Tony

I am using the SmartLock lock down system (Boyer) with good results. Like everything, it comes down to personal preference, but these are simple & they work, ie. they stay locked when they should & let go when you run out of water.

Go to http://www.ahpc.com.au/ & look in the Technical Support section for "Using the Smart Lock Snap Down Rudder System". There is a .pdf file with pics explaining the system. If your rudders don't have the "ears" to take the rod I can explain how that is overcome.

Cheers

Andrew