Month: December 2020

Worth Supporting @CleanSailors

dave42w2 Comments

So we have been found by Clean Sailors
“Sailors who love the sea, mobilising the global sailing community in conservation of our oceans.”
#sailmightytreadlightly

A not for profit organisation who are based in one of our favourite places: Falmouth (Cornwall). We look forward to being able to sail there and meet up.

Well worth reading their pages and supporting them. We think their aims are great.

For us the issues around plastic in our Oceans are a significant set of issues within the big picture of the Climate Emergency and acting for Climate Justice.

So many of our changes to Vida, in the name of Sustainability, work towards this:

  • Shampoo, soap, washing up liquid etc We have been using Soap bars, Shampoo bars, Toothpaste Tablets and Bamboo toothbrushes for over a year now. Also I’ve been using a “Crystal Deodorant Stick” for months, which has been great. I’m still using up old stocks of shaving stuff, but have a traditional safety razor, blades and a shaving foam bar ready to go. All plastic free (packaging as well as contents). Been shopping mostly from Anything But Plastic and Ecovibe
  • Removing waste water seacocks and grey water plans. We are now going to explore adding filters to catch any microplastics before they get into the tanks. So wherever our grey water gets pumped out (ideally into a shore based sewage system), or on ocean crossings into the ocean it should be free of harmful products.
  • Toilets: I’d like to see as bit more focus on toilets on the Clean Sailors agenda. We should never be putting raw sewage into the sea and composting toilets are, in our firm opinion, the very best option. They are just about the simplest, they don’t require any plumbing, they don’t use any chemicals, they don’t require you to work with sewage pipes or tanks etc etc. I have been thinking about how we might be able to empty our solids into reusable boxes rather than plastic bags. That would enable us to store aboard until fully composted for safe use on any ground.
  • Antifouling paint. So we think we have a good solution for removal and at least one option for what to put on that shouldn’t be toxic (effectiveness is unclear though).
  • Zero fossil fuels so no diesel or petrol pollution (from the dinghy outboard, main boat engine, boat heating, water heating, watermaker)

Clothing and Laundry

Reading the Clean Sailors got me thinking further about clothes and washing them. We have mentioned Laundry before and we have been careful to move to clothes with far fewer plastics. However, I think we need to do more. In hot climates Rash tops are clearly really practical for sun protection and are easy to wash/dry. However, they are essentially plastic (more and more of them are using recycled plastic, some are made from plastic recovered from the sea) and when washed they will shed microplastics. We haven’t seen any live-aboard cruisers with any form of filtration system and many people are (very understandably) doing their washing in buckets with rainwater and then tipping it into the sea.

We will be looking for a microplastic filter that can be used with a high capacity funnel. This can then be put into a cockpit drain and all water from washing clothes filtered on it’s way into the sea (recommendations for a suitable filter are needed please). Our preference is still to combine a “WonderWash” style hand powered washing machine with an electric spin dryer (needed to stand a chance of drying warm clothes in a British winter). The water from both these can go through the filter.

I was reading that most microplastics are shed in the first 8 washes. Would seem sensible not to wear a new garment for swimming until you have washed it a few times and caught those microplastics before they get into the sea.

Using a public laundry service isn’t going to help in places that do not have efficient microplastic filtration systems in their waste water processing (does anywhere?)

Missing?

I’d like to see a bit more emphasis on improving the facilities and standards for boat users. A few examples:

  • Rather than just putting pressure on consumers to avoid single-use plastics we should be stopping suppliers and shops using them in the first place.
  • Instead of asking boat owners not to put waste water with microplastics into the sea we should be providing legislation on grey water tanks and filters, on more places to pump out, on restrictions on where we can empty tanks (as Turkey have)
  • We need more legislation on recycling at every level. On the materials used, on the places to put waste for recycling and on making sure it really does get recycled. It is pointless to put pressure on consumers if there are no plastic free items to buy, few places to put stuff for recycling and if at the end of the day it is shipped abroad into waste piles without being actually recycled.

