Fatigue... of the metal variety

This was the chainplate from an old aluminium open 60 I skippered. This happened before I joined on the voyage back from South Georgia to the Falklands. The boat got badly knocked down and the cap shroud hole in the chainplate pulled out, resulting in the mast getting a rather nasty bend just above the 1st spreader (it was amazing that they didn't loose it!). It took the resourceful Falkland islanders 10 days or so to pull the mast out, straighten it, sleeve the distorted area and re-install it (an amazing job...) While they were at it they welded in a set of massive new chainplates. All done with very basic facilitys. As you can imagine we had our hands full cleaning up the boat and fixing the million and one other broken things from the knockdown.

Also broken was the staysail stay chainplate, you can clearly see another crack underneath the point of failure. This thing was just waiting for an excuse to let go, and it failed before the knockdown... 

A full inspection revealed a crack starting in the stainless steel solent stay fitting (right side, at the top of the weld), This is a common place for failure, right near the heat affected zone, just outside a weld. Once the crack starts it concentrates loads at this point creating a stress riser and accelerating failure, also nasty things like crevice corrosion can start inside the crack, eating further into the metal....

The forestay chainplate wasn't too crash hot either... lets not push her too hard...

The point of all this is not to bag out the boat, just to say that on older boats don't assume that just because things have not broken, doesn't mean to say they won't. Metal fatigue and corrosion can invisibly weaken parts that otherwise look solid. The Open 60 had a complete new rig 7 years before this, but the chainplates were over 20 years old, and possibly slightly underspecified to start with. She had had a hard life, alot of it in Antarctica, (cold may accelerate fatigue - any engineers out there?). Nobody had thought the solid looking welded in chainplates could give any problems....

The most highly loaded parts of any boat are normally the rigging and what they are attached to (and maybe the keel bolts...). Sailors are well aware of the need to replace stainless steel shrouds every 7-10 years or so, but many fail to realise that the rest of the load path is also highly stressed and subject to fatigue. Quite commonly people replace the wire religiously (to keep insurance company's happy..) but never change the highly loaded through mast tang bolts, or the tangs themselves... The tang bolts particularly seem to fail quite often, then dropping both port and starboard shrouds, meaning you can't even tack to stabilise the mast.... Turnbuckles also need replacing every so often, as can the chainplates.

To be really safe I think it makes sense to consider replacing all the components every 2nd rigging change (20 years or so) and very carefully inspect all components at every rigging change. Chainplates should either be massively oversize, or easily replaceable. Be very wary of any stainless that passes through a damp deck, stainless can corrode very quickly in a damp low oxygen environment.

I replaced some U Bolt chainplates as a precaution before a delivery, and was horrified to find two of the ones I removed had lost 90% of the metal due to corrosion, they had looked perfect.... Lucky I had been told to watch out for this by a friend who had one fail on his boat. Stainless is treacherous stuff....

My chainplates are mild steel (with SS edging and inserts) to reduce the problems with fatigue. Mild steel has some pretty forgiving properties, one being that if you keep the stress below a certain point (the endurance limit) it doesn't really fatigue, unlike most other materials which will always get slowly weaker with each load cycle (that year of mechanical engineering was useful after all!). My bottlescrews are also galvanised steel, as is my rigging wire - both come with industrial test certificates and a SWL (unavailable for yachting stuff...). When I next re-rig my boat I will replace my stainless tangs with galvanised mild steel mast fittings as well.

There are some non destructive ways to test for cracks, but they are not 100% and could give you a false sense of security. I normally use a magnifying glass and look carefully, but I really should invest in some dye penetrant and developer, this supposedly highlights any cracks, has anyone used it?

Anyway I guess I have just given you yet another thing to worry about... Thats good if it means you might be less likely to loose your mast. If anyone has had a rigging failure I would be very interested to hear all about it....

Cheers

Ben

Icing and escape hatches

                     Winch starting to ice up, I leave the winch handles in to stop socket icing up - Ideally a hard cover would be good, to enable instant use. Also in extreme conditions tiller may ice up as happened to Totorore.

The other day I was thinking about Berserk, and it got me thinking about hatches and icing and getting stuck inside a boat.... What got me thinking was that Jarle has finally spoken out
and it makes interesting reading...

