Performance Problems Crownline 242 - Any Suggestions

[dominic221]

Hi my first boat last June was a Crownline 242 with Volvo KAD32 (2001) and Duo prop with 300 Engine hours.

I have always noticed it was a bit slow to get to plane; (around 60-90secs) in calm conditions. 2+ mins in anything other than calm.

Would get about 30mph at WOT 3300rpm once planning in calm

If drop back throttle, would loose power then regains repeatedly. Almost as if something is slipping or turbo is cutting out. (I was told that I shouldn’t drop throttle back, not sure how true this was, but means that I have to drive at WOT or ¼ throttle, nothing in between – seems a bit strange to me)

Fuel and fresh water tanks are normally around 50% or less; crew would be 2-3

Last month I had a full service done on the engine, the dreaded diesel bug was found. This was cured, engine fully serviced and all belts were also changed. The of the dieing of the engine seems to have stopped now and engine sounds better. However....
Even in very slight seas struggle to get above 17knots and never on full plane. I've worked trim in various scenarios and still can only achieve a 17knot max not on full plane even at WOT

Again fuel and fresh water tanks are normally around 50% or less; crew was only two in last test run. Its almost the engine its running at full power or something is holding it back.

I looking for any advice on how I can improve performance, am at the stage now where I have lost trust in the engine and fear taking it out in case I get stranded out on it.

Would a new more powerful engine be cost effective? Also I heard that auto trim can help with performance, would that be an idea? Or different prop. Is there any engine tests that can be done. Does anyone know someone that specialises in powerboats in the Cork, Ireland area.

At this stage I'll try anything or suggestion.

 

[Whitelighter]

Having been in the water for a while, have you had the boat lifted and cleaned recently? Badly fouled props can stop a boat getting on the plane, never mnd just dropping top speed.

What is the condition of the leg and props?

 

[MapisM]

I have always noticed it was a bit slow to get to plane; (around 60-90secs) in calm conditions. 2+ mins in anything other than calm.

That's not "a bit slow". Totally unacceptable is more like it.
You should give us more details to try and make some sensible guesses on what's going on. Fouling is one thing, as WL suggested, but it would be necessary to know also which props you have, and which max rpm you're reaching while at 17kts WOT.
At first glance, unless the engine is knackered or the hull/leg covered with fouling, it looks like you're spinning props with a pitch MUCH longer than the hull and the engine power requires.

 

[alt]

Sorry I can't help much, BUT....

You should be getting about 3800-3900RPM at full throttle from the KAD32, so something is amiss.

Do you know what props you have on?
Is the hull of the boat clean? (Including the out-drive)

Simple things but best to check these first as they cost nothing to check

 

[Whitelighter]

Yes, I was just off researching what WOT is on a KAD32.

If you are only pulling 3300rpm then it sounds like you have the wrong props on. Over pitched props will cause slow acceleration and over stress the engine making it work too hard.

I would go down at least two sizes from what you have now. I suspect you have Ally props, and probably a massive pitch something like A6's or A7s. That boat shoud have A4s probably.

People change props for all sorts of reasons in the belief they will get better fuel. I had a Bav that was massivly underpitched with C2 Stainless props. CHanged for C6s and it was much better...

 

[[2068]]

Wide open throttle should get you 3700-3900rpm on a KAD32: 3300rpm is waaaay too low.

I'd expect the propellor to be something like an A4 or A5 on a boat like that, but you could check with the manufacturer or importer to find out for sure.

dv.

 

[dominic221]

Thanks guys, didnt expect responses so soon. The outdrive and props I'm assuming are the standard factory fitted ones as previous owner hadnt seem to do anything with her. On a receipt I have the transmission is DP-E195 and the transmission assembly is TSK-DPE (290). Im not sure what that means, I was just told its a Volvo Duoprop.

With regards cleanliness, It was newly anti-fouled in June when it was launched. From the surface the hull looks clean and I spend most weekends giving it a soft brush,(due to fear of going out!). The outdrive and props, again are what I would say are pretty clear and clean, trim tabs tend to get a bit of seaweed growing on them, but always brush it off.

When I say Wide Open Throttle, I am meaning that the throttle lever will not go any further forward, prior service I could get to maybe 3500rpm, since, and when I lasted tested (today) WOT was only about 2700.

Is there someway I can check what type of props are on it visually by a type number or such on them?

The boat length is about 24 feet. One other thing I have always noticed, not sure if its related or not, is that the boat lists slightly on the starboard side. Today before taking it out I removed everything that was not attached, all gear, microwave, tools, everything. Still lists slightly.

If you can let me know what details I need to get, I will get them, even if it does mean diving under the boat to read of a part number! Like I say I'm at the end of my tether with it.

