stainless or alloy ?

[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 .................................