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Old 04-15-2013, 04:27 AM   #21
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You`ve tried 3 different props,you would have noticed any abnormal underwater condition, surely that`s covered. The cavitation and white water suggests the prop is getting well spun. There could be more than one issue operating, but essentially you`d go back to what changed, and how that could affect things. What do the people who did the engine work say? Did they hit the wall, thus this understandable appeal? Were the fuel tanks redone same time as engine, or before or after? You might carry less fuel but location is unchanged. The weight of teak removed should be balanced with new glass decking.
I hope someone can help. Did anything change with the gearbox or prop shaft? That steering/white water issue sounds like prop involvement, but you`ve been there. What about a second mechanical consult by someone fresh?
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Old 04-15-2013, 04:33 AM   #22
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As a single data point we have two FL1202 in our boat. The props are 4-blade, 23" diameter with a 16" pitch. At 1650 rpm the boat does just under 8 knots.

The original props were 3-blade, 24" diameter, 18" pitch on the starboard prop, 17" pitch on the port prop. The different pitches were to compensate for the different prop speed due to the counter-rotating gear in the starboard marine gear that changed the ratio. According to a previous owner's info these props gave the boat eight knots at about 1600 rpm. Most Grand Banks boats were deliberately over-propped by the manufacturer. The original prop pitch let the engines get to about 2,200 rpm at wide open throttle.

The current props after re-pitching, tuning, and balancing lets the engines turn up to their maximum rated rpm under load which is 2,500 pm. The governed maximum rpm with no load for the FL120 is listed in the manual as 2,650 rpm.

If you are getting 2,800 rpm at no load you are over-speeding the engine. The governor could be mis-adjusted or your tachometer is off.

This would not explain your low speed or steering problem but it would seem to indicate that your injector pump, which contains the fly ball governor, is not set properly.
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Old 04-29-2014, 09:08 AM   #23
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This is an old thread....

Just wondering if you ever got this figured out?
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Old 04-29-2014, 11:46 AM   #24
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Basic troubleshooting 101:

If it worked fine before you messed with it, the problem is probably with what you did to it.

So, if it worked fine with a specific propeller before you messed with it, it's unlikely that the problem is with the propeller. Same for everything else.

Go back and check your work. If you can't find the problem, have someone else check your work.
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Old 04-29-2014, 12:22 PM   #25
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suggestion get a photo timer and mark the shaft and time it. Then do the math re. gear ratio and see if what is getting to shaft and prop matches your tach readings and photo timed rpm on fly wheel. You have to narrow down to one of these causes engine power output drop-transmission issue- increase boat resistance-prop problem. running on a bucket of fuel is a good suggestion and will eliminate that problem up to point where fuel is plugged in. What I would do is find a good mechanic sometimes that saves time and money.
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Old 05-01-2014, 06:54 AM   #26
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It might seem obvious, but are you sure your anchor is still stowed, and not hanging
below the boat? This might slow you down and cause you to plow.
Otherwise, maybe something is caught on the front of your boat below the
waterline that doesn't weigh much, but causes a good drag when moving.
Someone mentioned a net or something like that. Maybe you have more than
one problem. Fuel/engine and dragging something.
When you changed props anything dragging would have surely been
noticed. This is a puzzle.
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Old 05-01-2014, 09:48 PM   #27
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This thread is a year old, but i read it and am really curious how it was resolved.... He just left us hanging!
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Old 05-02-2014, 07:49 AM   #28
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This thread is a year old, but i read it and am really curious how it was resolved.... He just left us hanging!
Yes, it would be nice to hear what the cause was...it sort of defied explanation in a way.

Mind you Bligh, not a lot more puzzling than why you use a sinking boat as an avatar. Captain Bligh's vessel did not sink...the crew mutinied and set him afloat in a lifeboat.
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Old 05-02-2014, 08:28 AM   #29
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Ha ha, so I also read this a few weeks back and PM'ed him. The cause was that he had moved his new batteries too far forward and in effect pulled his prop where it didn't have enough water flow on it. Caused cavitation and that equated to no power to push the boat. He said he moved the batteries aft and all is good.

From the original post my wife and I were betting a wrong handed prop. Cavitation and not wanting to turn in one direction....

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Old 05-02-2014, 09:04 AM   #30
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Greetings,
In spite of it's age, interesting thread. I am "somewhat" familiar with the 34' CHB and I looked up the difference in battery weights (roughly 150 lbs.-68 kg for our southern brethren). If, as the OP stated, the batteries stayed in the same general location just in front of the engine (allowing for the potential larger footprint of the 6v. deep cycles) it's amazing to me that so little weight would have such a profound influence on performance. The space between the front of the engine and the next forward bulkhead can't be much more than 5' (1.5m) so even if the new batteries were right up against said aforementioned bulkhead it's quite surprising to me. Maybe if I move the reserve beer (only 796 cases) more amidships and away from my port side it will eliminate that slight list....
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Old 05-02-2014, 10:44 AM   #31
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Some of these the engine is pretty far fwd already, not sure if the case here. And he might have added a lot of battery.

