How deep the rudder?

[Caboteur]

I have a B31 with a 4'3" shoal keel. There is very little protection for the rudder which is nearly as deep as the keel.
The Sunday before last there was a hurricane force wind here for a short while: 120Km/hr sustained for a minimum of three minutes. My boat pulled it's mooring and ended up on the rocks. There was enough water that the hull wasn't damaged.
The keel is scratched and a little gauged; nothing serious. There is at least 10cm (4") missing on the rudder. The lowest part of the interior stainless grid is showing.
When I repair in the fall, how much rudder should I "leave off" without adversely affecting performance?
So far I haven't noticed any difference with the missing piece. The rudder had already some damage before this event; I always thought that having the rudder about the same depth as the keel was a design weakness.
Thanks
Pierre

 

[Gunni]

I assume that you have the boat insured. If you pay to have the work done I think you will find the cost of repair to OEM will be very close to the cost of a new rudder because the yard will want to assure they have the entire damage inspected / scoped/ repaired. Do you know if the rudder post was compromised?

If I was surveying this at re-sale I would call the shortened/repaired rudder defective and back out the cost of a rudder, so you might as well get the rudder your boat was designed with while you have it. If you are insured, talk to your agent and make sure that any modification will be insurable. An inadequate/too small rudder puts higher stress on the steering gear.

 

[Caboteur]

OEM vs repair

You're right about it not being worth having any repair done: The cost of a new rudder is only 2130$ (plus shipping). However it seems Beneteau has changed it's rudder since there is also a "New Model" on the site! Maybe it's a little shorter... I'll have to give them a call.
As for insurance... my deductible is higher than that!
Thanks

 

[Cayennita]

My Idylle 15.5 (51') had a rudder that was the same length as the keel. Unfortunately my slip at low tide did not have enough depth for the rudder. When I took my boat to Trinidad, I had 4"removed and refiberglassed before doing the bottom. I no longer get gouges on my rudder and there has been 3 surveys since then and no one has noticed the difference. I have traveled to from Trinidad to Maine, down to Cuba, Mexico, Honduras, Guatemala, Belize, Cuba again DR, PR, and back to St. Croix. No difference in performance except that when I entered Rio Dulce in Guatemala de keel touched but not the rudder.