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Shaped blade vs Flat blade Comparison

Blade Shape:
Propellers with flat blades (Planar blades) are like a paddle. The flat shape is not efficient at producing thrust. At anything less than max RPM the thrust produced will be greatly reduced. Independent test have shown that at a cruising RPM flat blade propellers produce very low thrust & therefore the boat-speed produced is very low. Lower than a standard fixed propeller.
The Gori propeller blade has true camber and shape (aerofoil) to each blade. Therefore the thrust developed will be greater than a flat blade. This is especially true at the cruising RPM or in adverse condition such as motoring into a head sea. The efficiency will at least match that of a fixed propeller. The Gori produces lower noise due to the twist and camber of the blades reducing the amount of wash off the blade

Drag Factors:
All of the flat blade propellers are feathering propellers, not folding. They have a greater blade area exposed to the water flow, which increases drag. This drag is even greater when the shaft is angled downwards’ presenting even more blade to the water flow.
At higher sailing speeds the feathering propeller will begin to auto-rotate. If the engine is in gear, the propeller can cause the engine to turn over and this would create water problems within the engine. The feathering propellers are prone to catching lines and debris, like bags, weeds, lobster/crab pots etc.
The Gori is a folding propeller and so leaves less area exposed to the water flow….less drag. Blades are “hidden” behind the hub. Tests have shown that the Gori has the lowest drag of all three bladed folding, fixed and feathering propellers.
The Gori will not auto-rotate, as it is a folding propeller. Therefore there is no need to engage the gear to stop possible rotation, even at higher sailing speeds. This also applies to hydraulic transmission installations.
It is for this reason that Gori is always the choice for fast cruising and racing catamarans and maxi mono-hulls.

Reversing:
Again flat blades cannot produce the same thrust in reverse as blades with shape. True, their performance in reverse will be better than a fixed prop in reverse. However it may still have pop-walk.
The Gori blade has the same camber and curve shape of blade and leading edge in reverse as fwd and so therefore increased thrust over the flat blade propellers, and gives a dramatic reduction in prop-walk (almost non-existent).

Installation:
Most all flat blade feathering propellers are delivered disassembled. The hub is installed first and then the gears, blades and pitch setting are re-assembled onto the hub. If the incorrect pitch setting is made it will require another haul-out to make that change.
Gori comes completely assembled, pitched and dynamically balanced at the factory. With the supplied tools there is some minor simple assembly required to install, but there is no re-assembly of blades, gears and pitch settings to choose. No chance of making a mistake. In addition no greasing is required.

Performance:
The feathering propellers have only one pitch setting under power.
Gori has two settings; standard and ‘Overdrive”. Motor-sailing is vastly improved when in “Overdrive”. Increased thrust & speed at lower RPM. Using the “Overdrive” function when motoring in calm conditions gives better speed at low RPM.
Less engine RPM results in lower wear and tear, less noise, increased fuel economy and a greater cruising range.

Design:
The planar blade shape has remained unchanged for 20+ years.
Gori propeller blades have under gone design changes as progressive knowledge of prop design has advanced.
Blade Area Ratio(BAR) %, design etc have all been changed and improved.

Gori 2-Blade Advantages

The Gori 2-blade propeller was first introduced in 1975 … that is 30+ years of folding propeller design and experience.

Folding propeller:
• Extremely low drag… geared propeller
• 2.7lbs at 8kts … the lowest of them all.
• Increased speed under sail.
• Less turbulence over the rudder.
• Less vibration in ahead or astern.
• Geared blade design ensures that blades open and close together… always.

No rotation under sail:
• No strain or loading on the transmission either mechanical or hydraulic.

True profile blade:
• Increases efficiency in forward and reverse.
• 57% efficiency rating in forward … 52% efficiency rating in reverse.
• Reduces noise caused by blade wash.
• Dramatic reduction in prop walk.

Simple Installation:
• Pre-assembled to ensure complete balance.
• No gear or pitch settings to make.
• Available for both shafts and saildrive installations.

Low Maintenance:
• No grease fittings involved.
• Manufactured of NIBRAL…high impact and corrosion resistance.

