Which is Worse for my Motor? - If I had to choose...

[ShapeShifter]

I'll start this by saying that I know that the correct answer to my question below is "Just go home", so please dont reply with that nautical wisdom.

Family boating on the lake this weekend, I hit something early in the day and chunked up the leading edges of my prop. Considering the time, effort, and money speant just getting the boat in the water I decided to not "Just go home".

I straightened the twisted chunks on the leading edges on two blades, and filed and fared it smooth as best I could with a multi-tool. It was not pretty. I do keep a spare prop on board but it is an oversize prop. I know that running an oversized prop will cause undue stress on the powerhead and drivetrain. I also know that an un-balanced prop can cause vibration and potentially damage the lower unit. Running the boat for the remainder of the day with either of these two setups was not going to destroy anything and since I already dismissed the "Just go home" answer, I had to make another decision - Use the dinged prop, or use the oversize prop for the rest of the day?

What would YOU have done (besides go home)?

 

[Will Bark]

Re: Which is Worse for my Motor? - If I had to choose...

If the "dinged" up prop was not causing any vibration I would still use it, if it was I would swap props and run it for only that day and stay under WOT.

 

[fmalott]

Re: Which is Worse for my Motor? - If I had to choose...

my prop had been dinged up for years never had a probelm yet

 

[boobie]

Re: Which is Worse for my Motor? - If I had to choose...

Take the "dinged prop" into a prop shop and have it repaired. If a prop has dings in it you may not feel it in the boat but it is still hard on the gear case.

 

[Solittle]

Re: Which is Worse for my Motor? - If I had to choose...

And what do we have for a motor? And the diameter & pitch of both props? And - And - is this motor mounted on some kind of boat???

 

[yorab]

Re: Which is Worse for my Motor? - If I had to choose...

I do keep a spare prop on board but it is an oversize prop.

Just curious: if there is a question as to whether an oversized prop should ever be used, why do you carry it with you?

 

[ShapeShifter]

If the "dinged" up prop was not causing any vibration I would still use it, if it was I would swap props and run it for only that day and stay under WOT.

This is the exact course of action I took.

And what do we have for a motor? And the diameter & pitch of both props? And - And - is this motor mounted on some kind of boat???

None of that matters in the context of my question. However if you must know, the prop is attached to a large rubber band strung to my bow cleat. Once she gets on plane, I have to stop and wind her up again.......

Just curious: if there is a question as to whether an oversized prop should ever be used, why do you carry it with you?

I don't know anyone whose spare prop matches their service prop. But then again, I don't hang around the yacht club much.....

 

[Frozen]

Re: Which is Worse for my Motor? - If I had to choose...

I don't know anyone whose spare prop matches their service prop. But then again, I don't hang around the yacht club much.....

Then why even have a spare prop if it isn't the correct one? :facepalm: Such a odd statement. My spare prop is the same as my service prop so if I even bang it up I can swap it out. Hence the "spare" part of spare prop. And by yacht club do you mean my boat on its trailer in my backyard?

 

[fireman57]

Re: Which is Worse for my Motor? - If I had to choose...

Solittle, see what happens when you are serious and try to help? Btw, good to see you again.

 

[ShapeShifter]

Re: Which is Worse for my Motor? - If I had to choose...

Solittle, see what happens when you are serious and try to help? Btw, good to see you again.

Asking if my motor is mounted "on some kind of boat" is not exactly being serious now is it...? As your mom always told me, "Ask a silly question get a silly answer".

I was actually asking for opinions this time but I always appreciate help when needed and offered. I'm not a noob to boating, nor to properly sizing propellers, so I did not intend for this to become a discussion about that. This is simply a "What would you do?" question, not a "What should I do?"


I'm happy to list the hardware but again, in the context of my question, I dont see the relevance. What am I missing? Given the same two prop conditions why would a decision like this have anything to do with horsepower, hull shape, or prop spec?

 

[5150abf]

Re: Which is Worse for my Motor? - If I had to choose...

As far as the engine is concerned I think the oversized prop would be better and have less chance of causing damage, you know the dinged one was out of balance so I would have swapped props for the day then gotten the dinged prop repaired.

You are probably okay either way but just for grins keep an eye on your lower oil in case you messed up the prop shaft seal.

 

[yorab]

Re: Which is Worse for my Motor? - If I had to choose...

Okay, I was just curious. My motor has 3 or 4 OMC-recommended props that work. Therefore, it's really easy for me to be sure that my spare prop is not oversized. But, getting back to your question as what I would do, I would go with the oversized before trying a dinged prop. But, I am a relative noob at boating, especially relating to prop selection. Just my $0.02.

BTW, I've never been to a yacht club except for the one on Lake Clarke, PA when my motor died on the lake in a nasty thunderstorm and I had to beg them to let me use their phone to call a buddy for a ride back to my truck.

