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Prop question
- Thread starter walterv
- Start date
Not that I notice. Just wondering though are props done on a schedule like maintenence? Can there be a problem you can't feel but will damage the cutlass bearings or seals? There big props and being on the bridge when I drive I may not be able to feel a problem.
Just curious what all do here about this.
Just curious what all do here about this.
"Going on my 4th season with my boat and was thinking on getting the props balanced and trued up.
My question is if there are no noticeable dings, I achieve the proper speed at the proper RPM, is this necessary?"
Some thoughts on this include:
- Were they ever scanned?
- Do you get equal fuel use pt and stb?
- Any vibrations (as mentioned already)
- Do you compare your running performance to a baseline?
- Have you veered off of previous baseline or cruising data?
These are reasons that I would rescan or balance existing props but not on any kind of schedule if the reach WOT +3-5%.
Hope this helps
My question is if there are no noticeable dings, I achieve the proper speed at the proper RPM, is this necessary?"
Some thoughts on this include:
- Were they ever scanned?
- Do you get equal fuel use pt and stb?
- Any vibrations (as mentioned already)
- Do you compare your running performance to a baseline?
- Have you veered off of previous baseline or cruising data?
These are reasons that I would rescan or balance existing props but not on any kind of schedule if the reach WOT +3-5%.
Hope this helps
Smitty,
PO, had them scanned and actually made changes to the pitch so the boat would perform as per Silverton's specs rpm vs speed
This boat (45C) and my other Silverton (34c) always seemed to burn a tad more fuel on one motor (measured at cruise and done so electronically, not math)
As mentioned earlier (know noticeable vibrations, but that is hard to feel being up on the bridge)
"Running performance" please elaborate.
PO, had them scanned and actually made changes to the pitch so the boat would perform as per Silverton's specs rpm vs speed
This boat (45C) and my other Silverton (34c) always seemed to burn a tad more fuel on one motor (measured at cruise and done so electronically, not math)
As mentioned earlier (know noticeable vibrations, but that is hard to feel being up on the bridge)
"Running performance" please elaborate.
I would say yes for a number of reasons.
You "really" don't know what is going on down there. You may have tiny prop related vibrations and have had them since day one. How would you know the difference.
You are running through salt water. Salt is an abrasive. The props are not the same as they were 4 years ago.
I had a "matched" set of new Michigan wheels on Saint Max a few years ago. Michigan should have been disgraced as to how far out of whack the "matched" set was. I didn't know the difference. I thought the boat ran great. When I had it hauled for some work and new bottom paint, I sent the props to Wildcat Propeller to have them PropScanned. Wildcat "matched" the props. Night and day difference and it cut my fuel consumption to boot. I'm sure there is a Hale MRI or PropScan shop up your way. IMO, it's well worth the investment.
FWIW, the shops I know of in VA Beach area that have computers, scan all their new sales props to avoid what happened to me. They say what happened to me happens all to often. The only brand they don't scan is Veem. Veem's are spot on from the factory. They figured that out after the first 100+ they scanned! Even if you are running Veem's Walter.... They are Veem's with 4 years of wear.
You "really" don't know what is going on down there. You may have tiny prop related vibrations and have had them since day one. How would you know the difference.
You are running through salt water. Salt is an abrasive. The props are not the same as they were 4 years ago.
I had a "matched" set of new Michigan wheels on Saint Max a few years ago. Michigan should have been disgraced as to how far out of whack the "matched" set was. I didn't know the difference. I thought the boat ran great. When I had it hauled for some work and new bottom paint, I sent the props to Wildcat Propeller to have them PropScanned. Wildcat "matched" the props. Night and day difference and it cut my fuel consumption to boot. I'm sure there is a Hale MRI or PropScan shop up your way. IMO, it's well worth the investment.
FWIW, the shops I know of in VA Beach area that have computers, scan all their new sales props to avoid what happened to me. They say what happened to me happens all to often. The only brand they don't scan is Veem. Veem's are spot on from the factory. They figured that out after the first 100+ they scanned! Even if you are running Veem's Walter.... They are Veem's with 4 years of wear.