Connections

Plus we still need to make the connections. Plastic waste is one aspect (that does need dealing with) of unsustainable living. There are many more, they all need to be tackled if there is to be any chance of a Sustainable future with Climate Justice for all people. The big picture is needed to make sure that we don’t lose sight of the need to work for Clean Oceans as well as Zero Fossil fuels as well as Healthy Soil as well as eliminating Poverty, stopping wars, protecting eco-systems etc etc. They are all important, most are highly interconnected (eg poverty, war, fossil fuels) and we do not have time to tackle them one at a time.

Supporting Sustainable Sailing

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[Update]

No plans to change the basic assumption here. However, we are looking to grow towards some financial support from the blog, from our YouTube channel and more.

One new step is that we now have a Ko-fi page for donations. Compared to other sites for making donations such as Patreon we like Ko-fi as there are no fees for donations. If you donate £3 via paypal then we get £3. We might later upgrade to the Gold version which would allow us to offer memberships with no fees (but even now they are only 5%, which is way lower than Patreon).

[End Update]

We have no plans to restrict our content or hide anything behind a paywall.

However, if you would like to support our journey towards Sustainable Sailing then there are two ways.

First, our awesome t-shirts, hoodies and bags from our shop at Teemill, great quality and as Sustainable products as you can find.

Second, we can now take donations by PayPal.

Donation to Sustainable Sailing

A donation to support Sustainable Sailing.

£10.00

We do not want any to feel obliged and we value the readers who can’t afford to spend money the most.

Simplifying fitting a Jordan Series Drogue

dave42w5 Comments

One of the most significant advances in yacht safety in recent years has been the development of the Jordan Series Drogue. It was developed in response to the 1979 Fastnet Disaster and has been widely used by a wide variety of yachts in some terrible conditions. Attainable Cruising has many articles about it (and I think some are on their free pages).

So we definitely plan to carry a Jordan Series Drogue with us. Examples from Jordan Series Drogues by AceSails (lots of the history by the late Don Jodan himself), Ocean Brake and DIY instructions from SailRite.

Once you have a JSD (Jordan Series Drogue) one of the key concerns is how top attach it to your boat. The loads could be enormous and so typically the solution has been big stainless steel chainplates through bolted to big backing plates, one on each aft quarter so that they stick out beyond the stern.

That is heavy, and is going to require some substantial engineering (and to be fair John Harries, from Attainable Cruising, admits that he had misunderstood that bolts in a line with the load do not share the load well – something Jane keeps on at me about from her Civil Engineering days).

The chainplate solution would be possible, but expensive and hard work on our boat (the bulwark is the obvious place as it has both the hull and deck thicknesses together) but it isn’t very high so the gap between the cap and the deck is a bit tight for a good sized backing plate.

So I was pondering and I realised that there might be a good solution similar to the Dyneema chainplates we have come up with. After a couple of iterations this is what I have come up with for boats like ours that have a strong enough bulwark or toe rail (essentially the rule of thumb is these need to be strong enough to hang the weight of the boat from). For us the strength of the 12mm dyneema we are likely to use for our main mast shrouds is a lot more than double the design weight of the boat. The issue is much more about spreading that load rather than the strength of the line.

[Update] I have written a lot about Dyneema standing rigging so I now have a guide to it all in: Dyneema / Synthetic Rigging Summary[End Update]

So I’m thinking one 12 mm dyneema line for each side of the boat. Both ends to be fastened to the boat with the loop going through the eye on the end of the JSB bridle. So the load will come to 4 attachment points on the boat and will be pretty equally balanced (the elastic stretch and creep of the dyneema will work to equalise the loads between the two bridles and on each side the loop will move through the bridle loop to equalise the load.).

All 4 ends of dyneema will have an eye splice (carefully done should achieve 80% of the original strength) and the eye will have a chafe protection sleeve as will the loop where it goes through the bridle.

To attach these eye splices to the boat we cut scupper drains holes through the bulwark. These are angled so that the outside is pointing aft. They will need to be very smooth and large enough for the dyneema eyesplice. It might be worth using HDPE tubing. Otherwise I’ll make them oversize, fill them with thickened epoxy and then drill and smooth that.

On the inside of the bulwark we will pass a stainless steel rod (probably similar to our propshaft) through the eye splice and lay it horizontally along the inside of the bulwark as the “backing plate”. To spread the load of the stainless steel rod we would build up thickened epoxy between in and the bulkhead. We will coat the rod in mould release first so that the rod can be removed once the epoxy has set and only placed there when needed.