Performance ~ Reliability ~ Reputation ~ Quality ~ Longevity:
• Winner of ID design in 1976.
• Winner of Dame Award in 1994.
• Certified to DS/EN ISO 9001:2001 Quality Management System Standards.
• The first choice of skippers, designers, custom boat builders, OEM’s and
cruiser /racers worldwide.

Gori 3-Blade Advantages

The Gori 3-blade folding propeller marks a technological and functional leap forward in the development of propellers for sailboats.

Folding Propeller:
• Lowest drag possible of any 3-blade fixed, feathering, folding propeller.
• Increased sailing speeds.
• Less turbulence over the rudder.
• Geared blade design ensures blades open/close together & simultaneously.

No rotation under sail:
• No strain or loading to the transmission either manual or hydraulic.

True Profile Blade Shape:
• Blades have both camber & curve (aerofoil) to their shape.
• Increases efficiency (thrust) under power and over a greater RPM range.
• Higher efficiency at lower RPMs settings.
• Lower propeller noise from blade wash due to curve of blade

Same advanced blade shape in reverse:
• The unique folding action allows for the identical leading edge to be the
same in reverse.
• Greater thrust ~ power in reverse.
• Dramatic reduction in prop-walk (almost non-existent)

Overdrive function:
• Allows for a pitch increase over normal of approx. 2~3 inch.
• Increased thrust and speed when motor-sailing due to increased pitch
setting.
• Lower engine Rpms for cruising in calm weather… less engine wear,
vibration and noise.
• Increased fuel economy increases cruising range and lowers engine noise,
quieter.

Simple installation:
• No gear & blade assembly or pitch settings to make at time of install.

Low maintenance:
• Manufactured using NIBRAL, high impact & corrosion resistance. No grease
fittings involved.

Performance ~ Reliability ~ Reputation ~ Quality ~ Longevity:
• Gori propellers have been in business for over 30+ years.
• Winner of Dame Award for design in 1994.
• Certified to DS/EN ISO 9001:2000 Quality Management System Standard
• Currently installing propellers with serial numbers in the 65,000 range.
• The prominent choice of the top skippers, leading designers, custom boat
builders, OEM builders and cruiser and race owners.

2-Blade Installation

2-blade Standard Shaft Installation Instructions

Parts List:
( 1 ) Hub 1 x ea
( 2 ) Blades 2 x ea
( 3 ) Pins 2 x ea
( 4 ) Shaft nut 1 x ea
( 5 ) Allen screws 1 x ea
( 6,7 ) Allen Screws 4 x ea
( 8 ) Loctite 243 1 x small bottle
( 9 ) Allen key 1 x 4mm

Please read these instructions prior to installing your new propeller.

A) Take the propeller apart – note that there are 2 x allen screws (6,7) that lock each of the blade pins (3) in place. Note that the blades, pins and hub are marked for re-assembly.
B) Check that the hub fits the shaft taper without interference from the key. To do this first slide the hub onto the shaft without the key in place and mark the shaft at the fwd end of the propeller hub. Now place the key into the keyway and slide the hub back onto the shaft. It should come to the same mark that you had made before. If not then file the key until the hub reaches the shaft mark.
C) Check the nut on the shaft thread.
D) Mount the hub on the shaft and tighten the nut (4) to the shaft to 70ft/lb-95nm.
E) Install the allen screw (5) into the hub to lock the shaft nut. Do this by first smearing the threads with the enclosed Loctite–243. Tighten the screw in place using the allen key supplied.
F) Grease the moving parts of the blades-gears- with water resistant grease. Mount the blades (2) and the pins (3) to the hub. Be sure that you mount them in accordance to their numbers. ie #1 and #2.
G) Install allen screws (6,7) into aft end of hub using Loctite -243, on the threads. The second screw is a locking screw. Be sure to tighten both in place.
H) Check that the blades move freely from open to close.

WARNING:
• Do not start the engine while the boat is out of the water
• The prop may have sharp edges… be careful not to cut yourself
• Make sure the blades do not open or close suddenly and trap your fingers
• Stop the engine before diving or swimming in the vicinity of the boat
• Propeller blades can cause considerable damage when rotating … be careful.
• Do not remove fish nets, rope or similar from the prop with the engine running.
• Check that the prop works in both fwd and reverse before each trip. If any strange sounds or vibrations are noticed coming from the propeller stop the engine and investigate the reasons/solve the problem.

