MORGAN OUT ISLAND RUDDER ?'S

[Abendicum]

Any one out there ever see how the Morgan OI 41 0r OI 51
Rudders are constructed ?

I am thinking that they are all pretty similar -
Double Clamshell
Large SS Solid Shaft
Numerous horizontal welded supporting framework
Foam Filled
Heavy Glass Laminate Hand Lay Up

I have an OI 51 and assume the OI 41's were made in a similar fashion
So few 51's made - but there are a bunch of 41's out there !

Ab

[Bill O]

Originally Posted by Abendicum

Any one out there ever see how the Morgan OI 41 0r OI 51
Rudders are constructed ?

I am thinking that they are all pretty similar -
Double Clamshell
Large SS Solid Shaft
Numerous horizontal welded supporting framework
Foam Filled
Heavy Glass Laminate Hand Lay Up

I have an OI 51 and assume the OI 41's were made in a similar fashion
So few 51's made - but there are a bunch of 41's out there !

Ab

Sounds like a typical rudder construction, why do ask?

[Abendicum]

Thinking of Modifying Rudder to be Articulating...

[Bill O]

So basically a trim tab. Curious what you would like to gain with such a modification?

It's probably a decent amount of work to add the flap/trim tab. There are other rudder designs that I've looked at which will give you better lift, like a Schilling/fishtail rudder shape. These may be easier to do just by reshaping the trailing edge of your rudder than trying to add a flap.

Here is an overview paper on rudder designs that I looked at before building our new rudder. Maybe this will help.

[Abendicum]

I have owned my Morgan OI 51 for 12 years and maneuvering at slow speed is difficult.

In cruising trim she is just south of 25 tons. It takes few bursts of big power to turn her quickly - in tight situations. The Diesel is a Perkins 6.3544 NA. Most of the 51's I have seen are 4 cylinder...

The videos on line for trawlers jockeying - are quite amazing -with articulating flap rudders. The "flap" can double the angle of the rudder. Mine is 35 degrees per - side - so I might see 70 degrees deflection of the prop wash.

I like this style of linkage it is up high and it could be made with a cover plate to keep sea weed from getting caught and removed for maintenance www.nauticexpo.com/prod/talleres-blanchadell-sl/product-34204-514442.html If you page down there is a video

Here is another link to one with a lower gudgeon that I have on the 51
https://www.becker-marine-systems.com/products/manoeuvring-systems/sa-heel-pintle-rudder.html

Here is one with a closed Linkage that would work better on sailboats with a faired in cover
https://www.becker-marine-systems.com/products/product-detail/becker-flap-rudder-with-closed-linkage.html

Here's one in Composite (or Fiberglass) that I could blend into my existing Rudder if I cut off say 25% off the back-
https://www.becker-marine-systems.com/products/manoeuvring-systems/flextail-composite-rudder-flap.html

I am a welder and really good with fiberglass - so the work doesn't bother me. I am also a commercial diver so maintenance underwater is not an issue either...

Ab

[Bill O]

I believe the Becker rudder is a Shilling w/a flap.

I can't find the paper that I had where someone made a Shilling /fishtail rudder which helped them turn the boat better for tight maneuvering.

While this is another paper about high performance rudders which I think is still applicable for sailboats. Look at the relative turning performance in figure 4, it will speak for itself.

Do lots of research before you build and watch out if you make a metal rudder so it is not too heavy. The general thought is to have neutral buoyancy and too heavy is worse than too buoyant.

Good luck w/your project and keep us up to date on your progress.

[Glenne2]

I remember as a kid seeing the Morgan OI 51 double page ad in Cruising World magazine. 1976/7. I've always wanted one. Once this lockdown in this third world country I live in allows travel to and from the US I'm planning on going to the States to find one. Even a fixer upper would be considered! Interesting modification you are planning. Please let me know how it works out for you