Here’s the finished product after installing three new rings of packing material.
When initially installing the rings of packing lightly tighten the nut just until you start to feel some resistance then stop. DO NOT OVER TIGHTEN THE NUT. The final adjustment will be made after running the motor and shaft for a while.
Setting The Drip Rate
Proper adjustment for GFO, GTU or Ultra-X is up to a few drops per minute when the shaft is spinning. You’ll ideally want it adjusted for nothing more than slightly different from the sea or lake water temp, about a 15 – 20 degree differential, or slightly warmer to the touch. Measure these temps after the shaft has spun for a while.
Adjustments should be made in either half a nut-flat or “one nut-flat” (of the nut) at a time. Adjust in small increments only and not more than one full flat of the nut at a time.
W.L. Gore recommends not adjusting the stuffing box until you have run the boat in gear for about two hours of time. This allows the packing to take a set and break in some.
When adjusting other types of flax the stuffing box should be relatively cool/warmish to luke warm, at most. With traditional flax packing it should drip and must drip while the shaft is spinning.
The cooler your stuffing box runs, the longer shaft life you’ll have. With GFO they claim temps up to the 125-130F range are technically safe for the packing. In my opinion & experience monitoring stuffing box temps over a 6+ year period, 125F – 130F generally means there is not enough cooling flow through the box.
Any entrapped air, with normal temps this high, can cause a big spike in box temp. Aim for 15-20 degrees warmer than the ocean or lake temp but a little higher, with GFO, GTU or Ultra-X, should not kill the deal.
Some boxes will even drip when the shaft is not spinning and this can be entirely normal depending on the condition of your shaft. Do not get stressed if you can not make it drip free at rest as not all shafts are in good enough condition for this to always be the case. Ideally they should be but many are not.
Please do not get in the habit of tightening the stuffing box when leaving the boat. Natural flax based packing’s are not elastic and do have a memory, in a sense, and they will not necessarily return to their uncompressed state. Doing this will severely shorten the life of your packing and it will start leaking, continuously, in short order.
I generally don’t like rules-of-thumb for drip rates and really hesitated to even put one on here. My reason for this is that every shaft has differing levels of wear and thus the drip rates are usually slightly different in every installation.
The best rule of thumb I’ve found over the years is this:
Aim for the least amount of drips when the shaft is spinning but before the box develops any heat rise beyond 15-20F, beyond sea or lake temps.
Again, it’s a drip to heat ratio not necessarily just a drip ratio. Little to no heat is the most desirable. Traditional flax packing can drip as little as about 5-10 drops a minute, if adjusted correctly, while running, and this drip rate allows lubrication of the shaft.
Do not make any adjustments to the packing nut, with traditional flax, for at least 24 to 48 hours after launching as the plant based flax packing will absorb moisture and swell. This swelling can cause overheating of the stuffing box, if it’s adjusted too quickly after launch.
Premature tightening of traditional flax packing can result in potential problems. A good and safe practice is to adjust the packing by half-a-flat turns after two hours of use or until you have your drip to heat ratio correct. You can actually use an infrared thermometer, often called a pyrometer, to make this adjustment process easier but usually your hand will suffice as a good gauge.
If you want a totally dry bilge then a dripless type seal such as a PSS or Las-Drop is the way to go. I’ve provided full installation instructions for that type of seal too in another article.
Good luck & happy boating!