Over 190 lbs of ToolsStill unprepared A short story

"As told, this is an unusual

"As told, this is an unusual series of events. : Went fishing Saturday and both engines roared to life as they always do. It usually takes a few cranks to get fuel into the carb so extra cranks between the two engines is typical and I now watch the oil pressure gauges build while I switch cranking between engines so as not to overheat the starters.

Moved around the ocean quite a few times and the engines just need a bump once they have been running. On the way back in we stopped at a few inshore sites one locally listed as the Atomic lump. ( I don’t know why but the fish did not glow) the last three starts the starboard engine had a clunk when we hit the key. One more drift across this “lump” before heading in. The starter on that starboard side just spins and spins with no sign of a starter gear.
Started the port engine and headed into shore….Jeff, the test of one engine was as you had stated…we are turning some oversized props and in order not too labor that one side we did about 10 knots MAX back to shore. In the center of the inlet…the engine red lined. Immediately threw it into neutral and pondered this situation. Starboard side …Can’t start the engine as we have a starter problem…Port side…Seem like we may have lost the prop. Two great running engines and we can’t go anywhere.
As I had said, I carry over 190lbs of tools, and meters in 5 heavy duck type bags but the only saving grace was that emergency towing card. So what happened to the prop…my brother jumped in and check but it was there. Once in the sling we discovered the prop key … that ¼” square 3” long brass stock…had literally split in two and sheared so the shaft was turning but the prop did not. There must have been quite a bit of torque on that shaft. Since we were out of the water, put the old props back on, new starboard starter, new transducer for the 4212 Garmin and 9am we were back in the water.

Who would have thought that with all of the preparations and spare parts….NONE were repairable afloat. I’d even said before we left the dock. If I take all this STUFF…I won’t need it, if I leave it in my truck…I’ll need almost everything."

"Hey; be a sport and pull that

"Hey; be a sport and pull that prop in deep water! In any case, glad you made it back OK overall.
There actually is a bit of a trick in reducing the load on the shaft key. If you don't know the secret, just ask. I note that my spare key is stainless, btw."

"Dave, My new keys are stainl

"Dave, My new keys are stainless and ...What is the trick to reducing load on a shaft key? And don't say...reduce throttle "

I'll bet someone lubed tha

I'll bet someone lubed that shaft before putting the prop on. That is an absolute No-No. THe friction developed by the tapered shaft--not the key---is what keeps the prop from spinning on the shaft.

Jeff

"It should have been on the pa

"It should have been on the paperwork the propscan shop gave you....you did follow ALL the directions, didn't ya???

Glad no one volunteered to chum and the fix was quick and easy."

"I can vouch for the right pro

"I can vouch for the right procedure. I actually have a 24" adjustable and a 3/4" drive socket set that I use only for the prop nust on and off. BOTH are Harbor Freight but I have had em for years....any other brand and I would still be paying them off! Those tools are so big, I really don't have any other use for them BUT they do crush the heck out of those 2 nuts. Thin one first then the fat one against it. This is one occasion where the cotter pit saved the prop.

They gentleman at the marina we were at ( a really nice guy )said he had seen it before in his 37 years there. I would not have thought it happens but I can't get close to 37 years of marina work. I'll bet there are some stories there !

Here's an interesting question: Does it make any sense to use a set of washers to take up the space on the last few threads of the shaft between the nut and the cotterpin so that the pin is firmly seated againts the washers and could prevent the nuts from possibly spinning loose?"

"Primary, is to make sure the

"Primary, is to make sure the key does not interfere with the complete mating of the prop to the shaft. Secondary, is to make sure the first prop nut is torqued sufficiently.
To make sure the prop seats, install the prop with NO key, and make a mark on the shaft to indicate position of the prop. Then, install with the key, making sure the prop is as far up the shaft as before. If not, use a grinder/file on the key as needed. Even before the work with the key, lap the prop on the shaft using valve grinding compound. As Jeff indicates, the final fitment is done dry."

"Thanks Dave,

Points well n

"Thanks Dave,

Points well noted. Any idea what the torque specs may be or is there a chart somewhere? I am using 1 1/4 " SS shafts."

"Note what Diver Dan said abou

"Note what Diver Dan said about the valve grinding compound.

Hydro racers use it to make sure their flywheels seat properly and don't shear the key. I've done it myself a few times to make a troublesome flywheel behave, and a discussion of how it's done might prove educational:

Smear the compound on the shaft, then wiggle-turn the flywheel back and forth a few dozen times to lap the two surfaces together. Thoroughly clean the grinding compound off, install the key, and bolt the flywheel back on.

Never heard of this being done for props, but it makes a ton of sense! I'll be sure to do it next time I mount my props.

Jeff"

"Al:

Didn't the propsca

"Al:

Didn't the propscan shop give you a sheet with all thses tips? The few cases of sheared keys i've seen were do to loose fitting/improperly seated props. Hate to say it but i'd bet yours is not an outlier.

The best way I found is to do the lapping compound process to ensure the whole tapered face is mated. You can use Prussian blue if you can't read the compound easily. Then clean the whole thing and seat the prop. Mark the shaft at the front of the prop.

Then ensure the key fits 'cleanly'. You do the key after the lapping to make sure it won't bind as the lapping will let the prop seat 'deeper' on the shaft.

Then you put it all together and make sure the prop goes back up to that mark. As far as torque goes, I use a 15" pipe wrench with a block of wood.

