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At what approx. H.P. do you start to see a real speed/performance advantage for s.s. over alum. ?

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25

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I bought a Tom W Clark recommended stainless propeller for my boat and am looking forward to using it (1979 22 foot Revenge soon to being powered by 200hp HO E-tec). I trust Tom's opinion. Some local fellows here prefer to run aluminum propellers saying that when hitting an obstruction, the aluminum would break and not damage the internals of the outboard. Is this true or an old wife's tale? Lawn mowers have an aluminum shear key to protect the motor. Do any outboards have a "shear key"? What is the percentage of advantage of the s.s vs. aluminum for performance.
gchuba

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Yeah, outboards have a shear pin.

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A. Not true, it is an Old Wives Tale

B. All outboard propellers have protection built into the hub in the from of a sacrificial insert or shear pin

C. Depends on the application

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Tom and Silentpardner. Thanks.
Garris

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I know my Merc 90 has a shear pin to protect the prop but I have stayed with an aluminum prop. I fish in a lot of skinny water in NC and SC with a lot of oysters. I have hit oysters that would have broken a shear pin.
Instead of calling Boat US for a tow and missing a day or weekend of fishing I kept on going with an ugly prop and maybe a little vibration. Most of the time you don't even notice the cut or bend in a blade.
If I only fished in deep water or offshore I would use a stiffer stainless steel prop which would probably give me a 2-4 mph boost.

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Your Mercury 90 has no shear pin.You are just perpetuating that Old Wive's Tale. All that aluminum prop does for you with the oysters is ensure the prop gets mangled where a stainless steel prop would come through unscathed.

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I agree with Tom. I live in coastal South Carolina. In the past 24 years I've had 5 different Whalers with 8 different engines, and who knows how many different props, both aluminum and stainless. It's hard not to go over oyster beds around here. I'd say we hit one every third time we're out on the water. The aluminum props are typically good for one to one and a half seasons (I do generally save them for spares). I have literally never replaced a stainless prop from oyster bed damage.

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I have no idea if Harvey Boysen's Merc 90 has a shear pin or if it has a rubber insert in the hub to protect the prop when it's stuck in an oyster reef. I am CERTAIN, however, that it does have prop protection.

This being said, I would and do use a stainless steel prop on any motor susceptible to getting hung up on anything, including oyster reefs. The Stainless Steel will suffer much less damage from these obstructions than an aluminum prop.

I have had many prop collisions with oyster reefs over the years redfishing in the shallow water cuts off the Intracoastal waterway around Freeport and Sargent, as a matter of fact, I almost always get into one that crosses the entry to one of my favorite cuts, and I have never had to replace a SS prop. I have had to have repairs done to one I had back in the 90's, but I actually sheared a pin and had to replace it that day to get back to the dock.

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Tom
I know I don't have a shear pin. I have a rubber/plastic sacrificial hub that functions like a shear pin. I was lazy in my post and didn't explain it.
I had a stainless steel prop on my 170 and hit oysters/rocks and sheared/spun the hub. Took several hours to get towed home.
Had to unload the boat. Missed a day of fishing. Fishing days are important to me because I live in Texas and the boat is in South Carolina.
I replaced the stainless steel prop with aluminum. I 've hit oysters since and have not sheared/spun the hub. I've replaced the prop but haven't missed any fishing time.
I don't have empirical evidence that one is better than the other but I'm going to stay with aluminum on my small boat. I have stainless steel props on my Grady White which is in Texas.
Thank you for your time and your support of whalercentral. We all learn a lot.
Thanks
Harvey

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Well said Harvey! :)

I am looking into getting a replacement hub kit for emergencies on both my Outrage 18 with the Yamaha 115, and the Whaler 27 with the new 300's. I am using a standard hub with my 115 and the black SS prop, but my 300's have Mercury Revolution 4 props and are installed with rubex hubs. I figure I might have to replace a hub if I get a spin-out these days, as all these new motors use the hub spinout safety instead of the old style shear pins. I used to keep spare shear pins in the old days, I guess hubkits are required now:(

I am not looking forward to having to replace hubs. My Outrage 18 has a kicker on it to get back to the dock, but if I lost both hubs on my offshore boat, I could be in trouble.

I really appreciate your explanation of the use of aluminum vs. SS props in the oyster reefs. I will probably keep powering through 'em with SS, but your explanation certainly gives food for thought :)

Happy Whalerin' (and Gradyin', as the case may be), and see you out at the gardens soon I hope:) The Wahoo bite appears to be ON!

