PROPS.....again

[rhycebullimore]

just wanting to know roughly what sort of gains you can expect from spinning a stainless steel prop....
currently its a 13.5 p aluminium on a 50 tohatsu on a 4 mtr seajay and top speed with 2 people and gear is around 60ish k/hr. Going in for service Monday and will be getting motor lifter 1 hole (around 20mm) already has custom anticav plate, and a powertech 12p (same diameter) stainless prop fitted, bloke who setsups outboards for racing and ski boats couldn't reccomend them enough in lower power applications saying they are one of the best he has seen, as it has cupping rake and in general a really well made prop.

cheers rhyce

[Crocodile]

Hello rhycebullimore,
When you say 60ish kmh, how is that measured? GPS or measured mile?
If you are going to experiment with expensive props you need to be able to measure performance outcomes accurately and repeatably.
When testing allow for tidal currents etc., do a two way run.
I would be very surprised if a swap from a 13.5" pitch aluminium to a 13.5" pitch SS would make any noticable difference.
The fitting of a 12"pitch should in theory make the boat have slower top speed but better acceleration.
Before you fit that prop come to a firm agreement on return if unsatisfactory.
When you look at all the articles on prop comparisons there can be small gains in top speed but crusing speeds offer very little improvement.

[rhycebullimore]

the main benefit i am looking for is to stop some minor cavitation i have...measured with gps...the guy was saying to drop a whole pitch degree for a general rule of thumb as the blades under load from aluminum bend or flatten, making it comparable to a 12 or 12.5 there for only giving minor enhancements in the form of top speed and hole shot as there is reduced slippage, none of which i NEED more but can come in handy if you have it

[FNQCairns]

The bloke is right but it depends on the application, for instance I have a 15p Yamaha aluminium and it has been scanned at 15p too, at WOT rpm it behaves like a 15p prop should so no deformation there.

Racing applications are racing applications though.

The powertech 13 and 14 diameter SS semi clevers are great props dunno about any of the others.

cheers fnq

[ozbee]

good quality stainless props can make quite a difference compared to the basic sale ally prop. the reason being the back edge of the blade is cupped on last bit of the face which grips the water better than the basic smooth trailing edge on a ally at higher speeds. on my 250 about 5 knots difference. you don't see large outboards on the floor with ally props these days .there use is mainly as a cheap spare. in smaller outboards its the cost factor which keep ally props around otherwise they would of disappeared years ago.

[rhycebullimore]

getting around the same speed with loaded boat and 2 people but at cruising speed (40kms) it's sitting on only 12 lts per hr where it was around 14/15 before...one person couldn't get a full speed test was too scary as there was way too much wind and other boats around to trim it where i wanted to and take it to WOT but assuming it will surpass 60kms hr at cruising .with one up was great only using a mere 10 lt's an hour at about 42 km/hr and i can't beleive the amount of trim i can play with now and still have a good bite on the water, when you come off the plane it looks like you have been putting around in 6 inches of water the motor is trimmed that much. over all very happy with it.

rhyce

[Coontakinta]

My experience with the standard Tohatsu alloy props is that they are of poor quality. I swapped to the same size Vengeance stainless for my TLDI & havent looked back. Much better grip in turns & when triming out. Tope speed is the same currently, but when I get that boat back out on the water I hope to be testing more.

[ThePinkPanther]

S/S props give you from 5 to 10 % extra grunt!

Biggest advantage is they punishment they can take without requiring major repair

[Moonlighter]

I agrre with Coonta - both of us have Tohatsu TLDI 90's and the std Tohatsu alloys are pretty ordinary, especially re poor grip on the water and slow out of the hole. As he said, the Vengeance SS, even though its nothing fancy as far as ss props go, is so much better it's not funny!

A good SS prop will definitely perform better as you've already found out for yourself, both in speed and fuel econ.

But there is a downside.

If you hit something hard with an alloy prop it will bend and even break, most times before you do damage to the gearbox. The stainless, on the other hand, is not nearly so easy to bend and the likelihood of damage to gearbox increases as a result.

So if you're predominantly fishing up creeks, round the timber and rock bars, if you bump into beaches/boat ramps ....... sometimes a good quality alloy prop can be a better choice, if only for those sorts of reasons. Its the weakest link in the drive train and will usually break before anything else.

Cheers!

ML

[rhycebullimore]

are they rubber hubbed ??