 

[[2068]]

If the props are original, I'd still be suspecting your attack of diesel bug. You say it was cured, but have you checked all the fuel filters again for black crud or water?

Propellor part numbers can be hard to read if they've been in the water a few years, but the numbers should be stamped on the outside of the cylindrical bit.

The front one will be one of the following, if Aluminium:
872259 A0
854774 A1
854775 A2
854776 A3
854777 A4
854778 A5
854779 A6
854780 A7
854781 A8
854782 A9
854783 A10

Similarly for the rear:
872264 A0
854784 A1
854785 A2
854786 A3
854787 A4
854788 A5
854789 A6
854790 A7
854791 A8
854792 A9
854793 A10

 

[MapisM]

when I lasted tested (today) WOT was only about 2700

Aha! That's why I asked.
30mph @ 3300 was already too low, but 20mph (17kts) @ 2700 is awfully low!
I'd try to check both props P/N, as explained by FP.
Re.the stbd list, were you alone and helming on stbd side? If so, that's not unusual for a 24' boat.
Otoh, if you had some crew and they were evenly distributed, there's something else wrong.
A wrong coupling of the two props might explain both the poor performance and the listing, for instance.

 

[moonraker 36]

why not get a 5 gallon brum and fill it with white diesel.drop a fuel line in it and see if it run's any better.(i only say white diesel because if you get it from a petrol station no problem's with bugs in fuel).

 

[Whitelighter]

Where are you based Dominic?

 

[hlb]

If drop back throttle, would loose power then regains repeatedly. Almost as if something is slipping or turbo is cutting out.
...............................................................................................

Sounds to me that you've still got the bug and your filters are blocked. Fairly classic symptoms. Take off primary filters and empty into a glass, let it settle and see what you've got. It should be clear like red wine., If it's cloudy, or any black bits in it, it's probably bug. Change filters and add Soltron, then use boat as much as possible, adding Soltron each fill up. You also need to look for water at the bottom of the glass, thats the other problem that you may have.

 

[dominic221]

I'm in Cork, Ireland.

I have a buddy thats giving me a lend of his dry suit so should be able to get prop part numbers this week, work and weather permitting.

 

[aquatom]

If the engine revs are surging around 1/2 - 3/4 throttle then you should have a look at your turbo. You need to check that it spins freely and that the gap between the blades and the housing (on the exhaust side) is no more than about 2mm max.

If the acceleration has been getting steadily slower then I would suspect this.

Tom

 

[hlb]

Look at simple stuff first, dont trust that the bug will just have gone away.

 

[moonraker 36]

Look at simple stuff first, dont trust that the bug will just have gone away.

exactly start with the simple stuff first.
sound's like fuel starvation.
change filters (check old one's even if you have to cut them open)
and if you can run it on a drum of fresh clean fuel(get the fuel from a different place than you have been doing)
it will only take 1-2hrs to do all this

 

[dominic221]

Question on using regular diesel from a temp. tank...

1) I thought that green/red diesel was high in sulphates and that regular diesel cause a problem with engine?
2) Is it just a case of disconnecting pipe from main take to temp. take? Do I need to worry about bleeding the line or anything? I thought you couldnt let diesel engines run out of fuel 'cause they needed bleeding if you did?

 

[hlb]

Question on using regular diesel from a temp. tank...

1) I thought that green/red diesel was high in sulphates and that regular diesel cause a problem with engine?
2) Is it just a case of disconnecting pipe from main take to temp. take? Do I need to worry about bleeding the line or anything? I thought you couldnt let diesel engines run out of fuel 'cause they needed bleeding if you did?

I would not bother with that idea, it's more trouble than it's worth.

Besides you'll stil be going through the same filters, so it wont make any difference.

 

[Chris_d]

As HLB says stick with the simple stuff, its classic dirty bottom, blocked filter syndrome.

Any planing boat needs approx 60hp per ton to get on the plane, i'm guessing a Crownline 242 weighs nearly 3 tons dry, so with 3 ppl, half tanks a bit of fouling a slightly dinged prop, partialy blocked filters, you ain't going to stand a chance.

If its been in the water since June it could be fouled enough to cause a problem, have you changed primary and secondary filters? has the air filter been changed? 2700rpm wot is about hump speed on your boat so almost certainly its being starved of fuel and/or too much drag to get over the hump and plane. You won't get the revs higher unless on the plane.

I doubt its more complicated than that, but as its a KAD engine you may need to check that the supercharger is cutting in, this provides extra power to get over the hump then cuts out, but its easy to check just by looking in the engine room at the belt and clutch when accelerating.

 

[moonraker 36]

it wont be going through the same filter's if he change's them first!
and yes you would have to bleed the system.if it run's ok on clean fuel you will no were the problem lie's
their is alot of advise on here you chose were you want to start from!