Pootling - I get it now.

[Robg71]

How many hours a year is average...
Cant be many... Mine has 28years on them for less than 500hours.

Apart from you chaps on here, and the odd die hards, i think most boats dont do any work, and the idea of universal hours per year like miles per year in a car is not a true reflection of value...

 

[Spi D]

.. I fitted a fuel flow meter to our old 30hp Evinrude and was shocked to discover 0.9L/mile on the river at 4kts vs 0.7L/mile at 22kts open water...

The key word is 'old'. Outboards that meet later emission requirements will stretch fuel a lot and definitely not pump it into the sea

 

[spannerman]

The recent MBY mag with the article about Sweden is just how my boating is in Norway, its great to 'pootle' along at 5 knts admiring the fantastic proerties on the shoreline while meandering inbtween holms and skerries as the sun browns you. Also smiling when you look at the fuel consumption readout of 4-5 lph.
Was out pootling at the weekend, as they say half the fun is in the journey itself, plus reduced fuel bills mean I can go out much more often.
A word to the wise though, its important to run the engines up to max several times each trip to prevent cylinder glazing, we have a customer with an S34 with 2 x D4's which drink horrendous amounts of oil, he only ever runs a tickover and has glazed the bores.

 

[Nick_H]

its important to run the engines up to max several times each trip to prevent cylinder glazing

There seems to be lots of different opinions on how often, and for how long, you need to run at higher rpm. I tend to run them up for 15 mins once every few hours, is that enough? Once you have cylinder glazing, is it permanent, or will an extended period of high RPM running slowly remove it?

 

[BartW]

There seems to be lots of different opinions on how often, and for how long, you need to run at higher rpm. I tend to run them up for 15 mins once every few hours, is that enough? Once you have cylinder glazing, is it permanent, or will an extended period of high RPM running slowly remove it?

I'm a bit skeptic on that "glazing" phenomen,
no experience nor real knowledge I have to admid,
perhaps it depends on the type of engine,
I would be pleased to hear real live experience / knowledge

my MAN's run max 2300Rpm
planing speed average is 2000 rpm
poodling which I use a lot is 1100 rpm, sometimes for hours without planing or higher rpm
I have been confirmed from two completely different MAN engineers that there is absolutely no harm to the engines running them long time at 1100 rpm
in industrial applications these engines run 24/7 at 1500 rpm

 

[BartW]

Mmm, I'm not against pootling per se, in fact I was doing it today myself. Just remember that at 7kts, you're putting 3x as many hours on your engines as you would do at 21kts so any fuel saving is going to be swallowed up by extra depreciation on your boats due to higher hours

also skeptic on that one Mike,
I know this is one of your favourite arguments, and has been discussed on here a few times,
but talking from experince in real live the hour count will not be x3 nor x2, your sailing planning will just be different,

also on average there are many more parameters that will influence the hour count on a boat,
and generally speaking, the hour count on boats is usually dramatically lo,
lo enough to have marginal influence on resale value (all imho)

by the way,
I might have mist some posts, how are you getting on with your purchase and travel to HR ?
my trip is postponed untill the end of may (last weekend weather prediction was not good enough)

 

[rbcoomer]

The key word is 'old'. Outboards that meet later emission requirements will stretch fuel a lot and definitely not pump it into the sea

Yes agree with that - there's a lot of old 2-stroke out there however and I guess the low speed inefficiency came as a bit of a surprise to me. I'll have to hurry-up with the inboard V8 project so I can do more pootling...

 

[Harpsden]

Love the ST 34', lovely looking boat.

What sort of economy do you get at 7 or 8 kts?

Out on the water today and measured the fuel use:-

1000 revs 6.1 knots STW 5.2 lph
1300 revs 6.9 knots STW 6.8 lph
1400 revs 8.1 knots STW 9.2 lph

Glorious day for a pootle!

 

[MapisM]

I am a pootling convert now and would recommend it to one and all. Only works on sunny and flat calm days though I guess.

