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View Full Version : Props & Ratio's Anyone!



BilgeBoy
08-09-2006, 09:35 PM
Hi all

just bought a 2002 4.35 forward steer Alley Craft with a oil injected 50. The boat is second hand and clean as...but the prop looks like its been cultivating paddocks and is a bit worse for wear.

Anyone got any good advice...should I invest in a Stainless...and whats would be a good size/pitch for the combo I have. Keep in mind I am a novice boaty...So I will appologise now to all the sand banks I am going to hit.

:-[

BaysideMarine
08-09-2006, 09:41 PM
What engine is it and what prop is presently fitted (either stamped on the side of the prop or stamped into the hub of the prop around the lock nut.

Cheers

BilgeBoy
08-09-2006, 10:14 PM
Yeah sorry

Its a Yamaha 2 stroke 50 oil injected (model 50HWHTO) cant find a code on the prop...but will have a look in the daylight! here is a pic of the setup as well

It came with a Warranty manual...but that just says the propeller selection is "ST"

BaysideMarine
08-09-2006, 10:28 PM
OK. Yammy props usually have their pitch stamped on the prop side and if my memory serves me correctly it will have the pitch (ie 12) followed by the letter T I think....

In any case, the right prop for general purpose boating is the prop that puts your engine within the recommended full throttle range (or WOT for all the wowsers) when you are at full throttle.

Somewhere close to 5500rpm would be max throttle for your engine with a range of say 5000-5500. You want to be near the top end of the range.

An engine that slightly OVER revs is not usually an issue but an engine that UNDER revs is an engine that is LUGGING and an engine that is unhappy and will blow up..... leaving you with funky rearranged pistons..... and a funky empty wallet...... :( :(

Stainless is good if the areas you operate in you know well. If you are not in familiar territory then go an ally prop. Reasoning is that hit a hard object with an ally prop and all you generally do is break or bend blades. Hit the same with your lovely stainless prop and the prop says "What was that" and forward gear and the pinion spit their teeth in to the gearbox............

And then you spit your teeth for a several grand box rebuild......


Cheers

I_Like_Fish
08-09-2006, 10:32 PM
BM....I wish I payed more attention to that as I'm a victim of what you described.
Oh well....good excuse to upgrade to the 100hp 4 stroke ;).

BilgeBoy
08-09-2006, 10:35 PM
thanks BM

You are full of good advice...I will take your advice and do an alley prop.

regards

BB

BaysideMarine
08-09-2006, 10:57 PM
No worries Bilgy... best option I think. After all, its not a high performance, go faster than the wind ski boat you have so why complicate matters.....?

I like fish..... OUCH!!!! :( Looks like your piston got too hot, grabbed the ring and then it got dragged up the piston on the down stroke and then did the merry broken ring dance on top of the slug......

How many pots are damaged? Its a 4 cylinder 100 yes? It can be repaired for a shite load less than a new donk.... Or pm me if you want to flog the dont off. I will probably buy it.

Cheers