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Old 05-19-2012, 02:20 PM   #1
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Can a Californian 34LRC get on a step and cruise?

Posted this on Californian forum, but permit me to repost here since I need maximum exporsure to your expertise.
Got our boat out again with the full fuel load, but trim tabs still in extended position. 2400rpm, 15 knots but the whole hull, waterline length seems to be in the water. At least there is water spray coming out from under the bow of the boat clear forward. Is that because too much trim tab or don't these boats achieve anything like crusing on a step even when properly trimed. WOT even more bow down as would be expected if too much trim tab. Also only making about 2600 rpm WOT so probably too much prop at 22x24, no cup. But won't know for sure until I get the trim tabs working and get a better understanding of the planing capability of the Californian 34LRC hull. Any thoughts appreciated
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Old 05-19-2012, 03:09 PM   #2
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You could always get a jar of whatever you use for fluid in your trim tabs, disconnect trim tab tube at pump, stick line in said jar to avoid air entrainment, secure jar and line somehow and go for a ride. The water pressure should force the tabs up to a neutral position and you can see what your boat will do. Most tabs are set-up so that there is virtually no way for a marginally powered boat to "force" its way up on plane with tabs fully deployed. 15 kts though, you are on plane. Your boat is just plowing more than it should, I wouldn't expect a boat this size and hull configuration to "break over" and be able to be throttled back and cruise easily in the mid-upper teens. Atleast my 34 Mainship doesn't and I think we have very similar hull designs.
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Old 05-19-2012, 03:39 PM   #3
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My ex, an old Mainship 34 model I would easily get up on plane after I repowered her with a Cummins 6BTA 270 hp. The old Mainship hulls run nice with just a scooch more power than they had oem. Get them over 16 knots and they squirrelly though as they "chine walk" or whatever its called (don't want to start that thread again). But if you power them to cruise at 15-15.5 they are sweet.
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Old 05-19-2012, 05:10 PM   #4
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I have a new Bennett pump but not sure I want to give up the tabs just yet. Snapper season opens June 1st and we have at a minimum of 30 miles to run to get fishing. Boat will run 15knots now at 2400 rpm, but don't know what it will do with out the extended tabs. Without trim tabs will this boat get up on plane or just mush when power added? If there are problems with the tabs themselves after we get new pump on than that would be a haul out.
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Old 05-19-2012, 09:14 PM   #5
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Why don't you put in the new pump? It should literally be able to be changed in 10 minutes if its accessible.

If you are able to reach the tabs rig up some dowel rod/broom handles to keep them extended while doing the change out. after swapping the pump, retract them fully, that will pull any minute amount of air back out of the line at the newly connected junction and you should be good to go.
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Old 05-19-2012, 10:03 PM   #6
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Good idea. leave the connections cracked so the air will bleed out. Do I have that right? Pump is easy to get to and I think I will have a go at it. Just hate to run 100 miles bow down when I think should be able to get a little less drag while cruising.
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Old 05-19-2012, 10:14 PM   #7
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Quote:
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Good idea. leave the connections cracked so the air will bleed out. Do I have that right?
No you want to tighten the fittings back down. Otherwise it will entrain air when you engage the pump. When you have the system buttoned back up, remove whatever you used to keep the tabs extended. Then using the trim tab controller, fully retract them (bow up). They have a reservoir on the bottom of the pump assembly and it will pull the oil through the lines from the tabs back into the reservoir. It should also pull any little bit of air back as well. I would only put a very small amount of fluid in the reservoir before retracting the tabs just to prime the pump. If you fill the reservoir and then retract the tabs you could find yourself with a small mess in the bilge! after the tabs have retracted then fill the reservoir to the full mark. Then you should be able to extend and retract until your heart is content!
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Old 05-19-2012, 10:44 PM   #8
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If it were me I'd change out the trim pump, It is a real easy task. Only 2 hydraulic lines. Takes a 9/16 wrench if my memory serves me. They are single line per cylinder with a spring return. I never did anything special to bleed the lines, when I changed out the pump on the last boat. I believe they will burp themselves.
My 34 LRC ran 19.5knts when I had it surveyed. That was with full fuel and water tanks, and a very dirty bottom. It hadn't been run in several months, and was real 'hairy' when we pulled it to inspect the bottom. . From what I recall, the trim tabs only help at slower speeds. At or near full throttle the boat ran a whole lot free'er without the tabs. The heavy bow spray disappears, and the whole thing is lighter on its feet. I've got 200 perkins instead of your 210 Cats, but I'm guessing your heavier engines would make a difference in a good way since the weight is forward. I bent the props too soon to have a lot of experience with performance, but with luck I should be back floating with one new and one rebuilt props by Memorial day hopefully.
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Old 05-19-2012, 11:31 PM   #9
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Gotcha on the trim tab change. Thanks
Regarding trim tab use--"trim tabs only helped at slower speed". By that do you mean had to use them to get up out of the hole or when you add power without tab down this boat doesn't bog down as much as some. The heavy bow spray is a good description of what I am seeing now.
Based on your advice and experience I have decided to change out the pump.
If I have a bad cylinder once we start moving them I could probably get along until we haul out. Previous boats I have had, 31 Chris Craft Commander, 29 Aquasport Tournament Master, and a 2750 Hydra Sport WA all needed the trim tabs to get up out of the hole. Not so bad on the Hydra Sport because the outboards could be trimmed, but the others hated getting up to go. Thanks for the words.
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Old 05-20-2012, 10:49 AM   #10
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While the tabs might help the boat climb out of the hole faster, I don't think they are necessary to plane it. I find them helpful at slower speeds. It seems for a given throttle setting, say 1500-1800 rpm's I believe dropping them relieves some load on the engines as evidenced by the engines gaining 50 or so rpm's as compared to to full up. Their biggest benefit though is levelling the boat underway. If you go back in the Californian thread to a post by Flywright, he posted a scanned boat test article about the 34LRC with 200 Perkins that claimed the boat did not come with trim tabs and didn't need them. Good Luck and Good Fishing.

