Prop Selection Advice

[Pierce89]

Good morning,

I'm looking for a prop for my aluminum 18ft 1960 Lonestar El Dorado with a 2003 Yamaha 90hp 2 stroke (90TLRB) and a little confused with what diameter, pitch, brand to look into. The boat should be 700lbs dry weight and will be used for lobstering and fishing reefs shallow reefs with 2 - 4 people. I bought the engine without a prop and have been restoring the boat, which is almost ready for the maiden voyage. Aluminum prop should be fine for South Florida sandy bottoms.

Someone suggested going over 30mph in this boat may be dangerous for steering so I'm looking for a suggestion on an all-around good prop for cruising, not so much go-fast or get up on plane quickly. All around good gas milage?! I appreciate any advice!

 

[Texasmark]

Go to the prop sales/selection chart on the top of the site. Select your engine and then being a 2.3 gear ratio, I'd opt for a 15" pitch. The other details are provided once you select your engine for particulars.

A quick check of 2.33 gear ratio, 5500 RPMs, 20% prop slip, 30 mph........Go Fast.com reply: https://www.go-fast.com/Knowledge-base/Find-your-prop-slip/Prop-slip-calculator

Things can change if your RPM runs on up to 6000 I think is the upper recommended limit for that engine...would give you 10% increase and your 30 MPH with nothing else changing...which could happen and improve your speed.

Then there is prop slip I guessed at 20%...your boat should be capable of planing at around 18-20 mph where your slip would decrease due to less resistance caused by the hull being IN the water and not ON the water as is the case when on plane. However, with 4 people you are carrying a lot of weight and the boat may remain IN the water somewhat causing the high slip to remain.

Only way you know if 15 is the correct pitch is to run it. Next guess would be 17P same parameters from your selection chart otherwise. If you seldom run with 4 folks then I would opt for the 17P: https://www.go-fast.com/Knowledge-base/Find-your-prop-slip/Prop-slip-calculator

That would/should get your 30 MPH and maybe more.....with either it depends on everything about the boat, operator, and environment.

3 blades on here run around a hundred bucks or so, not that big of an investment if you pick one and don't like it and decide to go with the other.

 

[Pierce89]

Go to the prop sales/selection chart on the top of the site. Select your engine and then being a 2.3 gear ratio, I'd opt for a 15" pitch. The other details are provided once you select your engine for particulars.

A quick check of 2.33 gear ratio, 5500 RPMs, 20% prop slip, 30 mph........Go Fast.com reply: https://www.go-fast.com/Knowledge-base/Find-your-prop-slip/Prop-slip-calculator

Things can change if your RPM runs on up to 6000 I think is the upper recommended limit for that engine...would give you 10% increase and your 30 MPH with nothing else changing...which could happen and improve your speed.

Then there is prop slip I guessed at 20%...your boat should be capable of planing at around 18-20 mph where your slip would decrease due to less resistance caused by the hull being IN the water and not ON the water as is the case when on plane. However, with 4 people you are carrying a lot of weight and the boat may remain IN the water somewhat causing the high slip to remain.

Only way you know if 15 is the correct pitch is to run it. Next guess would be 17P same parameters from your selection chart otherwise. If you seldom run with 4 folks then I would opt for the 17P: https://www.go-fast.com/Knowledge-base/Find-your-prop-slip/Prop-slip-calculator

That would/should get your 30 MPH and maybe more.....with either it depends on everything about the boat, operator, and environment.

3 blades on here run around a hundred bucks or so, not that big of an investment if you pick one and don't like it and decide to go with the other.

This was very informative, thanks for taking the time to explain. 90% of time it's just my wife and I, so I will opt for the 17 pitch. Do you have any experience with the Ebay props? They're $100 less for same style like below

13 1/4X17 Pitch Outboard Propeller Fit Yamaha 50-130HP 6E5459450100 6E5-45945 | eBay

Our representatives will provide you with detailed instructions on how to proceed.

www.ebay.com

 

[Texasmark]

I shop ebay often for lots of things. Purchases are guaranteed by ebay, not the seller so you are covered. On returns, different sellers have different rules on things like prop returns. Usually its if you mount it you bought it....seller's comments....reason being that seller has to sell it to somebody else and it has to be NEW to be sold as NEW, not marks from a prior owner's return.

 

[Pierce89]

Ah no I wouldn't buy and return it! I meant the quality of the props on Ebay, for example the same diameter, pitch, and # blades can be found on Ebay for $75 as compared to $175 on this website or others on google. I was wondering if anyone had experience with them. My thoughts would be aluminum is aluminum, whether an expensive Yamaha one or a cheaper one off Ebay. I've never bought a prop though so I don't really know....

 

[JimS123]

Ah no I wouldn't buy and return it! I meant the quality of the props on Ebay, for example the same diameter, pitch, and # blades can be found on Ebay for $75 as compared to $175 on this website or others on google. I was wondering if anyone had experience with them. My thoughts would be aluminum is aluminum, whether an expensive Yamaha one or a cheaper one off Ebay. I've never bought a prop though so I don't really know....

If you want a yami prop and know the part number, a cheaper price on ebay is of no concern. Its the same prop.

There are aftermarket props, like Michigan Wheel, which are the same quality, but may be at a lower price.

If the price s SIGNIFICANTLY cheaper, its used or damaged.

 

[Texasmark]

If you want a yami prop and know the part number, a cheaper price on ebay is of no concern. Its the same prop.

There are aftermarket props, like Michigan Wheel, which are the same quality, but may be at a lower price.

If the price s SIGNIFICANTLY cheaper, its used or damaged.

Ebay postings list the condition when they post the ad. If new is says so, if new but opened packaged, for some packaged items, like it was opened for display purposes but not used, it will say so, if pre-owned it will say so.

I've purhased about 400 items from them when I was building my N scale train layouts a few years ago, besides many other purchases for different things from marine items to car/truck parts to farm equipment and parts and so on. I can count on one hand and have fingers left over the number of times there was a dispute and never did I wind up the loser.