The length of the stainless steel rods will depend on the curvature and strength of the bulwark or toe rail. If there are concerns then use more and connect the dyneema in a cascade to distribute the load to 4 or more points per side.

This way we get better draining side decks (more scupper holes). We get a JSD attachment system that

  • is stored away from UV and other damage except when on ocean passages.
  • is easy to fully inspect every part of before use
  • can have any part replaced at sea if it shows wear
  • doesn’t add permanent clutter or any potential leaks
  • is lighter and stronger than a stainless steel chainplate
  • is much cheaper than the parts for stainless steel chainplates

Of course there are disadvantages and key among these is the potential for chafe. However, this can be easily monitored and if required a temporary Dyneema line could be used while a replacement is fitted at sea. We are not kidding ourselves that it would be easy but won’t require hanging off the back of the boat and is possible. Whereas making and fitting a replacement stainless steel chainplate would not be.

If your boat doesn’t have a bulwark/toe rail that is suitable then a more permanent solution more like multiples of our various dyneema chainplates idea might be possible.

Almost certainly we will be trying something along these lines, but we do so at our own risk and you would have to do your own risk analysis and design.

[Update] Another “brilliant” sketch of this design.

More on sustainability

dave42w1 Comment

I get quite frustrated with a number of ways in which claims are made for sustainability. Too often they can be most charitably be described as greenwashing.

So I took the Footprint challenge (again) at https://www.footprintcalculator.org

This time we came out at 2.3 that means 2.3 worlds would be required to maintain our lifestyle. It can also be presented as 3.9gha (global hectares per person). The world can sustain about 1.63gha, the UK average is 7.93gha and the global average is 2.75gha.

So while we are currently living at about 50% of the UK average (2016 data) and just below the global average (again 2016) we still have a long way to drop before we could consider ourselves to be living sustainably.

This is a reduction from what we have achieved in the past. However, by far the largest single item within our footprint is our housing. As that comes with my job we have almost no control over it, at the moment. The second (although only about 1/3 of the first) is driving our van. This calculator doesn’t factor in the cycling I do for transport and of course we are working towards replacing the van with a small electric car ASAP (that reflects changes including Jane commuting for the first time).

Factors that have reduced our score include:

  • No flying (more than 15 years since our last flight)
  • All our Electricity and Gas is the greenest, most renewable available (Ecotricity)
  • We are now nearly completely vegetarian
  • Most of our veg comes through a weekly veg box from a farm only 15 miles away (and everything in the box is grown organically on that farm).

However, Sustainable Sailing is about our long term, our retirement. At the point of retirement we have to find our own home (and we can’t afford to buy a house) and we want to be contributing to life not tearing it down for future generations.

So our goals are a retirement we can afford (which is why the catamarans costing hundreds of thousands of pounds are irrelevant) and which has a really low footprint (which is again why the big catamarans are out as well as diesel engines, new boats etc).

But we also believe that there are mental and physical benefits to a simpler and more sustainable life. So the choices are also good for us personally. Less stress, more beauty, more experiences, active lifestyle away from air pollution.

So it isn’t surprising that the people we prefer to read or watch are typically not the lifestyle experts, they typically don’t have old boats and low budgets.

It isn’t surprising that we reject the experts saying that fossil fuel free sailing boats are not possible because we have not seen them consider the footprint of their choices. Our goal isn’t to achieve or maintain a lifestyle that the planet can’t sustain. Our goal is to to live at a sustainable level, and within that, to live well.

A good recent example was that Jimmy Cornell who has had to abandon his attempt to sail around the world with zero carbon emissions. Our approach is very different.

When they start with a brand new 45 foot catamaran the embedded carbon footprint is incredibly different to that of a 43 year old 38 foot monohull and this is almost always ignored.

The key advantages of a performance catamaran for cruising without using fossil fuels are the large area for solar panels and the higher sailing speed which means that regeneration from spinning the propellers which turn the motors into generators.

However, we plan about the same amount of solar panels, and we plan to boost their efficiency by tilting them and moving some so that are not shaded by the sails as much.

