Need New Props On My 34' LRC

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maninboat

maninboat

Member
Joined
Mar 27, 2010
Messages
13


Hello All,

I have a 1981 34' Californian LRC with the Cat 3208 engines. Gear ratio is 2:1. I found out recently the boat needs new props. Does anyone on the forum have the same engine/gear ratio setup on their Californian? If so can you tell me what you get for performance and what size prop/pitch you are using? I would like to have a real world example or two when I go to get new props from the prop guy. The props that were on the boat were undersized and I was not anywhere near what the performance should be on the boat. He is recommending a 22" by 24" prop. Diesel forum recommends a 23" by 24" which seems too big.... I am only looking for prop info on Californians with the Cat engines and the 2:1 gear ratio. The perkins powered Californians had a different gear ratio and thus would have a different prop size....


thanks.....
 
Have the old props re pitched. What do you mean under performed?
 
Undersized usually means small diameter but some people mean small load capability. If you go bigger diameter make sure there is enough clearance between the props and the hull. I'm guessing you'll need 1.5 to 2". If you are already at max dia you will probably need to get props w one more blade or greater blade area. You could call Michigan as they have very knowledgeable people on hand.

You could get a recommendation from boat owner that did'nt have it right either. Have the experts and ideally the engineers figure this out.
 
If you are really sure the props are sized wrong, you will have to buy new.

Are the 3208 N.A. or turbo?
the naturally asperated 3208 are at 210 h.p.

Can you achieve Wide open throttle at or near 2800 rpm's
She may be propped right.
why do you need to replace them?

Have the old ones rebuilt or repitched

Lot's cheaper.

Sd
 
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The old props are bad enough they can't be re-pitched. The boat has two of the cat 3208N engines that make 210 hp a piece. With the old props on the boat the boat was turning up to the rev limit on the engines (3000rpm) and only making about 16knots at that rpm. at cruise (2400rpm) the boat was at around 10knots and pushing lots of water. I had a spare set of props on the boat but both sets of props are not worth reworking based on bad electrolysis and worn out blades. Looks like the prior owner didn't believe in zincs. The reason I am asking for information from people with the same engine setup on the same boat is to see what performance they get and see if the props they have are the same as what my mechanic and prop guy are recommending. The problem with just asking the experts is they all seem to have a slightly different idea about what prop the boat should have. Boat diesel.com says 23 by 24. My prop guy says 22 by 24. Another calculator says 23 by 23. I don't want to drop the 3000 on new props without knowing what others with the same setup and same boat are running and what their boats are doing. With the old props turning up to rev limiter on the engines it's difficult to tell how far off we are.
 
I believe Fighterpilot has the same boat and drivetrain as you. He might be a valuable source of info. I have twin 200 Perkins ( a bit lighter than the Cats) and a 1.52:1 reduction. Mine came new with 22x21 3 blades. currently has 21 x 21's. This would produce ~ 24 mph (statute) at 2575 rpm or 1700 rpm shaft speed, for me. Not very comparable. If you struts are the same as mine, you could probably swing a 23" Dia.
 
If you start out with the proper diameter, the pitch can always be adjusted by a qualified prop shop.
 
A good place to buy new props is:

North Harbor Marine Propellers

Tacoma Propellers

Deep Blue Sea Yacht Supply
Deep Blue has good prices but they DO NOT do returns. I found out the hard way.
 
Do you know what the present props are? Sounds like the props are about right. Might want to go up a tad in, but with out know the present props? So for 3 grand what are you hoping to a chief? Take the old prop to a repair prop shop just to find out what the present props are.

You indicate it’s a 34' Californian LRC. This is off the internet, “ability to cruise at 15 knots and reach 17 knots WOT, but sips fuel at trawler speeds.” So it sounds like you are right there also. Usually LRC means slower speeds and longer range. So putting bigger props probable will not make the boat go fast. :confused:

You might want to also look at other things like trimming the boat and/or cleaning the bottom and props of growth which can affect the performance and range.
 
Thanks for all the information gents. If you read up on the 34' Californians you will learn exactly what the boats are supposed to do.There is an entire thread including the initial tests of the boat which has been valuable information in my restoration. In my initial post I stated the props are damaged enough by the electrolysis/age and the previous owner apparently dredging a channel with them that the prop shop will not repair them. I appreciate all the posts saying to get them repaired and I fully understand how much cheaper that would be but the props are old enough and damaged enough that is not possible. All I am asking for is help by anyone who has a californian lrc with cat engines and the 2:1 gearing to see what they are running and what they are getting for performance. That way when I choose the new prop size I will have as much information as possible. Thank you for the post on good places to buy props. I will be sure to check them out.
 
