Californian 34 LRC Props

[Knot Salted]

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.

 

[FF]

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..

 

[Knot Salted]

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.

 

[Jeff F]

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.

 

[Knot Salted]

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.

Don’t want to blindly order same if I can make an improvement.

 

[Comodave]

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.

 

[FF]

"Don’t want to blindly order same if I can make an improvement."


Define "improvement".

 

[jleonard]

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!

 

[Capn Craig]

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.

 

[Knot Salted]

"Don’t 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 I’m 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.[emoji38]

 

[Knot Salted]

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.

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.

 

[Knot Salted]

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!

 

[Knot Salted]

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 we’re back in the water for that. Thinking my props are well past prime, but will be looking into tuning them if they’re still solid. If not, they’re spares.
Thank you!

 

[Knot Salted]

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 cruise…

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 better…I just do not want to screw (no pun) it up.

 

[Capn Craig]

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.

 

[Knot Salted]

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.

Yes mine is 1.52:1 I believe. I certainly wish a better season for you, and look forward to sharing information.

 

[C lectric]

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.

 

[Knot Salted]

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 I’m sure.

I will be purchsing a phototach.?

 

[Comodave]

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.

 

[Knot Salted]

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 I’m looking at, and made in Ohio. (Not as good as Michigan, but not Taiwan..)?

 

[Knot Salted]

Common sense, commonly ignored I’m sure.



I will be purchsing a phototach.[emoji106]

So I got the photo tach and it matches precisely with my tachs onboard.

Wondering now if a shallower pitch four blade is what I need/want in order to:

Idle and troll slower

Reduce some vibration

Be able to see max rated 2400 RPM at WOT

Presently I have three blade 22x21 props now on our ‘81 Californian 34LRC. Max RPM achieved at WOT is 2200; 15-17kts

Boat is roughly 20,000lbs
34 at the waterline
12.6 ft beam
Twin Perkins T6.354M rated at 200hp each.

 

[kapnd]

So I got the photo tach and it matches precisely with my tachs onboard.

Wondering now if a shallower pitch four blade is what I need/want in order to:

Idle and troll slower

Reduce some vibration

Be able to see max rated 2400 RPM at WOT

Presently I have three blade 22x21 props now on our ‘81 Californian 34LRC. Max RPM achieved at WOT is 2200; 15-17kts

Boat is roughly 20,000lbs
34 at the waterline
12.6 ft beam
Twin Perkins T6.354M rated at 200hp each.

I’d try reducing the pitch in your existing propeller.
As mentioned earlier, you may be closer than you think, so switching the number of blades at this point is just going to confuse the issue.
I don’t think going to 4 blades will help slow the troll, probably opposite, as it will increase blade area significantly.
Find a reputable propeller shop to work with, their expertise and database are far more valuable than random internet opinions, mine included!

 

[Knot Salted]

I’d try reducing the pitch in your existing propeller.
As mentioned earlier, you may be closer than you think, so switching the number of blades at this point is just going to confuse the issue.
I don’t think going to 4 blades will help slow the troll, probably opposite, as it will increase blade area significantly.
Find a reputable propeller shop to work with, their expertise and database are far more valuable than random internet opinions, mine included!

Right.
Ive been through the process with a good prop shop and ACME Propeller.
To change and tune my existing props is within 75% of new.
Was looking at 4 blades for smoother operation-smaller diameter and shallower pitch.
The missing data was the thought that my tachs might be off.

 

[SoWhat]

Wondering now if a shallower pitch four blade is what I need/want in order to:
Idle and troll slower
Reduce some vibration
Be able to see max rated 2400 RPM at WOT

I went to 4 blade and reduced pitch. Main benefit was much slower idle speed.
No change in vibration. RPM increased. No significant change in top end speed. (4 blades were in stock, 3 blades were 6 mo back order)

Coming into dock at less than warp speed is really nice. Less response to throttle while docking so there was a learning curve.

 

[Knot Salted]

I went to 4 blade and reduced pitch. Main benefit was much slower idle speed.
No change in vibration. RPM increased. No significant change in top end speed. (4 blades were in stock, 3 blades were 6 mo back order)

Coming into dock at less than warp speed is really nice. Less response to throttle while docking so there was a learning curve.

Nice to know.
What boat and props -old vs new please?