Hamilton Jet HJ212, Инструкция по установке и обслуживанию

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Precautions Against Corrosion
Installation and Service Manual
Corrosion Monitor
It is recommended that a high impedance corrosion monitor be fitted.
There must be no possibility of an electrical connection between the jet units and the ships batteries.
If the jet units are isolated from the hull, corrosion monitoring of each jet unit external wetted surface and
internal intake duct should be carried out.
If the jet units are electrically connected to the hull, corrosion monitoring of the hull only and each jet unit
internal intake duct should be carried out.
Trim Tabs and Other Submerged Fittings
When 2 dissimilar metals are electrically connected and submerged in seawater, then galvanic corrosion can
occur.
If a large stainless steel fitting (such as a trim tab) is electrically connected to the jet unit, then the corrosion
protection of the jet unit will be compromised.
In order to ensure adequate corrosion protection for the jet, stainless steel trim tabs should be fully painted
or electrically isolated from the jet unit, or preferably both. Normally an anode would be fitted to the trim
tab to provide corrosion protection to the tab. Trim tabs made of aluminium will not affect the jet corrosion
protection.
Earth Connections for Electronic Equipment
Radios, radar and other transmitting equipment should not use the jet unit for an earth plate.
Be guided by the installation instructions for the equipment, but in general these systems should be
electrically insulated from the jet unit except that both the earth plate and the metal casings of the
transmitting equipment should be connected to the earth bonding system.

An unpainted metal earth plate is required which is always in electrical contact with the sea water, even
at planing speeds.

The plate is typically 400 x 400mm and should be located close to the transmitting equipment but well
forward of the jet units.

For a metallic hull, the earth plate can be a thickened area of the hull, formed by welding additional plate
inside the hull skin, up to 25mm thick.

For a non-metallic hull a separate metal earth plate must be fixed externally to the hull. It should be of
material compatible with both the "bonding strip" and hull (stainless steel is likely to be the best option.
It is not advisable to use copper as it can cause corrosion problems for other metals).

The "plate" should have a large stud welded to its centre and protruding inboard to which all the zero
voltage wires from equipment can be connected to.

The earth plate should be connected by an insulated wire to the vessels "earth bonding system".
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