propeller advice please

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kashurst

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I am experiencing a strange problem on my Targa 43 with 63Ps (yes I know I bought the wrong one but I like it anyway). The temperature down in the med is 32 degrees my boat has a dark blue hull and the alleged 2 X 370HP engines. I suspect my props are too big/overpitched a bit. I'll explain.

in the spring and autumn boat gets on the plane no problem, now its scalding hot she is a bit hesitant. I had the bottom cleaned off, props and shaft cleaned and antifouled (you need it around these parts) and cleaned out the intercoolers etc and I think the engines are running great (same, temps pressures, exhaust levels etc). Flat out on a calm day she does 32 kns. WOT speed is 2700 on port, 2800 on starboard. I generally cruise at @ 22kns, which is @ 2100 rpm. If the sea gets very rough (F5 wind against tide stuff) the port engine starts to give off grey smoke as though it is overloading. If I reduce throttle a bit smoke goes away again. starboard engine is fine regardless.

Also I have noticed that the boat hits the "hump" at 11.5kns (gps) and exactly 1500rpm. Now it is really hot the engines struggle up to 1700rpm when she takes off like a stabbed rat. When the weather is a lot cooler the engines barely hesitate at all. I have looked at volvo's data sheet for the 63Ps and the power and torque are both much greater at 1650rpm than at 1500rpm.

Bearing in mind that the boat is 13 years old, and have 800 hours on them, I think if my props were a tad smaller or the pitch reduced by @ 10% then the boat would hit the "hump still at 11.5kns but at 1700rpm and jump onto the plane with no hesitation regardless of the weather. I would loose a bit of top speed but I rarely go ever 25kns anyway so I dont mind. I would rather have her respond more positively and not have to work as hard. I don't know if my props are the originals but I am beginning to suspect not as an old MBY boat report states that the 370HP targa 43 came with 3 bladed props but mine are 4 bladed, and they gave a top speed of 30Kns, where I get 32-33.

Finally port engine uses @ 15% more fuel than starboard - is this normal or is there another potential issue? Other wise it behaves exactly the same as port engine.

any one know a good prop company I could talk to, or point out my no doubt glaring error somewhere. Thanks
 
tinkicker0 said:
Temp and humidity both bleed off horsepower.
Click to expand...

Was boat specced for Med or is it UK vessel which just ended up in the Med. As a rule of thumb higher ambients require about inch less pitch Vs Northern European seawater ambient temperatures.

Remember you do not have 370 Hp, this is somewhat fanciful 40 Degree C fuel rating of the motor, only intended of glossy sales brochures. Work on the basis of 25 Degree C fuel, that will give you 265 kW or 355 PROPER not Metric Hp at the flywheel. Also consider that one gearbox has around 3% transmission loss, the other one which is running ass backwards may be costing you 7% transmission loss. All this needs to be taken into account when doing prop calcs.

Just a thought, when were charge coolers last serviced?? Grunged up charge coolers will cost you a bucket load of power.

Are you currently making rated rpm at WOT?
 
I get 2700rpm on the port engine and 2800rpm on starboard at wot. just cleaned out the port intercoolers (all of them) that has helped as port engine was showing signs of overheating and lots of steam out of exhaust. cleaning them out has cured overheat and steam has almost gone. before clean out I could only get 2500rpm at wot on port engine. boat was originally built for the med, but it had no history when I bought it and it has moved about a bit.
 
Before we go too far down the propeller route....Paul is an OK guy, however he does seem to prop a little on a knife edge. PM me your propeller size and I can do you a quick and dirty calc by Crouches Method.

Another question for OP, you mentione cleaning both coolers, I assume by that you cleaned your heat exchanger as well a your charge air cooler. Did you strip your charge cooler and clean both the water AND air side. Personally I like to see cores go into ultrasonic cleaning tank, airside can get real full of oil and soot carryover from those KKK torbochargers.

I do not have anything to do with VP motors, but I suspect the 63 will pass at least as much if not more lube oil and soot as Yanmar 4HLA. Take a look at typical charge cooler air side..........
 
