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Date Posted: - Friday - 09/28/07 - 2:24pm
Author: Jake
Author Host/IP: c-71-234-230-236.hsd1.ct.comcast.net / 71.234.230.236
Subject: Rudder?

Has anyone thought of making a larger rudder for our mariner 32'? It seems to take some time to tack across the wind with our boat. I've try doing different things with head sails when tacking, speeds, etc.... but, the boat almost stalls every time we tack. So, I though of having a larger rudder made to see if that would help.....thoughts? Thanks, Jake s/v Maranatha

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[> The keel's to blame :) -- Randall, M31, - Friday - 09/28/07 - 8:52pm (204-16-158-68-static.ipnetworksinc.net/204.16.158.68)

Personally, I think being slow to come about is the nature of things for a full keel boat with lots of windage up top—i.e. two masts and all the extra rigging. Murre is never quick in stays (quickness is not really in the cards for Murre), but typically we only miss stays when tacking into a thick chop. Then, if the wind is light, the chop can knock too much way off before we’ve swung around, or if the wind is really honking, the chop and the windage can stop us cold. Even then, we can usually time the tack with the chop to get the best advantage. And we always use the jib to pull her head around.

It’s hard to imagine a larger rudder on Murre. The thing is already as big as a barn door. And I’m not sure bigger, beyond a certain point, is better. The issue is not lack of turning force, but rather the drag that the hull’s wetted surface creates, and especially when it’s turning. A full keel going 5 knots can only be made to go about so fast.

Might be a good question for Terry of Valhalla who can be contacted via the Fuji yacht bulletin board. I was looking through his 2006 refit photos the other day and noticed he has recently enlarged his fiberglass rudder on his Fuji 32. But it started out much smaller than the Mariner rudder and is now the same shape and size as mine.

Valhalla refit photos here: http://www.yachtvalhalla.net/projects/refit2006/refit2006.htm

RR

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[> [> you are correct, sir! -- ian mcgehee, - Tuesday - 01/15/08 - 5:38am (ip68-6-255-182.sd.sd.cox.net/68.6.255.182)

Backwinding the jib- learn it, live it, love it!

Besides the drag issue you mention, another reason that rudder modifications shouldn't be made without *very* careful consideration is that even small changes in rudder area can cause the hull's center of lateral resistance to move forward or aft...increasing the rudder area enough will do the latter, which will gradually introduce lee helm (or maybe not so gradually). Not only will this defeat the purpose of trying to make the boat easier to tack, lee helm can be dangerous.

Messing with your rudder design is kind of like messing with the fork angle on a motorcycle...it can be done and serve a purpose, but it isn't something to do unless you *really* know what you are doing, because even very small adjustments can have a major impact on your steering, and not necessarily the one you were going for.

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[> Notes on a Fuji 32 rudder modification project -- Randall, Murre, M31, - Monday - 10/22/07 - 9:08pm (204-16-158-68-static.ipnetworksinc.net/204.16.158.68)

Hey Jake,

Thought you might be interested in the project notes from a guy named Brian Cleverly. Terry on the Fuji site was nice enough to pass on the connection, and Brian responded quickly and with lots of detail.

He "barn doored" the rudder on a Fuji 32 he's restoring, but went much further and refashioned the shape of the rudder to a "NACA 0012 foil profile". (I put that in quotes cause I have NO solid idea what it really means.)

His detailed descriptions are here:

www.anzam.com

Go to "refurbishing examples", then "current Fuji 32 rebuild".

The various projects on his site are organized by a dates tab, and the rudder work descriptions are on the following tabs:

-06/28/2005
-07/21/2005
-12/18/2006
-01/06/2006
-04/06/2006

This guy's doing a sh*t load of cool work. Check it out.

RR

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