Prop swap

[Four Suns]

Well... I seem to have gone the "cruising" season without whacking my props/bottom on something this year. However, I always wonder what I have hit and don't know about it. My annual haulout/bottom paint job is coming up and I'm thinking of swapping the props with the spares "just because" and having them checked by a local prop shop.

What is the best practice in this area? Do you just run the props until something can be felt or do you have them tuned up every few years? I'm sure I hit stuff that is minor through the year...

 

[Petep]

Have them Hale MRI'd (or Propscanned), same basic thing just different manufacturer , every 2-3 seasons. This way they get computer turned/balanced and brought to almost military spec. precision. I don't think that you need to do this every year unless of course you feel any vibration. I'm also a diver so I do visual inspection quite often on my wheels while in the water. Make sure you are getting full WOT rpm's and run the boat to full throttle often to insure your getting full RPMs, log it in and talk to your prop shop guy about your findings.

 

[rondds]

with the boat now layed up for the winter, i pulled my props for the first time since i bought the boat. i'm going to take them in to a place that comes highly recommended for a PropScan, just because. they have served me well for the 2 1/2 seasons and over 100 hours that i have owned the boat, but i dont know their history and i'd like to establish a baseline. it's kinda like going to the dentist for a checkup even though nothing's bothering you :grin:

 

[fwebster]

I subscribe to the " If it ain't broke, then don't fix it" school of thought.

If your props run smooth and you can turn up WOT rated rpms with a full normal full load, than I certainly wouldn't mess with it. If you are itching to spend most of $1000 at the prop shop, then take your spares in and have then trued and balanced so you are not faced with down time when you do it something.

I don't follow tha dentist check up analogy. Your props don't decay if you fail to brush them, and they don't get out of true unless you hit something or run 10,000 hours and thin the blades. Do you take your car to the tire shop and have the tires removed to check the condition of the wheels every other year?

 

[sbw1]

Gary, I have prop scanned wheels on the boat and a set of prop scanned spares. If there is no vibration, wot is same from year to year and my milage is where it needs to be, I keep the spares in the box. Just pulled my boat and the wheels are smooth with no knicks anywhere. I'll keep these on the boat until something changes. Keep good records of wot and milage, noting any change in vibration. If something feels not quite right, look at cutless bearings, props, etc and decide what needs to be done. I think Nibral props are pretty sturdy and don't lose their pitch unless you hit something. SBW

 

[Skip]

Gary,
i have a set of spare wheels for Truly Blessed but plan to keep 'em in the box unless I dinged up the primary set this season...and I won't know that until I pull her next spring. I dive under the boat each time we go out (well, OK, until 01 October) and the props look good...given that I churned mud for about 100 meters in June in a narrow channel I consider myself awful lucky. I do plan on checking cutlass bearings as well come March.
Skip

 

[rondds]

scanning your props and altering them are two different things. if there are no necessary changes, the prop guy, who comes highly recommended, will not change anything. if there are slight problems that i cannot detect because i have no baseline to work from and i have a 17 year old boat that i have no service records or history on, i feel it is money well spent, if nothing else, for peace of mind.

the oral health analogy pertains more to the dangers of self-diagnosis. if someone hasnt been to the dentist in 15 years, it would probably be a good idea to see one, even if "it aint broke."

and yes, even if my brakes seem to be stopping my car pretty well and there is no squealing, i will pull the wheels to see how the pads look and feel the rotors for wear.

 

[fwebster]

Your analogy still does not work.......brakes are wear items which is why you check them. Props do not wear. Likewise, we are not discussing a living breathing being or a mechanical machine with fluids and moving parts...we are talking about a hunk of metal that just lays there bolted to the end of a stainless steel shaft.

There is also a huge difference in the cost of checking and truing the props on a 340DB and the 4 blade 28" props on the 480DB in question.

There is no doubt that a blue printed prop is the best approach. If you have vibration or if the boat will not run up rated RPMs, then by all means get your props trued and balanced. However, if your OEM props turn up WOT rpms and the boat runs smooth, the haul out ($7-$10/ft) plus the $1000-$1200 may make you feel better, but I just don't think its worth it.
.

 

[tc410]

Gary,

Back to your original question - no tire or dental analogies here. Have your spares ever been scanned? If not, get them scanned before you put them on, even if - especially if - they're brand new. My local Propscan franchise will tell you that brand new props are almost always off when run through the Propscan proprietary analysis. Most important, the scan is free, so you're not out any money despite what some are saying here.

Put the scanned and certified spares on the next time you haul the boat, and then have the current props scanned and, if required, tweaked. Again, the scan is free so if they're at spec you're not out any money and you can hold them as spares and be ready to go if you have the need.

Like some, I thought my props ran and felt great until I took the local free scan and found out how far off they were from each other. Putting them back on the following spring, I was amazed at how much smoother and quieter the boat ran. I didn't notice a problem before they were done, but I noticed a huge improvement after.