We too hope to get some regeneration from the propeller but haven’t really budgeted for it.

Where the biggest difference lies is in consumption. That is where the expectations of sustainability are so different. We plan to live within what we can generate not generate enough for a particular lifestyle.

Within the consumption side of the equation comes a really significant disadvantage of catamarans. They can’t be steered by wind vane steering systems that use no electricity. We have seen a number of people whose boats use electric autopilots have to run their engines every couple of days because of the power drain of the autopilot. While we are going to maintain the original electric autopilot (useful for sail changes or when motoring) we won’t be using it on passages.

When you add electric winches, multiple fridges etc it becomes obvious that it is the luxury lifestyle that can’t be achieved. Yet for hundreds of years sailing boats have crossed oceans without fridges, washing machines, water makers etc. Even on a catamaran with it’s autopilot Cornell managed on a “minimal” use of electrical equipment.

Yet the naysayers always home in on the induction cooking and the electric motor as the problems that make zero carbon footprint sailing impossible. Neither of these need to be used if you don’t have enough power in the battery bank. Especially when crossing oceans.

For us the two biggest concerns (and the reason why, in the end we may well carry a generator) are:

  • Fossil fuel free heating (because electric heating is always going to be needed most when solar generation is at it’s minimum).
  • Canals and rivers (eg to get between the English Channel and the Mediterranean) where hours of motoring can be needed against currents or where timetables need to be kept (eg Panama Canal).

To be honest it is amusing that those telling us that a sustainable life isn’t possible haven’t even thought about the most difficult challenges.

It is important to note that we don’t think we have everything sorted yet. We are building up gradually on storage, generation and consumption of electricity so that we can find a good equilibrium for us – and yes, that will include restricting where we go to those places and seasons where we can maintain the equilibrium because anything else isn’t sustainable.

The urge to be the first

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Saw some exciting news today.

Just read that Peter Lawless is going to be sailing his Rival 41 around the world single handed, unassisted and non stop. He has a website and a YouTube channel. His aim is to be the first Irish man to achieve that combination.

It is nice to see such confidence in the next size up boat in the Rival range 😁 While we know several Rival 38s have circumnavigated, I’m pretty confident none have done so non stop, and probably not routing south of all 5 major capes.

If you haven’t looked at sailing routes in detail it might surprise you that there is a fundamental difference in the routes between those sailing around the world fast and cruising.

Typically fast circumnavigations are Eastwards (so from Europe via Africa, Australia, Americas to Europe) and they go a long way south to keep the distance down (typically circling Antarctica as close as possible). This is the route of the Vendee Globe, the Jules Verne trophy etc. It goes under 5 major capes: Cape of Good Hope (South Africa), Cape Leeuwin (Australia), South East Cape (Tasmania), South Cape (New Zealand), Cape Horn (Chile) There are normally a series of low pressure systems circling the globe above Antarctica so Eastwards is faster downwind sailing.

For cruisers that Southern Ocean is unattractive, if the objective is to enjoy visiting places then a route to the most remote parts of the oceans where storms are normal and it is very cold is unattractive. Cape Horn is particularly feared as there is a pinch point between it and Antarctica where winds and seas rush through. So the majority route Westwards using the Panama Canal to avoid Cape Horn. Then you can cross the Pacific via some of the beautiful island groups in warmer weather with downwind sailing to Australia. If piracy wasn’t an issue many would return to Europe via the Red Sea, Suez Canal and Mediterranean thus avoiding the more challenging Cape of Good Hope.

So there is this huge difference right from the beginning depending on whether you want to go around non stop (or just a few stops) or whether you want to see more places, go slower and take fewer risks.

We are definitely in the cruising camp (and with a grp boat relying on solar energy we won’t be going to far North or South into the Arctic or Antarctic). But it made me wonder if we have any urges or expectations to be first at anything. We certainly are not considering single handed firsts, nor a non stop circumnavigation, nor do we aim to be unassisted.

On the other hand wherever we go we will be the first Jane and Dave to sail a Rival 38 Centre Cockpit Ketch there 😂

Is that enough?

For us it definitely is. We love watching and supporting others doing amazing things (like the Vendee Globe) but that isn’t us.

