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Old 01-27-2022, 04:43 PM   #1
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Californian 34 LRC Props

Hi All,

KS (a 1981 Californian 34LRC) is powered by twin Perkins T6.354 engines rated at 200hp each.

Props on the boat, and the old spares are Michigan Wheel three blade 22x21.

I want to presume, and from TF discussions they appear to be factory original.

At 20,000lb or so, we seem to be over propped.

Reasoning that Engine raings are:
2400 RPM max
2250 max sustained cruise

Boat top speed is 18-20kts?

We can make 17 kts on a good day, and WOT will sometimes hit 2270, but usually more like 2170 on the mechanical tachs. I realize that there are better ways to measure RPM.

ACME propeller says We are over propped and need four blade 20X18 lightly cupped props to allow more RPM based on our boat weight, dimensions and HP.
I surely do not want to under-prop.

Any opinions or thoughts please.
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Old 01-31-2022, 07:44 AM   #2
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Many owners will "over prop" to lower the cruise RPM .

Actually its not over proping as most folks will pull back 10% or more from WOT for cruise .


If you will operate at WOT much 10% gives a good cushion against overloading.


If you prefer longer engine life , lower fuel burn and less noise and vibration I would leave it as is , as long as cruise is at least 10% down from WOT.

I prefer 300 RPM down and a quick check that there is NO black smoke in the exhaust, as max for cruising.

WOT is very fuel consuming , most trawler folks cruise at 6-8K and enjoy 3 or 4 times the range..
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Old 01-31-2022, 10:39 AM   #3
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Californian 34 LRC Props

Thank you.
We do not cruise at WOT, but have been thinking that the full RPM range should be acheivable, along with the 18-20kt top speed claimed by the manufacturer-though she is no doubt a bit heavier than when rated.

I also thought that fuel consumption at hull speed of 6-7kts and high cruise- 14-16kts might be reduced if we took some load off the engines, even though RPM would be higher.

Presently no black smoke at any RPM.
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Old 01-31-2022, 02:30 PM   #4
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I also thought that fuel consumption at hull speed of 6-7kts and high cruise- 14-16kts might be reduced if we took some load off the engines, even though RPM would be higher.
I don't think that you'll see reduced fuel consumption at any speed.

Maximum speed would likely be increased with props that allow you to reach rated maximum RPM, and that may allow a slightly higher maximum cruise speed. If you're interested in max cruising speeds burning > 15 gal/hr it's worth getting right to avoid overloading. For lower cruise speeds there is no advantage to increasing RPM.

If you do want to make adjustments it's probably cost effective to have one of your existing set of props depitched a bit rather than ordering new props. Get an accurate RPM reading at WOT first with full tanks and loading and use that to determine the required pitch reduction.
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Old 01-31-2022, 08:47 PM   #5
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I don't think that you'll see reduced fuel consumption at any speed.

Maximum speed would likely be increased with props that allow you to reach rated maximum RPM, and that may allow a slightly higher maximum cruise speed. If you're interested in max cruising speeds burning > 15 gal/hr it's worth getting right to avoid overloading. For lower cruise speeds there is no advantage to increasing RPM.

If you do want to make adjustments it's probably cost effective to have one of your existing set of props depitched a bit rather than ordering new props. Get an accurate RPM reading at WOT first with full tanks and loading and use that to determine the required pitch reduction.
Thank you for that input. Existing props are still in decent condition but at end of life. Tips appear to be gradually thinning. They will be great spares.

Donít want to blindly order same if I can make an improvement.
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Old 01-31-2022, 09:25 PM   #6
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I would get a photo tach and see what your actual RPM at WOT is. Then prop in order to reach the recommended max RPM. A good shop can probably repitch your props to get to that RPM. And it will be much cheaper than buying new props. Photo tachs are not very expensive, probably under $50.
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Old 02-01-2022, 07:30 AM   #7
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"Don’t want to blindly order same if I can make an improvement."


