superheat6k
Well-Known Member
The issues of primary concern with a trailing shaft are shaft seal and gearbox lubrication.
The seal will normally get sufficient water from outside the boat below planing speed, for instance PSS state a maximum of 12 knots for a non water fed seal. A stuffing box would be just fine.
With a hydraulic box the oil pump is providing oil to the critical parts, but only if the input shaft is turning. If I were faced with a long haul under one engine I would pour in extra oil so the gears were immersed, which would ensure they and the bearings received a reasonable supply of oil.
That said virtually all fishermen go to sea on just one engine.
However, my own motivation for two engines is to some extent the get me back factor if offshore. But a sensible toolkit, decent maintenance and clean and dry fuel tanks (bad fuel is the number 1 cause of engine failure) will provide for most situations.
In my own motor boating I have suffered four engine / propulsion failures - 1st shaft seal failure - got her back swiftly without assistance; 2nd gearbox failure - Seastart; 3rd Fractured injector pipe - got to harbour OK with coastguard alerted; 4th Engine coolant leak - sorted at sea. The first three were on a single shaft boat. Prior to that I hoisted main engines ! Since having two engines I haven't renewed Seastart.
The seal will normally get sufficient water from outside the boat below planing speed, for instance PSS state a maximum of 12 knots for a non water fed seal. A stuffing box would be just fine.
With a hydraulic box the oil pump is providing oil to the critical parts, but only if the input shaft is turning. If I were faced with a long haul under one engine I would pour in extra oil so the gears were immersed, which would ensure they and the bearings received a reasonable supply of oil.
That said virtually all fishermen go to sea on just one engine.
However, my own motivation for two engines is to some extent the get me back factor if offshore. But a sensible toolkit, decent maintenance and clean and dry fuel tanks (bad fuel is the number 1 cause of engine failure) will provide for most situations.
In my own motor boating I have suffered four engine / propulsion failures - 1st shaft seal failure - got her back swiftly without assistance; 2nd gearbox failure - Seastart; 3rd Fractured injector pipe - got to harbour OK with coastguard alerted; 4th Engine coolant leak - sorted at sea. The first three were on a single shaft boat. Prior to that I hoisted main engines ! Since having two engines I haven't renewed Seastart.