Parts List:
( 1 ) Hub 1 x ea
( 2 ) Blades 2 x ea
( 3 ) Pins 2 x ea
( 4 ) Shaft nut 1 x ea
( 5 ) Allen screws 1 x ea
( 6,7 ) Allen Screws 4 x ea
( 8 ) Loctite 243 1 x small bottle
( 9 ) Allen key 1 x 4mm

For any additional questions or assistance with the installation or removal of your Gori propeller please contact AB Marine, Inc at:

• Tel: 401-847-7960
• Fax: 401-849-0631
• Email: Sales@ AB-Marine.com

2-Blade Saildrive Installation

2-Blade Saildrive Installation Instructions:

Please read these instructions carefully before installing your new Gori propeller

Parts List:
(1) Hub 1 x each
(2) Blades 2 x each
(3) Pins 2 x each
(4) Washer 1 x each
(5) Shaft nut 1 x each
(6) Split pin 1 x each not used on all installations
(7) Allen screws 2 x each
(8) Allen screws 2 x each
(9) Locking bolt 1 x each
(10) Collar zinc 1 x each … 2 x halves
(11) Zinc screws 4 x each
(12) Loctite 243 1 x bottle
(13) Allen key 4mm
(14) Allen key 5mm

A) Take the propeller apart – note that there are two allen screws (7,8) that lock
each of the blade pins (3) in place. Note that the blades, pins and hub are all
marked carefully so as to re-assemble in the correct location.

B) Check that the hub (1),fits onto the output shaft of the saildrive leg.
The hub has a matching spline and so simply slide it on. Check that the shaft
nut (5),threads on to the end of the output shaft

C) Ensure that the washer (supplied with the saildrive unit) is in place at the fwd
end of the output shaft. Now grease the output shaft on the saildrive with
some water resistant grease and slide the hub back on.

D) Install the shaft nut (5), onto the shaft and tighten to 65-72 ft/lbs - 88-97nm. Now smear
some loctite (12) onto the threads of the lock bolt (9). Place the washer (4)
in place and tighten the lock bolt (9) to 10-11ft/lbs - 13 -15nm, into the output shaft.
On older saildrive models there may be holes drilled through the male thread
area at the end of the shaft. If so then align these holes with the holes on the
lock bolt (9) and insert the split pin (6) and bend over.

E) Grease the moving parts of the blades (2) and re-assemble the blades with
the pins (3). Be careful to place pins, blades and hub in the same numbered
locations.

F) Apply locktie (12), to the allen screws (7,8), screw them tightly into the holes
at the aft end of the propeller hub. Be sure that the blade pins (3) are smooth
and neat on the ourtside of the hub…this will ensure that the allen screws
have seated themselves into the dimple on the pin. Remember there are 2
per blade pin.

G) Check that the blades will operate freely in all directions from open to closed.

WARNING:
• Do not start the engine while the boat is out of the water
• The prop may have sharp edges… be careful not to cut yourself
• Make sure the blades do not open or close suddenly and trap your fingers
• Stop the engine before diving or swimming in the vicinity of the boat
• Propeller blades can cause considerable damage when rotating … be careful.
• Do not remove fish nets, rope or similar from the prop with the engine running.
• Check that the prop works in both fwd and reverse before each trip. If any strange sounds or vibrations are noticed coming from the propeller stop the engine and investigate the reasons/solve the problem.

For any additional questions or assistance with the installation or removal of your Gori propeller please contact AB Marine, Inc at:

• Tel: 401-847-7960
• Fax: 401-849-0631
• Email: Sales@ AB-Marine.com

3 Blade Installation

3-blade Standard Shaft propeller installation instructions:

Please read these instructions before installing your propeller.

Warning ~ do not remove the blades from the blade housing when installing or removing the propeller from the shaft!!!!

Installing the Propeller
The propeller is delivered assembled. This ensures that at the factory the propeller has been checked, and balanced prior shipping.
If your propeller has a fwd collar zinc installed ... remove the collar zinc (22 + 23) first.

