Four fin-seal failures that look like a helm fault
Start with the rule. This list is how a hydraulic fin pretends to be a control problem. Find the oil, then open the county note for where that oil is allowed to go.
The short version
A rod weep, a barrel blowout, a cooler rupture, and air after a filter change all can blank a fin or throw a pressure alarm. They are not the same part, and only the cooler puts oil into seawater without a puddle under the ram.
| Failure | Where the oil is | Wrong next step |
|---|---|---|
| Rod weep | Wet wiper, slow tank loss | Ordering a display because the alarm chirped |
| Barrel blowout | A sudden puddle or a bilge full | Pumping the bilge to “see if it stops” |
| Cooler rupture | Oil in seawater, or seawater in the oil | A rod-seal kit while the cooler stays online |
| Air after a filter change | Foam in the tank, lazy fin, no puddle | Condemning the amplifier |
How these four were ranked
Rank follows the volume and where it goes, not how dramatic the helm screen looks. A barrel blowout is first in consequence because it can cross a county report line in one event — Broward’s published marine-facility sheet uses 10 gallons or 80 pounds. A rod weep is second because it is the common misread: slow loss, loud alarm, no report yet, still used oil. The cooler is third because it hides. Air after a filter change is fourth because there may be no spill at all, and the fix is bleed and level, not a network card.
- Barrel blowout. Pressure left the cylinder at once. Contain it before you discuss parts. If you are in a Broward yard, the BMP report line is the yard note.
- Rod weep. Oil at the wiper and a falling sight glass. Still containment. Not a reason to open a gyro sphere.
- Cooler rupture. Sample the oil for seawater and look at the overboard side for oil. The discharge rule at the berth applies even when the bilge looks dry.
- Air after a filter change. Foam, a soft fin, a recent element. Bleed it. If the page is dark and the local controller is also dark, move to the network list instead.
Questions from the wheelhouse
Why does a seal leak show up as a helm alarm?
Low pressure, high temperature, or a controller that locks the fin when the header tank is empty will paint an alarm on the display. The evidence is still oil: at the wiper, in the bilge, in the seawater side, or as foam in the tank after a filter change. The alarm text without the oil location sends you to the network list by mistake.
Which of the four is a spill?
Any of them, once oil can reach a drain, a bilge pump, or the water. The county note then matters. Broward’s yard BMP, the Miami River permit, the sanctuary bilge exception, and the St. Petersburg storm section are different documents. This list does not pick the county for you.
Is a cooler full of seawater a seal kit?
It is a ruptured heat exchanger until proved otherwise. Seawater in the oil sample, or oil in the seawater discharge, is not a rod wiper. Replacing the rod seal and leaving the cooler online puts the new seal in contaminated oil and puts oil back in the discharge.
Do I open the gyro if the fin header tank is down?
No. Tank loss is this list. Vacuum history is the other list. The rule page is where those two stay apart.
Return to the rule if you still cannot say where the oil is.