What is the correct propellor for Silver Century Plus?

[johntr]

I have a SilverCentury Plus as the auxiliary motor on my 20' open work boat down here on Sydney Harbour. The Serial Number is WSPCL1378HH7. It is fitted to my boat 'Sarah' with a Spartan outboat motor mount. We tested it for first time on the weekend and was not overly impressed with the performance in the water. Currently the prop is a four blade rounded prop* and I see in all photos of Silver Centuries that it should have a 5 blade 11" hydrofan prop. Would the 4 blade rounded prop on the engine now give less performance in the water?

Silver Century on Spartan outboard mount

Interior of the work boat with Chapman Seadog Engine

The rear of the boat

*dont have photos of current prop now as seagull engine is on my moored boat.

[Keith.P]

Welcome, They do say the hydro fan prop is a better option than the clover leaf.

[JERSEYMAN]

I think the big hydrofan prop is hard to beat for push.

[jerseydave69]

I think the hydrofan is a good bet too! I tried a four bladed one like yours on a century, pushing a six metre rib ,albeit a rib is hard to push until up on the plane. I was getting three and a half knots in non tidal water ,but the motor wasn't getting to maximum revs I thought,so a hydrofan could well be the way to go !

[AusOB_Collector]

I have been led to believe that most, if not all Century model Seagulls are supposed to turn a five-bladed hydrofan type prop, not four blade or otherwise.
If some Silver Century's left the factory with four blade props, I'm sure someone will let us know.

Cheers
BP

Again, thanks to SOS for the pic.

[Collector Inspector]

Hi JTR

A propeller correctly applied will give the maximum RPM of a motor depending on what mass you are going to be trying to move regardless of external factors.

You have to start from there.

Your lack of performance was noted but was it because the motor could not reach operating RPM limits or was it because it was over revving and not actually having any effect.........

Start with the propeller supplied as standard for your Gull model is the best thing. Not that many choices I am afraid as props match gearboxes as a rounded rule of thumb.

Gulls push water.......volume and weight remember.

BnC

[Oyster 49]

Yes, key thing to remember is as Bruce says props should be matched to the gearbox you have. The Centry plus is designed to push heavier boats along at a steady plod. I would suggest that the 5 blade hydrofan (Great description!) will be perfect.

Performance is never going to be hot though.

[JERSEYMAN]

The later weedless prop design on a model 80, still a silver century though.
I don't think it had as much push as the Hydrofan

[johntr]

Thank you every one with the help re the correct prop for my engine. The boat it is on is at least 1 ton and I wanted the Silver Century to be a definite auxiliary. Not wanting great speed, just to get me home if the Chapman Seadog lets me down. So now looking for a 11" 5 blade original prop. I am sure I will find one!

Thanks everyone again.

I will let you know the difference when the new blade is on.

John
Sydney Harbour - not a bad place to own a boat!

[Hugz]

Been debating whether to part this motor. Corroded gearbox and bent crank. I guess you can help me with that decision. I can meet you at Northwood Wharf.

[johntr]

Hi,

Keen to meet. Is this possible today?
I would be coming by car, not boat. But good to meet you.
I am over your way today. Your choice of time.

If not today, what suits you?

John Treloar
0414227777

[Hugz]

Gosh, this is the world of Gentlemen and Seagulls, nothing so fast, we need to mull and consider.

Ok, mull and consider completed. I'm in Lane Cove. Earlier the better for me. I've got a chikie babe flying in this afternoon. (oops, the gentleman bit just flew out the door )

[johntr]

Get the point re mull and consider. I need to slow down.
So where are you? Can you send address to mobile number below?

John

0414 22 7777

[Hugz]

Prop has now changed hands!

[johntr]

Hugo is a true gentleman. We had a good chat about his WW era seagulls, discussed how beautiful Sydney Harbour is and I purchased the very good condition propellor.
Again thanks for everyone's help. Particularly Hugo's.