Take apart the jacket (1) from the blade housing (6). To do this …First remove the 3 x allen head bolts (5) holding the jacket (1) in place.
Now undo the jacket using the C-Spanner (16). The thread on the blade housing assembly is a standard right to tight and left to loose. You may use a hammer with care, to get the jacket started as it is a firm tight fit.
You will now have the jacket and blade housing (with blades installed) and the hub cone (2) separate.

Check the fit of the hub cone (2) onto the shaft. Do this by sliding the cone onto the shaft without the key installed. Mark the shaft at the fwd end of the cone. Now replace the key in the keyway and again slide the cone onto the shaft. It should come to the same mark that you have made. If not then file the key and try again until the cone does come to your first shaft mark.

Check the shaft nut (3) with the shaft threads.

Slide the jacket (1) onto the shaft first. Lightly smear the jacket threads with a waterproof grease. Now slide the hub cone (2) onto the shaft and tighten the shaft nut (3) very tightly ... typically to 70ft/lbs - 95nm of torque.

Coat the three dog point allen screws (4) with Loctite-243 and tighten these dog point allen screws into the hub cone (2), locking the shaft nut(3), firmly in place. To do this you will need to rotate the jacket to line up an access hole with the allen screws (4).

Slide the blade housing assembly onto the hub cone (4), making sure that the tabs engage the hub cone. Push it fwd until you can start the thread of the jacket (1). Remember to have smeared the threads on the jacket with water proof grease.

Tighten the jacket (1) to the blade housing assembly. Use the C-Spanner (16) to tighten and align the 3 threaded holes (5) with the holes in the jacket. Now using the Loctite-243, re-install the 3 allen head bolts (5) into the holes and tighten firmly.

Check that the blades will move freely from fwd to reverse.

Removing the propeller:
Warning ~ do not remove the blades from the blade housing when removing the propeller from the shaft.

First remove the 3 x allen head bolts (5), from the jacket.

Now using the C-Spanner, undo the jacket so that it separates from the blade housing and push it fwd on the shaft.

Carefully remove the blade housing assembly by sliding it aft from the shaft/hub
Undo the allen screws (4) to allow removal of the shaft nut (3). It is not necessary to remove them completely from the Hub cone (2).
Unscrew the shaft nut (3)

Install the bronze puller (17) into the hub cone (2). Thread it in all the way.
Tighten the large bolt in the centre of the puller (17) and this will draw the hub cone off of the shaft.

Replacing the Aft Zinc:
This should be done if more then 50% of the zinc (7), has been eroded away.
Undo the allen head bolt (8) and remove the old zinc (7) … if not gone completely.
Clean the surface of the propeller hub to ensure a good clean contact between the hub and the new zinc.
Replace the zinc with a new one … index the fwd end of zinc with the end of the hub.
Use the new allen head bolt supplied … smear with loctite before re-installing the bolt. Check that the blades will swing freely from fwd thru to reverse.

Replacing the Fwd Collar Zinc:
First remove the 4 x allen-head bolts and remove what is left of the zinc.
Clean the surface of the propeller hub to ensure a good clean contact between the hub and the new zinc.
Install the new zinc using the Loctite (supplied) on each of the 4 x allen-head bolts

Replacing Flexible Stops:
These can be replaced without removing the blades.
Using a flat screw driver … pry out the old or worn Flexi-stops (15)
Push the new flexi-stops in place. It may be necessary to swivel the blades open and closed to obtain the best angle for re-installing the new ones. Remember they are flexible.

Removal of blades from the Blade Housing !!!
This must only be done when cleaning and full service of the propeller is required.
Blades are not removed for the installation and removal of the propeller.
Remove the centre bolt (8) and the zinc anode (7), using a 5mm allen key (19).
On propellers 18.0” and larger it will also be necessary to: remove the threaded pin (9) using a 6mm allen key … then remove the lock bolt (10) using a 5mm allen key.
Failure to remove these pins first will result in damage to the internal threads of the blade pins (11).

Disassemble the blade pins (11 & 11.1) from the blade housing using a 6mm allen key. Note that blades, pins and the housing are matched and numbered. They should only be reassembled in the correct location … that is #1 - # 2 - # 3.
Remove the blades.
Remove the gear-wheel (13) and the spacer (14).
Remove the flexible stops (15) using either a flat blade screw driver or pliers.
When re-mounting the blades and gears to the housing it is important to apply loctite-242 to … blade pins (11 +11.1), lock pin (10), threaded pin (9), fixing bolt (8).
The lock bolt (10) and the fixing bolt (8) are the very last items to be reassembled.
Be sure that all components fit back together and that the blade pins (11) are located exactly as before removal, as they are indexed inside the hub to lock bolts (10+8).