Instead, our goals are clearly much more about the means (ie Sustainable) rather than specific firsts. To travel well (by our definitions) rather than to set records.

Boat access update

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So we were last on Vida for Friday 9th October (Friday Progress 28). Since then the restrictions either for North Wales or for Manchester (and for a lot of the time both) have not allowed us back.

We had hoped to get a few days after Christmas but Manchester is still in tier 3 and Wales goes into a pretty full lockdown from the 28th December.

With very little prospect of change for a couple of months it does mean we will need to plan carefully whether to try to get enough done to launch in 2021 and finish over next winter or see if we can get a more complete refit complete for 2022.

I have a 3 month sabbatical in 2022, we would love to use that for our first extended cruise but we would need to have completed so much and tested it beforehand.

Feeling more than a bit frustrated by the knowledge that going and working on our boat is incredibly low Covid risk. We don’t stop on the way. We typically don’t meet anyone. The only shopping we do is for electricity cards from the boatyard chandler.

Yet the rules are clear and we are not about to break them. We have seen too much of the devastation that Covid causes.

The mysteries of sizing Dyneema standing rigging

dave42w8 Comments

When planning Dyneema rigging the area we have found most confusing is deciding on the size of Dyneema we should fit. In our search we have found three sites particularly helpful. However, between the sites we have found at least four ways of deciding what size is needed. Despite that, they do all agree that Dyneema needed to be sized for Stretch rather than for Strength. That is because a Dyneema line the same strength as the Stainless Steel it replaces would be too stretchy to work.

Stretchy is slightly problematic because there are multiple forms and the terminology used isn’t consistent. From Marlow Ropes we have this:

  • Initial loading will result in elastic extension. This is immediate upon loading and is immediately recoverable upon release of the load (elastic contraction)
  • After the elastic extension of the initial loading, the rope will experience what is known as viscoelastic extension. This is further extension over time and is fairly limited. Unlike elastic stretch, viscoelastic stretch will only recover slowly over time once the load is released.
  • Finally there is creep, which is permanent, non-recoverable and time dependent. Creep occurs at the yarn molecular level when the rope is under constant load.
  • Once the load is released and elastic and viscoelastic extension recovered, the rope will ultimately have experienced an element of permanent extension. This is a factor of both creep and “bedding in”, which is when individual fibre components in the rope and / or splice settle into their preferred position when under load.

Others refer to Elastic Stretch, Constructional Stretch and Creep. Unfortunately lots of the information isn’t clear about which they are referring to in their guidance.

I’m least concerned about Constructional Stretch or bedding in. Most lines are pre-stretched. If you measure a pre-stretched line before splicing then you can stretch it after and by measuring know if you have removed the constructional stretch. If your design includes lashings (which are normally setup to have plenty of adjustment) then there is only the inconvenience of a tightening a few times initially if you didn’t get rid of all the constructional stretch.

Creep will mean your rig needs re-tensioning over time. This is mostly a problem if you only use turnbuckles due to their limited range. If you have a lashing in the design you can have shorter shrouds and a longer lashing so that you have plenty of space to keep tension as creep lengthens the shroud. It can be minimised by keeping static loads as a small % of the breaking strength, so grades of Dyneema with a higher breaking strengths will creep less under the same load.

Elastic Stretch is much the same to work with as creep except that it will show up quite quickly, so a few re-tensions in the first few months should sort it. Again, increasing the line diameter reduces the problem as does being able to get enough tension to stretch out the elasticity so that the rig doesn’t flop around.

What makes this even more complicated is that a) there are lots of variations of Dyneema available, also b) each rope manufacturer has their own ways of treating Dyneema (eg pre-stretch, heat treatments, and coatings) which makes comparisons even more difficult.

