Mast rebuild

After a final clean up with a wire brush on a drill to clean the last traces of old epoxy and to remove oxidation from the alloy sail track, I laid down a bed of epoxy on the mast and the track. While this was going off, I rigged up a “clamp” to hold the mast firmly so that it wouldn’t move while working on the mast.

A kettlebell proved to be very useful for keeping the mast in position. That’s the alloy sail track lying on the deck.

A bed of epoxy laid along the length of the mast. I did the same with the sail track.

The idea I had was to utilise the “wet on wet” ability of epoxy. By letting it go off a bit, the track would grip the mast and not slide off while it was being attached. This worked very well and there was just enough movement possible to allow fine adjustment of the track’s position. The other reason for letting the epoxy cure a bit was to ensure that the bed of epoxy forms a barrier between the carbon and the alloy. This is to prevent electrolysis which would eat away the alloy track, especially when a bit of salt water is added to the mix.

The track is attached. Packing tape clamps the track very effectively. It was important not to clamp too tightly as I didn’t want to push too much epoxy out of the joint.

While the epoxy was curing, I began adding the aramid fibre “stitching'”. Aramid fibres, (also known as Kevlar, Twaron or Nomex) are about 7 times stronger than steel. After impregnating the fibres with epoxy, I used a  twist tie wire to pull the thread through the holes in the track and then simply glue them down.

The next pic shows one of the aramid fibre ties. In this pic you can also see the slit cut in the track to prevent the track kinking when the mast bends. These slits are cut all the way along the track.

I then turned my attention to the joint between the carbon fibre tube and the alloy mast base. This was first wrapped with bidirectional glass tape. Subsequent layers were unidirectional carbon fibre as follows:

1. bi-directional glass tape
2. unidirectional carbon laid vertically
3. unidirectional carbon laid horizontally
4. unidirectional carbon laid vertically
5. unidirectional carbon laid horizontally

This was then wrapped with gladwrap and bound tightly with packing tape to squeeze out excess epoxy resin. The result is a very strong joint. Al that remains now is to drill the hole for the boom gooseneck and give the mast a coat of polyurethane to provide UV protection for the epoxy.

Oh, I forgot. I do have to make a new 3-point stay spreader as the original one was corroded and cracked.

Mast restoration commenced

The carbon mast is in a poor state, so this is next on the list. The good news is that the carbon tube itself is in great condition, so it will be a matter of

1. removing the sail track,
2. cleaning off the old epoxy
3. undoing the epoxy joint where the carbon tube joins the aluminium tube.
4. re-joining the tubes with fibre glass
5. restitching the sail track onto the mast with Kevlar tow
6. coating the mast to prevent a reoccurrence of UV degradation of the epoxy.

Epoxy basically has no UV resistance, so it has to be coated with a suitable spar varnish or paint.

 

This is the joint that needs fixing. As you can see, the epoxy has degraded completely and provides no strength whatsoever.

Epoxy degradation:

Kevlar tow joining the sail track to the carbon mast has come loose along its whole length:

The sail track has been removed and both track and mast cleaned up in readiness for its re-attachment. This took me quite a few hours today with careful use of a heat gun and scraper. I had to be very careful to avoid heating the mast and melting the epoxy/carbon laminate. As you can see, the carbon mast tube is in good nick.

The joint between the carbon mast and aluminium mast base has also been cleaned up in readiness for fibre glassing. The hole you can see is for the gooseneck pin. It goes through to the other side as the boom rotates the mast.

The next post will show the re-attachment of the track.

Colour!

I’ve been looking forward to this day as I’ve been interested to see how the Toplac performs. We’ve heard a lot about this replacement for the famous Brightside so, how good is it really? The colour is Squall Blue, and I’ll attempt to evaluate its application.



On opening the tin, it obviously needed stirring to mix in the solids. The first thing that strikes you is the unique odour. It’s not nearly as bad as most paints, but it’s unique. I was curious as to what the solvent is so looked up the data sheet. Oh, dear, I shouldn’t have done that. It’s almost as toxic as the day following a nuclear explosion. Well, that’s how it reads anyway. Sheesh, if this was on the label it would have stayed on the shelf! How  could something with a colour this pretty possibly be so bad for life on earth?

Anyway, I paint with the doors open at both ends of the garage and a coat takes 45 mins. Then I’m outa there! Seriously, if you paint boats for a living, then find another job because this stuff isn’t good for you.