Operating Instructions:
The Gori 3-blade propeller has the possibility of two distinct pitch settings in the fwd direction … standard and “overdrive”

Standard fwd is the pitch setting that the propeller will be designed to, and will allow the engine to perform to the required RPM just as a fixed pitch propeller or any other propeller would.
In “overdrive” the pitch setting in fwd, is increased changing the engine RPM between 300~600 RPM less. The boat will attain the same boat speed at lower RPM in the “overdrive” position … as it is a pitch increase.

Ahead:
The propeller will operate in the standard fwd setting when the blades open due to the centrifugal force of the shaft when in gear.
Should you have backed out of your slip and then engaged fwd while the boat was in fact still moving aft you may well be in “overdrive” without knowing it. To go back to standard fwd, gear simply move the shift lever into neutral for several seconds … (allowing the blades time to fold together), and then go back into fwd. You will soon learn the difference between standard and “overdrive” by checking boat speed and engine RPM/sounds.

When maneuvering around the marina you may well remain in “overdrive”. Therefore when leaving the marina and beginning your trip always check that you are in the drive position you want be it standard or “overdrive”

Astern:
In the reverse position the blades swivel 180˚ opposite the forward position which ensures the same blade shape and leading edge to the water … resulting in higher efficiency. This will also greatly reduce or even eliminate prop-walk when maneuvering in reverse in the marina. If the boat has not been used for sometime, it is wise to shift cautiously between fwd and reverse a few times before going out sailing in order to clean the teeth of the blades and the gears from further fouling.
In the reverse position the pitch on the blades is at a greater angle/pitch then when in standard fwd. This is done purposely as many transmissions have higher ratios in reverse then fwd and so require a greater pitch to take into account the slower shaft rpm when in reverse.

Overdrive:
As mentioned above this position is obtained when the blades are set in the reverse position … but the blades and shaft are rotating fwd. In this situation you will have a propeller with an increased pitch setting. Overdrive allows a lower cruising RPM for the same boat speed. It will be as much as 300~600 engine RPM lower than when in standard fwd.

How to get into or out of “overdrive”?
Overdrive » standard drive: Be sure that you are moving ahead at around 3~4kts … now move your shift lever into the neutral position (if you have dual lever control then reduce RPM accordingly) … wait several seconds, to allow the blades to fold to their sailing position … now reengage fwd with the shift lever (and if necessary increase engine RPM with the second lever). You should now be in standard fwd and this will show with increased engine RPM, which perhaps were not attainable, while in “overdrive”.
On some larger vessels it has been found that to stop the shaft rotation even more quickly than as above … simply put the shift lever into the reverse position momentarily, this will cause the shaft to stop its freewheeling more quickly than just relying on the water flow. Once the shaft has stopped re-engage fwd and increase engine RPM.

Standard » overdrive: Reduce RPM and move the shift lever into neutral … now go into reverse and increase engine RPM to around 1000 RPM. This will set the blades into reverse. Now go from reverse to fwd position without hesitation … you will now be in “overdrive”. By moving the shift lever smartly from reverse thru to fwd the shaft and blades will not have the opportunity to stop and the water flow fold the blades as for sailing … thereby remaining open in the reverse or “overdrive” position.
Do not press the engine to the max RPM when in “overdrive” as this will result in overloading
Only use “overdrive” when motoring in clam weather or when motor-sailing.

*Gori propeller disclaims the responsibility for any damage caused by overloading the engine. In case of doubt about the engine loading, you should contact the authorized engine service agent and Gori propeller as well.

Sailing:
When sailing the blades will fold and the shaft will stop spinning giving you less drag and more speed. With mechanical transmissions you should pout the shift lever into reverse (per the engine manufacturer’s instructions), this will further hold the shaft stationary. Hydraulic transmissions will not rotate when under sail with the Gori propeller.

