stainless or alloy ?

[haggis]

Hi im looking to find out your thoughts o whether stainless or alloy props would be better for my boat . i ve got a 460 bay raider runabout with a 4st 6o yammie
what would be better & are the stainless props too heavy for the 60 ?
cheers jimmy .........

[Blackened]

G'day

Def. not too heavy.... where is most of your boating done? bay / blue water or up creeks and estuaries?

Dave

[stinky-stabi]

alloy is better for where there is a chance of hitting something(creeks etc) as it will give way b4 the gearbox oppisite for s/s more chance of damage and props are twice the price+

[Noelm]

the biggest advantage of stainless is extra performance, they can be made much thinner and as such you can usually go to the next size up and retain your max RPM, the biggest negative is cost! there is a few other pros and cons, but they are the biggest.

[Spaniard_King]

There seems to be a stigma associated with stainless props and creeks. Gearboxes have come along way in the actual componentry where as the heat treatment and metal composition of gearboxes today will take a dam good hit before sustaining terminal damage.

IMO if I was doing a lot of creek work I would rather have a stainless prop on so as to minimise the wear on the prop itself. Think of the difference on the prop from the same hit.. the ally will be deformed by small knocks where the stainless would most likely be unchanged. If you sustain a significant hit the stainless may be damaged and the ally would be destroyed. in this circumstance the right thing to do would be to change the gear oil anhd check for metal particles.. do it again after a few hours of runing to ensure the gearbox is still intact.

If the gear box does sustain damage, then claim it on your insurance.

Seems to be a lot of people going through life with if, buts and maybe's where as they could be really enjoying themselves.

[Noelm]

fully agree, but every time I used to say it a dozen people would give me the old, I know a bloke, or, I would never use stainless because... but you are 100% correct, the chance of any more severe gearbox drama from using a stainless prop is practicaly none! that's what the rubber bush is for!

[haggis]

thanks for the replys guys
i mostly fish in the bay around the close in islands mud green and the like
also the local rivers and creeks also the barra dams
the cost i can cope with but just want to be sure before i part with my hard earned cash
cheers haggis ::)

[PADDLES]

g'day haggis, if you are actually replacing a damaged prop or changing an incorrect prop then go for it and buy a stainless one. if you are buying a stainless one to replace a perfectly servicable alloy one then i personally reckon it's a waste of money, the performance gain will be minimal and certainly not worth the hard cash you will be paying for a new stainless prop.

[ozscott]

I have had both and wouldnt go back to alloy. I had no end of nicks and wear with alloy and some cavitation problems at times...never again. As said above the shear bush is for very severe impacts.

Cheers

[Wayne_Red]

Haggis
I would agree with Paddles
On a boat like yours you would need a good reason to spend a lot of $ to change props. If you boat or motor is under performing would be the main reason. If you are hitting the rev range ok and the boat is performing well then you may not get any advantage. A change of prop or prop design apart form rev range is generally done to improve hot shot, boat lift etc etc a lot of times on bigger motors heavier boats and performance hulls but if it aint broke don't fix it. The 4st 60 has quite a large diameter prop to suit the lower ratio gearbox, motor torque etc, the men in the white coats at yamaha designed the motor and prop that way for the majority of working conditions to get the best out of their motor.
Regards Wayne

[stevej]

prop 500 box 2k?

ill live with a 300 alloy prop and go a few kay slower, and get laughed at for believing old wifes tales as i cant afford a new box but a could afford a new alloy prop every few years

[haggis]

thanks guys , thought i new what i was going to do
but now im not sure , will have to investigate things more
cheers jimmy ................

[Noelm]

prop 500 box 2k?

ill live with a 300 alloy prop and go a few kay slower, and get laughed at for believing old wifes tales as i cant afford a new box but a could afford a new alloy prop every few years
not exactly 100% sure what you are saying, but I guess you do, and maybe everyone else.

[wrxhoon]

I would go S/S every time ,
Alloy has only one advantage over S/S PRICE, NOTHING else .
Alloy props can't even keep the pitch on bigger motors the harder you spin them the pitch gets smaller , so you reving the engine and not going anywhere fast, you can't use a bigger pitch to counter it because at low RPM they don't change so you can't take off .
On a 10-20 hp motor they are OK ( only just) anything bigger if you can afford it buy a S/S and when you do you never buy an alloy again.
The smashing of gearbox is all bull....., If you hit something the prop will spin on the rubber/plastic hub , if its S/S it will probably bent a blade or 2 , if its alloy you put it in the bin .

[Crocodile]

Hello Haggis,

Why do you want to change props?
Does your motor get to correct RPMs at full throttle? (5000 to 6000rpm)
How fast does the boat go now?
Does it struggle to get on the plane with a load?
Is your 60 a bigfoot/high thrust?
What size prop do you have on it now?
The size will be on the prop somewhere and say 11"1/8 x 11" or similar.
Have alook at this,
http://www.yamaha-motor.com.au/pdf/marine/power_reports/Quintrex_475_Freedom_Sport_F60.pdf
It is the Yamaha Australia engine test, on a very similar boat.
Do you boat in shallow or rocky waters?
IMHO, if all is well at the moment, switching from aluminium to SS in the same size prop would make no noticable difference to performance on your boat.
When you look at all of the prop comparisons the big gains are made only on boats that go 40 knots +.
At more reasonable speeds there is very little advantage for the extra $$$$.

Lots of questions, but need to know to offer advice.