Nope. Rather the opposite, in fact: it does work equally well, if not better, in the rough stuff.
Just think about it: by increasing speed when the sea is rough, in order to limit the boat rolling, you're actually treating the symptom, rather than the cause.
Plain common sense, together with just a bit of experience, suggests that the worse the sea state, the lower the speed.
You do need a stabilised vessel, though.

 

[MapisM]

I might have mist some posts, how are you getting on with your purchase and travel to HR ?

LOL, I don't want to answer on Deleted User behalf of course, but there's one thing I can tell you for sure.
If this week is anything to go by, his purchase gets my approval with flying colors!

Btw, you could never believe how quiet a couple of MAN engines like yours can be.
Possibly, some improvements through the years, the electronic control etc. can be part of the reason.
But I would think that this is mostly down to the Ferretti exhaust - absolutely impressive.
Actually, I don't think it would be trivial to rearrange BA exhaust along the same lines, and maybe not worth the effort anyway.
But the difference is amazing, really day and night!

 

[Deleted User YDKXO]

also skeptic on that one Mike,
I know this is one of your favourite arguments, and has been discussed on here a few times,
but talking from experince in real live the hour count will not be x3 nor x2, your sailing planning will just be different,

Whether its 2x or 3x, it still affects the resale value, maybe less for an older boat but maybe more for a newer one. Consider a brand new boat. Normally for a planing boat, the annual hours is going to be around 100 so after 5yrs, the boat will have 500hrs on it. However, if you've done a lot of pootling, the boat could have 1000hrs on it after 5yrs and it will definitely be worth less, no question. How much less, I don't know but certainly enough to offset a big chunk of any fuel saving made due to pootling. Until such time as boats are sold on the basis of miles, like cars, rather than hours, then this will always be the case

 

[rustybarge]

Out on the water today and measured the fuel use:-

1000 revs 6.1 knots STW 5.2 lph
1300 revs 6.9 knots STW 6.8 lph
1400 revs 8.1 knots STW 9.2 lph

Glorious day for a pootle!

4.5mpg at 6.9kts is very impressive indeed!
And 4mpg at 8kts ain't shabby either.

Compared to the bigger longer displacement Boats that seem to chug along at 2mpg, this a considerable saving in fuel.
I think 1300 revs is a fast enough speed to keep the motor happy, double the idle revs.

Sort of flies in the face of 'the longer the boat the faster it's hull speed'.

Thanks very much for those numbers, at last a real life result not downloaded from the manufacturers brochure!

 

[mjf]

The recent MBY mag with the article about Sweden is just how my boating is in Norway, its great to 'pootle' along at 5 knts admiring the fantastic proerties on the shoreline while meandering inbtween holms and skerries as the sun browns you. Also smiling when you look at the fuel consumption readout of 4-5 lph.
Was out pootling at the weekend, as they say half the fun is in the journey itself, plus reduced fuel bills mean I can go out much more often.
A word to the wise though, its important to run the engines up to max several times each trip to prevent cylinder glazing, we have a customer with an S34 with 2 x D4's which drink horrendous amounts of oil, he only ever runs a tickover and has glazed the bores.

I too am interested in the glazing issue - the advice given when my boat was new , was to ensure I ran at decent rpm when running in to prevent this occurring.

My normal mode now is to warm engines (only in gear) for harbour/river transits and WOT for a mile or so and then back of to 8/10knots pottle then a spot on the plane before mooring back at base. So at a guess 90% run at low rpm throughout the season. Can this be damage causing? Engines sound sweet, no soot to speak off and no oil top ups ever needed - oil looks clean on the dip stick

 

[Harpsden]

Quickly edited pootling video from yesterday on the Solent.

Absolutely glorious afternoon.

 

[MapisM]

Sort of flies in the face of 'the longer the boat the faster it's hull speed'.

Well, actually there's nothing in those numbers that goes against that rule.
In fact, "hull speed" is meant as the max speed that any given hull can achieve in full displacement.
You won't be able to make a 30kts D speed with an ST34, while you can with a cruise ship.
Otoh, this doesn't mean that the cruise ship burns less fuel than the ST34 at 6 knots...

 

[spannerman]

I too am interested in the glazing issue - the advice given when my boat was new , was to ensure I ran at decent rpm when running in to prevent this occurring.