I said in the previous post the boat was only achieving close to 17 knots when it was hitting the rev limiter on the cats at 3000 rpm. It should be cruising at 17 and topping at 20 to 21 at 2800 rpm if hooked up right.
 
I have a 1983 34LRC with the 3208NA cats and the 2:1 tx ratio. Bought the boat in Oct. and have been working with it thru the winter. Props were 22x24 three bladed. At sea trial boat did 21 knots wot and 17knots at 2400rpm. At haul out for survey noted props in bad shape so put on the "new" set that came with it. They were 22x24 three bladed with some slight cup. 21knots wot and 16knots 2400rpm with full holding tank, half water, and half fuel, clean bottom, and boat loaded for partying etc. Lots of dishes, pots, pans, silverware, glasses, spare filters, belts, etc.

We replaced one tank that was leaking, but still had 30 gal. in it, and have now filled both tanks. 106 gal. in new set and 125 in the orig. one. Tweaked the props looking for cause of vibration and had cup taken out since I felt we were marginal for making rated RPM when we would get it loaded down for fishing plus 6 souls onboard. We haven't taken it out to see where we are with the full fuel tank, empty holding tank, and cleaned out pots and pans etc. Maybe today or this weekend.

A qualifier--trim tabs not working, but in extended postion so boat comes up on plane quickly but appears to be running a little nose down for the lightly loaded conditioned described earlier. Seem to be getting a lot spray further forward on the hull than would expect if trimmed correctly. Have new trim tab pump, but with snapper season coming hate to break the lines and lose that trim setting at the risk of having other problems with the cyl. and being unable to use the boat until that is fixed. Going to see what the trim is with the full aft fuel tanks before we make a decision on repair now or after first day of snapper fishing.

Boatdiesel.com for this boat configuration suggest a 23.6x23.8 prop. Average planing, 23,000wt 32 ft. waterline. For prop clearance 22in dia. is as far as I would go. But this suggest a 22x24 is in the ball park considering the input I furnished for the calculator.

As soon as we can get a new test run I will let you know the results. Props move boats. I suggest you join Boatdiesel.com. It is an excellent forum with some of the most knowledgeable moderators in the business. One of the recent articles is on props. There are some great articles on fuel filtration as well, which is always a concern with me regarding diesel fuel.

I would not go with less than a 22 inch dia. prop. Hull clearance is adequate and dia., in my mind is more important than pitch. It may turn out when fully loaded for fishing 24 inch pitch is a bit much for me. Time will tell, but I can always reduce pitch. If it is too much once the bottom gets dirty, and the weight increases than it will apparent that maybe the 23 inch pitch to start with would have been better. But the props came with the boat and are what they are. With the 22 inch. dia. I can say I don't think one would ever use anything larger than 24inch pitch. With 23 inch pitch one can go up or down. I don't want to suggest right now that you go with 23 inch pitch until we have run ours, at least with the new load and working trim tabs. If we have too much hull in the water that could be limiting performance and the 24 inch pitch would be fine, but now I feel it is marginal.

FP
 
Fighterpilot,

Thank you for the in depth reply. My prop guy also recommended the 22 by 24 blades. I do have a membership with boat diesel .com and find it a very useful source of information, but since they recommended a different prop size I wasn't sure what was right. Do you have a generator already on your boat and if so what size? Also, at WOT were you going above 2800 rpm's? Thanks very much for your reply.


Best,

Gabe Wood
 
I interpret Boat Diesel's prop as optimum if diameter would be ok. But with diameter being a limiter in this case the lesser diameter could justify the 24 inch pitch. But I'm not sure but what I may be over propped. 2800 was all I could get but until get the trim tabs working so I can maximize speed I am not ready to say over propped. If actual triming to best speed is an increase over what I have now than rpm should go up a bit as well--at least that is the way I understand it.

Generator is 4.4 Westerbeke. Wish it had been bigger since I think I will need to add another A/C unit. Presently have just one 16,000BTU unit which Genny handles but from my past experience with boats here in Florida that single unit isn't going to move enough air to cool the cabin. Too much glass and to much humidity. The 4.4 is a two banger hence not as smooth or quiet as the newer 3 cyl. but will live with it until we sort out requirements for power.
 
Mainboat, where are you located?
Wilmington propeller service is well-renowned in southern california.

I have a 38' LRC with 3208 260hp turbo with 4 blade 23x22 cupped bronze props.

I do not get WOT, probably due to being overpropped, think the PO like the cruise performance better at 12kts... I have considered to get an extra set 3 blades to see if i would then get full rpm (2800).
 
