Cheekplates

[LarryE-old]

After looking at my cheekplates I have come to the decision that they are good for 4-5 years in salt water, if the boat is used year round.
Alum. plates+ SS straps in salt water = battery. I have had this boat for 9 years and am looking at getting the third set.
Thinking of doing 316L SS and lasering them out to weigh the same.
As long as the rudder assembly weighs in. Right now it is 7 lbs heavy. Would I be legal?

[Stef]

Aluminum is approximately 1/3 the weight of stainless steel. Cheekplates are 1/4" thick, in order to maintain the same weight you would need to go down to .083" or 13 gauge. I believe you will find them not rigid enough, plus you wont have enough material for the countersunk holes on the inside. Make a set out of 6061 T6, have them hardcoat. When assembling use .005" thick teflon tape (available from McMaster-Carr) to isolate all the washers and the gudgeons straps. I think you will be happy with the result.

[LarryE-old]

Thinking to do something like drilling holes or do some bridgework cutouts until I achieve the desired weight. 1/4 in thick.
This year I sandblasted the ones I have now and Iridited them. Then painted with military spec paint. Will try that to see how it works out.

[dave]

There is a way around the plate thickness/countersink issue. You can use thinner SS plate and spot weld the pintles to the plate. Your idea of cutouts is a good one but I would suggest leaving most of the area around the rudder head intact. That spot carries a LOT of load, especially if the user tends to be a "heeler". The Rudder blade is so counter balanced that lots of folks never realize the true amount of weather helm they are carrying, because you don't really feel much of it through the tiller. You have to look at the angle of the tiller and compare it to the centerline of the boat. When the tiller is pointing at the windward cabin top winch [or higher!] as I have seen on some 7.9's being sailed, there is not much pull on the tiller but the rudder is under tremendous load! I'm sure this has alot to do with the rudder head cracking/breaking problems of the 7.9.

[Tim Bosma]

Larry,
Back to your '...legal?' question. The rules set out a minimum weight and a defined shape for the rudder blade. No mention of rudderhead except that it may be strengthened. My opinion (highly unofficial) is that if you make weight, then the material you use is not a concern.

[tpf]

If you want to use stainless I would keep the same thickness and cut holes to remove the excess material. I used to race motor cycles and it was a common practice to drill the brake discs to reduce the weight/rotating inertia.

In this case you would probably want to make the holes larger than using a drill so laser cut them also.

[Dale Eager]

The largest problem I had was the 1/2" SS pivot bolt interacting with the AL cheek plates. On the replacement cheekplates I purchased from Stef, he used oversized holes in the cheek plates to accomodate delrin bushings. I was a little concerned at first that the bushings might be a weak point but after two (or is it three?) years, the pivot bolt is still nice and snug and obviously no signs of corrosion. Great solution!