Undersized Rudder

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schrater

schrater

Senior Member
Joined
Sep 4, 2016
Messages
130
Location
USA
Vessel Name
Matilda
Vessel Make
Ponderosa (CHB) 35' Sundeck
I'm starting to think that the rudder on my 35' Ponderosa with single 120hp engine is undersized. I notice this especially while docking at slow speeds and in even mild following seas. There are plenty of times where I just can't swing the aft around, or keep it straight.

I've seen some threads where people talk about modifying their rudders. Is anyone aware of new size/configuration rudders that can be purchased and installed? Or is this something that can only be done through custom modification? IMG_4402.JPG
 
On our previous boat, a 32' Ennos Sapphire, the previous owner was having slow speed challenges so he went to his NA buddy, Bill Garden, who suggested he add a "fishtail" to the back of the rudder. This was essentially a triangular shape (looking from above). I believe it made a difference; I had no problem with the handling.
 
Since you showed me yours, I'll show you mine :D

Badger is 30' and the rudder appears to have quite a bit more surface area than yours. Handles fine at slow speed and 'jumps' when giving it a goose one way or the other.

Looks like your swim grid is substantial enough to offer a bigger rudder some crash protection...maybe.
 

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I can think of two solutions to your problem:

1. Install a bigger rudder. Buck Algonquin has a line of standard rudders that might fit. This is a good solution if there is room and you travel at displacement speeds or less. If you cruise faster then the bigger rudder will require more power.

2. Replace it with an articulated rudder. These have a vertical joint that lets the rudder act like it curves when turned. A friend added one on his boat and it made an amazing difference. Not cheap. Google articulating rudders to find the supplier.

David
 
Extended rudder is far less additional drag than all the kinky tricky rudder mods.

I'd just weld on an addition to the trailing edge. Dosn't look like you've got much room to add to the LE for balance but I wouldn't worry about it ... unless your steering becomes exceedingly heavy. Just need a bigger rudder.
 
The fish tail or any wedge shape addition to the aft potion of the rudder will help. I have seen a 4X10 ripped diagonally to create the wedge and through bolted on the rudder work well.
 
do you know if your rudder are in stainless steel ?
If yes easy to weld a extended part on back.

Hugues
 
I agree with the throttle comment as well as the zinc comment - move it!
 
I had the rudder made larger on a previous boat, I suspect what I had was not original but a smaller (?post damage) replacement.
Made a huge difference to turning and turn tightness. It`s true judicious use of throttle helps but it will help more if the rudder is correctly sized, they are 2 different issues.
 
alormaria said:
Try using the throttle more.
Click to expand...

+3. SOP on many vessels. A term used is "goose and fill" for turning a single screw in tight quarters. I've two big rudders but using the throttle makes them work even better.
 
Schrater mentioned that he had two issues - low speed manoeuvring
and control with a following sea.

Bursts of throttle will definitely help at low speed but the only thing that will help at cruise speed running with a swell is more purchase in the water ie a bigger surface area for the rudder.
 
schrater,
Gaston may have wanted you to ask .. ?
I don't know but it may have something to do w electrolysis.
I position mine above or below the propwash for less drag.
 
You're correct Schracter, your rudder is short-changed. Mine is better. ;)

 
schrater said:
I'm starting to think that the rudder on my 35' Ponderosa with single 120hp engine is undersized. I notice this especially while docking at slow speeds and in even mild following seas. There are plenty of times where I just can't swing the aft around, or keep it straight.

I've seen some threads where people talk about modifying their rudders. Is anyone aware of new size/configuration rudders that can be purchased and installed? Or is this something that can only be done through custom modification?View attachment 64524
Click to expand...

Sorry for some of my short reply's often Im on the water running up and down into the ER checking for problems that are never there and only have my smart phone .
That anode would be creating a massive dead zone from where it is now all the way to the rear edge of the rudder above and below so in effect you would be loosing 10% ? of your rudder surface area .I have no Idea what that hole in you rudder is doing apart from creating even more turbulence ??? Move the anode up to the top right had corner left of the shaft about middle and use a torpedo shape anode on both sides . This is where I would place my anodes but what do I know ??:)
 
The hole is so you can pull the shaft without taking the rudder off.
 
I think when the rudder is disconnected from the ram assembly (necessary to turn it to 90 degrees) the rudder can be raised as necessary for shaft removal.
The hole is not there for turbulance.
 
Maybe it's for measuring spaghetti...
 
The hole in the rudder is to allow you to pull the prop shaft w/o removing the rudder.
 
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