ARC

[Bajansailor]

Just completed the ARC and worried about exactly this problem. there are solutions available that are mandatory for some offshore races. I had an emergency rudder in a bag that attaches to four strong points on the stern.

Welcome to the Forum X49 and to the Caribbean! I hope you had an excellent passage across, and that the ARC is living up to all your expectations.
Re your emergency rudder, have you tried doing a trial fit at sea, or in conditions that were not flat calm, to see how easy / difficult it would be to attach it to the 4 strong points on the transom?

 

[davethedog]

Just as an aside. I am getting quotes for a poosibke new boat for us and to cross tha Atlantic next winter and go further afield after that.

3 insurance companies have all stipulated we need 2 autopilots and one of them must be wind vane.

DTD

 

[dunedin]

Just as an aside. I am getting quotes for a poosibke new boat for us and to cross tha Atlantic next winter and go further afield after that.

3 insurance companies have all stipulated we need 2 autopilots and one of them must be wind vane.
DTD

Interesting. Is it a smallish and/or oldish boat?

It would be interesting to know the percentage with wind vanes on things like World ARC, Oyster World Rally and Grand Large equivalent. Probably tiny.

To be honest can't think of many/any boats over 50 foot built this century that I have seen with wind vane on. Apart from anything else, would need two, one on each side as the extra rudder would lift clear of the water if centrally positioned.

Regarding rudders, isn't it a bit like aeroplanes - better that they engineer sufficiently that the wings don't fall off, than install biplanes?

 

[davethedog]

Interesting. Is it a smallish and/or oldish boat?

It would be interesting to know the percentage with wind vanes on things like World ARC, Oyster World Rally and Grand Large equivalent. Probably tiny.

To be honest can't think of many/any boats over 50 foot built this century that I have seen with wind vane on. Apart from anything else, would need two, one on each side as the extra rudder would lift clear of the water if centrally positioned.

Regarding rudders, isn't it a bit like aeroplanes - better that they engineer sufficiently that the wings don't fall off, than install biplanes?

This is for a 47ft centre cockpit boat.

 

[Bajansailor]

@davethedog that seems to be a rather strange request by the Insurers - what do they say about the minimum number of crew for the crossing?
Could you perhaps substitute an extra crew member in lieu of the wind vane?

 

[davethedog]

To be honest not that bothered as the plan will be to fit a form of wind steerage anyway (likely to be a Hydrovane).

 

[Fr J Hackett]

It seems that every year the ARC has a steering gear failure and the associated loss of the boat no doubt insurers have begun to factor this into their premiums and specifications. A wind vane seems a practical adjunct to a long distance cruising yacht particularly a short handed one. However there are only a few that will operate independently of the ships steering system so the choice in respect of a back-up to that and autopilot is limited and centre cockpits don't help. Whilst within reason depending on the boat I would always if at all possible carry a wind vane my first attention would be the boat its steering system ( I have a particular perhaps unjustified) mistrust of cable systems and the type of autopilot drive again I don't particularly like rams either hydraulic or direct drive preferring a motor drive like the Lewmar.

 

[davethedog]

Either way, we will have at least 2 methods of self steering (likely 3 as boat we are interested in already has 2 electronic autopilots, even if one is an old version) for safety and the Hydrovane will give a form of spare rudder also.

Nothing wrong with minimising risk!

 

[dunedin]

It seems that every year the ARC has a steering gear failure and the associated loss of the boat no doubt insurers have begun to factor this into their premiums and specifications. A wind vane seems a practical adjunct to a long distance cruising yacht particularly a short handed one. However there are only a few that will operate independently of the ships steering system so the choice in respect of a back-up to that and autopilot is limited and centre cockpits don't help. Whilst within reason depending on the boat I would always if at all possible carry a wind vane my first attention would be the boat its steering system ( I have a particular perhaps unjustified) mistrust of cable systems and the type of autopilot drive again I don't particularly like rams either hydraulic or direct drive preferring a motor drive like the Lewmar.

The first statement isn’t true in my experience - there are always breakages of all sorts of stuff, but certainly not boats abandoned each year - and the reasons vary, often medical like this year also. The sheer number of boats crossing increases the numbers of failures of course, by nature of more boats = more problems.
The
ARC does do a detailed survey of gear failures, so if you want to quote stats from there pleas do.

 

[Fr J Hackett]

I may be stretching my memory but I recall abandoned boats for steering failure in the last 3 ARCs I haven't the interest to go back further but as you say it's not only ARC crossings that suffer from it most recently there has been a case of the Amel Super Maru. I happen to be an advocate of wind vanes and certain types of autopilot drives and the ability to self service and repair people can take from that what they wish.

 

[Laser310]

Steering failure is a pretty big problem for ocean-going sailing yachts.., maybe not because the actual number of failures is that high.., but because a high percentage of them end up with the yacht being abandoned.

One would think that more boats could be built anticipating some of the problems...

The worst case is loss of the rudder.., as this is the most difficult for which a jerry-rigged solution, that can go say1500 miles on the ocean, can be effected.

Sometimes loss of the rudder leads to water ingress, and that's even worse.

Even if one applies a reasonable amount of though and money, before leaving the dock, to devising an emergency rudder - to deal with complete loss of the rudder - it's going to be fairly difficult on many yachts to come up with something satisfactory.

This needs to be anticipated at the design stage.., not a couple of months before starting a voyage.

The same with flooding - yes.., it's difficult to isolate the steering behind waterproof bulkheads.., but not impossible. Also, they don't need to be 100% waterproof. There could still be openings for cables, wires and so on.., with ingress to the rest of the hull limited to a flow rate that can be pumped out while the leak is plugged.