 

[ShapeShifter]

Re: Which is Worse for my Motor? - If I had to choose...

Okay, I was just curious. My motor has 3 or 4 OMC-recommended props that work.

The spare I carry is oversized for dragging people around on a tube with a small boat full of crew and gear. If I raise the motor up one hole, then take the boat out alone with a light fuel load, properly trimmed that same prop is a rocket engine!

 

[eterry]

Re: Which is Worse for my Motor? - If I had to choose...

Yea, I completely understand the not wanting to "just go home". I had to do that 2 sundays ago and it sucked, not to mention the loss of time, fuel, bait, fees, PLUS the upset wife sitting next to me when my motor decided to crap out on me in the middle of the lake.

I think I would have also swapped props and run under WOT and made a day of it, then have the prop repaired....but what do I know, I AM A noob.

Eterry

 

[Frozen]

Re: Which is Worse for my Motor? - If I had to choose...

The spare I carry is oversized for dragging people around on a tube with a small boat full of crew and gear. If I raise the motor up one hole, then take the boat out alone with a light fuel load, properly trimmed that same prop is a rocket engine!

Thats not oversized, it's the proper prop for a heavily loaded boat. I would of absolutely used the spare prop. Plenty of boaters have 2 different sized props for different uses of the boat. If I'm head to a sand bar with 3 friends I use one prop if I'm headed out to go fishing with full fuel and water and several hundred pounds of ice and gear its a different prop.

 

[jay_merrill]

Re: Which is Worse for my Motor? - If I had to choose...

Your spare prop should be a usable prop, otherwise there is no point in keeping it in your boat. While it doesn't have the be exactly the same pitch as the one you use regularly, it should be close.

Most outboards have an acceptable WOT rpm range of about 1,000 rpm. Since WOT rpm changes about 200 rpm per inch of pitch change (up or down/decreased pitch or increased pitch), swapping to the spare prop should not cause serious problems. If you regular prop is well chosen, the spare should remain within acceptable limits if a higher pitch (slightly lugging the engine, but within acceptable range), as it should be if a lesser pitch (slightly over-revving, which can be dealt with by using less throttle).

If your spare is so different in pitch that it would concern you to use it for an afternoon, you have the wrong spare.

 

[1946Zephyr]

Re: Which is Worse for my Motor? - If I had to choose...

The way I see it, if the prop fits on the motor and it was made for the motor, then it should be okay to use. Do you think that the company that built the outboard would have built a prop that would harm a motor? I wouldn't believe so. So, if the shoe fits, wear it. LOL

 

[archcycle]

Re: Which is Worse for my Motor? - If I had to choose...

Hard to answer because you won't give specifics. It's like saying you're starving and there are two different rotten sandwiches that have been sitting in the sun for days-- which do you eat? I don't know if you won't tell me what they are. That makes it a non-starter of a premise. So,

I'm just going to jump on you about the spare you won't use too. Craigslist it and buy a spare you will use.

Gotta ask.. do your life jackets fit or is that for the yacht club elite

 

[AEROCOOK]

Re: Which is Worse for my Motor? - If I had to choose...

The way I see it, if the prop fits on the motor and it was made for the motor, then it should be okay to use. Do you think that the company that built the outboard would have built a prop that would harm a motor? I wouldn't believe so. So, if the shoe fits, wear it. LOL

I respectfully disagree. Larger HP motors dont leave the factory with props on them because the type / size of boat that it is going to be installed on has not yet been determined. It's the responsibility of the installer to choose the appropriate prop for the application in order to reach the desired WOT RPM range. I can buy a BRP / OMC 21 pitch prop and it will fit right on to my 110 V4 but since my boat is on the heavier side with a less that efficient hull design, I'm only going to get 4000 rpms out of it which will hurt the motor over time...As a very temporary emergency spare, I'm sure it would be okay to use it.

 

[Tim Frank]

Re: Which is Worse for my Motor? - If I had to choose...

Solittle, see what happens when you are serious and try to help? Btw, good to see you again.

+1 ^
I think that because this was mis-posted in Engine repair and Maintenance instead of SHT, it fooled him into thinking that this was a serious thread.
When an OP starts by stating that he does not want honest responses, it is bound to go downhill from there....:facepalm:

I dont see the relevance. What am I missing?

1) The correct forum section. This one is titled "Repair and Maintenance questions".
2) A poll might have been a better option.
3) Dockside Chat or Stupid human tricks would have been equally good choices....maybe even Non-repair Outboard Discussions or Prop questions and Topics.
4) At this point I'd be curious whether you own a Mercury O/B, but you might not see either the intended humour, irony, or relevance of the question.


This is a very helpful and usually civil forum, but you usually get back the attitude that you exhibit.
IMO you have perhaps not been as "uncondescending" as you may have thought.