how to do a "soft " cleaning of the bottom ?

[BartW]

we only reach 2100 RPM on SB engine, while max is 2300RPM
fuel and water level at 70%
the props are clean, scraped them myself under water.
Man engineer blames fouling ;
so we want to do a sea trial with clean bottom,

I'm considering to do a short lift out, and have the bottom softly pressure cleaned, without taking off the anti fouling,
usually the antifouling goes off for 90% after heavy pressure cleaning, we use International Micron 77.

I would like to do postpone renewing the antifouling until spring 2017
but would like to do the sea trial asap.

any advice or comments ?

 

[Deleted User YDKXO]

we only reach 2100 RPM on SB engine, while max is 2300RPM

What about the port engine?

the props are clean, scraped them myself under water.

When was the last time you did this and did you do shafts, P brackets and rudders as well as props?

 

[Nick_H]

I didn't get round to organising lift and antifoul one year, so on the first day of the holiday we found a quiet anchorage and I went under with dive gear and a gentle scouring pad glued to a plasterers trowel (the large pads you use for deck scrubbing). I gave the hull a scrub manually, trying to clean off the layer of algae whilst removing as little as possible of the antifoul. It's more controlled than a pressure wash because you can vary the pressure you apply to the pad.

I comfortably did our 57' boat in under an hour, so 2 divers on your boat would do it on one tank each.

 

[BartW]

What about the port engine?



When was the last time you did this and did you do shafts, P brackets and rudders as well as props?

I did a test without cleaning the props, and than the P engine gave >2000Rpm, but the SB engine appeared like limited at 2000 Rpm,
the P engine could go higher, ...2200 or 2300 don't remember exactly but didn't want to run long at this unballanced situation,

then I cleaned the props very thorrow, but the shaft and the P bracket only briefly (just take of the long wisps)
after this cleaning,
the P engine could run all up to 2300Rpm, but the P engine was limited at 2100Rpm,
there was a significant improvement despite the very mild growth on the props, last time they were cleaned was only 2 months before.
actually I was surprised that it made such a difference, and that made me believe that there still is some improvement possible by cleaning the Hull,
and yes, also the shaft and P-bracket.

the hull was fairly clean, almost no growth, but there is a thin layer of slime over the surface.
The antifouling is from May this year.

 

[BartW]

I didn't get round to organising lift and antifoul one year, so on the first day of the holiday we found a quiet anchorage and I went under with dive gear and a gentle scouring pad glued to a plasterers trowel (the large pads you use for deck scrubbing). I gave the hull a scrub manually, trying to clean off the layer of algae whilst removing as little as possible of the antifoul. It's more controlled than a pressure wash because you can vary the pressure you apply to the pad.

I comfortably did our 57' boat in under an hour, so 2 divers on your boat would do it on one tank each.

Thanks Nick, I have been considering this self cleaning, but thought it would take much longer and a lot more effort.
Have been reading with much interest a recent thread about cleaning the hull while boat is in the water, but thought its a lot of faffing, that can be avoided by spending some euro's on a lift out / back in

but I believe I 'am going to give it a try myself when I'm next on the boat, as per your sugestion.
Only problem is atm I have just 1 dive set onboard ;-(

 

[MapisM]

the P engine could run all up to 2300Rpm, but the P engine was limited at 2100Rpm

B, I can't for the life of me imagine a scenario where a fouled hull can explain that.
Even if (due for instance to the prevalent sun exposure) the bottom fouling would be asymmetrical, that would still affect both engines.
In the worst case, requiring a touch of rudder to keep the boat straight, but not putting more load on one prop vs. the other.
Assuming that both engines produce the same output (which is what you are interested to check, as I understand), the reason for the lower rpm on one side can't be hull-related, so to speak.
There must be something engine/transmission-specific, like a more fouled prop/shaft/bracket or a different prop pitch - though I guess you would have mentioned it, if that would be the case.
Sounds like a tricky troubleshooting, I'm afraid... Good luck!

Ref A/F, I know nothing of PM peculiarities - if any.
But FYI, years ago I left my old tub in the water in the N Adriatic during the winter, after a strong powerwash and without refreshing the A/F (long story...).
And upon lift for the new A/F around April or May, the growth was surprisingly low.
In this respect, the difference between winter and summer was night and day, and I see no reason why this shouldn't be true also in PM.

 

[Phildorset]

And upon lift for the new A/F around April or May, the growth was surprisingly low.
In this respect, the difference between winter and summer was night and day, and I see no reason why this shouldn't be true also in PM.

I guess this must be the same along the S Coast here too then, ie; much reduced during the winter season and then full on once the weather warms up?

 

[benjenbav]

And upon lift for the new A/F around April or May, the growth was surprisingly low.
In this respect, the difference between winter and summer was night and day, and I see no reason why this shouldn't be true also in PM.

I guess this must be the same along the S Coast here too then, ie; much reduced during the winter season and then full on once the weather warms up?