BTW, the usual process for the sheared key is the minute fore and aft movement of the prop on the shaft due to accelerating and backing. Eventually there's enough slop created to fully load the key. When you get a good load on it, the key shears and the redlining occurs. if the prop is fit to the shaft properly, that 'slop' isn't created and the key can't shear..."

"Jeff; good story. So far, a

"Jeff; good story. So far, all the flywheels in my life are bolt ons with just an alignment pin. that is, no keyway. I haven't really done all that many, ~ 8 total. edit: whoops, forgot about outboards, never mind
Yeah, I forgot the prussian blue, I have a tube for this purpose. Note that there are believers in using thin never seize on the taper; I think it is good to use light oil on just the threads to offer better (tighter) nut torque."

"..."Note that there are b

"..."Note that there are believers in using thin never seize on the taper"

Uh-huh, and one of them may have installed Al's prop.

Jeff"

"Well, Admittedly, I put those

"Well, Admittedly, I put those props on myself. I could never afford to have people do my work..its' me or it ain't. In reading all of this it makes very good common sense but it only makes the BEST common sense AFTER the fact.

As I replay the tape in my head about the process, lapping is a great idea. The part about the board to hold the tension I was told by propscan is a no-no....only because there is a tendency to cause the "balancing act" they just performed to get out of whack by un-equal pressure on one part of the blade.

This does'nt blow my mind completely as it provides me the opportunity to have the 4 blade props reduced in pitch for winter haul out...AND...I had to replace a 2 season old transducer and fairing block that thought the water everywhere was always 163.3 feet deep and 12.7 degrees farenheit. This was very important as the water goes so shallow in the southern section of Barnegat Bay at the drop of a hat. Besides, my brother told me when he jumped into the water, it felt like 12.7 degrees. Now it is all working properly."

"Yeah, the purist will use a s

"Yeah, the purist will use a strap wrench to hold the shaft, while you use a torque wrench on the nut(s). I use a 2x4 and a 3/4" drive socket and no torque wrench. Nibral is likely more tolerant of this "abuse"."

"Al,
I am with you. I do my o

"Al,
I am with you. I do my own work as I can't afford what the marinas want, and my wife works at one of the nicer ones up here. So I can get advice from the folks there. Then do the work my self."

"Paul, Not only will I do more

"Paul, Not only will I do more of what I enjoy BUT... I have learned such VALUED information that should the need to fix something arise while I am somewhere...odds are better that I might be able to deal with it. I have adopted the same policy with my restored motorcycles. You wont see too many 1930's vintage bikes 200 miles from home. Of course, your selection of tools and spare parts is limited to saddle bags only !"

"Me too, Al: I fix it or we do

"Me too, Al: I fix it or we don't boat.

Jeff"

I want to know how he was jump

I want to know how he was jumping "into" the water that was less than 13 deg F????

"Mark,

That was an indicati

"Mark,

That was an indication of how well the Airmar transducer with temperature sensor was working... It was also supposed to be 163 feet deep.

I would guess that most of us here exchanging ideas, probably do most of the service on our boats. Where else would this vast knowledge base have come from ?"

"I have done most of the work

"I have done most of the work on my boat, engines, and generator these last 21 years. Too bad to say but now I have to find a smaller guy to replace the spark plugs on the far side of the engines. Overweight has a price after all. Sometimes I believe I am not to heavy, just too short.

Chuck Hanson"

"Al -it was working...just exc

"Al -it was working...just exceeded your acceptable level of accuracy, for both depth and temp.

the best way to learn is by doing - asking before usually saves a lot of time and a reasonable amount of money. being able to "do" also gives a bit of independence.

Chuck - you could always consider a larger vessel. I'd think one with those shiny white awlgripped engine rooms with 7' of headroom would be more than adequate....."

"Chuck, I'll bet we get a

"Chuck, I'll bet we get a deal if we all get together and buy a few of them !

Mark, Point well taken..FAR exceeds my acceptable level of accuracy."

"Al

Starting to get some fe

"Al

Starting to get some feedback from the mechanical guys around here on Torque reccomendations. They are having trouble coming up with appropriate values as the 'standard marina terminology' doesn't show in their reference materials. I used my 1.5" shafts as a point of departure....torque values have come back ranging from 140 #*ft up to 360 #*ft...Even with a snap-on breaker bar, you'll have a lot of trouble getting to the higher end of the band.."

"Hey Mark, Thanks....I used a

"Hey Mark, Thanks....I used a 24" long 3/4" drive ratchet.. This gave me some gusto behind the nut but I would assume you are absolutley right using the shaft diameter and possibly thread pitch combined with the hardnesss of the shaft. That might give way to the correct range....

Gee, Is there a book of Standard Marina Terminology. Look up the phrase you hear when someone smacks into the pilings ?"

I heard there are a couple....

I heard there are a couple....can't find a publisher with enough b@!!$ to publish it. My case was the marketing end of the phrase-ology...what grade of stainless is aquamet 22 - there no aquamet anything on my material CD...

"To top this all off; I have

"To top this all off; I have an article picked up a few years ago. This yard expert uses never-seize, wd40, oil, marine tex or 5200 as prop fitting material. He also cross drills the shaft, using safety wire and a castle nut. That is, he doesn't use cotter pins. If anyone wants to read this treatise, I can email it."