Construction details of Rudder question after the sailboat sunk at Cowes

[tsenator]

I have some general Rudder construction question after hearing about the sailboat that sunk at Cowes after they rudder 'caught' the channel marker and ripped the whole rudder and snapped the shaft of that sailboat and it eventually sunk .


How are many sailboat rudders constructed ? What are the internal construction details of many sailboat rudders ?


On some boats like my previous one the upper half (of the actual rudder in the water) was where the actual structural metal that was holding the rudder was and the lower half was just foam ( fiberglass over top) and did not have any metal of structural connection to the rudder post. The reason for this was if, per chance, you hit something with the bottom of your rudder that part would just "break away" but you'd still have the top half of rudder that had the metal connection to the rudder shaft and be able to steer in "emergency mode"


Does anyone know what their rudder looks like apart and looked inside ? How about Jeanneaus built in the early 2000's (my present boat) ?

[GordMay]

You’ll probably find as many rudder construction details, as there are boat designers.
Most commonly, the spine of the structure is a metal rudderstock (also sometimes called a rudderpost) off of which sprouts a lateral armature that supports the rudder blade. Traditionally, this armature is welded to the rudderstock and consists of a series of lateral rods or bars, or perhaps a simple flat plate. More recently, foil-shaped fins similar to those seen in the frames of airplane wings have become more common. This skeletal structure is embedded in a high-density closed-cell plastic foam core, which is sheathed in a thin fiberglass skin.
According to WEST SYSTEM/Gougeon Brothers, "A typical spade rudder for sailboats is made up of two fiberglass skins that define the shape of the rudder, a metal mandrel that is an extension of the rudder post, and foam core which bridges the space between the skins and mandrel..."
➥ https://www.epoxyworks.com/index.php/rudder-repair/

[tsenator]

Gord,


Thanks , I might have to go to Jeanneau USA and see if they have the construction details of my particular model.


I know my previous Catalina 36 had the lateral armature welded & bolted to the rudderstock in the upper half of the rudder and nothing in the bottom half so as to "breakway" in a collision with something.



Tom

[atoll]

Originally Posted by tsenator

Gord,


Thanks , I might have to go to Jeanneau USA and see if they have the construction details of my particular model.


I know my previous Catalina 36 had the lateral armature welded & bolted to the rudderstock in the upper half of the rudder and nothing in the bottom half so as to "breakway" in a collision with something.



Tom

most of the french built boats rudders and steering systems are built by these people,see link
https://www.jp3steering.com/

[tsenator]

Originally Posted by atoll

most of the french built boats rudders and steering systems are built by these people,see link
https://www.jp3steering.com/

Interesting site - Thank you . It looks like they sometimes have the rudderstock and lateral fins go all the way down to near the end of the rudder and some only half way

[mglonnro]

Here are some similar pics from another major rudder constructor, Jefa:

https://www.jefa.com/rudder.htm

This link actually goes to the page I intended to link to: https://www.jefa.com/examples/steering.htm

[Chotu]

The case for kickup rudders is a strong one.

[Frank 101]

Originally Posted by Chotu

The case for kickup rudders is a strong one.

The stump jump plough was as Aussie invention. Looks like someone has jumped on a good idea and modified it for boats. Good on them!

[anacapaisland42]

Anyone know the make of the boat?
Bill

Originally Posted by tsenator

Gord,


Thanks , I might have to go to Jeanneau USA and see if they have the construction details of my particular model.


I know my previous Catalina 36 had the lateral armature welded & bolted to the rudderstock in the upper half of the rudder and nothing in the bottom half so as to "breakway" in a collision with something.



Tom

[psk125]

Originally Posted by anacapaisland42

Anyone know the make of the boat?
Bill

Another site has an English poster who believes the boat was a Sunsail charter from Port Solent, a Match First 40. (The ports in the topsides do make it look like a French design.)

The consensus on the other site is that the guys sailing the boat really had to mess up to foul the anchor chain of a large navigational buoy around their rudder. A photo shows the boat down at the bow, with the stern out of the water, and the rudder gone. While kick-up or pivoting rudders are useful for boats venturing into shallow waters, a rudder that would “snap off” without damaging the rudderpost might "snap off" at the wrong moment. The seems to have been towed to port.

[mitiempo]

I think that there should be a water-tight bulkhead ahead of the rudder, whatever its construction. That way even if it is ripped off in a collision the boat will not sink.

[anacapaisland42]

a 40 fot boat weighing 16,000 lbs and we wonder why something snapped??
Bill

Originally Posted by psk125

Another site has an English poster who believes the boat was a Sunsail charter from Port Solent, a Match First 40. (The ports in the topsides do make it look like a French design.)

The consensus on the other site is that the guys sailing the boat really had to mess up to foul the anchor chain of a large navigational buoy around their rudder. A photo shows the boat down at the bow, with the stern out of the water, and the rudder gone. While kick-up or pivoting rudders are useful for boats venturing into shallow waters, a rudder that would “snap off” without damaging the rudderpost might "snap off" at the wrong moment. The seems to have been towed to port.

[atoll]

Originally Posted by anacapaisland42

Anyone know the make of the boat?
Bill

Tupperware 40

[waterman46]

Originally Posted by mitiempo

I think that there should be a water-tight bulkhead ahead of the rudder, whatever its construction. That way even if it is ripped off in a collision the boat will not sink.

That is a very good idea, and one that I have seen mentioned on CF before. In my boat the bottom of the rudder post sits on a large bronze fixture that is embedded into a substantial skeg aft of the prop. Bit I thought, what would happen if this bronze fixture or the lower end of the SS rudder post corroded enough that the bottom of the rudder might be released? The rudder can't fall all the way out of the boat, since there is a large clamp on the post, inside the boat, securing the actuating arm to the post. But in a hard turn, I could see there might be enough leverage, if the lower attachment failed suddenly, to fracture the hull in the area of the rudder post gland.

We do have a bulkhead just forward of the rudder post, but it was not totally sealed off from the rest of the boat. I intended to seal this off except for a small limber hole to allow slow drainage into the bilge, of water that seeps around the rudder shaft. It is still on the to-do list, I am afraid.

[atoll]

this thread might be of interest,an account and videos of a CF menber losing his rudder mid atlantic onboard a similar vessel

http://www.cruisersforum.com/forums/...ng-129942.html

https://www.youtube.com/watch?v=7EO0o8kFZTU