Boy, you dragged this one up from the vault !
For marine applications I think you may find a Calcium Sulfonate thickened grease will beat an aluminium thickened grease hands down.
Lubrimatic market one that I'm very partial to.
It uses conventional (highly refined) base oils with a calcium sulfonate thickener and has very good Timken and 4 ball load ratings as well as being extremely good for corrosion control.
NLGI Grade: 2 Thickener Type: Calcium Sulfonate Complex
Color: Green Texture: Smooth
Brief product description: An automotive and industrial grease with excellent shear stability, load carrying ability and water resistance. It is free of heavy metals and resists burning. It is formulated with oxidation inhibitors and has excellent resistance to rust and corrosion. It meets NLGI GC/LB requirements.
ASTM Typical
Test Method Result
Penetration @ 77°F = D-217
Unworked = 276
Worked 60 Strokes = 279
Worked 10,000 Strokes = 287
Worked 100,000 Strokes = 296
Roll Stability (% change) D-1831 = 293(+5.0)
Rust Protection D-1743 = Pass
Dropping Point, °F(°C) D-2265 = 550°F (288°C)
4-Ball EP Performance D-2596
Load Wear Index = 72
Weld Point, Kgf = 500
4-Ball Wear Protection D-2266
Scar Diameter, mm = 0.45
Timken OK Load, lbs. D-2509 = 65
Wheel Bearing Life Test, hrs. D-3527 = 120
Water Washout D-1264
@ 175°F, % = 0.4
Water Spray Off, % D-4049 = 67
Oil Separation, % Loss D-1742 = .17
Base Oil Characteristics
Vis @ 40° cSt D-445 = 219
Vis @ 100° cSt D-445 = 18.7
Vis @100°F SUS D-2161 = 1000
Vis @210°F SUS D-2161 = 85
Viscosity Index D-2270 = 96
Low Temp Torque-Wheel
Bearing D-4693 = 9
-40°C, N • m