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I went through a similar situation last year.
I was considering changing props to a lower pitch to compensate for the reduced performance.
However before doing that I had the Turbos repaired due to an unrelated issue.
This improved engine performance and there is no need to re-prop anymore.
What I am trying to say is that you need to address to core issue, the engines reduced performance, and not the secondary effect.
My guess, look at turbo first, then injectors.
 
thanks for all the replies, I completely removed the intercooler inserts and took them home for a real good scrub, inside and out. the air charge cooler was a bit greasy but it mostly washed off with GUNK and a good stiff brush. The design is simpler than the one in your picture and you can see between the brass tubes and through the insides of the tubes which I rodded out really well and inspected. I think my turbos and injectors are basically OK as I can get the correct WOT speeds and the boat has a higher than anticipated maximum speed through the water.

Sorry Latestarter, I don't know my current pitch and diameter. Next time the boat is out I will have a look. I assume its stamped on the hub somewhere.
 
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You issue is not at WOT but at intermediate loads, turbos are usually oversized and a drop in top performance sometimes is not critical. However the intermediate performance of the turbo is where this drop in performance is most evident, in particular the point where the turbo wakes up(about 1700rpm in your case).
You mentioned that you have smoke from the port engine, when there is extra load(bad weather). The main cause of smoke is either lack of air(turbo) or a bad injector.
May I suggest, next time you are testing the boat, observe the two tachometers(at about 1700 when the boat takes off), if there is delay in the port engine. If you have presure indicators for your turbos, even better, see if there is a difference in response time between the two engines.
One other way to do that is to run each engine alone and observe where the turbo wakes up, however this is not allways possible since the load on the single engine is to high and the turbo never wakes up.
 
you may be on to something there, the port engine lags the starboard engine as the boat accelerates. I have had a look in the inlet side of the turbo and all looks well, all fins intact and undamaged on the impeller. the turbine spins easily and there is no end float in the shaft. however I have not looked at the exhaust side. Can they get "bunged up" or damaged in some way? By the way the engine doesn't burn any oil or suffer any kind of leaks. Also there is a silicon/rubber hose connecting the turbo to the charge cooler. Do these fail after time?
 
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We had the same problem on a 63p and it was the hose that you just mentioned. One of the clips had failed on that hose. Have sent you a PM
Neil
 
The suggestion of P430 about the hose is a good one, you need to check all the connection after the turbo up to the air cooler and from ther to the inlet manifold, the best way, but I am not sure if is possible, is to check with the engine running above 1700 rpm and feel by hand for air leaks.
Regarding the turbo, what happened in my case kad 44-1998, was that when looking to the impeller of the turbo from the exhaust side the radial gap between the impeller and the housing had increased from the normal value of less than 1 mm to something like 3 mm. This allowed gas to pass from this gap, and delay the waking up of the turbo. I eventually replaced the exhaust housing on both engine turbos.
The wear was mainly due to age/corrosion and not due to usage. I have 450 hours.
Another way of doing it is to get a pressure gauge and check the pressure produced on both engines after the turbo.
 
Kas id say that its the wastgate thats not working correctly, its either sticking open and not making full boost of its even rusted away as you have described its symptoms at that rpm when the wastgate is at its most usefull, in other words when the engine needs max boost to give correct air to fuel mix, id get the engines working correctly before you start changing prop sizes as fairline do a very good job at matching props etc.

BTW your boat was bought by York marina from majorca from the islands fairline dealer to sell on.
 
I think my idea of props being too big is nonsense. just checked the clamps and silicone hose from the turbo to the charge cooler as suggested by P430. bottom clamp was not tight and there is evidence of blow by out of the hose. (castings a bit sooty on the outside below the hose). I checked the hose and there are no holes or splits, fitted new clamps this a.m. and went for a blast. port engine still lags behind when climbing onto plane but new clamps have improved things. I guess the next thing to check is the wastegate. Is it possible to access it be removing the gate regulator (the pine cone shaped thing sticking out the side held on with two allen bolts) or am I looking at a turbo off job and a recon? I have also found that after cleaning the charge cooler and fitting new hose clamps fuel consumption seems to have visibly reduced. thanks for all the help everyone, feel like I'm starting to get to the bottom of it.
 
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Tried removing wastegate but hit a problem. removed the three bolts and the feed pipe but the regulator wont/can't come out of the turbo body. I can pull the regulator so far (about 1 inch) then it stops as it seems the casting doesn't allow the valve/piston to come out of the main body in this direction. Am I missing something as my turbo doesn't seem the same as the diagram posted previously???
 
It does come out, whats stopping you is years of corrosion and soot build up in the housing, once clear try and rotate it to remove the build up of debris, spray with wd 40 as well.
 
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