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El Pinguino · 29-01-2015, 01:04

The way fin keels should be attached...... the 'mothership' is in the background...

El Pinguino · 29-01-2015, 01:20

And the way rudders should be 'hung'....
That spade rudder stock extends from inches under the deck to the bottom of the rudder ( tapered after it exits the hull ) and involves a s/s 7/8 scale rudder with webs that the actual working rudder is built upon. Lose that and you have probably lost the back of the boat.....
I have seen crappo rudders with and without skegs where the whole interior bit of the business extends less than 12 inches within the hull.... a truly bonzer 5:1 lever if you manage to smack something....

Polux · 16-04-2015, 04:46

This one is not about a circumnavigator but about a guy that sailed extensively offshore a little "modern" Bavaria 32:

https://www.youtube.com/watch?v=QiuVFPX_PvU

https://www.youtube.com/watch?v=ctmvPcdH1vs

He is a member of this forum (Mel1970), he has a thread here:

http://www.cruisersforum.com/forums/...do-144485.html

**Dockhead** · 16-04-2015, 07:53

Quote:

Originally Posted by El Pinguino

And the way rudders should be 'hung'....
That spade rudder stock extends from inches under the deck to the bottom of the rudder ( tapered after it exits the hull ) and involves a s/s 7/8 scale rudder with webs that the actual working rudder is built upon. Lose that and you have probably lost the back of the boat.....
I have seen crappo rudders with and without skegs where the whole interior bit of the business extends less than 12 inches within the hull.... a truly bonzer 5:1 lever if you manage to smack something....

That your boat, Ping?

That looks really well engineered.

In my opinion, a really well done spade rudder should not be that much less strong than a skeg-hung one. Just because you've got a skeg doesn't make it bulletproof -- if the skeg is just glassed onto the outside of the hull, for example.

And no rudder construction will guaranty you against ripping it off, if you bash the rudder into a rock. It's just not feasible to build a rudder which could withstand 10 or 20 or however many tons of impact, with that much leverage.

Also, however tempting it might be to the designers, the rudder should be quite a bit less deep than the keel; to do otherwise is just asking for trouble.

Polux · 16-04-2015, 10:58

Quote:

Originally Posted by Dockhead

...
Also, however tempting it might be to the designers, the rudder should be quite a bit less deep than the keel; to do otherwise is just asking for trouble.

That is really a problem with shoal draft versions of most modern cruising boats that have a smaller keel (and draft) but a much more exposed rudder.

The only way to prevent that (maintaining the same rudder control) is with a twin rudder set up.

**Dockhead** · 16-04-2015, 11:05

Quote:

Originally Posted by Polux

That is really a problem with shoal draft versions of most modern cruising boats that have a smaller keel (and draft) but a much more exposed rudder.

The only way to prevent that (maintaining the same rudder control) is with a twin rudder set up.

If you need shoal draft, and you intend to sail, you need a movable keel.

Rudder same depth as the keel is a recipe for trouble.

There's an Ovni getting a bottom job near me in the boatyard -- I was admiring the elaborate protection of the rudder today. Really beautifully engineered to prevent damage to the rudder. That's a hot tip for people who need shoal draft and like to take risks in shallow estuaries, etc.

Bilge-keelers with sturdy skegs made for drying out are also good for that.

Finnsail · 16-04-2015, 12:38

I am not making any claims about the suitability of our Beneteau Oceanis 35 (33 ft hull) for blue water cruising, but wanted to share a photo showing how rudders are attached on the latest Beneteau designs (the 35 and the 38). I personally feel quite comfortable with the design, especially because the short twin rudders have relatively small moment arms compared to longer single rudders. The supporting structure is also glassed to the hull.