I have tended to keep boats (S Coast, UK) in the water throughout the year and there always seems to be a dramatic change in fouling once the water temperature gets above about 19C; late May, or thereabouts.

 

[Deleted User YDKXO]

B, I can't for the life of me imagine a scenario where a fouled hull can explain that.
Even if (due for instance to the prevalent sun exposure) the bottom fouling would be asymmetrical, that would still affect both engines.
In the worst case, requiring a touch of rudder to keep the boat straight, but not putting more load on one prop vs. the other.
Assuming that both engines produce the same output (which is what you are interested to check, as I understand), the reason for the lower rpm on one side can't be hull-related, so to speak.
There must be something engine/transmission-specific, like a more fouled prop/shaft/bracket or a different prop pitch - though I guess you would have mentioned it, if that would be the case.
Sounds like a tricky troubleshooting, I'm afraid... Good luck!

Yup thats why I asked why Bart only mentioned the starboard engine. IMHO such a variation between P and S engines is very unlikely to be due to fouling even if the hull or sterngear has been asymetrically fouled (which is possible I guess if one side of the boat faces south)

 

[Portofino]

I know you have them both rebuilt but can you give us some figures -this season for rpm s and Knots ?
Like 2000 rpm -how fast when -May -July -now ?
What's your normal cruise knots (P not D speed ) and what do they sit at ? 2150 ?

Did you get round to fitting EGT monitoring equipment ?

 

[BartW]

B, I can't for the life of me imagine a scenario where a fouled hull can explain that.
Even if (due for instance to the prevalent sun exposure) the bottom fouling would be asymmetrical, that would still affect both engines.
In the worst case, requiring a touch of rudder to keep the boat straight, but not putting more load on one prop vs. the other.
Assuming that both engines produce the same output (which is what you are interested to check, as I understand), the reason for the lower rpm on one side can't be hull-related, so to speak.
There must be something engine/transmission-specific, like a more fouled prop/shaft/bracket or a different prop pitch - though I guess you would have mentioned it, if that would be the case.
Sounds like a tricky troubleshooting, I'm afraid... Good luck!

Ref A/F, I know nothing of PM peculiarities - if any.
But FYI, years ago I left my old tub in the water in the N Adriatic during the winter, after a strong powerwash and without refreshing the A/F (long story...).
And upon lift for the new A/F around April or May, the growth was surprisingly low.
In this respect, the difference between winter and summer was night and day, and I see no reason why this shouldn't be true also in PM.

yes indeed it sounds like a weird problem, and also for me it sounded very unlikely that fouling can produce such a asymetric load,
its just that after cleaning the props (very minimal growth) that this already gave a noticeable improvement,
that we think we need a clean bottom before doing further tests...

I can also confirm that there was more growth on the SB shaft, and I only took off some wisps, but I can't believe that fouling on the shaft can produce such a difference

 

[BartW]

I know you have them both rebuilt but can you give us some figures -this season for rpm s and Knots ?
Like 2000 rpm -how fast when -May -July -now ?
What's your normal cruise knots (P not D speed ) and what do they sit at ? 2150 ?

Did you get round to fitting EGT monitoring equipment ?

Ok, here is a summery of performance since the rebuild’s

After the SB engine rebuild in 2015, we started that season slowly to give a smooth run in period for the new engine,
So mostly sailed at 1100Rpm/10kn and towards the end of the season, more and more at 2000rpm/20kn (performance as before the rebuild)
I don’t remember if we ever tried at full thr, I was more concerned not to damage anything,
But in august, the P engine broke because of overheating.
We continued the last week of that season on one engine only (SB) at approx. 1300Rpm

Last winter they rebuild the P engine and in spring this year (after new antifouling) we sailed quite some hours with the boat,
first run in at 1100Rpm, and after a few hours gradually up to 2000Rpm,
and we did a test for a few seconds both engines at approx. 2300 Rpm, speed approx. 25kn (normal as before)
but again didn’t want to punish the engines too much

Then beginning July, left for our long trip to Venice,
First week (7000l fuel on board) we mostly sailed at 1100Rpm, by the end of the week also some passages at 2000Rpm
When we arrived in Venice, I noticed there was a oil leak on the SB injection pump, (o-ring between pump and engineblock)
We started our trip back south along the coast of Croatia, at 1100Rpm only ! for 1,5 weeks
while permanently inspecting the amount of oil leaking ;
Approx. 1l of oil leaked every two hours of navigation.
A appointment for a repair was organized in Trogir, and late that evening engine was running again and leak was repaired,

Unfortunately only the next day late afternoon, we tried to sail the boat at >1100Rpm, but noticed that the SB engine Rpm appeared to be limited at approx. 1200Rpm
We did a few other inspections and replaced fuel filters but no success. Continued our holiday / trip south with guests onboard at 1100rpm 10kn.
Second week of august we arrived back in Tivat, the man Guy came onboard, and noticed that the guy”s in Trogir had forgotten to fit a hose that connects the intercooler with the injection pump,
(for the injection pump to “measure” the turbo air pressure)
This hose was completely hided below the intercooler, so didn’t see it myself…
After a short test we could run again at 2000RPM, and thought the problem was cured,

Only during a trip in September we noticed that the SB was limited at that 2000Rpm, and could not do more.