Before you spend any money use a prop shop and/or boatdiesel to get you in the ball park for a prop. With calculator on boatdiesel you can use both 4 and 3 blade props. You might be able to just reduce pitch enough to get your wot rpm, but you need some idea of what would work. Prop shops should have a calculator you could use to plug in your numbers, weight, type of hull, water line, engine hp, rated rpm, cruise rpm etc. and get some prop ideas.
 
Thanks again Fighterpilot for the good info. I will let you all know how it turns out.
 
Got the boat out Sunday and only making 2700rpm at wot--about 20knots
with the tabs fully extended. Cruise at 2400rpm was 16knots. Reducing any trim tab extension resulted in decrease in speed.

Suspect overpropped but won't know for sure until I check tachs. Bought a laser photo tachometer to measure the crackshaft pully rotation and get a good accurate rpm on the engines. Will compare that to tach readings and get a better idea of prop acceptability.

Was disappointed that needed full trim tabs for best speed. Thought for sure backing off a bit would reduce drag by lifting the bow out of the water, but guess the trade off was stern drag, mushing, etc.
 
FP, have you tried intermediate trim settings at WOT or are you using full-up and full-down only?

There might be a sweet spot between the two extremes that brings it all into proper balance.

20 Kts at WOT sounds pretty darn good!! I'm half that with my little 85HP Perkins.
 
Another solution, which may not apply here for your boat, if prop clearance is limited can be to go to more blades. Carey's custom lobsterboat with 420hp could not make its speed target with a four bladed prop. Either the engine shop we all use or a prop shop recommended a five bladed prop. IIRC this enabled Carey to reach his boat's target speed.

Not sure this solution works with lower powered boats with low cruise speeds like ours. But for higher powered go-fast(er) boats it's apparently one way to get better performance if prop clearance is a limitation.
 
Running with full tabs down I start backing off, that is tab up buttons, but even with just a slight adjustment tab up the speed starts to drop off. My limited experience with tabs on other boats and the reaction here leds me to believe the situation won't get any better in between full up and full down.

Bought a laser photo tach yesterday and going to check out tach. engine rpm today to help further define my prop situation. Considering we aren't fully loaded yet for fishing I am pretty sure I am overpropped, but how much I won't know till I get a crankshaft rpm reading.
 
I have a 34 LRC with 3208 NA's and 2:1 gears. Just put rebuilt props on because the old ones dissolved over the 6 months I have owned the boat due to a lack of prop shaft zincs. The props are 23x23 3 blade. Full tanks and all the stuff that will fit on a boat I get to 2700 rpm on each engine and reach 20 knots. I cruise at 1400-1600 rpm and that is 8-14 knots depending on current. Adjusting the trim tabs impacts speed by about .5 knots max. I use them more to level the boat since with full fuel and water tanks and a 8kw westerbeke generator centerline aft the boat does squat in the aft.
 
1600 rpm will get you 9-10 knots without current
 
Mgtd...I see the light!!!
I bought my 34 LCR 6 months ago...starting to learn about her. Twin 3208NA on Cat trans 2:1, I have no idea what size props are on or shaft diameter. I would love to cruise at 12-14 and have a 18-20 WOT. Reality, 2400 WOT at 12-14 knts. Engines are in good condition, no smoke at all, a bit black smoke on WOT when bottom is not clean.
I"ll have props taken out next week to see what I have.
 
Anybody with 4 blades props on a 34 with twin cats?
I think I saw somewhere that the factory spec was 22X24 4 blade
 
I have no way of knowing if mine are original but I have 3 bladed props on my 3208 powered 34 LRC.
 
Number of blades depends mostly on blade area. If your pitch is too low you're loosing efficiency from excess drag from too much blade area. If your pitch is too high you're loosing efficiency from too much water tumbling around the blade tips ("tip losses"). The correct amount of blade area will bring about the ideal amount of pitch. The aspect ratio and blade design are also involved.

For most trawlers a 3 blade prop should produce the best efficiency. The ones best suited to 4 blade props don't have enough clearance for a 3 blade w a good amount of pitch. So basically the four blade prop is only for boats that lack the vertical clearance to run a 3 blade. Not so much an issue w trawlers is blade loading. If you've got too much power for a properly pitched 3 blade you need more blade area and a bigger blade 3 blade prop or a 4 blade prop is the answer.

I suspect many trawlers have 4 blade props because owners think they will run smoother. If that's true from what I've heard the difference is so small blade design is probably a bigger factor. But a proper propeller on a trawler is probably least likely to cause vibration if it's pitched and balanced properly.
 
Finally they are out. 23x21 on 1 1/2 shaft.
 
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