In terms of suitability for us, we have got that down to this list of basic Dyneema variations (we haven’t found a comparison between the different ways of treating the same type of Dyneema):

  • DM20 (least creep, but also not as strong, most expensive)
  • SK99 (Strongest, similar creep to SK78)
  • SK78 (the first Dyneema with reduced creep)

Rigging Doctor describes all these (and others that we are not considering), not much has changed since that was written in 2015 apart from the gradual introduction of Bio-based Dyneema (expected to reach 60% of all Dyneema by 2030) and a reduction in the premium pricing for DM20 and SK99. Also Marlow describes them all and includes comparison charts. I found the Colligo information less helpful, it feels to me that they have stayed with the same materials despite the new developments. As Jimmy Green put it in an email to me “In terms of picking between DM20 and DynIce Dux, the choice comes down to whether you want the better performing fibre (DM20) or the better performing rope once braided and heat stretched (heat stretched SK75). Marlow recommend one thing, Colligo another, they both swear by the logic!”
[Update]
See the first comment below from John Franta, Colligo Marine where he explains the difference between heat stretching at Fibre level (SK78 and SK99) vs at the Braided level (SK75). So I am going to be adding Hampidjan DynIce Dux into my calculations and it is cheaper than the LIROS D-Pro-XTR, plus available in more sizes.
[End Update]

As we go through the sizing calculations comparisons are difficult as they don’t use the same version of Dyneema. So the sites we have used are below and for each I have sized replacements for our Mizzen mast (currently 6mm or 6.5mm Stainless Steel – can’t be sure until we can visit) and our Main mast (currently 8mm we think).

So these are the sites I’ve found most useful in working sizes for our boat.

Colligo Marine

Still the biggest name that we have found producing fittings for Dyneema rigging. Their page (from 2015) Before Ordering Your Colligo Dux Rigging… links to a PDF table for sizing.

From them we get either 7 or 9mm for the Mizzen and 11mm for the main.

Jimmy Green Marine

Our preferred rope supplier, Jimmy Green Marine, has lots of information and a range of Dyneema for standing rigging from different suppliers. They sell 100m drums and 50m hanks which is handy (they can also make custom lengths with a variety of splices etc). They have been very helpful in responding to email enquiries. They make the information from manufacturers such Marlow rather more accessible.

If we follow the table they include from Marlow for their DM20 line (Marlow M-Rig Max) then sizing is huge: 11 or 12mm for the Mizzen and 15mm for the main.

Rigging Doctor

We are Patreons of Rigging Doctor, the combination of their YouTube channel and website has more practical resources on real world cruising use of Dyneema than any other I’ve found. Our preferences are going to be to tune the rig for a bit higher performance and sail a bit harder than they do but it is still be best source of information we have found. Their sizing post is Sizing for Creep. That has two ways of calculating the size.

The first is the RM30 heeling test to calculate rig loads. “RM30 is the force that is required to heel the boat over 30 degrees.” We are ruling this one out for us. a) we need to replace the mizzen rigging before we launch b) there is no dock or anything at the boatyard so difficult to do c) I’m not sure how this would work for a mizzen mast as it is shorter and so far aft, therefore it would be very difficult to heel the boat that far with just the mizzen and not very typical of the mizzen usage.

The second is a calculation based on the current rigging size. We start by calculating the designed tension of the shrouds by assuming it is no more than 20% of the breaking strain of the stainless steel. Then we choose what percentage of the breaking strength of the Dyneema we want this to be. Herb suggests under 15% or even better under 10%. I’ve taken the stainless breaking limits from the Marlow table off Jimmy Green (see above).

For 6mm stainless steel the breaking strength is 2880kg. 20% is 576kg so if we size at the 10% we get 5760kg (we can simplify the calculation to looking for a Dyneema line that is at least twice the breaking limit of the stainless it replaces). Looking at the Jimmy Green table for all the Dyneema they sell we find that 7mm is good (except Liros don’t sell 7mm so it has to be 8mm for the Liros D Pro Xtr [SK99] or 10mm for the Liros D Pro Static [DFM20] ).

For 6.5mm stainless steel the breaking strength is 3220kg. So we are looking at approx 6500kg breaking strain Dyneema. The Dyneema sizes can be the same as for the 6mm Stainless above except that the Marlow M-Rig Max (DM20) might be better in 8mm.

For 8mm stainless steel the breaking strength is 4640kg. So we are looking at approx 9300kg breaking strain Dyneema. The Dyneema sizes can all be 10mm except the Liros D Pro Static [DFM20] which would need to go upto 12mm (no 11mm available).