Sure'd be nice if he came back to fill in the gaps!!!
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Old 05-02-2014, 10:55 AM   #32
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Greetings,
Mr. S. From the OP: He changed out 2 group 27's to 4 6 volt deep cycles. VERY rough calculation of about 150 lbs. difference and from the 34' CHB's I've seen, he would only have at maximum 5' or so to locate them more forward of the original location. That's what has me scratching my head.
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Old 05-02-2014, 09:49 PM   #33
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Quote:
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Greetings,
Mr. S. From the OP: He changed out 2 group 27's to 4 6 volt deep cycles. VERY rough calculation of about 150 lbs. difference and from the 34' CHB's I've seen, he would only have at maximum 5' or so to locate them more forward of the original location. That's what has me scratching my head.
That is one average sized person walking from one area of the boat to another. Hard to believe it would make that difference.
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Old 05-02-2014, 10:21 PM   #34
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Agree very unlikely but we probably will never know. Maybe whatever he used to get boat speed started working again.
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Old 05-03-2014, 06:35 AM   #35
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Forum: Taiwanese Makes 04-14-2013, 07:06 PM


His last post was a year ago...
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Old 05-03-2014, 08:51 AM   #36
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I have a CHB 34, and I cannot conceive of the moving of just 4 bats about 2-3 feet for'd as having that much effect either. I wonder if the fuel tanks were also moved forward when he replaced this with plastic ones from memory, smaller, and in same position, but possible further forward..? Then again there might have been a tank breather issue as well starving the engine as a result - then the combined effect might have had the reported effect. Otherwise hard to explain power loss and altered trim and cavitation under load yet full rpm at WOT, when the basic boat was unchanged - other than the somewhat pointless swapping of props etc that went on. How on earth they thought the original prop etc which worked fine before could suddenly not was beyond me, I must say. Maybe the real reason was a bit too embarrassing to 'fess up to - is that naughty of me..? Otherwise why did he drop off and disappear..?
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Old 05-03-2014, 09:12 AM   #37
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Greetings,
Well, the unknowns and the speculations have started so MY theory is his twin sisters took up residence in the v-berth...The only image I could come up with are Fiona and Flossie debating over who gets the last case of donuts...
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Old 05-03-2014, 12:33 PM   #38
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Peter wrote;
"I have a CHB 34, and I cannot conceive of the moving of just 4 bats about 2-3 feet for'd as having that much effect either"

First there's the question "what if that's been done 10 times over the years?"

But over thirty years or so much weight and many things could get moved around by the above philosophy but probably the biggest offender getting out of trim is add ons. And after 20 or 30 years one could be shocked to find how far one's boat was out of trim. And probably there is room for stuff where the designer and manufacturer avoided putting stuff. Consider a V drive boat w the engines aft. The designer and manufacturer probably put things fwd to compensate for the weight aft leaving plenty of space aft to get filled up w stuff over the years aft. The obvious could likely happen and people don't often feel the need to consult w the designer before adding weight to their boats. Frequently a slightly undesirable situation could be made worse or even bad given the boat's history.

The Willard 30' line of boats had one or two models w the engine quite a bit further fwd than others. There's generally more space aft though and I think generally a boat is more seaworthy w an aft CG than a fwd CG. But some boats (like a 32 NT) have a big fuel tank in the Lazerette. Since fuel isn't a fixed amount of weight I wonder what the designer was thinking. Probably by the time there was room consumed by a gen set, holding tank/s, batteries, air conditioning and other stuff there was no more room left for the fuel tank/s.

One of my jobs at Uniflite (when I worked there years ago) was to move heavy installations around (dwg and design wise) to bring the boat's port/stbd trim as level as possible for most of the installations that would be required for a given group of options. Most boats went out w a slight list (all if ya wana to get nitty) but some went out w more. Always considered acceptable of course but no one knew what the owners over the years would add or remove from the boat. And of course when someone sights a whale to one side all 10 people aboard move as far as possible to that side. Never mind that the fuel tank on the other side was the only one low and the whale side full.

From pics on TF the most common out of trim condition I see is bow down.

My Willard has grooves in the plastic hull to make it look like a wood boat and not far above the WL (4" or so) there is an additional groove that is horizontal. I've thought for some time it could be trim and max load WL.
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Old 05-03-2014, 06:14 PM   #39
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Some threads make you shake your head and wonder. This is one of them.
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Old 05-03-2014, 07:15 PM   #40
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