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Old 05-20-2012, 01:55 PM   #11
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Quote:
Originally Posted by Fighterpilot View Post
Gotcha on the trim tab change. Thanks
Regarding trim tab use--"trim tabs only helped at slower speed". By that do you mean had to use them to get up out of the hole or when you add power without tab down this boat doesn't bog down as much as some. The heavy bow spray is a good description of what I am seeing now.
Fighterpilot,

Think of the trim tabs as takeoff flaps. They shorten the takeoff run, but after you get going, you want them retracted to get to cruising speed. If you leave them extended, they'll drive the nose down and increase drag dramatically.

If you don't use them for takeoff, you might experience a longer takeoff roll (hole shot), but your cruise performance will not be affected.

If I needed my tabs in one position, I'd take them in the retracted position and live with the (possible) slower acceleration from a dead start.
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Old 05-20-2012, 02:30 PM   #12
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That is great information. I'll go replace the unit today and if they still don't work will try it as is before I haul out and do any more work. Don't mind the time to get out of the hole. When loaded with the Chris Craft sometime would have people move forward into the cabin to facilitate getting over the hump.
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Old 05-20-2012, 06:12 PM   #13
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Well, changed pump, got tabs working and took the boat out. Californian 34LRC with 3208NA, nearly full fuel, 1/2 water and empty holding tank. 5 adults and two children, all on the bridge. Started out with no tab to see if boat would do OK with no tab as one report suggested. Never got up above 15-16knots WOT so added tabs, eventually full down--cruise 16 knots at 2400rpm. Still producing a lot of spray so back off on tabs thinking that would help--immediately slowed down to 15 knots. So for this boat, this configuration best speed is with full tabs. Anything less drops the stern down and drag increases. Must be the test report was with a lighter engine boat--suspect the 3208s weight is the big factor.

Also determined over propped with the 22x24s, no cup. 2600 to 2700 rpm all we could get at WOT. Next time out of the water will have them remove an inch of pitch as a start. Speed will go down but the engines will be happier. Thanks for all of your advice.
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Old 05-20-2012, 08:08 PM   #14
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What RPM are you wanting to get? I thought 2800 was it for NA 3208s. 2700 would be plenty close enough for me before I'd start messing with my props. that is too close of a margin to not even consider that the tach could be off by that much!
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Old 05-20-2012, 08:22 PM   #15
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The experts on Boatdiesel.com would like to see a hundred over rated rpm, or in this case 2900 at max load, which would give some cushion as the bottom got dirty. I am not fully loaded for fishing and the bottom is still reasonably clean so am not very close. Later this summer when we head out to the fishing grounds expect to loose another 100rpm and end up at 2600rpm WOT.

The overload on the engines which is present even at a reduced setting to 2400rpm will shorten the life of the engine. In the case of the old 3208NA I don't know how significant this is.

Maybe the engine people at boatdiesel.com are overly cautious but they are pretty outspoken on prop 100 over at full load, clean bottom.

True the tachs could be off, but not likely both by the same amount. I will put a light on and check for a more accurate tach reading. Thanks for the suggestion.
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Old 05-20-2012, 11:08 PM   #16
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FP, About a year ago I had a phone conversation with Gil Marshall, the son of Jule Marshall who designed and built the Californians. Jule was at the next desk listening to the conversation.

