, so it needed to come off and be re-sited and then properly riveted on again.

Hurley 22 Mast Foot

The mast foot is not square on the foot. One edge has a wider gap than the other end (and one bolt has been removed here)

Finally he looked over the mast cap which was wobbly and also needed refurbishment…. So in a nutshell, he pretty much condemned it all and started talking in terms of a new mast and rigging.

Oh crap.

The evolving riddle of Duet’s mast rake – Part 3

June 26, 2014 at 8:42 pm

So Duet’s mast was too raked and her forestay and roller reefing foil was too long… and then one evening I remembered that on a historical survey in her paperwork there was a picture of the foot of her mast showing corrosion, and there was a receipt from a local yard for removing 25mm off the bottom of the mast.  (This survey had been done in 2011 and had shown up a few issues that had been rectified before sale).

My hunch was then that her mast had been shortened to remove the corrosion but her rigging had not been readjusted correctly…

Survey Mast Corrosion

This is the picture from the survey of her mast corrosion before it was fixed.

So I contacted the previous owner who did confirm that this was the case and the work had been carried out by a professional yard.  Apparently 2 inches were removed from the bottom of the mast, and rather than adjust the rigging, the chainplates were shortened by the same amount… except that the forestay has no chainplate and couldn’t be shortened.  So they left it long!  The previous owner also admitted that he never sailed her again after this work was completed.

Professional Repair

This is a picture, also taken from Duet’s file, of the repair immediately after it was done. The yellow stuff is Duralac to help prevent further corrosion.

At least this confirms what I kind of have already figured out!  As mitigation on my part, when I bought Duet she was on the hard in a very tightly packed yard and it wouldn’t have been so obvious to see that she was so raked.  I did start to notice it when she was in the marina but thought it might have been due to ballast (she did have a very heavy engine hung on the transom) but it was only this year when she was out on the hard again at the Academy that it really started to niggle me and I put it together with the weather helm.

However, the previous owner did also give me some advice for reducing the weather helm:

  • Keep weight out the back end, keep the prop out of the water (but he had the outboard mounted on the transom and I’ve put it back in the well)
  • Reefing the main first (this will move the centre of effort forward)
  • Ease the mainsheet (again this will move the centre of effort forward)
  • He also recommended new sails, apparently he’s got a fully battened main on his new boat which made a big difference (this is quite an expensive option though)

Note:
I’ve done some research on this now and it seems that taking off a few inches of corrosion on the bottom is a really common, and is the correct way to fix this issue. Apparently if a mast fails it usually goes further up around the spreaders.  As long as the mast is sat in the shoe correctly it’s not a weak danger point. So that gives me peace of mind at least.

 

 

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