Subject: [harryproa] Beam mounts and tillers |
From: Mike Crawford |
Date: 3/1/2011, 5:22 PM |
To: harryproa@yahoogroups.com.au |
Reply-to: harryproa@yahoogroups.com.au |
Gardener,
You brought up two points on which I thought I'd comment.
BEAM MOUNTS:
The beams are seriously strong and very accessible. It's a great
place to mount something that needs to be strong and accessible.
The beam-mounted design also made it easy for the rudders to kick
up while *also* allowing you do adjust their depth separately
without changing helm pressure that much.
However, the beam-mounted design didn't translate into the larger
proa as well as the smaller test platform. Perhaps because
elementarry had more submerged rudder area, perhaps because of the
amount of leeward hull immersed, perhaps because of something else.
Mini beams further from the centerline would be a nice
compromise. They would cost more than the existing beam-mounted
design because you'd have to add the mini-beams and their supporting
structure to your build (whilethe main beams are already there), but
they'd provide the kick-up, variable depth, and helm balance
desired.
TILLERS:
One strategy for helming the larger proas is to lock one rudder,
perhaps at a few degrees, and then steer with the other. This would
be perfect for tillers. You'd just need a long trimaran-type carbon
fiber tiller extension on each tiller in order to steer from your
cockpit.
If your rudders are far enough apart, and/or deep enough, you
might even be able to lock one at zero degrees and steer with the
other. If not, you could have two optional locking points: zero
degrees (for motoring) and three degrees.
A shunt would be pretty quick: flip one rudder, drop the tiller
extension into its lock, flip the other rudder, and begin steering
with it. You could probably flip both rudders at once with a little
practice, and look cool doing it.
The mechanism would be very simple: rudder, tiller, long carbon
tiller extension (perhaps of adjustable length), and a locking
mechanism at the helm with several stops (zero degrees, three
degrees, whatever) where you can place the end of the extension.
If the extension is adjustable, then you could always change it by
a centimeter or two before putting it in its stop, and thereby gain
infinite control of the angle of the locked rudder. Then you could
have just a single stop/locking point for the end of the extension.
This would be much less complex and costly than a wheel, steering
lines, quadrants, an so forth. As an added benefit, you could
recline in the cockpit seat and steer with one arm while leaning
back when feeling lazy, and then switch to standing when you want a
better view for docking. It's almost the best of both worlds.
I can't decide if I'd want this setup on a cruising boat, but on a
raider or daysailer, it should be cheap, quick, and quite efficient.
- MIke
Gardner Pomper wrote:
Rudolf and Rob,So, what is the advantage of having the rudders mounted on the beam? The obvious solution would seem to be to use the same sort of mechanism that I have drawn, but just move it to dedicated "mini-beams" further out on the leeward hull. I remember photos of Rob's rudder for Solitarry that looked like it was mounted that way, but I have gotten the impression that Rob has moved back to the beam mounted rudder idea.Am I just rehashing what has already been answered? I know I have read every post in this forum, but I could be forgetting.- Gardner