WARNING!!!
• Do not start the engine while the boat is out of the water
• The prop may have sharp edges… be careful not to cut yourself
• Make sure the blades do not open or close suddenly and trap your fingers
• Stop the engine before diving or swimming in the vicinity of the boat
• Propeller blades can cause considerable damage when rotating … be careful.
• Do not remove fish nets, rope or similar from the prop with the engine running.
• Check that the prop works in both fwd and reverse before each trip.
• If any strange sounds or vibrations are noticed coming from the propeller stop the engine and investigate i the reasons/solve the problem.
• In case of problems in connection with the mounting, use or other function of the propeller, contact Gori propeller or the local agent/importer.

PARTS LIST:

1. Jacket
2. Hub (Cone)
3. Shaft Nut
4. Allen Screws (3) for Locking Shaft Nut
5. Lock Bolts (3) for Jacket (item 1)
6. Blade Housing
7. Aft Zinc Anode
8. Fixing Bolt for Zinc
9. Threaded pin
10. Fixing bolt for Blade pins (Item11)
11. Blade Pins (3)
11.1. External Pin Locking Bolts
12. Propeller Blades (3)
13. Gear-Wheel
14. Spacer
15. Flexible Stops (3)
16. C - Spanner
17. Propeller Puller
18. Allen Key 4mm
19. Allen Key 5mm
20. Allen Key 6mm
21. Loctite (Blue)
22. Fwd collar zinc
23. Collar zinc fixing bolts

For any additional questions or assistance with the installation or removal of your Gori propeller please contact AB Marine, Inc at:

• Tel: 401-847-7960
• Fax: 401-849-0631
• Email: Sales@ AB-Marine.com

3-Blade Saildrive Installation

Please read these instructions before installing your propeller.

Warning ~ do not remove the blades from the blade housing when installing or removing the propeller from the shaft!!!!

Installing the Propeller

The propeller is delivered assembled. This ensures that at the factory the propeller has been checked, and balanced prior shipping.

Take apart the retaining cap (1). To do this … First remove the 3 x allen head bolts (5) holding the retaining cap (1) in place.

Now undo the retaining cap using the C-Spanner (16). The thread on the blade housing assembly (6), is a standard right to tight and left to loose. You may use a hammer with care, to tap the C-Spanner to get the retaining cap started as it is a firm, tight fit.

You will now have the retaining cap and blade housing assembly (6), (with blades installed) separate.

Check the shaft nut (3) & the nut-locking bolt (4.1) with the output shaft threads.

Remove the inner hub (2), flexible bushing (2.2), and bushings (2.1-2.3) from the blade housing (6).

Slide the retaining cap (1), bushing (2.1), inner hub (2), flexible bushing (2.2), and bushing (2.3) on to the saildrive shaft, matching the splines on the output shaft with those in the inner hub (2).

Fit the nut (3), and tighten. Typically up to 72ft/lb. of torque.

Smear locking glue (Loctite 243) on the thread of the nut-locking bolt (4.1). Place the washer (4) into the shaft hut and then thread the nut-locking bolt (4.1) using a 5mm allen key (19). Typically tighten to 10 ft/lbs of torque.

Slide the complete blade housing assembly (6 thru 17.1), onto the flexible bushing (2.2), so that the 2 x security cams slide into the grooves of the flexible bushing (2.2)

Continue to slide the blade housing onto the assembly until the thread of the retaining cap (1), and the blade housing (6) are touching.

Screw the retaining cap (1) RH or clockwise onto the blade housing assembly (6). Using the C-spanner (16) tighten until the 3 x holes in the retaining cap are aligned with the 3 x half circle cutouts in the blade housing assembly.

Now using the Loctite-243 (21), re-install the 3 allen head bolts (5) using the 5mm allen key (19), into the holes and tighten firmly.
Check that the blades will move freely from fwd to reverse and that the tip clearance with the hull is 10% of the blade diameter.

Removing the propeller

Warning ~ DO NOT remove the blades from the blade housing when removing the propeller from the saildrive leg.

First remove the 3 x allen head bolts (5), from the retaining cap

Now using the C-Spanner (16), undo the retaining cap so that it separates from the blade housing assembly (6). This is a right hand thread… simple right is tight…left is loose.