SBW1 can probably confirm that Mitch at Holland Propscan is an artist when it comes to prop science.

And as for Frank W's tire analogy, yes I do have my tires removed, actually every other oil change, and rotated. I get them balanced every 12 - 15 months also. As far as decay, the worst props I had were on my previous 330DA. Not from hitting anything, or running 10,000 hrs., but pitted from excess cavitation.

 

[rondds]

jeff
your story parallels a testimonial i heard from a friend of mine who took his props in for a PropScan. i am going to take mine in to a Atlantis Propeller here in NJ. i wasnt aware that the PropScan is free, nor is that going to sway my decision. i am fortunate in that i have the ability, i enjoy doing it, and i have the time to do most of the work that my boat requires. that being said, i have NO problem paying for stuff i CANNOT do. as for props, all i know how to do is get them off. beyond that i'll have an expert scan them, examine them, make any necessary corrections and SAVE THOSE CORRECT READINGS ON A COMPUTER FOR FUTURE REFERENCE. there is no haul-out cost, since my boat sits on the hard from mid oct to late april anyway. all i need the guy to do is mark which way they go on. i marked them when i took them off, just in case!

 

[tc410]

rondds-

You won't regret your decision for one minute. Having my props done to Propscan tolerances was the best $500 I spent on my boat. The scan is free (at my local franchise anyway - I think they all are) and one of my props, while visually clean, was out of spec on all blades, but one more than the other three. The other prop was pretty close to spec, but out a bit. Holland Props brought both into tolerance for, as I said, $500.

Check out www.propscan.com to read all about the process and find local franchises.

 

[First Born]

all i need the guy to do is mark which way they go on. i marked them when i took them off, just in case!

Is there a certain way that they go on? :huh: Now I am confused.

Wesley

 

[ImpulseIII]

Ron,
You will not be disappointed by the work Tom at Atlantis Propeller does. The guy knows his "stuff". I have had the props on this boat and my 340 "scanned" and the on the 340 it actually improved fuel consumption and increased my mid range speed by a knot. The 410 always ran perfectly well at WOT but after the props were done, the minor vibration I had disappeared.

As far as left and right handed props. If they are not marked, take the prop and sit it on the ground and pictaure it as if you were looking at the prop from the back of your boat while it was installed. Now picture a compass around the prop. If you are the south, have one blade of the prop facing north. Now picture pouring some water on the blade of the northern prop and notice the direction the water runs off. If it runs to the left, that is the left side prop.

 

[fwebster]

If you folks can get the props scanned for free, by all means , have at it.

It is ceratinly not a free service around here, but perhaps that is a product of year round boating and more marine growth in warmer water.

Wesley - the props are all stamped on the hub as to RH or LH rotation along with the pitch and cup in the prop. Marking the wheels is not necessary unless you are afraid that you or some yard guy is going to make a mistake. You can definitely put them on the wrong side, in which case the boat goes forward when you put the transmission in reverse.

 

[brimanst]

I think the key is to have the "known good". For me it means to have the props tuned up and record the performance of the boat at normal cruising speeds as well as WOT. That way it is not much of a guessing game to know when they need it again. I agree that if it is not broke, don't fix it, but it is important to know what "broke" is.

briman

 

[mrsrobinson]

I too subscribe to if it isn't broke don't fix it. In 10+ years of boating we never hit a log. We had the boat pulled in November, bottom painted, hull compounded and waxed and we had the props pulled and tuned for the first time 'just because'. Back in the water 1 hour and we hit a log. She did run much better though until we hit the log. Oh well. New props will be here shortly.

 

[geriksen]

Gary,

Back to your original question - no tire or dental analogies here. Have your spares ever been scanned? If not, get them scanned before you put them on, even if - especially if - they're brand new. My local Propscan franchise will tell you that brand new props are almost always off when run through the Propscan proprietary analysis. Most important, the scan is free, so you're not out any money despite what some are saying here.

Put the scanned and certified spares on the next time you haul the boat, and then have the current props scanned and, if required, tweaked. Again, the scan is free so if they're at spec you're not out any money and you can hold them as spares and be ready to go if you have the need.

Like some, I thought my props ran and felt great until I took the local free scan and found out how far off they were from each other. Putting them back on the following spring, I was amazed at how much smoother and quieter the boat ran. I didn't notice a problem before they were done, but I noticed a huge improvement after.

SBW1 can probably confirm that Mitch at Holland Propscan is an artist when it comes to prop science.

And as for Frank W's tire analogy, yes I do have my tires removed, actually every other oil change, and rotated. I get them balanced every 12 - 15 months also. As far as decay, the worst props I had were on my previous 330DA. Not from hitting anything, or running 10,000 hrs., but pitted from excess cavitation.

Exactly what I was going to say.
New props are very often far from true.