Man guy did again some inspections, (check that air hose, valve clearance, timing, etc…) all was normal,
After cleaning the prop the SB engine can do 2100Rpm, and that’s where we are right now.

Appart from that, both engines run very smooth, no abnormal smoke,
It seems more like a limiting in the injection pump, similar to the state when that turbo air pressure hose was missing.
Without load (no gear) both engines run at 2300Rpm


We have not yet installed EGT instruments,
Was not really needed according Man guy, engines have been running perfect during 20y / 3000 hrs,
He did service and has rebuild quite a few of these mechanical engines on different boats.

 

[BartW]

IMHO such a variation between P and S engines is very unlikely to be due to fouling even if the hull or sterngear has been asymetrically fouled (which is possible I guess if one side of the boat faces south)

I think exactly the same, but,
on our berth in PM, SB side faces south, and the berth on our SB side is empty since august.

we want to clean the hull before we do further investigation,
and the fouling is completely ruled out to be the problem.

 

[MapisM]

I can also confirm that there was more growth on the SB shaft, and I only took off some wisps, but I can't believe that fouling on the shaft can produce such a difference

Actually, also the shaft fouling does matter, B (as well as the shaft bracket).
It's not so much because of the higher drag of these parts alone, but because being them right in front of the prop, if heavily fouled, they can create a more disturbed water flow towards the propeller - and this can indeed affect its performance.
And of course, any port/stbd difference would have completely asymmetrical effects, as opposed to the hull.
That said, I'm also skeptic that this alone can explain what's happening...
All the best, and let us know about the investigation!

 

[BartW]

...All the best, and let us know the result!

thanks !, yes I will,
hopefully this is the last episode in our engine rebuild saga

 

[Portofino]

I don,t think it's asymmetric fouling of the shaft ,because the extra disruption of water flow is more likely ( if you sign up to this theory ) will at best only take a few knots off .The clean props and the engines will still spin equally .
100 rpm gain for a prop clean is normal .
Any how worth cleaning all the other underwater stuff ,this will increase speed knots of the boat .
Having eliminated drag .

Rpm is controlled by the diesel pump

Look at the injector pump---- can they be swooped to eliminate - ? Leave them swooped if it makes no diff .

Air intake side -restriction (s)

Timing -I,am thinking something's worn ,cogs teeth ,chain links stretched -only manifests at top end rpm .Or for what ever reason it's out a tiny bit -only manifests at the top end .

Turbos just starting to wear a bit loosing that final rpm ?

Exhaust back pressure -at the top end a restriction prevents it all getting out -some change inside out of sight in the riser ?

I get the 20y -3000 hr thing ,but weights a killer for P boats it's not the same boat today than 20 y ago .I understand various modifications (with good intent ) .
Weight basically increases the wetted underwater area -it can,t get up as high = more drag = more load on the engines for a given speed .
Early symptoms of excessive EGT could be the valve don,t seat as well as they could leading to power loss .
These are tiny effects at first cumulative over time .It's probably more noticeable at the top end at first .

I do hope it's some thing simple for you .

 

[Deleted User YDKXO]

we want to clean the hull before we do further investigation,
and the fouling is completely ruled out to be the problem.

Agreed that is the right thing to do and then you have eliminated one possible cause but I will be gobsmacked if that is the reason. If it is then we'll all be turning our boats around half way through each summer Btw I have never found hull fouling (as opposed to sterngear fouling) a major issue in the Med particularly the Adriatic which IMHO is cleaner and colder than the W Med. Once I went 2 seasons in Croatia without a lift out and by the end of the 2nd season I had lost only 1-2kts but I did keep the sterngear clean. Personally before you lift the boat I would get a professional diver (or do it yourself) to clean all of the sterngear and that includes anything which isnt antifouled or to which the antifoul may not be adhering well and that would include props, shafts, P brackets, rudders, trim tabs, underwater water intakes and outlets and underwater exhaust outlets - anything that could possibly affect the performance of the boat

Btw I guess you've checked the primary and secondary fuel filters on the S/b side for debris?

 

[BartW]

...Rpm is controlled by the diesel pump

Look at the injector pump---- can they be swooped to eliminate - ? Leave them swooped if it makes no diff .
.....

yes, the injection pump regulates the RPM,

we experienced that it "measures" the Turbo air pressure,
and limits the RPM, when the air pressure is too low

now, the behaviour of the SB engine is exactly that,
there is no smoke, the engine doesn't "feel" that it is over loaded or whatever
so my feeling is that the injection pump is limiting Rpm for a certain reason...

so after doing tests with a clean hull,
we could "measure" and compare the turbo pressure of both engines
and Man guy could swap the injection pump's

in this case, this has nothing todo with weight imho,
weight of the boat including mods' hasn't changed much since 2013