So what I was thinking (all this thinking was starting to hurt..) was that in a severe icing condition at sea it seems quite possible that the hatches could get badly iced up. I have always been abit claustrophobic, and the thought of being trapped below decks with a stuck hatch is terrifying.. So I guess it would be smart to have some means of forcing them open and also another escape option, hopefully not also iced up badly and frozen shut...

Sprirt of Sydneys main hatch. Note my boots

 Spirit of Sydney had a main companionway door that opened inwards (into the cabin). This is very unusual in my experience. I have never seen one that opens inwards before on any vessel, and it can be abit of a menace. It is heavy and if it gets loose could do damage to fingers and such. From an engineering perspective it is kind of backwards as well, with the major loads from a wave going entirely onto the closing dogs and hinges and trying to open the door, forcing it off the rubber seal rather than pushing it tighter onto the rubber seal with the loads evenly spread into the rim. But the door is strong enough, it has been well proven over many years and in the worst conditions at sea on this vessel.

Thinking about this strange door in relation to severe icing conditions - It would be much easier to open even if heavy snow and ice had filled the cockpit and blocked the doors. It would also be easy to open with a cockpit full of water, or after any event that meant the cockpit was obstructed (ie a dismasting with a broken piece of boom in the cockpit) - Infact I find it hard to imagine a scenario that would trap a person below with this door. I suppose the whole door frame being distorted might jamb it, but this would jamb any door.

Actually for any offshore sailing getting stuck below decks, or maybe even worse stuck on deck would be pretty dangerous. Rolf and Deborah From Northern Light told me about a main hatch securing rope getting caught in it's V cleat inside the boat locking the hatch shut. They were both on deck and quite a few days away from land - stuck outside with no food, water, shelter or tools (all below decks). Eventually (after long enough for the seriousness of the situation to sink in) the boat rolled heavily and the line freed itself.....Whew!!

Snow Petrel has a backup escape/entry hatches - My lazarette hatch only opens and closes from outside and my main-saloon skylight is always free to be opened from inside even when the dingy is ondeck and covering the forward hatch. But both could still be blocked by severe icing.... Maybe I should add an inwards opening hatch somewhere?

Ice melting fast, and wind dropping.

The only moderate icing I have had was whist at anchor and then the main hatch was protected by the dodger. We had to make sure our ventilators remained somewhat free of ice, but that was all, I think we probably had about a ton of ice onboard at it's peak.... Gerry Clark had some very bad icing on the little 32 foot "Totorore", while heading towards Boyvetoya, deep in the south Atlantic (55 south) in late September. It sounded horrible... It's well worth reading his book, probably the most epic small yacht voyage ever, and it was a voyage that did some very useful scientific work, by getting the first accurate data on seabird populations in the southern ocean and it's islands.

I am interested to know if anybody has experienced severe icing at sea on a yacht, what problems it caused, and how best to minimise it's dangers?

Cheers

Ben

A High Latitude Dodger.

The dome needs abit of "De-icing"

I was Lucky when I bought Reiger, Jim Dilly had already put a canvas spray dodger on her. If he hadn't it probably would have taken me a few years to work out how great they are. I am sure I would have maintained that I liked the taste of salt water and by not having a spray dodger it improved my "feel" for the boat or some other utter rubbish along those lines, so Jim did me a big favor...

Reigers dodger had a fantastic canvas flap that zipped onto the back of the dodger and bungeed down to the cockpit completely enclosing the whole area under the dodger. With this fitted I could actually cook standing up in the companionway, inside my little canvas tent, warm and dry, even with driving rain from astern. The steam from cooking would rise and condense inside the dodger and not the cabin. Wet weather gear could be stashed either side of the hatch, out of the cabin, and in cold weather it kept alot of the heat in the boat, like an airlock, but still provided ventilation.  I could even sail with the flap on. and of course the dodger kept me warm and dry at sea, all up it was brilliant...

My only complaints were that I couldn't work out how to fit a perspex dome to the hatch, and when I was sailing across the Tasman on my own I needed to climb right out into the cockpit to have a good lookaround, This required wet weather gear and a harness, and waking up properly - and I usually got at least a face full of salt water..

