Prop

paul127

Have a 6 meter rib with a 90 4stroke Yamaha on it . Lost a bit of the prop last season and need to get a new one , what is the best one to get stainless steel or aluminum what are the advantages and disadvantages off each also where is a good place to buy . Thanks paul

fergal.b

The stainless steal ones have thinner blades and as they are stronger they are less likely to flex so better performance but at a price, if you are going with ss you might have to go down in pitch so check your engine manual.
You could also look at having your prop fixed might work out cheeper.





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breghall

If it was me I'd go aluminium, benefits of SS is prob 2-3 mph increase. Also SS cost a lot more to buy originally and if you boat in an area where your prop is at risk of getting damaged again then the fix is always dearer for SS, and it passes a lot more of the hit down into the gearbox (that's if the bushing inside the prop doesn't go like if should when you hit hard)

But if there isn't a chance of it getting damaged in the water then SS would be fine plus they do look pretty.

Def check the manual as Fergal said, ain't nothing worse than forking out for an oversized prop that makes you go slower and puts the engine under more pressure.

megafan

+1 for an Aluminium prop stainless much tougher but you've damaged one already & if that was stainless steel good chance of bending prop shaft/damaging gearbox.....

megafan

& any good boat chandlers could as at least order a prop for you.... Maybe 125e ish (guess) for your engine & Find these people good if your on the northside of Dublin http://www.marineparts.ie/boats-and-motors/ & just to add not a great fan of repairing prop (good part of the cost of new prop) as balance may not be good (think of what an out of balance wheel on your car feel like) & in the long run also damage gearbox as not designed for side loads... Could be a good chance to get ideal prop for your RIB... will it rev out to full revs with a fulll load or over rev? http://www.marineparts.ie/propellers/yamaha-1/yamaha-propellers-from-60hp-to-130hp.html

Daibheid

paul127 wrote: »

Lost a bit of the prop last season and need to get a new one , what is the best one to get ...paul

There's your answer - get another aluminium or next time you'll be pricing a gearbox. As the others have said the stiffer SS prop will cost a lot more and if you strike something it won't break so the gearbox will instead.

You should really identify what diameter and pitch you have but with a 6m rib and a 90 I'd guess a Yamaha K series 13 1/2" by 17" pitch but maybe a 15" prop. You also need to know what rpm the engine maxed out at and what Yamaha recommend as max RPM. If you're close to max I wouldn't fit an identical S/S prop as they cut a little easier through the water and so add a few hundred engine revs so you might need to pitch up.

IT also depends on what you want to use the boat for, if you're into watersports -towing or carrying lardass divers-you might pitch down for acceleration and just watch the revs when running at the top end. If you're cruising a caorser pitch will help economy. Yamaha F100s are known to give trouble if laboured with too coarse a prop and I expect the 90 would be the same as they're very similar engines. That said I run a 19" prop on my F100 and a fairly heavy 5.5 rib and it's a nice combination of speed and power.

Unless you find a dealer who can try different props out for you, changing from standard by buying and trying can be a very expensive trial and error process.

I'd have no qualms abut using a repaired prop - they'll all get some sort of a ding sooner or later. My Zapcat has a full prop guard and inexplicably still has marks on the prop:(

fergal.b

A good prop shop can repair and balance a prop as good as if not better than a new one, I have had it done many times and also have no qualms about doing it again. "recycle,reuse and reduce "









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paul127

I know I didn't hit anything with the prop the person I got it of (second hand ) said that a stones from the bottom in shallow water might have done it(dose this happen ), going to get the one I have repaired and keep it for a spare and buy a new aluminum one are there any difference in brands if so what is a good one . Thanks for all the advice. Paul

fergal.b

You can get a sierra one for a good price but if your engine is new just check that it will not affect your warranty.




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