I am not really knowledgeable about what is required for Class A Ocean status - but it doesn't seem like it includes much provision for this type of problem...

 

[Laser310]

Just completed the ARC and worried about exactly this problem. there are solutions available that are mandatory for some offshore races. I had an emergency rudder in a bag that attaches to four strong points on the stern.

it would be interesting to see some pictures of this setup.

 

[X49Sailor]

This is what it looks like mounted . Broken down it fits in a 6’ by1’ bag. To the earlier point I have not tried installing in big seas. The method is to attach the top two points and then hinge it down. My thought is that in big seas I might deploy a drought first to stabilize the boat. I read the account of Pip Hare installing a new rudder in the Vendee Globe - should be a lot easier than that, but then I’m no Pip Hare.

 

[X49Sailor]

Welcome to the Forum X49 and to the Caribbean! I hope you had an excellent passage across, and that the ARC is living up to all your expectations.
Re your emergency rudder, have you tried doing a trial fit at sea, or in conditions that were not flat calm, to see how easy / difficult it would be to attach it to the 4 strong points on the transom?

The was a great experience- certainly learned a lot. I feel a lot more confident for the next big voyage whenever that is. See below for comments on emergency rudder installation.

 

[X49Sailor]

Interesting. Is it a smallish and/or oldish boat?

It would be interesting to know the percentage with wind vanes on things like World ARC, Oyster World Rally and Grand Large equivalent. Probably tiny.

To be honest can't think of many/any boats over 50 foot built this century that I have seen with wind vane on. Apart from anything else, would need two, one on each side as the extra rudder would lift clear of the water if centrally positioned.

Regarding rudders, isn't it a bit like aeroplanes - better that they engineer sufficiently that the wings don't fall off, than install biplanes?

if you want something bulletproof then I think a skeg hung rudder should do that. I wanted the performance and feel of a spade rudder but added an emergency rudder for backup.

 

[dunedin]

if you want something bulletproof then I think a skeg hung rudder should do that. I wanted the performance and feel of a spade rudder but added an emergency rudder for backup.

Nice boat and good emergency rudder.
And of course there is absolutely no engineering reason why a spade rudder cannot be made plenty strong enough, without the need for a skeg. Just like jumbo jet wings don’t fall off, it is a matter of calculating the loads and engineering a safety margin.
(And interestingly in the recent Orca attacks, one analysis suggested the spade rudders seemed to be surviving better than skeg & long keel rudders etc, possibly because of the need for a spade rudder to have stronger stock)

 

[Wing Mark]

Nice boat and good emergency rudder.
And of course there is absolutely no engineering reason why a spade rudder cannot be made plenty strong enough, without the need for a skeg. Just like jumbo jet wings don’t fall off, it is a matter of calculating the loads and engineering a safety margin.
(And interestingly in the recent Orca attacks, one analysis suggested the spade rudders seemed to be surviving better than skeg & long keel rudders etc, possibly because of the need for a spade rudder to have stronger stock)

There's also no reason to assume a skeg is especially strong.
Sometimes it's just weak fibreglass fin which messes up the rudder.

 

[Roberto]

And of course there is absolutely no engineering reason why a spade rudder cannot be made plenty strong enough,

Not in engineering terms but there is a hydrodynamic reason, at least for people keen on getting that +.001kt.
Racing boat rudders tend towards the highest aspect ratio, a high AR rudder (ie very deep) has its lot of advantages, more efficient, relatively less surface needed, etc. This means long span and relatively short chord: long span means the center of hydro forces is relatively away from the last support (not sure of the correct term, where the rudder exits the hull), that is increased stress; also a short chord -if one wishes to use some reasonable section foil- means a limited maximum foil thickness. Example take a NACA 0012, typical for cruisers, 50cm chord gives 60mm maximum thickness, possibly limiting the rudder shaft diameter to 45-50mm.
If one wants a more efficient rudder foil there will be a trade-off between a deep, high AR spade rudder with optimal section thickness, and a "sufficiently strong" one: if you make it "that thin" it will break sooner, if you make it sufficiently thick you will lose hydrodynamic efficiency.

 

[Laser310]

Example take a NACA 0012, typical for cruisers, 50cm chord gives 60mm maximum thickness, possibly limiting the rudder shaft diameter to 45-50mm.
If one wants a more efficient rudder foil there will be a trade-off between a deep, high AR spade rudder with optimal section thickness, and a "sufficiently strong" one: if you make it "that thin" it will break sooner, if you make it sufficiently thick you will lose hydrodynamic efficiency.

some race boats are going with solid stainless steel rudder stocks

with a 50mm solid stainless rod, you can easily lift most boats out of the water

 

[Laminar Flow]

some race boats are going with solid stainless steel rudder stocks, and i ima

with a 50mm solid stainless rod, you can easily lift most boats out of the water

The resistance to bending for a solid stock versus a hollow one is marginal and Roberto is perfectly correct in what he says. You most certainly can lift a boat by a 50 mm rudder stock, whether it would still be straight afterwards is another question.

The four factors governing rudder stock diametre are:
1). area
2). distance to centre of load to bearing
3). speed of boat through water
4). torsion loading

The shorter the cord, the more limited the choice of stock diametre. The faster the boat, the stronger the stock needs to be. Displacement is actually irrelevant.
It should also be noted that with the intention to keep the gap between rudder and hull as small as possible the slightest bending in the fore and aft direction, such a when striking a submerged object, can cause the rudder to jamb against the hull, or, as has happened on occasion, to piece the same.

Choice of material for rudder stock is also limited to availability of standard stock.