Jim McEntyre's Modification of His M-382's Rudder
Profusely Illustrated
With Afterward Comments and Illustration by Lenny Reich
The rudder on my M-382 has always looked smallish and "odd" to me. She was a handful downwind, and it bothered me that the boat would not back down to starboard. I knew that the M-383, with its slightly larger rig, needed a piece added onto the top of the rudder in order to control the boat in heavy air. Putting these facts together, I concluded that the M-382 rudder size was marginal and would benefit from being enlarged. I didn't think the M-383 pie-shaped add-on piece would make enough of a difference, so I made a Xerox copy of the stock M-382 rudder design and enlarged it to 11X17 so that I could easily sketch-in different design ideas. I pinned the competing ideas on the wall and thought about it for a month or two before doing anything. I strongly believe in the old adage that "If it looks right, it probably is right". And, after the mods were completed, not only did the rudder finally "look right" to me, but it also worked much better; so once again the old adage proved to be true.
The modification I chose added about 25% more area to the M-382 rudder (15% more than the M-383/4 rudders), mostly to the upper portion. My biggest concern was that a larger rudder might make the boat harder to steer, but to date I have been unable to detect any difference at all in the effort required. Had it been necessary, I was prepared to install a larger quadrant in order to get more power at the wheel, but happily everything is fine. A secondary consideration was that I wanted to be able to easily reverse the change if it didn't work out well. Thus, all of the original rudder is still there, making it possible to undo the changes. The actual modification was simply a piece of structural foam, heavily glassed and faired onto the top and back of the stock rudder. It can be removed with just a couple hours of grinding and sanding. I like it and it's staying, but a future owner may want to return the rudder to its stock shape (for racing purposes?), so I took pictures to show what I did.
The first picture shows the stock rudder after it was sanded down to the gelcoat.
The second picture shows a cardboard template taped in place to illustrate for the fiberglass yard-worker what I wanted him to do. The work was performed in Mexico and my Spanish is not that good, so graphic aids were VERY helpful. The guy was a pro and did top quality work.
The third picture shows a piece of structural foam which had been cut and sanded to the same shape as the cardboard template. After confirming that the foam fit the rudder properly, it was taken to the shop and covered on three sides with a layer of fiberglass mat and woven roving. Only the face which touched the matching edges of the rudder was left bare. Sufficient clearance was maintained in the add-on piece so that the rudder would turn port-to-starboard without the add-on touching the hull. Note that the rudder bottom end is unchanged and remained at the stock front-to-back length, but the more vertical new trailing edge makes the rudder profile progressively wider nearer the top.
The fourth picture shows the fiberglass-reinforced piece of foam after it was glassed and partially faired onto the stock rudder. Note that the add-on piece fills in the area from the aft lower corner of the rudder all the way up to a point at the bottom edge of the bootstripe, then forward and down, following the counter all the way down to the top of the rudder. Sufficient clearance was maintained in the add-on piece so that the rudder would turn port-to-starboard without the add-on touching the hull. The rudder bottom end remained at the stock front-to-back length, but the more vertical new trailing edge makes the rudder profile progressively wider nearer the top. The resin and microballoon filler that was applied to fair-in the add-on piece was applied as an eyeball process, and it was helpful to have an experienced yard worker to approximate a good foil cross section.
A couple of very important things should be noted here. First, we discovered during this work that the stock rudder had a seriously defective shape to it. It had a twist or 'kick' of about 2 inches to port in the bottom half of the rudder. Also, the port side was close to "board flat", while its opposite side had most of the curve. I called the Morgan rudder supplier, Foss Foam in Florida, and they said that they had never heard of, nor seen, such a defect, and suggested that it was one of the few "experimental" rudders that Morgan built themselves in order to try to reduce costs. The rudder seems solid and well made otherwise, so this goes down as a mystery. Additional microballoon fairing was subsequently added to help reduce this problem by adding curvature to the flat rudder side. Second, you may notice the exposed lower gudgeon where it fastens to the skeg. This is because new hex-head bronze bolts and nuts were installed to replace three brass flathead bolts which had de-zincified and gone away (a bad repair from the past). Proper flathead bronze bolts were not available, but at least the gudgeon is really strong now! Only luck and habit held the gudgeon in place until the problem was noted and what was left of the brass bolts was replaced with bronze.
The fifth picture is of the completed rudder after being coated with blister-block protection, waiting for its first coat of new bottom paint, but now "looking right." The bulge at the skeg area is due to more fairing being added in order to get better flow over the exposed heads of the bronze nuts and bolts.
The sixth picture is the same as #5, but with bottom paint applied, and was included just in case a darker image shows up better. What appears to be a triangular piece added inside the aperture, just above the top propeller blade, is not part of the boat, but instead belongs to the mobile lift. When the boat is at rest in her slip, about 1" of the aft rudder tip peeks out above the water.
In summary, the new rudder size and shape allows far more control in reverse than before. From a dead stop, I can now back into a 90 degree turn to starboard in 1 to 2 boat lengths. The boat also now steers more precisely downwind and in following seas. In general, the boat seems to respond much more authoritatively to the helm, both while powering and sailing, yet there is no noticeable difference in effort required at the helm at any wind angle. There may have been an incremental increase in drag due to the small increase in wetted area, but if it has slowed the boat any, I couldn't tell. It's very possible that the drag may in fact be less due to a considerably more efficient rudder shape. The relative positions of the keel and rudder bottoms remains unchanged, so the rudder is still protected in a grounding. And finally, the rudder won't attract lobster pots any more than the stock design did. As far as time and cost are concerned, the work progressed, off and on, over two days (while the bottom was being prepared for new bottom paint) and the cost was 950 Pesos (about $125 in 1997). In all regards I'm extremely satisfied and will never go back to the stock rudder size and shape.
Afterward by Lenny Reich: I got out a picture of my M-383's rudder for comparison to Jim's stock M-382 rudder and to his modification. I carefully measured my photo against his photos and scaled them to check the relative proportions. What I found was that Jim's modified rudder is almost exactly identical to mine. If I'm correct, this means that Morgan did not just add the filler to the top of the M-382 rudder to make the M-383/384 rudder (as I believe Jim assumed)--they added the tapered trailing edge as well, making the new one about 25% larger (by Jim's calculation). I should mention that my rudder was also asymmetrical--much flatter on port side than on starboard. This caused the boat to try to turn right most of the time. It was faired winter '97 and now works fine.
The photo of my M-383 rudder appears below. Compare it to Jim's pictures. [Note that the painted waterline on my boat is lower than on his--see their relationships to the cockpit drain holes.]
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