Hello Walterv,
Sounds like you are pretty close to perfect from what you say.
Baseline or running performance is a listing of how the boat runs at one known point in time during the year and recording those readings.
Typically in the northeast it is at season start and since I cannot remember anything anymore I either write the stuff down on s simple form or take a digital picture of my gages to fill in later. I keep these over time and many seasons to use and help to see if I need prop or engine attention.
I do this when the boats bottom is known clean and when the weather tends to be cooler and less humid with light seas - adjusted for any tides if they exist.
I record speed at a given rpm (actually a few rpm levels) with the associated engine temps, oil press, boost , pyro and fuel use (if you have them) and note the days temperature and humidity as well as any sea states.
I also record the max rpms as a brief test only for referring to later in the season and/or engines life.
Then I have a baseline to compare to later on so I can see if I am getting any degradation for any reasons (hull ,running gear, weight weather, engine issue , etc).
Practically speaking over the past few boats I have done this with I have found that the weight of the boat during the year is the least offending item which can change. I have found that bottom and running gear cleanliness to be the biggest issue / next is weather (temp/humidity) / and last is the weight I have on the boat at the time. Whenever I have had a larger issue come up suddenly (like a speed , boost or pyro reading) it was almost always related to some rope or growth tagging along. I have not had any engine issues to speak of on this last boat but when I have seen sudden changes in loads (as measured by fuel use or pyro) on friends boats compared to baseline they have been very specific such as a failing flex turbo hose or maybe a throttle/injector issue. Often I can tell exactly how many barnacles I have on the props and what size they are by reading the boost gages or the baseline speeds - I dive on the boat regularly so it is like a proof of the collected data.
I began to balance engine loads using the boost gages rather than my strobed tachs and I find that I am about 20 rpms off of the tach readings (when boost balanced) but my fuel burn is almost exactly even over time. Even though my trans ratios are exactly the same and props have been scanned they are not able to make them exactly equal so that is how I run.
Sounds like you are in good shape - Hope this helps
Sounds like you are pretty close to perfect from what you say.
Baseline or running performance is a listing of how the boat runs at one known point in time during the year and recording those readings.
Typically in the northeast it is at season start and since I cannot remember anything anymore I either write the stuff down on s simple form or take a digital picture of my gages to fill in later. I keep these over time and many seasons to use and help to see if I need prop or engine attention.
I do this when the boats bottom is known clean and when the weather tends to be cooler and less humid with light seas - adjusted for any tides if they exist.
I record speed at a given rpm (actually a few rpm levels) with the associated engine temps, oil press, boost , pyro and fuel use (if you have them) and note the days temperature and humidity as well as any sea states.
I also record the max rpms as a brief test only for referring to later in the season and/or engines life.
Then I have a baseline to compare to later on so I can see if I am getting any degradation for any reasons (hull ,running gear, weight weather, engine issue , etc).
Practically speaking over the past few boats I have done this with I have found that the weight of the boat during the year is the least offending item which can change. I have found that bottom and running gear cleanliness to be the biggest issue / next is weather (temp/humidity) / and last is the weight I have on the boat at the time. Whenever I have had a larger issue come up suddenly (like a speed , boost or pyro reading) it was almost always related to some rope or growth tagging along. I have not had any engine issues to speak of on this last boat but when I have seen sudden changes in loads (as measured by fuel use or pyro) on friends boats compared to baseline they have been very specific such as a failing flex turbo hose or maybe a throttle/injector issue. Often I can tell exactly how many barnacles I have on the props and what size they are by reading the boost gages or the baseline speeds - I dive on the boat regularly so it is like a proof of the collected data.
I began to balance engine loads using the boost gages rather than my strobed tachs and I find that I am about 20 rpms off of the tach readings (when boost balanced) but my fuel burn is almost exactly even over time. Even though my trans ratios are exactly the same and props have been scanned they are not able to make them exactly equal so that is how I run.
Sounds like you are in good shape - Hope this helps
"You may have tiny prop related vibrations and have had them since day one. How would you know the difference."