Our choices

The price difference of the DM20 lines over SK99 or SK78 is still huge. Jimmy Green have 100m drums of 8mm in all 3 types of Dyneema from Marlow:

Marlow Excel D12 Max 78 (SK78) is £1,145
Marlow Excel D12 Max 99 (SK99) is £1,400
Marlow M-Rig Max (DM20) is £1,337

The Liros 8mm ropes are:

LIROS D-Pro-XTR (SK99) is £868
LIROS D-Pro Static (DM20) is £1,140

The Hampidjan (recommended by Colligo) 8mm rope is

DynIce Dux Dyneema SK75 is £800

While I would love to buy Marlow as a British company, they are a lot more expensive.

We were thinking LIROS D-Pro-XTR (SK99) as by far the cheapest option (and as SK99 is stronger than SK78 we should have less creep than the cheapest Marlow option which is SK78). Of course what we have not been able to compare fully is the performance of Marlow vs Liros in heat treatment, pre-stretch and coatings. If I were only using turnbuckles for tensioning then I might have gone for DM20 to avoid running out of tensioning due to creep.

However, DynICE Dux is now back in the running, and with the possibility of 9mm for the Mizzen for about the same price as the 8mm Liros D-Pro-XTR.

But what about the size?

One seemingly easy option is to over-size. As you size up creep and stretch will always be reduced. Plus there will be more spare strength if there is UV or Chafe damage. But the disadvantages are cost (not just the line but also the thimbles) and windage (but we have a big boxy wheelhouse so are not exactly aerodynamic).

Let’s be very conservative and assume we are looking at existing stainless 6.5mm for the mizzen and 8mm for the main (will check as soon as we are allowed to visit the boat). Let’s go up whenever there doubt. So the 3 different calculations give us (for the Liros D-Pro-XTR)

Mizzen 6.5mm Stainless:

Colligo (SK75): 7mm
Marlow from Jimmy Green (DM20): 12mm
Rigging Doctor for SK99: 8mm

Main 8mm Stainless:

Colligo (SK75): 11mm
Marlow from Jimmy Green (DM20): 15mm (but 13mm is pretty close)
Rigging Doctor for SK99: 10mm

The choices get more tricky as Liros don’t make every size (no 7, 9 or 11mm).

For the moment I’m thinking of 8mm for the Mizzen (might be a bit stretchy but at the end of the day it is only the mizzen and normally loads are low because it doesn’t have a genoa). I might have gone for 9mm if Liros offered that.

For the Main I’m thinking 12mm (larger than either the Colligo and Rigging Doctor calculations) and the largest size of Liros D-Pro-XTR available).

[Update] or 9mm DynICE Dux for the Mizzen and 12mm for the Main

100m of the 8mm should be plenty for the Mizzen with enough spare to replace several shrouds.
Possibly from our back of the envelope calculations 150m of the 12mm for the Main should also give enough for several replacements. We won’t be re-rigging the main until after the 2021 season so have plenty of time to measure properly.

In the design of the Dyneema chaimplates I mentioned sizing them up, but of course the line is doubled so I’ll use the same size for the chainplates as for the shroud/stay attached to them.

One area still to be worked out is how much length to allow for creep. I need to ensure that the lashing length is enough for me to still tension the shroud at the end of it’s life.

This post has taken an age to research and write. It is based on our specific boat and shares our thinking for our uses. We are not experts but just trying to show our thinking processes. Don’t trust us for the sizing of your own rig!

Dyneema forestays and backstays

dave42w1 Comment

[Update] I have written a lot about Dyneema standing rigging so I now have a guide to it all in: Dyneema / Synthetic Rigging Summary[End Update]

All the posts I have been writing about Dyneema rigging and chainplates have been mostly focused on Shrouds (the standing rigging that holds masts up from the sides). Much of it also applies to Stays (the standing rigging that holds masts up from the bow and stern of the boat). However, there are some differences, for us especially because we have a ketch rig (two masts).

So I’ve been checking out how to apply the work I’ve done for Shrouds to Stays. It is quite different for our Mizzen and Main mast so I’ll write about them separately.