Define "improvement".
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Old 02-01-2022, 08:08 AM   #8
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As stated above, you really need to calibrate your tachometers to know where you are. They may be off.
At 2170 with no black smoke, you might be closer to having the right props than you think.
Regarding "top speed": You may never reach it with an older boat. Most likely the boat is quite a bit heavier than it was when new, and certainly heavier than when the factory tested that model and published the specs.
I'd prop it to reach a little over 2400 at WOT and be happy with the cruise speed you get.
Good luck!
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Old 02-01-2022, 08:43 AM   #9
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Your boat sounds very close to mine. Same model, same engines but mine is 82 medel year. One thing I discovered with mine is that its got 1 1/4” shafts. That’s very unusual for 22” diameter props. Twenty two inch props are usually at least 1 3/8” bore. I have found that they are usually stocked that size and bored larger if needed. My understanding is that they can be made 1 1/4’ bore by special order but the lead time is loooong, as they are special order. As a result, I run mine with nylon bore reducers with good results. I’m currently running 22d x 21p four blades x 1 3/8 bore props I bought second hand but new. They also have a bit of cup. I intend to rework them down to 19p as I only get about 2100 rpms with them. But they are the smoothest running set I have ever run. I typically cruise at 1400 to 1500 and seldom run them harder. Curious if you got 1 1/4” shafts too.
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Old 02-01-2022, 03:35 PM   #10
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Quote:
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"Donít want to blindly order same if I can make an improvement."


Define "improvement".


Better top speed, and lower fuel consumption at high cruise (less load on engines?) along with slower trolling capability. I run 48 inch bags, and still troll too fast at 650 RPM, one engine.

Right now we cannot make highest continuous RPM that the engines are rated for -even at WOT.

Not sure if Iím dreaming, or if I should spend the $4400 in attempt to accomplish the above. The charts and engineers are saying it should work.

I have contacted the Marshal group to see if they could have anything to offer on the subject. Not holding my breath.
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Old 02-01-2022, 03:41 PM   #11
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Your boat sounds very close to mine. Same model, same engines but mine is 82 medel year. One thing I discovered with mine is that its got 1 1/4Ē shafts. Thatís very unusual for 22Ē diameter props. Twenty two inch props are usually at least 1 3/8Ē bore. I have found that they are usually stocked that size and bored larger if needed. My understanding is that they can be made 1 1/4í bore by special order but the lead time is loooong, as they are special order. As a result, I run mine with nylon bore reducers with good results. Iím currently running 22d x 21p four blades x 1 3/8 bore props I bought second hand but new. They also have a bit of cup. I intend to rework them down to 19p as I only get about 2100 rpms with them. But they are the smoothest running set I have ever run. I typically cruise at 1400 to 1500 and seldom run them harder. Curious if you got 1 1/4Ē shafts too.


That is interesting. I have the 1 3/8 shafts.

I am looking at going four blade, but they are telling me to use 20X19 with .45 cup.

Seems like a bigger difference from the threeblade 22X21s than I might want.
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Old 02-01-2022, 03:43 PM   #12
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As stated above, you really need to calibrate your tachometers to know where you are. They may be off.

At 2170 with no black smoke, you might be closer to having the right props than you think.

Regarding "top speed": You may never reach it with an older boat. Most likely the boat is quite a bit heavier than it was when new, and certainly heavier than when the factory tested that model and published the specs.

I'd prop it to reach a little over 2400 at WOT and be happy with the cruise speed you get.

Good luck!


Seems logical. Thank you!
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Old 02-01-2022, 03:47 PM   #13
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I would get a photo tach and see what your actual RPM at WOT is. Then prop in order to reach the recommended max RPM. A good shop can probably repitch your props to get to that RPM. And it will be much cheaper than buying new props. Photo tachs are not very expensive, probably under $50.


Yes.
Gotta wait til weíre back in the water for that. Thinking my props are well past prime, but will be looking into tuning them if theyíre still solid. If not, theyíre spares.
Thank you!
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Old 02-01-2022, 03:59 PM   #14
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I don't think that you'll see reduced fuel consumption at any speed.

Maximum speed would likely be increased with props that allow you to reach rated maximum RPM, and that may allow a slightly higher maximum cruise speed. If you're interested in max cruising speeds burning > 15 gal/hr it's worth getting right to avoid overloading. For lower cruise speeds there is no advantage to increasing RPM.

If you do want to make adjustments it's probably cost effective to have one of your existing set of props depitched a bit rather than ordering new props. Get an accurate RPM reading at WOT first with full tanks and loading and use that to determine the required pitch reduction.


