By: Prop Protector  09-12-2011
Keywords: Cutter, Set Screw

Regular Installation
The diagram below illustrates the components associated with the selection and installation of all types of PROP PROTECTOR. Although the diagram shows one type of stern shaft bearing, the following notes apply equally to craft fitted with either P or A struts or brackets.

In most installations, the gap between the propeller hub and the shaft bearing is wide enough to allow the installation of a Prop Protector. This gap must be sufficiently wide to accomodate the cutter plus an additional gap of 1/4" (6mm) between the Protector and the bearing. Extra Large cutters need a gap of approximately 1/2" (12mm).

This extra gap is necessary to allow water to circulate to the shaft bearing for cooling and lubrication. It also allows for any end float on the prop shaft. If there is excessive end float due to gearbox end play or over-flexible engine mounts, this extra movement has to be provided for. The recommended gaps for all types of Prop Protector are shown in the specifications. If the gap on your shaft is inadequate, it can be increased by any ot the following methods:

1. For adjustments of between 0.08" (2mm) and 0.2" (5mm), it may be possible to disconnect the prop shaft from the prop shaft coupling, move the shaft aft by the required amount and re-tighten the connection. If this method is used it is important to ensure that there is still suficient engagement between the shaft and coupling to maintain a secure connection under full power.

2. For larger adjustments, a coupling spacer or a flexible coupling may be fitted between the coupling and the gearbox flange.

Installation Video

Watch the video and see how simple a Prop Protector is to install.


Underwater Installation One of the unique features of the Prop Protectors is that they can be installed with the vessel afloat.

However, the thread-locking compound supplied with each cutter to secure the fastenings is intended for use only with the vessel out of the water; Loctite/ Screwlock will not cure underwater.

Owners wishing to carry out underwater installation should not use the fastenings or the thread-locking compound supplied, but should order the special self-locking fastenings we supply for this purpose and which are described below:

For all SLIDE-ON CUTTERS FOR 3/4" TO 2" diameter shafts a single set screw is required per cutter for which the cost is $2.00 each.

For all CLAMP-ON STANDARD, MEDIUM AN LARGE cutters for shafts 3/4" TO 2 1/2" diameter, one set screw and two cap screws are required per cutter for which the cost is $10.00 per set.

For all CLAMP-ON EXTRA LARGE cutters for shafts 1 1/2" TO 4" diameter, a similar but larger set of fastenings is required per cutter for which the cost is $15.00 per set.
These fastenings have been fitted with a plastic insert which serves as a self-locking mechanism and can be re-used up to five times.


The information in this article was current at 06 Dec 2011

Keywords: Cutter, Set Screw

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PROP PROTECTORS which are found to be unsuitable for the buyer's purpose or which are found to be faulty or unsatisfactory, may be returned for credit, providing the return is made within 60 days of purchase and the cutters and packaging are in perfect condition for resale. PLEASE NOTIFY YACHTING SERVICES AT 1-800-618-6748 BEFORE RETURNING CUTTERS FOR REFUND IN ORDER TO OBTAIN THE CORRECT RETURN ADDRESS.