Propellor Size

[Paul D]

Spotted what I think will be a suitable propellor for my E-Tec.

 

Current propellor is 13 1/2 x 15 aluminium, so would a 13 3/4 x 15 stainless prop be too big ?

 

Apparently it fits a 4 1/2 inch gearbox ( whatever that means ).

 

It has the correct number of splines and I am 99% sure the diameter will fit and seems near enough to existing size.

 

Will it fit ?

 

[Afishionado]

I think the 4

[Maverick Martin]

Can't remember where I saw it or if I even dreamt it but was under the impression that you would normally need a slightly smaller prop/pitch in stainless. Reason being (I think) that there is no give in a stainless prop whereas lots of flexing in an ally prop. Can anyone confirm or not as the case maybe?

[Adam F]

Tis correct Mr Burt - thats what prop revs told me anyway - rule is to go 1" smaller.

 

However, the HP of Paul's engine may provide an exception to this rule. When I had my 60hp I enquired at PRev's about a SS - they told me not to bother as I wouldnt see any advantages in performance due to not having enough HP - they advised that over 90hp are worth it.

 

Unless you have found it at a bargin price - in which case you have a cheap replacement.

[duncan]

firstly I would be more concerned about the additional diameter than the additional pitch..........check carefully you have the necessary clearance beneath the cavitation plate.

 

the issue between stainless and alloy have been gone over many times and I am yet to see agreement re the smaller pitched SS= larger alloy. This was certainly not my experience. Hole shot was the same, mid range was smoother and top end delivered about 2 knots more at the same max revs. This was based on Merc 90 2S, never tried alloy on the 175 Merc...... There are also a significant number of additional differences between the 2 that will be reflected in some element of performance. If you have a trailer boat then you should always aim to buy/try where you pay over the full price on the baisis of a full refund if it doesn't suit and is returned in as new condition within a week.

 

finally without knowing the exact performance profile of the existing prop it's impossible to predict if this would be 'better' - ie if the existing one was already at the bottom end of the WOT revs recomended then it is extremely unlikely that this one would be more suitable (I would still try it because the different profile and other possible changes do not rule out an improvement.

 

personally I wouldn't run alloy in the Poole Christchurch area - where you might otherwise damage or destroy an alloy prop you will merely polish a ss one!

 

bottom line - try it after measuring and also having accurate figures for your existing set up.

[Paul D]

Agreed re: need for a stainless prop. If the price is right though

 

Mike, It is the same pitch as my existing prop, just an extra 1/4 inch in dia.

 

I am not necessarily looking for any improvement, just found it and decided it could be a good buy.

 

[Paul J]

Paul,

 

Call the guy at prop revs to be sure.

I have heard the same as martin re the reduced pitch for stainless.

 

PJ