Carefully remove the blade housing assembly, by pulling off from the flexible bushing (2.2) and inner hub (2). These two items along with the bushings (2.1-2.3) will remain on the output shaft

Unscrew the nut-locking bolt (4.1) and also remove the washer (4) using a 5mm allen key (19).

Unscrew the shaft nut (3). It will be necessary to lock the output shaft when undoing the nut

Pull the inner hub (2), flexible bushing (2.20, end bushings (2.1 & 2.3), and retaining cap (1) off the output shaft.

Replacing the Aft Zinc

This should be done if more than 50% of the zinc (7), has been eroded away.

Undo the allen head bolt (8) and remove the old zinc (7) … if not gone completely.

Clean the propeller so as to ensure a clean strong bond with the new zinc

Replace the zinc with a new one … align the fwd end of zinc with the end of the hub.

Use the new allen head bolt supplied … smear with loctite 243 also supplied, before re-installing the new bolt. Check that the blades will swing freely from fwd thru to reverse. If not and there are tolerance issues it may be necessary to lightly file the sides of the zinc.

Replacing the Fwd Collar Zinc

This should be done if more than 50% of the zinc (17), has been eroded away.

First remove the 4 x allen-head bolts (17.1) and remove what is left of the zinc

Clean the surface of the propeller hub to ensure a good clean contact between the hub and the new zinc

Install the new zinc (17) using the Loctite 243 (supplied) on each of the 4 x allen-head bolts

Replacing Flexible Stops

These can be replaced without removing the blades.

Using a flat screw driver … pry out the old or worn Flexi-stops (15)

Push or tap the new flexi-stops in place. It may be necessary to swivel the blades open and closed to obtain the best angle for re-installing the new ones. Remember they are flexible.

Removal of blades from the Blade Housing !!!

This must only be done when cleaning and a full service of the propeller is required.

NOTE: Blades are not removed for the installation and removal of the propeller

Remove the centre bolt (8) and the zinc anode (7), using a 5mm allen key (19).

On propellers 18.0” and larger it will also be necessary to remove the threaded pin (9) using a 6mm allen key (20) … then remove the fixing bolt (10) using a 5mm allen key (19).

Failure to remove all these pins(8-9-10) first, will result in damage to the internal threads of the blade pins (11).

Disassemble the blade pins (11 & 11.1) from the blade housing using a 6mm allen key (20). Note that blades, pins and the housing are matched and numbered. They should only be reassembled in the correct location … that is #1 - # 2 - # 3.

Remove the blades.

Remove the gear-wheel (13) and the spacer (14).

Remove the flexible stops (15) using either a flat blade screw driver or pliers.

When re-mounting the blades and gears to the housing it is important to apply loctite-243 to … blade pins (11 +11.1), lock pin (10), threaded pin (9), fixing bolt (8).

The lock bolt (10) and the fixing bolt (8) are the very last items to be reassembled.

Be sure that all components fit back together and that the blade pins (11) are located as before removal, as they are indexed inside the hub to lock bolts (10 +8).

Note:
• If more than 50% of either of the zincs (7-17) has been eroded away they should be replaced.
• If the gear wheel (13) has been damaged or worn…it should be replaced
• If the flexible stops (15) have been damaged or worn…they must be replaced.

Operating Instructions

The Gori 3-blade propeller has the possibility of two distinct pitch settings in the fwd direction … standard and “overdrive”

Standard fwd is the pitch setting that the propeller will be designed to, and will allow the engine to perform to the required RPM just as a fixed pitch propeller or any other propeller would.

In “overdrive” the pitch setting in fwd, is increased changing the engine RPM between 300~600 RPM less. The boat will attain the same boat speed at lower RPM in the “overdrive” position … as it is a pitch increase.

Ahead:
The propeller will operate in the standard fwd setting when the blades open due to the centrifugal force of the shaft when in gear.

Should you have backed out of your slip and then engaged fwd while the boat was in fact still moving aft you may well be in “overdrive” without knowing it. To go back to standard fwd, gear simply move the shift lever into neutral for several seconds …
(allowing the blades time to fold together), and then go back into fwd. You will soon learn the difference between standard and “overdrive” by checking boat speed and engine RPM/sounds.