Just considering your comment regarding high cruiseÖ

We love hull speed.6-7kts!!

In our location -Muskegon, MI.,
If we want to get anywhere, we cruise the eastern shore of Lake Michigan.

This lake, like all the Great Lakes, can roil up in a hurry, and ports are there, but rough water accessing can be a challenge to some of them, and you may be stuck for several days wherever you land.

We try for good steps to get us up north where there are better options for cruising calm water. Hence the need for high cruise periods almost every trip. We still work, so while we do not make unbreakable plans, we do not enjoy unlimited time.

This is why we chose our boat, and she has never dissappointed. If I can help her do betterÖI just do not want to screw (no pun) it up.
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Old 02-02-2022, 12:30 AM   #15
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No Salted: I didn’t mean to imply any specifics about my current props easpecially any cupping spec other than than I thought mine looked to have some, Modifications to mine would be done only after I had a chance to document more info than I could gather from the month I had mine in the water last year It was a crappy season based on a lot of distractions., Some medical on my part. I’m hoping for a better year next. That being said, its my experience that reducing pitch 2” generally affects rpm by about 400. That’s a very general statement. Mine have 1:1 1/2 reduction gears. I assume yours are same. I plan to document more specifics then seek a prop professionals recomendation. My numbers are close but deserve more discussion.
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Old 02-02-2022, 08:25 AM   #16
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No Salted: I didnít mean to imply any specifics about my current props easpecially any cupping spec other than than I thought mine looked to have some, Modifications to mine would be done only after I had a chance to document more info than I could gather from the month I had mine in the water last year It was a crappy season based on a lot of distractions., Some medical on my part. Iím hoping for a better year next. That being said, its my experience that reducing pitch 2Ē generally affects rpm by about 400. Thatís a very general statement. Mine have 1:1 1/2 reduction gears. I assume yours are same. I plan to document more specifics then seek a prop professionals recomendation. My numbers are close but deserve more discussion.
Yes mine is 1.52:1 I believe. I certainly wish a better season for you, and look forward to sharing information.
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Old 02-02-2022, 09:03 PM   #17
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I would get a photo tach and see what your actual RPM at WOT is. Then prop in order to reach the recommended max RPM. A good shop can probably repitch your props to get to that RPM. And it will be much cheaper than buying new props. Photo tachs are not very expensive, probably under $50.

I agree. IF you are looking at propping then you need accurate info such as rpms. Typical dash tachs won't cut the mustard. THey can be off a lot, enough to make your efforts almost futile.

The handheld laser pointer digital phototachs can be had from Ebay or Amazon for about $20. THey are accurate to +/- 2 or 3 rpm.

To dial in props and potentially purchase new ones you need accurate info to avoid as many adjustment as possible which can be costly especially if due to inaccurate info you buy the wrong props.

Yeah I know I am on a high horse but I've seen problems happen when people did not understand or ignored the need for accurate info.
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Old 02-02-2022, 09:42 PM   #18
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I agree. IF you are looking at propping then you need accurate info such as rpms. Typical dash tachs won't cut the mustard. THey can be off a lot, enough to make your efforts almost futile.

The handheld laser pointer digital phototachs can be had from Ebay or Amazon for about $20. THey are accurate to +/- 2 or 3 rpm.

To dial in props and potentially purchase new ones you need accurate info to avoid as many adjustment as possible which can be costly especially if due to inaccurate info you buy the wrong props.

Yeah I know I am on a high horse but I've seen problems happen when people did not understand or ignored the need for accurate info.
Common sense, commonly ignored Iím sure.

I will be purchsing a phototach.👍
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Old 02-03-2022, 12:30 AM   #19
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If you do buy new props before you mount them take them to a Prop Scan shop and have them scanned. It is surprising how bad a new prop can be. Usually they will scan them for free since it only takes a couple of minutes.
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Old 02-03-2022, 09:04 AM   #20
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If you do buy new props before you mount them take them to a Prop Scan shop and have them scanned. It is surprising how bad a new prop can be. Usually they will scan them for free since it only takes a couple of minutes.
Yes. A cast prop needs to be checked and tuned even brand new.

The ACME props are CNC machined from a solid block, and come out practically perfect. Not much more money for the size Iím looking at, and made in Ohio. (Not as good as Michigan, but not Taiwan..)😎
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