When it came time to fit a proper dodger to Snow Petrel I thought long and hard whether to put a canvas dodger or a hard dodger on the boat. We had built a series of hard dodgers for a few boats up at Launceston. The designer/artist was my friend Greg, he has a great eye for a nice looking dodger and after 3 builds we had worked out a quick strong method of building a hard dodger, But I was worried about how one might survive a southern ocean breaker landing smack bang ontop of it, at least with a canvas dodger I could just straighten the frame and stitch it back together, If I had been stupid enough not to fold it down...

The answer to building a stronger dodger came when I sailed on 2041, one of Chay Blyth's challenge 67's. The dodger onboard 2041 was maybe abit "practical" looking but had very strong knees at the after end that also doubled as somewhere to lean against. After seeing this I decided to go with a hard dodger, and as a bonus I could just squeeze a dome under the dodger on the main hatch and another on top of the dodger, above the hatch, meaning I would be able to have a look around without leaving the security of the main hatch.

It looks like this.

1 - 18 inch 6mm perspex dome, absolutely amazing view, doesn't steam up and can be used from inside the hatch or inside the cockpit. It is high enough to have a good view forward. It is a feature that I wouldn't be without. For tropical sailing I might fit it onto a hatch so it can be removed.

Little green hatted man is warm, dry and very happy!

2 - Hand rails set inboard to serve as longitudinal stringers, and gives a comfortable seat on the edge of the dodger roof. By setting them inboard the are easy to hold onto when on the lee deck.

3 - The dodger top is 2 layers of 6mm plywood laminated into a curve. It also has glass sheathing and non skid paint. This is more than strong enough to jump on. I intend to put a mainsheet traveller on top of it at some point...

4 - At the aft edge of the top and the sides is an external laminated beam. Inside this is an aluminium boltrope extrusion to take the canvas flap, to close in the dodger. This Beam stiffens and strengthens the top. It also stops water blowing back from the dodger top into the cockpit. And It forms a good handhold, hence burying the aluminium track inside the wood to stop my fingers getting cold.

5 - Big plywood and glass knees strengthen the aft end of the dodger, they also have handholds and make a nice backrest, or place to lean against. They also give the canvas flap something to overlap to stop rain driving in. They are tied with several heavy layers of unidirectional glass onto the top of the dodger, and bolted to stainless tangs on the coamings.

6 - Cabin top is used as a step to get onto the dodger, it also makes the dodger look better to set it slightly inside the cabin edge, and it is easier to build.

7 - Windows are 4 mm perspex, designed to break before the dodger does...

8 - Dodger sides are 9mm ply, doubled in high load areas, with heavy biaxial fibreglass tape in all the corners. They are bolted through welded stainless steel tabs on the cabin top. a Sikaflex fillet seals it to the deck.

From Astern, a bit of food on the wharf to store somewhere...

I spent alot of time looking at the ergonomics, mocking stuff up and trying to balance looks with functionality. I am happy with the results. There is room to sit in the cockpit completely under the dodger totally out of rain, snow or spray, and I can steer from this position, peering out the dome for a good look around. I need to add a few small windows to the top of the dodger so I can see the jib luff from this position.

I shifted the main winches aft 6 inches or so so I had space to sit on the cockpit coaming alongside the dodger steering with the tiller extension. This is very comfortable and gives a great view.

The dodger got its test on the way down to Antarctica, It copped a big southern ocean breaker, landed right on top of it, knocked us down and got some water below. I was sure it must have broken a window in the dodger but they survived. At some point I can imagine a storm bad enough to destroy the dodger, but if I survive I will just build another one, If I built it strong enough to survive anything it would be far two heavy, instead it is designed so that it cannot damage the watertight integrity of the boat.

One big advantage of having a dodger is that you can dress lighter, meaning when deck work needs doing you don't overheat, sweat and then get very cold as can happen if you are dressed very warmly for a windy cockpit watch with no shelter.

I think the dome/dodger combination is a big safety factor in cold water, keeping crew dry and warm, but some experienced sailors like Rolf and Deborah off Northern light don't have one, using the dome on the main hatch and an effective windvane instead. And I must say that if I got a bigger boat I would probably have more of a pilothouse setup, but with a sheltered area off the back.