[rodneyk]

dont want to sound like a smart arse but i cant see any need to change to sst blade on that boat been there done it the alloy props that come with engine are very compatible to a wide range of tinnies you may need to go up or down a pitch to get 6000 rpm after that one is shiny the other is white if you hit an object you have a repair to do anyway ive owned 2x 60hp yam 4st 1x 40 4st same blades on both bought a genuine sst yammy blade made no decernable differance ;)

[haggis]

crockidile the boat only revs to 5400 , she planes easily enough , top speed about 48 klms/h . at the last boat show the yamaha rep told me that it should rev between 5500 & 6000 rpm . I spoke to solas in great depth they advised me
to get the boat on the plain at flat biccies & check the height of the cav plate then I might have to raise the outboard height before changing props . I want a spare prop for the boat for when I am up at the dams fishing just incase I hit anything & damage a prop . the handbrake has released the funds for a prop so i want to go the best option . will have a play this weekend then decide .
cheers jimmy ..............

[haggis]

the prop size is 11 3/8 12 g

[stevej]

not exactly 100% sure what you are saying, but I guess you do, and maybe everyone else.

a replacment box is 2k or so

a alloy prop is $280 bucks

ill believe the old wives tales that say, hit something with a stainless prop and the box can be damaged and will stick with an alloy prop

a alloy prop i could afford to replace a new gearbox is a little harder

that clarify things for you

[dreemon]

I wouldn't have a problem with an alloy prop on my 90 yam , got a s/s only cause I got it cheap at $ 250 secondhand,

[fanplastico]

Stainless. Made the change & wouldn't go back. Gave the rocks in Cobby Passage a good massage one day & just put a couple of dings in the blades which I filed smooth. Only replacement parts was me undies.:-[

Les

[Crocodile]

Hello Haggis,

Revs do seem a bit low, raising the motor might help.
If you refer to the Yamaha article they used a 11" pitch prop and got 6000rpm.
Your 12" might be holding the revs down.
See if you can borrow an 11" from a dealer for a test.
It would be very interesting to see how much increase in rpm results from a 1" drop in pitch.
Your prop is aluminium?

[black runner]

Haggis, I have a very similar setup to you and find that the high bimini with front clears impose a significant amount of drag at the top end. Not sure if you have tested with bimini down, but it is worth doing for the exercise.

Dropping to 11 will start to eat into your cruise speed in the 4k range.

Following Noelm's theory you could go a 12p stainless, increase a few 100 rpms WOT. Can others confirm that stainless can give a 1" pitch performance improvement over alloy in this size?

Solas' recommendation sounds good to me - get height right first and then work from there.

Cheers

[Noelm]

get the setup right is the first thing to do, other wise you are just putting bandaids on a giant gash! then go for props, but be sure to see if you can try before you buy, it can get very expensive experimenting.

[haggis]

crocodile i have a ally prop at present
black runner that is with the clears & bimini down
hopefully get out this weekend to see what happens
cheers jimmy ......

[black runner]

Haggis,

I would have thought that you should be getting 5700+ on your hull with a 12P. Maybe motor height is the issue. Given the specs of the hull the 60 shouldn't need an 11P prop to achieve 5500-6000 wot. Are you actually getting WOT at the motor throttle body? Sorry to digress from the Alum vs Stainless debate, but best to make sure all the basics are ok before deciding prop size based on current performance.

Cheers

[BigE]

The prop set up in the yammie test posted by crocodile is the same as my 1/2 cab and is on the money. 3kms per ltr abour 75 kms to a tote tank. at 4200 which is 35kph. it revs to the limiter at just over 6000rpm & you can run her at 5000rpm for about 48kph but the fuel burn rises alot after about 4600rpm. above 4800 you will probably only get about 45-50 kms out of a tote tank if your lucky.
BigE

[black runner]

The freedomsport is a fair bit bigger boat rated to 80hp so would understand the 11p on that. Haggis should be getting more than 5400 with the 12p on the 460 hull and would need to drop to 10p to get near 6K wot. Somethings not quite right with the setup IMO.

Cheers

[gr hilly]

spanyard king has told you the right thing i think to. years back my stainless prop got me home when if it had been alloy i would have swam good advice has been given good luck glynn

[haggis]

I took the boat for a run on saturday with a mate , no fishing gear , flat strap 5400 rpm touched 5500 then back to 5400 . sent mate to back of boat to have a look at the outbaoard & cav plate . The second he went to the back of the boat the engine note changed and the revs picked up got 5800 out of her . tried it a few times always the same , then he drove & I went down the back same think picked up plenty of revs , the boat handles better , checked it this morning with the misses same think picked up revs so I am thinking that i have to drop the motor down a hole and not up . will do that this weekend & let youy all know what happened . Thanks for everyones input .
cheers Jimmy .................................

[Noelm]

doubt you will need to drop the motor down, for any reason, unless you have a cavitation problem, what you are doing moving people to the back is just changing trim, do you have power trim? if not move the stop up a bit and try it, if no go, try down a notch.

[haggis]

noelm that is with the out board trimmed up any more & she cavitates ,any lower she slows down , it also cavitates when turning so iam thinking that lowering the out board will help . I will do this before buying a new prop .
cheers haggis

[Crocodile]

Hello Haggis,

this all very interesting.
When running with two at the front seats does she seem nose-heavy?
Is there excessive spray coming from the forefoot.?
Do you have anything heavy stored in the bows that can be moved aft?
I see a lot of runabouts that seem to run bow-down with two passengers up forward.
Excessive bow-down trim will reduce speed.
If the boats runs nicely at cruising speed, why not leave it as is because that is where you spend most of your time.