Main Mast

As I have mentioned in other posts (eg Why Dyneema standing rigging?) we are not going to be replacing our forestay with a Dyneema synthetic rope. The roller furling for our genoa would chafe through a Dyneema forestay very quickly as it puts the forsetay inside a metal tube that is rotated to roll up the sail around it.

However, we are planning a removable inner forestay (see Progress on Sails for our first mention of this) and this will be Dyneema. With all that we have learnt we will probably fit a DIY Cheeky Tang (see Dyneema Termination and Chainplate update) for this. Earlier we would probably have used a Bluewave Forged T Eye (as mentioned in Termination of Dyneema Shrouds. The most contentious issue?), however, if this is to be capable of acting as an emergency forestay, holding up the whole mast, then we will want a thicker line than 8mm.

Our current plan for the inner forestay is to have it as far aft from the bow as we can manage. The limits are set by the space required for the dinghy on the deck and where we can reinforce the underside of the deck enough. This will allow us the option of setting a staysail so we have a cutter rig (two smaller jibs instead of a genoa). Depending on how high we fit it to the mast we might need to add running backstays (which our mizzen already has so see below).

To hoist a sail at the inner forestay we will need to add a sheeve to the mast just below where the inner forestay attaches for the halyard (and at the bottom for the halyard to come back out of the mast).

Our backstay is currently slightly complicated and the tension can’t be adjusted (something you often want to do when sailing to control the tension of the forestay which changes the shape of the genoa).

It starts with a single wire at the top of the mast.

Part way down the single backstay is split so that one can go each side of the mizzen mast.

I’m assuming this is to save weight, although it might also help avoid the back of the sail (the leech) from rubbing on the backstay when sailing upwind (the sail won’t be pulled in as far as the centreline where the single backstay section is, but it might be pulled in far enough to rub against one of the double lines if they go all the way to the top of the mast (because the sail “sticks” out from a straight line from the top of the mast to the end of the boom – this is called “roach” and it is supported by sail battens). Our current sail doesn’t have roach but the original design adds 21 square feet of roach (and it is in a very efficient place near the top of the sail).

The problem with the single to double backstay is that instead of having the safety feature of two independent backstays you have multiple single points of failure.

So looking at where the single backstay attaches to the top of the mast.

I’m thinking we can replace that pin with a longer bolt and two DIY Cheeky Tangs so that we have 2 independent backstays right from the top of the mast. With Dyneema lines being so light we would save a lot of weight and add redundancy.

If we find that we need the backstay central at the top to miss the sail then we can add a couple of low friction rings to pull the two lines together at an appropriate point. If one backstay fails then the other will be a bit slack but will still be there.

A similar technique is commonly used to tension the backstays. A line with a low friction ring is used to connect the two backstays. This line is then pulled down to pull the backstays together (and tension them) or slides up to allow the backstays to separate (and follow a more direct line) thus slackening them. This technique automatically compensates for any differences in the tension of the two backstays (the slacker one always moves more inwards to balance the tension).

Mizzen Mast

Our mizzen mast doesn’t have a forestay or a backstay. A forestay would stop the main boom from being able to swing from side to side. A backstay would require a much shorter mizzen boom (and so smaller sail) or something sticking out the back of the boat to fasten it to.

So instead we have 2 shrouds that come forward from the top of the mizzen mast to the sides of the boat. The main boom just misses them. These stop the mast falling backwards.

Then we have two shrouds (side stays) that start just below the spreader and are angled slightly aft. These stop the mast falling forward but as they do not go to the top of the mast they are not enough to hold the mast up if the sail is pushing forward. For this we have running backstays, one each side. These provide the extra support for the mast, but to let the sail out fully they have to be released. So when you tack or gybe you loosen one and tighten the other so that the boom can move across the boat.

The net effect is that our mizzen basically has 4 shrouds per side. One per side is a running backstay and so you need a means to tension and release it as needed. As far as replacing them with Dyneema there is no need for any difference in the shrouds themselves.

Remaining issues

  • We need to finally confirm the current sizes of the stainless steel wire (need to be allowed back to Wales).
  • Then we can finally calculate the size of Dyneema to replace our stainless steel wire.
  • We need to decide where to protect with a Chafe/UV sleeve.

Other than that we are close to getting on with building and fitting it all 🙂