Trimaran Rudder modification

[dcruz99801]

2 yrs ago I bought a tired Horstman Tri-Star 45 in San Diego and have been working on her since then. She is now more or less ready to cruise, but I am still considering a change to the rudder because (a) it is an unprotected spade rudder and deeper than the main hull, (b) that prevents deliberate beaching as well, and (c) I would like to have windvane steering, which would be feasible if it were a transom-hung rudder.

1. I recall CapnBrown or Doc50 said they had plans for a Horstman kickup rudder -- please respond, guys, I would like to see that option. Ed Horstman (when he actually replies) admits he has no such for the 45, "just buy my <H31> plans and scale it up".

2. If the kickup uses the existing rudder post/quadrant in stern cabin, should I give up the stern rudder/vane idea and concentrate on providing ample power for an autopilot? I was advised by another designer not to mess with it, but he could for a princely sum.

[twinzerfan]

I've got a Piver, and while it is a different boat, I have a similar problem.

What I've decided to do, is build a case for the rudder, with an open back, hung off the transom. The rudder can be completely loose in the sleeve, or hinged so that it can swing rearward in the case of impact. I'm going to leave mine un hinged, so I can slide it up an down as desired, and use heavy duty bungees to hold it in place - which will also give if I hit something. Lo tech, KISS is good for me

BTW - this isn't my idea, I saw it done somewhere online, and thought AH HA!

[Cavalier MK2]

Scaling up the 31 rudder sounds easy. Another idea is a skeg for the main rudder for beaching or shallower under hull rudder then mount a transom rudder with trim tab for the vane. This has been done often, Piver used one on Bird his 38.

Easiest idea is to get a plan sheet from John Marples for a large CC kick up rudder, but I think I've suggested this before.

[rberrey]

I'll dig out my kick up rudder plans for the 31 in the morning . I think it matches my basic dagger board profile . Why not just go with a dagger board rudder?

[rberrey]

The kick up rudder is transom mounted .

[Billy Higgins]

Check out the Open 40 web sites for builders of transom-mounted, cassette style kick-up rudders. Buying one off the shelf could save you a ton of grief.
If you want to have windvane self-steering in use with a kick-up rudder, you have an entirely different set of problems, none easy to solve. Probably best in this case to add solar panels and go for the autopilot solution.