David - you raise a very good point about vibration comparisons over time and telling any difference so I will repeat a trick I leaned from an old acquaintances. Generally for props the worst offensive speed (for vibration not sound) is a low speed around the area of 1,200 rpms for many boat but you must search for your worst spot.
What he showed me was to set an open cup of water half filled in the center of the cockpit and watch how badly the water bounced around or out of the cup - sounds stupid until/unless you pick something up on the prop like line and see that he water reacts completely differently with that vibration. I kept a real short video of what that looks like on my boat at 1,100 rpms after my props were done.
Hope this helps
David - you raise a very good point about vibration comparisons over time and telling any difference so I will repeat a trick I leaned from an old acquaintances. Generally for props the worst offensive speed (for vibration not sound) is a low speed around the area of 1,200 rpms for many boat but you must search for your worst spot.
What he showed me was to set an open cup of water half filled in the center of the cockpit and watch how badly the water bounced around or out of the cup - sounds stupid until/unless you pick something up on the prop like line and see that he water reacts completely differently with that vibration. I kept a real short video of what that looks like on my boat at 1,100 rpms after my props were done.
Hope this helps
Walterv,
Rereading your post again I see you have fuel gages -
Ensuring that your fuel burn at relative rpms is at or below (preferred) the engine manufactured prop curve would be very good also. Those curves are fairly easy to look up if you know the engine model and rating (hp).
Hope this helps
Rereading your post again I see you have fuel gages -
Ensuring that your fuel burn at relative rpms is at or below (preferred) the engine manufactured prop curve would be very good also. Those curves are fairly easy to look up if you know the engine model and rating (hp).
Hope this helps
FWIW- Every fall/winter storage season I have the winter yard take my NiBrAl I/B props off so I can take them to my preferred Prop Scan shop( in Middletown , RI) to have them scanned while I am there and asking questions always kindly answered in full.
Although the yard requires they remove/install the props, the PropScan scan and printed report is free so I have clear confirmation of prop condition and pair matching, and whether I decide to have either serviced to get back well within ISO 1 specs and closely matching it's mate is completely up to me.
But I've found on the occasional times props look perfect but have gotten out of my baseline spec PropScan has on competer record, it has been worth it to have any errant prop worked back to spec and pair-matched.
It's a personal preference, but there is no way to know for sure how true to spec your props may be until you have them scanned.
I know every year there are prop strikes on lobster or conch pots held just under the surface by strong currents and on some of the extensive debris caught up in the ubiquitous, at-times unavoidable weed lines , whether I am aware of the strike or not with all the other boat-related noise going on.
Having any anomalies discovered & fixed minimizes vibration and maximizes economy for me, and equalizes engine loads at equal, actively-synchronized engine RPM.
Is checking yours NECESSARY? Probably not.
Although the yard requires they remove/install the props, the PropScan scan and printed report is free so I have clear confirmation of prop condition and pair matching, and whether I decide to have either serviced to get back well within ISO 1 specs and closely matching it's mate is completely up to me.
But I've found on the occasional times props look perfect but have gotten out of my baseline spec PropScan has on competer record, it has been worth it to have any errant prop worked back to spec and pair-matched.
It's a personal preference, but there is no way to know for sure how true to spec your props may be until you have them scanned.
I know every year there are prop strikes on lobster or conch pots held just under the surface by strong currents and on some of the extensive debris caught up in the ubiquitous, at-times unavoidable weed lines , whether I am aware of the strike or not with all the other boat-related noise going on.
Having any anomalies discovered & fixed minimizes vibration and maximizes economy for me, and equalizes engine loads at equal, actively-synchronized engine RPM.
Is checking yours NECESSARY? Probably not.
HIGHLIFEII
Member
- Joined
- Apr 24, 2007
- RO Number
- 26009
- Messages
- 263
How many hours on the props in 4 years?
I don't see any need for regular prop maintenance unless you boat a lot in shallow or junk filled waters. Nevertheless a prop scan shop will scan them for free and if your boat is still out of the water all you pay is for the yard to R&R them.