When maneuvering around the marina you may well remain in “overdrive”. Therefore when leaving the marina and beginning your trip always check that you are in the drive position you want be it standard or “overdrive”

Astern:
In the reverse position the blades swivel 180˚ opposite the forward position which ensures the same blade shape and leading edge to the water … resulting in higher efficiency. This will also greatly reduce or even eliminate prop-walk when maneuvering in reverse in the marina. If the boat has not been used for sometime, it is wise to shift cautiously between fwd and reverse a few times before going out sailing in order to clean the teeth of the blades and the gears from further fouling.
In the reverse position the pitch on the blades is at a greater angle then when in standard fwd. This is done purposely as many transmissions have higher ratios in reverse then fwd and so require a greater pitch to take into account the slower shaft rpm when in reverse.

Overdrive:
As mentioned above this position is obtained when the blades are set in the reverse position … but the blades and shaft are rotating fwd. In this situation you will have a propeller with an increased pitch setting. Overdrive allows a lower cruising RPM for the same boat speed. It will be as much as 300~600 engine RPM lower than when in standard fwd.

How to get into or out of “overdrive”?
Overdrive » standard drive: Be sure that you are moving ahead at around 3~4kts … now move your shift lever into the neutral position (if you have dual lever control then reduce RPM accordingly) … wait several seconds, to allow the blades to fold to their sailing position … now reengage fwd with the shift lever (and if necessary increase engine RPM with the second lever). You should now be in standard fwd and this will show with increased engine RPM, which perhaps were not attainable, while in “overdrive”.
On some larger vessels it has been found that to stop the shaft rotation even more quickly than as above … simply put the shift lever into the reverse position momentarily, this will cause the shaft to stop its freewheeling more quickly than just relying on the water flow. Once the shaft has stopped re-engage fwd and increase engine RPM.

Standard » overdrive: Reduce RPM and move the shift lever into neutral … now go into reverse and increase engine RPM to around 1000 RPM. This will set the blades into reverse. Now go from reverse to fwd position without hesitation … you will now be in “overdrive”. By moving the shift lever smartly from reverse thru to fwd the shaft and blades will not have the opportunity to stop and the water flow fold the blades as for sailing … thereby remaining open in the reverse or “overdrive” position.
Do not press the engine to the max RPM when in “overdrive” as this will result in overloading
Only use “overdrive” when motoring in clam weather or when motor-sailing.

*Gori propeller disclaims the responsibility for any damage caused by overloading the engine. In case of doubt about the engine loading, you should contact the authorized engine service agent and Gori propeller as well.

Sailing:
When sailing the blades will fold and the shaft will stop spinning giving you less drag and more speed. With mechanical transmissions you should pout the shift lever into reverse (per the engine manufacturer’s instructions), this will further hold the shaft stationary. Hydraulic transmissions will not rotate when under sail with the Gori propeller.

WARNING!!!

• Do not start the engine while the boat is out of the water
• The prop may have sharp edges… be careful not to cut yourself
• Make sure the blades do not open or close suddenly and trap your fingers
• Stop the engine before diving or swimming in the vicinity of the boat
• Propeller blades can cause considerable damage when rotating … be careful.
• Do not remove fish nets, rope or similar from the prop with the engine running.
• Check that the prop works in both fwd and reverse before each trip.
• If any strange sounds or vibrations are noticed coming from the propeller stop the engine and investigate the reasons/solve the problem.
• In case of problems in connection with the mounting, use or other function of the propeller, contact Gori propeller or the local agent/importer.

Parts List:

1. Retaining Cap 11. Pins (3 x each)
2. Inner Hub 11.1 Outside locking bolts for pins
2.1 Bushing 12. Propeller blades (3 x each)
2.2 Flexible Bushing 13. Gear Wheel
2.3 Bushing 14. Spacer
3. Nut 15. Flexible Stops (3 x each)
4. Washer for nut-locking bolt 16. C-Spanner
4.1 Nut locking bolt 17. Zinc ring anode
5. Locking bolts for retaining cap 17.1 Fixing bolts for zinc ring anode
6. Blade housing 18. Allen key 4mm
7. Zinc anode 19. Allen key 5mm
8. Fixing bolt for zinc anode 20. Allen key 6mm
9. Threaded pin on 18-20 only 21. Locking glue / Loctite 243
10. Fixing bolt for pins 18-20 only