Propeller Advice

DSR-550SRMN · 09 April 2021, 00:28

I have a 550 SRMN with 90HP Yamaha F90LA. I bought the boat without a propeller. Any suggestions. Looking for something middle of the road performance and stainless steel. Suggestion to go with or stay away from would be appreciated. TIA

Limecc · 09 April 2021, 04:47

http://solaspropellers.com/index.php...ts/prop-finder

13.25x17 is middle of the road for 90hp (or 13x17 if a four blade).

Roflhat · 09 April 2021, 08:38

Can't go wrong with Yamahas own stainless semi cleaver range too, great props https://www.ebay.com/itm/Yamaha-Stai...0AAOSw31RgR9aH

DSR-550SRMN · 09 April 2021, 21:24

Thanks for the suggestions....Having never purchased a propeller before.

A side from diameter and pitch what mating issues do I need to look at to make sure it fits if I buy by mail order/Ebay?

Are all Yamaha F90LA's the same rotation?

What rotation is that CW or CCW?

(Just dropped off the boat for a seam repair so can't go out and start it up)

I see the shaft is a spline are all F90LA all the same fitment?

Thanks for the help!!!

Roflhat · 10 April 2021, 09:01

The other two things to make sure it fits are the exhaust tube diameter and the number of splines on the prop shaft. Splines will be 15, fairly universal between outboard manufacturers - mercury/yamaha/tohatsu etc share fitment. Exhaust tube is also fairly universal but for 15 spline motors there is a range. You can check by measuring the diameter of your gearcase.

99% of the motors will be CW - RH rotation. Not sure if the 90hp was even available CCW, some are but usually starting from about 150hp for people who have twin engine setups. The opposing propeller rotations help counter torque steer

DSR-550SRMN · 10 April 2021, 13:37

Much appreciated!! TY

jonp · 13 April 2021, 02:21

Also Yamaha's aluminium props are very good and a fraction of the price of stainless. I had a Yamaha dealer bring a box of props to water test my 550 and we found the aluminium actually outperformed the stainless. Depending on your work application an aluminium prop can be better on the gearbox if you continually need to gear change (in and out of gear). I drive commercial abalone boats where divers work bellow on hooka gear, the boat is not anchored but held in place by engaging gear to stay with the divers. Many commercial vessels such as tour boats will also use aluminium because of the less pressure put on gearing. The crocodile tour boats to my north clock up over 10,000hrs on their Yamahas where most of the day the boats are in and out of gear approaching then backing off from wildlife. These days aluminium props are far better than a few years ago and in many cases outperform lower cost stainless ones. This side of the pond (Australia) Yamaha offer a full prop exchange to allow you to select the correct prop for your application.

As already mentioned by others the 17 pitch would also be my starting point with the 90hp. Much will have to do with the weight of your outfit, fuel and passengers etc. I normally have two props for my boats, one for light loads and one when Im loaded up with dive gear and extra fuel and water for extended offshore week long trips etc.

Matt · 13 April 2021, 19:03

That's interesting about the inertia on an ali prop vs stainless, I hadn't considered that before.

Also good point that a good ali prop is probably better than an average stainless one.

DSR-550SRMN · 14 April 2021, 15:20

Much appreciate the insight & recommendations. I have yet to see a decent size RIB here in my area and so local experience is nonexistent.

I am looking at prop manufacturers and they reference the "gear case size" as either 4-1/4" or something different? I have the service manual but can't find the size?

One site say "Will fit most Yamaha F90's" but they have a "No Return" policy.

As noted above someone say's is 15 spline (2012 F90LA) so assuming it is. The boat is now at the tube repair shop so don't have here to check anything.

This is for pleasure use. I calculate the payload with 2 people, stuff & fuel at 2,000 lbs nominal and 2350 lbs if 4 people.

DSR-550SRMN · 06 May 2021, 15:08

To update this original post I purchased a Michigan Match propeller #101033 which is a 13.25/17. The propeller form, fit & finish looks of very good quality and install was simple & quick. I haven't got a chance to put the boat in the water yet but will report back when I have some experience with it.