In my case some years ago after a shop repaired and repitched my props I later took them to a propscan shop and had them tuned up and the improvement in speed at cruising RPM was noticeable. I cant say enough good about propscan.
That was ten years ago and I compared performance after each bottom job and it didn't change so I never scanned them again.
If the PO gave you the scan results or you know what shop did the work the results can be compared
In my case some years ago after a shop repaired and repitched my props I later took them to a propscan shop and had them tuned up and the improvement in speed at cruising RPM was noticeable. I cant say enough good about propscan.
That was ten years ago and I compared performance after each bottom job and it didn't change so I never scanned them again.
If the PO gave you the scan results or you know what shop did the work the results can be compared
quote:
Originally posted by HIGHLIFEII
How many hours on the props in 4 years?
Andy,
Threes seasons about 150 hours
I also should mention, last year or the year before, I did hit some submerged debri, must have been some waterlogged would that rose to the occasion. Was doing 5mph, hear clunk, clunk and looked in my wake and saw shredded wood.
Walter
I'm having mine scanned after about 4 years (I think, maybe more) with no issues. Be interesting to see how they are. I asked my mechanic and he had a good suggestion. He said to place a hacksaw blade or something on the face of the rudder with the other end just touching the edge of one of the prop blades. Then turn the prop and see how the other blades contact the blade. It's not precise but it will give you an idea if any of the blades are out. You can do it in a few positions along the blade.
quote:
Originally posted by MichaelNJ
I'm having mine scanned after about 4 years (I think, maybe more) with no issues. Be interesting to see how they are. I asked my mechanic and he had a good suggestion. He said to place a hacksaw blade or something on the face of the rudder with the other end just touching the edge of one of the prop blades. Then turn the prop and see how the other blades contact the blade. It's not precise but it will give you an idea if any of the blades are out. You can do it in a few positions along the blade.
What about the rest of the blade?
HIGHLIFEII
Member
- Joined
- Apr 24, 2007
- RO Number
- 26009
- Messages
- 263
Walt,
Nibral or bronze? My guess is nibral, which is very hard compared to bronze. 150hrs in 3 season, not enough time for saltwater to abrade the props.
If you can't feel vibration on the bridge have someone stand in the cockpit, or you stand in the cockpit while someone else runs the boat. I am sure you know what it feels like to have a bent wheel from past experience.
Nibral or bronze? My guess is nibral, which is very hard compared to bronze. 150hrs in 3 season, not enough time for saltwater to abrade the props.
If you can't feel vibration on the bridge have someone stand in the cockpit, or you stand in the cockpit while someone else runs the boat. I am sure you know what it feels like to have a bent wheel from past experience.
This method doesn't replace a computer scan of course. It will just give you an idea if a blade is significantly off. Realistically, on a 30-40 foot cruising boat, as opposed to a performance boat, if there are no vibrations or noticeable changes in performance, RPM, Fuel consumption, why spend several hundred dollars tuning props just to get them perfect?
quote:
Originally posted by MichaelNJ
This method doesn't replace a computer scan of course. It will just give you an idea if a blade is significantly off. Realistically, on a 30-40 foot cruising boat, as opposed to a performance boat, if there are no vibrations or noticeable changes in performance, RPM, Fuel consumption, why spend several hundred dollars tuning props just to get them perfect?
I would agree except I don't believe Walter has an accurate baseline to measure from unless the props were scanned and tuned just prior to his purchase.
I can only speak from personal experience and mine was it smoothed out the ride and cut fuel consumption.
There are a number of good reasons to get props scanned on these larger boats...
- Cannot make rated rpms +3-5%
- Have a balancing problem side to side
- Have a vibration or another performance problem
- Have veered off of a baseline comparison
- Have never had them scanned
FWIW - Salt water is not going to abrade these materials in a normal lifetime.
Hope this helps
- Cannot make rated rpms +3-5%
- Have a balancing problem side to side
- Have a vibration or another performance problem
- Have veered off of a baseline comparison
- Have never had them scanned
FWIW - Salt water is not going to abrade these materials in a normal lifetime.
Hope this helps