It seems quite thin, but it doesn’t drip off the roller, it goes on without any effort and there is no spattering. Coverage is excellent and there are no spots where the primer shows through. I would say coverage is 100% which is excellent for such a light colour. Tipping off with a brush sees the brush marks completely disappearing by the time I start tipping off the next section which is about 90 seconds. It flows out very nicely indeed. Coverage was achieved with just 300ml which I thought was pretty good. Conditions were around 20 degrees with low humidity, so pretty much perfect. I was surprised then that it took 6 hours to become touch dry as this time was double that stated on the data sheet.

Twenty hours later, the Toplac is surprisingly hard for a silicon alkyd based enamel. It is obvious that alkyd paint technology has advanced over the past few years. The gloss is quite stunning and no doubt will be even better after another coat.

Ready for paint

The bottom has had two coats of primer. The first coat was Norglass Marine Primer that was left over from a previous project and the second was International Yacht Primer. They are quite different I found. The Norglass dries very hard and goes on quite thickly. The International Yacht Primer goes on thinly but sands so much more easily. I sanded the whole boat with 120 NoFil in a little over 15 minutes by hand (not that big a task as it is a little 11’ Moth after all!).

So, which do I prefer? Well, I’m lazy and all this prep for painting is very tedious, but has to be done. I’m always looking for shortcuts, and I reckon the International product is the primer that offers just that.

All primed and sanded. I cleaned him down with water and then a turps dampened microfibre rag. (They make great tack cloths dampened with turps)


Oh, I can’t help myself. I found this great cartoon in a 1975 issue of the UK Moth Assn. yearbook. Little did the cartoonist know that these lightweight little boats would indeed fly one day!

Wing repairs

While the paint is drying on the hull, I’m getting on with the other stuff. As you may have seen in a previous post, the hiking wings were in a very bad state with severe corrosion. Rather than build a new set of wings, I decided that they could be salvaged, so out came the MAP gas and the aluminium brazing rods.

For aluminium brazing you need to be able to get the work up to about 400degC, which is pretty hot! This little unit is great for small jobs but it did struggle to get the tubes up to temperature because the heat so easily dissipates on such a big structure. I could really have done with more grunt, but we got there in the end.

Where the holes were small enough, I just brazed them closed. For the large holes, I made reinforcing patches from Laser mast tubing. I first ground off the anodising around the joints.

I think it’s worked well, as I tested the joints with my weight and they held!

You can buy MAP gas in handy disposable cylinders. MAP gets much hotter than propane.

The welding rods are pre-coated with flux.

Two examples of the repairs needed…

And the finished repairs…

Bottom sides stripped

Max’s bottom has now been stripped. Unfortunately due to the flexibility of the ply over the stringers it was impossible to avoid a blotchy look which you can see in the pics below. This has dashed my hopes of a bright finish for the bottom so have decided to paint the bottom instead. The colour has been chosen so this will be revealed very soon. Be sure to check back shortly to see his new look. The paint chosen is International Toplac, which is available locally from Whitworths in Broadmeadow. Unfortunately, International have discontinued production of their Brightside polyurethane based brand which was pretty much an icon in yacht paints. Brightside has been replaced with Toplac which is alkyd based. We’ll soon find out if Toplac is a worthy successor to Brightside. On the plus side, there is a much improved range of colours available in the Toplac line.

Incidentally, the guy at Whitworths was himself a scow Moth sailor during the 70s/80s, so we had a great chat and I learned some more about the development and the lightweight construction techniques used for these unique sailing boats. He was able to give me some tips about how to get the best performance from the scow.

I discovered a potential leak in a ply joint, so this has been repaired and the joint taped with epoxy. There was also a small puncture, similar to the one on the deck that had been repaired with epoxy. I originally thought this was rot, but it was just a soft spot so this area was reinforced with a dab of poxy and a small square of glass. The bottom is now solid and ready for paint.

Hiking wing restoration

Be prepared for surprises if you take on the restoration of an old boat. The hiking straps were rotten so I had to remove them. Look what they were hiding! I imagined myself being fully hiked and the wings giving way and my world going dark green. I’ll need to weld on some reinforcing bits before replacing the straps.

It’s a good idea to put down a silicon barrier before installing anything onto aluminium. Also wash your boat down well with fresh water and flush out aluminium tubes and spars after a day on the water.

Deck sanded

Two days of scraping and sanding sees the deck down to bare wood at last. With the deck ply so flexible, it makes the stripping much harder. I’m happy with the results so far and am now happy that we can go with a bright finish and not paint.

The part of the deck at the transom has been glassed, so that will remain as is. However, when the time comes for the application of anti-slip, this will get treatment. Because of the wings, after a capsize, you climb aboard from the transom, so some grip will be required here as well as mid-deck area. The foredeck is a no-go area as the ply is just 1mm thick.