My normal mode now is to warm engines (only in gear) for harbour/river transits and WOT for a mile or so and then back of to 8/10knots pottle then a spot on the plane before mooring back at base. So at a guess 90% run at low rpm throughout the season. Can this be damage causing? Engines sound sweet, no soot to speak off and no oil top ups ever needed - oil looks clean on the dip stick

You should be fine with that. its just that with prolonged low speed running the cylinder pressures are lower and the rings don't get pushed out against the walls which can lead to glazing. Its part of the procedure when running in engines to run them at varying speeds including max rpm to ensure the rings bed in, on aircraft piston engines there was a study back in the 80's and it was found to be essential to run them at full power when new to create enough cylinder pressure to push the rings out as they had encountered glazing problems.
Another issue is condensation, its important to get the engine hot enough to boil off condensation in the engine.
Two weeks ago I had a new Mercury 100 4 stroke which has so much water in the oil it flowed up out of the dipstick tube, also there was severe blowby on an engine that was only 5 mths old. I checked the run history with the diagnostic tool and it has never ever gone over 4000rpm yet was rated to 6000rpm, and it had spent most of its 40hrs under 2000rpm.
Mercury fortunately stumped up for a new powerhead, this was caused by slow running in the cooler waters up here so the engine never got hot and the condensation built up until it damaged the engine.
The owner got clear instructions to thrash it at least once on the way out and again on the way home!

 

[rustybarge]

Well, actually there's nothing in those numbers that goes against that rule.
In fact, "hull speed" is meant as the max speed that any given hull can achieve in full displacement.
You won't be able to make a 30kts D speed with an ST34, while you can with a cruise ship.
Otoh, this doesn't mean that the cruise ship burns less fuel than the ST34 at 6 knots...

But say you had a 34' cat, which is like having two 34' long hulls[sort of like a 68' long hull], which would be more economical at 8 kts with exactly the same hp?

 

[Robg71]

I remember an article, in maybe performance bikes, years ago. Testing theories on bore glazing, and power.
There research concluded, that if the bike was, not so much run in, more like thrashed in, from new, it actually made more power, than one run in as the book, and one given the kid gloves treatment.
It did use more oil than both the others..
They did this testing on a few different bikes. If i remember it started with the original honda fireblade in the early nineties....
This was backed up with dyno charts etc etc....

 

[MapisM]

But say you had a 34' cat, which is like having two 34' long hulls[sort of like a 68' long hull], which would be more economical at 8 kts with exactly the same hp?

Assuming that both the monohull and the cat have efficiently designed hulls and the same overall weight, I'd expect the cat to burn a bit less fuel.
But that has not so much to see with the hull speed point you previously raised.
In fact, even if it's true that the (max) hull speed of a 34' cat can be higher than the one of a monohull, I don't think it's correct to compare that with the hull speed of a 68' monohull.
Length remains more relevant than beam, AOTBE.

 

[rustybarge]

You should be fine with that. its just that with prolonged low speed running the cylinder pressures are lower and the rings don't get pushed out against the walls which can lead to glazing. Its part of the procedure when running in engines to run them at varying speeds including max rpm to ensure the rings bed in, on aircraft piston engines there was a study back in the 80's and it was found to be essential to run them at full power when new to create enough cylinder pressure to push the rings out as they had encountered glazing problems.
Another issue is condensation, its important to get the engine hot enough to boil off condensation in the engine.
Two weeks ago I had a new Mercury 100 4 stroke which has so much water in the oil it flowed up out of the dipstick tube, also there was severe blowby on an engine that was only 5 mths old. I checked the run history with the diagnostic tool and it has never ever gone over 4000rpm yet was rated to 6000rpm, and it had spent most of its 40hrs under 2000rpm.
Mercury fortunately stumped up for a new powerhead, this was caused by slow running in the cooler waters up here so the engine never got hot and the condensation built up until it damaged the engine.
The owner got clear instructions to thrash it at least once on the way out and again on the way home!

That's very interesting info, I never knew it affected petrol engines. Urban myth has it you can run your OB a tick over for ever without any problems.