In that conversation, Gil stated that in his mind, the optimum engine for the 34 hull was the 3208. (I think they only installed NAs in the 34.) He said that engine would put the boat comfortable into the high teens for cruise and low 20s at WOT. It was a reliable, powerful and efficient engine. The only negative he mentioned was the size and performing maintenance was a bit tighter than with the Perkins.

If you're not getting at least 20 Kts WOT, something is not right. Assuming the trannies are OEM ratios and you're making close to 2800 RPM, I'd look closely at the props. But it might be a diameter or blade count issue and not the pitch. If you can get a diver to pull the props and get them to a good prop shop, you might learn that your props are not the diameter or pitch stamped on the prop hub. How many blades do you have? If there's too much surface area, like on a large diameter 4-blade, it might prevent you reaching the correct WOT speed. But I'm just theorizing here...I'm no prop expert by any means.

When you raised your tabs and hit WOT speed, did you notice a difference in attitude? Was the bow riding higher and drier? I'm trying to understand how your WOT speed is greater with the tabs extended. Something seems counter intuitive to my feeble mind.
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Old 05-21-2012, 06:16 AM   #17
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IF the boat can actually pull 2800 on the pin,

reducing 10% or 300 RPM will usually not be an overload.
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Old 05-21-2012, 07:08 AM   #18
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I am in a hurry and didn't read all of the responses. The short answer is some of your boat is providing lift(planing) and some of it is not and some of it is somewhere in between. Hence the term "semi-displacement" or some people like the term "semi-planing". IOW, you definitely are going faster than hull speed and the reason you are able to is because of SOME lift generated by the hull...and it is the aft part of the hull.
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Old 05-21-2012, 08:41 AM   #19
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"new" shiny props put on at survey when we bought it in Oct. 22x24 labeled. 3 Blade. Worked on the boat thru the winter months and lacking confidence in the yard that put them on, had a diver pull them in April to check installation and took them to AccuraProp shop to check them out as well. Indeed they are 22x24 with a little cup, but since I suspected overpropped had them take the cup out. Print outs show 3 blade, 22x24.

We dock it in brackish water, but diver said bottom still in good shape. New paint when it was hauled out in October.

When I raise the tabs, bow comes up and speed goes down, hence my theory drag increases. Probably because the lost lift from the tabs lets the stern settle more into the water and getting a mushing affect.

With due respect to Mr. Marshall one can get high teen cruise and low 20s with the boat and the 3208NA when lightly loaded, since I saw that at the sea trial and in test report, but I doubt it at fully loaded for living and fishing.

When I take out some pitch I will lose some speed but rpm will go up. At least that is my experience with two other boats.

Don't know how significant the situation is. But the next paragraph from boatdiesel.com suggests It might be significant even though I am close to the numbers.

Diesel burns at a very high temperature. Higher than gasoline which is why it is perhaps as much as 30% more efficient than gasoline. And higher than the parts of the engine can withstand for long periods. Modern, very high hp per liter engines rely on pulling sufficient air through to keep the combustion air temperatures limited to that which the engine can withstand. At WOT and maximum rated power the air flow is too small for the amount of fuel thatīs being injected and the heat is tremendous. If you throttle back, the fuel flow diminishes but so does the air flow which is in proportion to the engine rpm. Thatīs why its an engine killer even if you donīt run at WOT. The heat stays too high for the life of the engine. That holds true until the engine speed and total fuel burned is small enough that the engine can handle it. I think that may be about one third of rated rpm. Maybe less. Anyway, its a bad idea to be set up that way. Its too tempting to push the engine just a little bit harder.

One of the mechanisms for destroying the engine is to have a hot spot somewhere that the coolant is removing heat. If the coolant should suddenly boil, just at the tiny spot, the coolant will slosh back on that spot and quench the heat. That thermnal stress can easily crack the casting. This contributes to many of the reported cracked heads and manifolds


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Old 05-21-2012, 09:20 AM   #20
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you could put in a couple of pyrometers and see what your engines are doing if you are that concerned about the absolute peak rpm and load. this is the true way to tell "how" your engine is doing. Not trying to sound like a know it all by any means but it sounds like your engines may be marginal HP for the speed you want to run. Your set-up may be a 13-14 kt arrangement. Add a set of spray rails and it could alleviate some of the bow spray. or possibly some permanently attached lift/spray rails at/near the stern to give your boat the proper attitude at speed and then your spray rails can be used to fine tune.

I totally agree about the manufacturers speed/rpm ratings. they are always done at optimum settings. Hard to duplicate in real world conditions
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