Campbell Boat Owners Website

Rudders and Prop Shaft Packing

Article by Campbell Boat Owner Ron Fasola, owner of "Strange Brew"

On V Drive Campbell's, two major through-hulls are their rudders and their prop shafts. Both these areas usually have adjustable packing glands to prevent excessive water from entering the bilge. Over the years, these through-hulls have sometimes been a source of confusion among boat owners regarding how they function and how they should be installed and adjusted.

RUDDER SEAL

The rudder shaft has a rather large brass nut around it when viewed from inside the boat, and it is actually primarily an adjusting gland nut as opposed to a lock nut. Underneath the nut, there are about three or four "rings" of flax packing material. This packing material is square shaped in cross section, and is sold in about two foot lengths at most marine stores, (West Marine carries it). It is sold in various sizes from 1/8" to 5/8" on a side. It is Teflon or wax impregnated. To replace it, you simply unscrew the big brass nut and remove the old packing using some type of pick tool. Installation of the new packing involves determining the size of flax you need to buy by measuring the old material, (which will probably be unrecognizable), or measuring the gap you need to fill, and fitting the strip of new flax around the rudder shaft and cutting off an appropriate length. Don't use a continuous winding of the new strip to build up the needed sealing volume, because water will then have a spiral pathway to travel past the packing. Use three or four or whatever number of individual ring layers are needed for the brass nut to fit and compress the flax logically. Space the end points of each ring of flax such that no two line up to ensure better water seal; much like aligning piston ring ends around a piston. Tightening the big brass rudder shaft gland nut compresses the flax, which squeezes against the rudder shaft, thus providing a seal.

The adjustment of the nut should be such that a drop of water should be leaking past the seal, or coming through the brass nut, every 15-30 seconds or so. The leak rate is not too critical, but it is critical that some water is indeed leaking through. Some leakage is necessary to insure that the brass gland nut is not too tight, because a too-tight condition, (no water leakage), can degrade or deform the flax, which will then eventually not provide a good seal. Too much leakage simply makes for too much water in the bilge, and makes the bilge pump work more than necessary. This adjustment is unfortunately a trial and error situation, that must be done with the boat in the water. It will usually take a few tweaks over a number of boat outings for the new flax to conform and stabilize and hold adjustment. Just look at the brass gland nut while underway a few times and make small adjustments.

Although the steering tiller arm that is attached, (clamped), to the rudder shaft above the brass gland nut provides some protection against the rudder simply falling out of the boat, it is a good idea to install a billet ring clamp on the rudder shaft on top of the metal rudder brace that is bolted to the stringers. This way, both the steering tiller arm and the ring clamp would have to be very loose for the rudder to drop out of the boat.

Shaft seal

The most common shaft seal is a white plastic unit that uses two plastic jam nuts, (the shaft runs through the middle of these two gland nuts), to adjust the tightness of the seal. These two jam nuts have multiple holes in their perimeter, through which a cotter pin is inserted to hold the adjustment or prevent relative motion between the two nuts.

As with the rudder seal above, some water must be visible leaking past the seal. Some water leakage through the prop shaft seal is a bigger issue than with the rudder. The prop shaft spins significantly faster than a rudder shaft, (in most Campbell's, anyway!), so heat generation and possible shaft scoring can become a factor with too-tight prop shaft seals. The same trial and error method of adjustment is used, only now the floorboards have to be removed for visual access.

There are some other types of shaft or log seals on the market that do not leak any water, but I believe most older Campbells have the white ones described above.

Again, like with the rudder shaft, a ring collar is a good thing to add to the prop shaft between the V-drive and the through-hull seal. The shaft is really only held in the boat by the clamp bolts at the V-drive. The primary driving force of the prop & prop shaft is forward, so the shaft butts into the V-drive itself because it can take the large force of forward propulsion from the prop. But in reverse gear, or more importantly, when you hit a sandbar at 40 mph, the force on the prop shaft is towards the rear of the boat, and the shaft can easily be immediately drug right out of the boat upon impact. The V-drive system isn't designed to resist big forces in reverse. So installing a ring clamp to help keep your shaft in your boat is a very cheap insurance item.

Related notes

Replacing the rudder flax is not a routine thing. On a 1977 low hour Campbell, it has been done only once. Adjustment has rarely been needed once initially set.

On the same boat, the prop shaft seal has never been replaced. Adjustment has been required now and then.

If you hit a sandbar hard, immediately check to see if you still have your prop shaft. If not, you've got seconds to stick a towel in the hole that the lake has already found. Tapered wooden plugs can be bought that can quickly and efficiently plug a round hole from either inside or outside the hull. Some ocean boats keep wooden plugs tied near each through hull. After the hole is plugged, immediately check where you are on the water, so you might be able to later find your prop shaft and prop.

If you ever have to replace the shaft strut bearing, use a rubber "BJ" bearing. A BJ bearing can tolerate a small amount of shaft run-out, hence reducing vibration, and can also pass sand through itself. Hard "racing" strut bearings can do neither, and will score the shaft. This was learned the hard way.

Trivia The rudder is NOT located on the exact centerline of the boat. It is slightly off to the starboard side to allow the removal of the prop shaft.

More Trivia Not all Campbell rudders are in the same place. Some boats with high horsepower motors came with rudders placed about 6 or 7 inches forward of the transom. This aided keeping the boat from continually "leapfrogging" out of the water and then digging back in under full acceleration. It also reduced the turning radius of the boat.

Chrome rudders will not last long. Gorgeous polished stainless steel rudders for Campbell's can be obtained from Bergeron Engineering, Mesa, Arizona. Special order item; they can, (or at least they DID), make them. (602) 834-1531 The owner, Phil Bergeron, knows and stocks parts for shafts and V-Drives also.

V-drive Reverse

In forward gear, the prop delivers a horizontal column of water roughly equal in diameter to the diameter of the prop towards the rear of the boat. The prop "screws" its way through the water. In the path directly behind the prop, (when the boat is in forward motion), is the rudder. So any change in rudder angle from straight ahead results in the deflection of lots of water from the water column; hence large forces are generated which deflect, (turn), the direction of the whole boat.

In reverse gear, however, the prop delivers a horizontal column of water in the opposite direction, towards the bow of the boat. This means the rudder is now not in the "output" column of water, it is now IN FRONT of the prop, where it is basically useless because there is no column of water ahead of a prop.

So the boat has no rudder in actuality, in reverse gear, and the steering wheel is pretty much a useless item. The boat will, as we all know, simply crab walk backwards at about a 45 degree angle depending on the rotation of the prop, either to the port (right hand prop) or starboard (left hand prop).