I have sailed on a few boats that have a dodger sheltering the crew at the front of the cockpit but not the helmsman at the back of the cockpit. In my opinion this is stupid, the helmsman should be able to get their body out of the worst of the wind and spray, and ideally duck and get their eyes away from a dollop of spray. I have had my eyes get so much salt water driven into them that I could hardly see, A sensible dodger would have solved that problem.

On Blizzard we really wished we had at least a half dodger over the exposed wheel to keep at least our hands dry (or a good autopilot...), but instead we had numb fingers and could only manage half hour tricks in bad weather. Spirit of Sydney had a big lexan dodger, covering most of the cockpit and giving the wheel some shelter, this worked well, and I could hand steer for hours in the worst weather. A big safety plus.

Now thats a dodger! All Polycarbonate on alloy frames, it goes right back to the helm, ideally the helm needs raising slightly for better visibility, but you can stand to the side and steer with you foot for excellant vis. Note the clutter on deck...

 My father got home from the trip on snowpetrel and quickly fitted a spray dodger and roller furling to their 45 foot gaff ketch, after the 30 years that we had to put up with being wet and cold, so at least he was convinced of the benefits. But he couldn't quite bring himself to add a dome. Saying it just wouldn't look right...

The original dodger that spawned provided the pattern for mine, Looks much sleeker on a 38 footer, Nice work Wayne, Greg and Grant. 

Gosh Dad a spray dodger sure would be nice.... Note the Reefed Staysail on a boom.

Note the slightly raked angle of the dodger, this helps remove the illusion of the dodger being droopy, very important as a level dodger top will often result in the side panels looking slightly droopy due to the camber and fact that the sides are narrower at the forward edge. 

Here you can see the lip at the aft end and the radius of the top. The inboard handrails are very good, providing a comfortable seat on the dodger. 

 Under construction, note the annex track buried all around the aft edge.

Another Sister dodger. 

Plenty of room under the dodger, just enough headroom, and your whole body is out of spray and rain.

The dome was fantastic, here I am still inside the hatch with the door closed, perfect 360 view and safely wedged in place. 

The only shot with the canvas closure flap at over the back of the dodger, Two bungees held it down so it was easy to lift and get out.It really kept in the heat, and kept out snow ,rain and spray.

Snow Petrel, an introduction

Snow Petrel in very open ice

Snow Petrel is a 34 foot (10.15m) steel yacht that has been my home and transport for a few years. She is strong and simple, the two of the most important qualities in any offshore boat.

She has taken me south from Tasmania to Antarctica and may be the smallest boat to sail to East Antarctica (the bit that doesn't include the antarctic peninsular).  
See the videos page.

I have sailed ever since I can remember, starting on my grandparents 34 foot ketch and then sailing my parents 45 foot gaff ketch. I Raced dingys as a kid and then did some some offshore racing. 

NZ Maid, My parents Herreshoff Mobjack

I went to sea as a navigating cadet when I was 17, sailing (steaming..?) around the world on  P&O container ships for 6 years, and getting my chief mates ticket.

Needing a change I jumped onto a square rigger as mate for two seasons around the pacific... A lovely ship. Soren Larsen

After sailing my 26 foot Warsash one Design (something like a Folkboat) across the Tasman singlehanded I have now settled in Tasmania. Since then I have done a lot of yacht deliveries across the Tasman and around Aussie, sailed to South America, and run an old open 60 charter boat on the Antarctic Peninsular, and more or less rebuilt Snow petrel (a never ending job, still not complete). See Snowpetrel The boring details for more information on the her.

Soren Larsen

Reiger

I will try to put up the odd post now and then, hopefully my writing style will improve with practice, please forgive any grammatical and spelling mistakes, writing is not a strong point...

Also be aware that there are many ways to sail an ocean, many ways to set up an ocean going boat and many valid opinions, I tend towards the crude and cheap options, but understand that those with better budgets may prefer other solutions. I also try not to get to set in my ways and always reserve the right to change my opinions without notice... Keep an open mind.

Fair winds

Ben Tucker