Propspeed

[Chris H]

Hows the trim ram seal maintenance going ? The steering two ram seals ?

No problems so far.

 

[MapisM]

Yep, that’s why I have to clean them every two weeks in the summer, it won’t get on the plane when they have that much growth on them.

I was sort of guessing/fearing that.

The reason why I said you really don't want to put your engines in that condition is that the throttle of diesel engines is akin to a cruise control.
By hammering the throttle, you're asking the governor to reach 2300rpm, and it will keep pumping as much fuel as it can until it does.
Or until it blows up, if it can't because restricted by a too high prop demand - which is what happens when you can't get into plane.
In other words, don't insist too much with the throttles when you struggle to increase rpm/speed, because in those circumstances (unbeknown to you, unless you fit specific additional instruments) the engine gets overfueled/overloaded, and the EGT skyrockets.
With potential nasty consequences, if that condition is maintained for some time.

BTW, out of curiosity, which ballpark rpm do you need for entering into plane?
I'm asking because I half recall that Pershing also offered the V10 1050hp engines on your boat, but weirdly enough, up to around 1400rpm the V8 is actually capable of a higher output...

 

[Portofino]

I was sort of guessing/fearing that.

The reason why I said you really don't want to put your engines in that condition is that the throttle of diesel engines is akin to a cruise control.
By hammering the throttle, you're asking the governor to reach 2300rpm, and it will keep pumping as much fuel as it can until it does.
Or until it blows up, if it can't because restricted by a too high prop demand - which is what happens when you can't get into plane.
In other words, don't insist too much with the throttles when you struggle to increase rpm/speed, because in those circumstances (unbeknown to you, unless you fit specific additional instruments) the engine gets overfueled/overloaded, and the EGT skyrockets.
With potential nasty consequences, if that condition is maintained for some time.

BTW, out of curiosity, which ballpark rpm do you need for entering into plane?
I'm asking because I half recall that Pershing also offered the V10 1050hp engines on your boat, but weirdly enough, up to around 1400rpm the V8 is actually capable of a higher output...

How do the torque curves compare for the V10 vs V8 and wasn’t it a V12 the other option back in the day ?

I seem to think we have had this conversation before the existence of a V 12 1050 mid to late 90 s , but Chris’s boat is early noughties so they may have refreshed the engines dropped the earlier V12 and subbed in the V10 as it started to overlap.

It is slightly annoying ( take note newbies looking in ! ) the mag test or internet reviews are done on factory loaned super clean boats .Also relatively light weight with zero cruising stores and mid level spec = read not real world weights .

Add a few months of fouling or indeed a couple of years when they hit the used market the kgs have pilled on .
Add a decade of two the layers AF caked on give a not so smooth as babies back side hull bottom .

I think perhaps with old boats say 10 y + you have to knock off as much as 5 knots in season cruise unless you maintain meticulous stern gear hygiene.
I am currently on 28/29 knots 1/2 tanks @ 1770 rpm with equates to 77 % load EGTs mid 500 * C 550/560 ish Burning 90 L / side .
Empty tanks into the red zone on the gauges the same ^^^ but 74 % load , and slightly lower fuel burn .

Yeh the fuel burn increases with the weight I see it .

I have seen EGT s 650 *C , cruise 24/25 knots , load 90%+ @ 1850 rpm , stupid fuel 3 figure fuel burn rates ………tells me it’s time for prop hygiene.

Don’t know if it’s true or just myth but the 80 % load rate I got not from this forum but from an American sport fisher forum .
They are professionals so time is $ , and need to run clients in / out to fishing grounds before work starts - the fishing !

Talk ing 1000 hr per season and 10 s of thousands before they “ tear down “ the motors to overhaul = new pistons , liners etc .

All makes but focusing on CAT , MAN , MTU , + Cummins for the smaller boats .

You don’t here it or see it mentioned by the U.K. boat builders or indeed the Ferretti group .
Having said that , tested a few Ferretti group boats ( spanking new show boats ) they do allow you to WOT them to see the money shot speed on the screen .When I have done that I have voluntarily settled them down to 80 % load , skipper / engineer nodding sagely in agreement.
And noted the fuel burn of the various V 12 s ..eek !

 

[Chris H]

As far as I’m aware, the 52 came with V10 - 1050 or V8 - 800, to get on the plane I usually throttle to 2k rpm then throttle back to 1800rpm, which gives around 28/30 knots/ 180 L per hour.
Mine was the first 52 made and we’ve come across a few features not fitted to later boats.

 

[jointventureII]

I bet you cant do it as well as if it were in the slings.

You'd be surprised, if you do it frequently and are just "lifting" the stuff that is about to take root.