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If you spun a hub on your Montauk 170, you should have simply swapped out the Flo-Torq II hub insert. That is beauty of the Flo-Torq (and other) square bore hubs: they are field replaceable. I always carry a spare insert onboard.

I'm sorry you missed any fishing time, but you can't blame that on a stainless steel prop. Indeed, your story reinforces what I've been saying: stainless steel props do not necessarily cause engine damage because the hub is designed to protect it.

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Tom, where is the best place to get spare inserts for hubs? I need to get a set for my Rubex 103's on the Yamaha 300's, and I will also need a spare for my Yamaha 115 and 9.9 on the Outrage. I have found the complete hub assemblies online, but I cannot seem to locate a supplier for replacement inserts.

Are the Rubex hub inserts field replaceable? What tools are required for hub insert replacement on the water?
During some recent research into this subject, primarily due to this discussion thread, I noticed that the Rubex hubs seem to have a bad rep for getting stuck in the prop. Ken says the Mercury Flo-TorqII hub is the easiest to remove, (probably because of it's Delron construction), but he also indicates that freezing the entire prop with the stuck hub in it could be required with the Rubex for removal. Do you know of any reliable field methods that could be used in an emergency?

Thanks in advance for your help!

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I don't know about the Solas Rubex inserts, I'd just buy the complete kits, they are not that expensive.

Yes, the Rubex hub inserts are field replaceable, in theory anyway. Ken Reeves (aka Prop Gods) was the guy who turned me on to the use of the Rubex hub kits for shift dampening and Ken has told me the Rubex hub inserts really stay put because of the grippy rubber.

Ken sometimes puts the entire propeller in the freezer to make the hub contract and make it easier to drive out. Obviously that is not going to happen on the water.

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Any idea of the shift dampening improvement of the Rubex compared to the Flo-Torq? Sounds like it's worth trying in that regard.

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The Solas Rubex hubs are softer than a Flo-Torq II but not as soft as a Flo-Torq IV

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I have never been on a vessel equipped with the FloTorqueIV hubs, but I know the Rubex hubs I have on my heavy rev 4 props on the 27 are smooth, and I really like them. I really appreciate Ken putting me onto them when I ordered my props for the new 300's. I would really like to compare them to the FloTorqIV's, but I have not found them for my Yamahas. When I do, I will try them for a comparison test.

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Fellows,
Great replies on this subject. I have a Yamaha 9.9 kicker with the 200hp HO E-tec for my boat. For "in the field replacement" what are the best parts to have on hand". Thanks in advance.
gchuba

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I carry a hub kit, ss cotter pin and a length of 2x4 with holes drilled near the ends.

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I've got an idea, but please explain the holes near the ends of the 2x4.

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Yes Kamie, please describe the field procedure you use. This is exactly what we are looking for here!

Thanks in advance!

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I did a lot of prop testing when i first got my outrage. In a lot of cases, i was in the middle of the river and any shallow spot to hop off and change a prop was 4 or 5 miles away. I have very long dock lines on the 18, i just thread them through the holes, tie both ends to the stern cleats or eye rings and now the board won't drift away even if i drop it. You can quickly position the board to hold the prop, while you lean over the stern to undo the prop nut. Leaves 2 hands free to catch the other little parts, like keeper rings and cotter pins.

Where I boat oysters aren't really the problem, it's the submerged log that floats just below the surface that will do the most damage. Especially when we have lots of spring rains and the river is running high.

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I will add that buying a new stainless steel propeller in order to get the new style flowtorque IV hub is not cost productive, but selling the idea that I can change out a spun hub in my boat is a good argument for stainless v/s aluminum if someone were wanting to change over now.When an aluminum prop breaks a blade or blades, there is no quick fix for that unless you keep a spare prop on board. The money wasted in fuel on prop slip will pay for the stainless prop anyway. The best thing to do is tread lightly at low tide.

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WOW --- I didn't know my little question would go so far! Now though I have a follow-up. My owners manual on my 60 Merc. says I need to go from a Flo-Torq II to a Flo-Torq III when going from alum. to ss. After reading these posts, should I go to a Flo-Torq IV or to the Rubex ?

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A Mercury 60 HP FourStroke BigFoot uses a Flo-Torq III hub kit. That is your best option. Once you own one, you can use any square bore propeller made.

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It seems like the Flow-torq IV aren't available to fit Evinrude? I was unable to find a cross reference for that hub kit. Will try the Rubex if that's the case.

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No, there are no Flo-Torq III or Flo-Torq IV hub kits to fit OMC/BRP motors, though they do now offer Flo-Torq III kits for Yamahas.