Thanks Rick for all the answers.
ryanonthebeach, it is possible to pull strings raise and lower the rudders each shunt, but in reality it is not required, especially with a schooner rig. The advantage of the big rudders is that they work at low speeds, ie post shunt. Therefore, as soon as you have enough flow over them, you have control.
There is also the problem that leeway jams the rudders against the cases so a lot of force is required. This can be reduced by swerving to unload them, but not until the boat has some speed. ie, not just after a shunt.
The rudder design spiral has been going berserk. For about the 10th time in the last couple of weeks, we have celebrated the "best" rudder set up, in terms of ease of use, ease of build, safety and low drag and spray. We have sacrificed the lifting option as on the big boats, the boards are too heavy to lift easily and on the smaller ones, it is often inconvenient. However, they can partially kick up and still steer, albeit less effectively so can still be used for balance. They kick up clear of the water so drying out, reduced wetted surface and storm tactics are not changed.
Lifting is an option, but it looks very draggy compared to the current state of play. We have also resolved the outboard rudder in a marina problem and the inboard rudder getting in the way of the tender. Steering is still being looked at, but the twin wheels with chain/line drive with a clutch to engage/disengage them looks to be superceded. The rudder article I promised last week has been rewritten several times. I will not be publishing it until the design frenzy has settled down a bit.
On Wed, Mar 27, 2019 at 1:12 AM ryanonthebeach@gmail.com [harryproa] <harryproa@yahoogroups.com.au> wrote:
Doug - Yes, by balance I mean Weather and lee helm which is caused by the interaction of CE and CLR, see:Rick - I think we are saying the same thing, and it seems you experienced first hand the performance boost of getting it all nicely balanced.Balance can shift a bit upwind and downwind as the sails (CE) moves around and with some of the racing boats they move the CLR with the boards (angled back, as you raise the board the CE moves forward) or with tri's multiple boards, center board and boards set more forward on the amas (sometimes C foils to help lift the nose downwind). They would drop the ama board downwind and raise the center board.GeneralYou can see this balance shifting as a disadvantage or an advantage with an HP, I'm sure the cat and tri racers will love to be able to shift the CLR around as much as is possible on an HP.. For cruisers it's a bit of a pain... same reason asymmetric boards are not used on cruisers, cruising boats are generally designed to already be balanced on either tack (slight weather helm), so you can thrown her over and get back to your beer without running around to much. To mitigate, there should be a system of lines leading to the cockpit on an HP to lift the front board and drop the aft one on a shunt to kick the CLR back. I've sketched one out, but was wondering if anyone has already solved for this.
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Posted by: Rob Denney <harryproa@gmail.com>
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