If you leave it a month (in the Med in summer) then yep you'll never get it back to just-launched condition.

As for loading the engines with (slightly) dirty props on arnesons, we get hi exhaust temp alarms immediately. They are so damn delicate!

 

[Hurricane]

You'd be surprised, if you do it frequently and are just "lifting" the stuff that is about to take root.

If you leave it a month (in the Med in summer) then yep you'll never get it back to just-launched condition.

As for loading the engines with (slightly) dirty props on arnesons, we get hi exhaust temp alarms immediately. They are so damn delicate!

I've tried cleaning the props etc in the water MYSELF - even with scuba.
Not only is it difficult, but you definitely don't do even as good a job as a pressure washer - let alone as good as an acid wash.
The other thing people forget to say when they clean the props in the water - and that is what happens to the scrapings?
In the Med, you end up with thousands of bits of barnacles.
If you wear a BCD (or Stab Jacket), you end up with little bits of barnacles in between the jacket and your skin.
And then there is your hair (if you have any) - all tangled with broken barnacles.

Believe me it is far far less hassle to pay for a lift and pressure wash.
And in our case it is a "no brainer" because we get one free lift and pressure wash off each year.

 

[jointventureII]

@Hurricane we're all referring to arneson / surface piercing props (I think!) - flat square edged blades, near the surface - easy to clean.

 

[MapisM]

As far as I’m aware, the 52 came with V10 - 1050 or V8 - 800,
to get on the plane I usually throttle to 2k rpm then throttle back to 1800rpm, which gives around 28/30 knots/ 180 L per hour.
Mine was the first 52 made and we’ve come across a few features not fitted to later boats.

That's my understanding also, with regard to the powerplants available.
And if you need to spool up to 2000 rpm to get on the plane, then I guess that the output difference between the V8 and V10 (236x2 Hp more) is more than enough to make up for the additional weight (170x2 Kg).

BTW, the fuel burn also shows that at 1800rpm you're running a tad on the high side of engines load, compared to the MAN average prop demand curves, according to which the fuel burn should be 20 liters less - which is right on the money for the same engines installed in my boat, FWIW.
I'd consider fitting EGT probes on each cylinder bank, in your boots.
That's in fact the closest indication of engine load that you can get, with mechanical engines like ours.
With the added bonus of being able to spot meaningful differences between each bank of the same engine, which is an early warning of an injector problem.

What features did the builder get rid of, after hull #1? Just curious.

 

[Portofino]

@Hurricane we're all referring to arneson / surface piercing props (I think!) - flat square edged blades, near the surface - easy to clean.

Also Chris s been quoted €1800 a pop for a lift .So multiply that every month or so or after 2 weeks of inactivity.

@ Hurricane.The gold std is indeed a lift+ acid wash no one’s denying that .

Nothing effectively sticks to Arnesons props , they can thankfully be trimmed up to snorkel depth ( well a std pair ) , all props are uber sensitive to fouling, unfortunately Arnesons need to be Uber clean at the transition phase when getting up on the plane otherwise a serious engine overload / excess EGT s scenario is created …..ok un intentionally , and with older mech motors unknowingly.Motors without EGT / load instrumentation and alarms that come with such sensors.

 

[Portofino]

Not had a Arneson boat , but seen a few taking off , getting up .
Correct me if iam wrong ( Jointventure ) but should you bring them up to a irate them initially as you rev up bringing on the turbos circa 1400/1500 rpm , them as the torque builds , the boats risers the drag starts to drop , the hull speed increase as it pops up , start dipping them for more bite at little increasing to 1700, to 1800rpm settling down to a nice cruise finally trimming the things for efficiency.


As opposed to dumping the throttles , waiting for the boat to attain the speed you want them pulling back ?
Which by the sounds of it is what Chris is doing ?

 

[Chris H]

Not had a Arneson boat , but seen a few taking off , getting up .
Correct me if iam wrong ( Jointventure ) but should you bring them up to a irate them initially as you rev up bringing on the turbos circa 1400/1500 rpm , them as the torque builds , the boats risers the drag starts to drop , the hull speed increase as it pops up , start dipping them for more bite at little increasing to 1700, to 1800rpm settling down to a nice cruise finally trimming the things for efficiency.


As opposed to dumping the throttles , waiting for the boat to attain the speed you want them pulling back ?
Which by the sounds of it is what Chris is doing ?

I don’t dump the throttles, just bring it slowly up to 2k rpm, sometimes a little lower, up on the plane and then drop back to cruising speed.

the props are fully lowered most of the time, it’s only when above 30 knots trimming the props makes a difference, the boat won’t get on the plane at all if the props are up.