Daverw
Well-Known Member
Ours was fitted that way four years ago by mistake by me, never been an issue. Did worry about at first but now just get on with sailing
Sea water scoop fitted the wrong way around!
- Thread starter Zagato
- Start date
pvb
Well-Known Member
How does that compare with the Bernoulli and pitot tube theories mentioned by Rogershaw in post 16?
Bru
Well-Known Member
Yup
A jelly fish or something similarly squishy at any rate... by the time it had blocked the skin fitting, the "no flow" alarm float (a clever but ultimately useless contrivance as we discovered on that occasion) and thoroughly gummed up the filter cage it was beyond my limited knowledge of such things to positively identify!
It took a good 45 minutes anchored in the outer reaches of the River Crouch to restore sufficient water flow to limp upstream to Burnham Yacht Harbour (we'd by then missed the tide to head up to Fambridge and punching the ebb with iffy engine cooling wasn't an attractive proposition)
It then took me several hours to fully clean out the whole system. Bits of the damn thing had even got past the impeller and partially clogged the heat exchanger tubes!
Amlov
Well-Known Member
After much debate in the yard when I fitted my Beta 20hp to a Sadler 32, I went with the consensus and fitted it the ‘wrong’ way round.
Ten years later when I sold the boat, it was still the wrong way round having about 900 hours on the engine and having covered the best part of 8,000 miles. I never had any problems with the engine flooding etc. and was quite untroubled by its orientation.
I therefore doubt that any damage will have been caused to your engine in the 50h but would pragmatically suggest that if it would help you sleep better at night it might be an idea to turn it round or change it for a simple skin fitting. Otherwise I would find something else to worry about; how about the rate of anode loss in the heat exchanger?
Andy
Ten years later when I sold the boat, it was still the wrong way round having about 900 hours on the engine and having covered the best part of 8,000 miles. I never had any problems with the engine flooding etc. and was quite untroubled by its orientation.
I therefore doubt that any damage will have been caused to your engine in the 50h but would pragmatically suggest that if it would help you sleep better at night it might be an idea to turn it round or change it for a simple skin fitting. Otherwise I would find something else to worry about; how about the rate of anode loss in the heat exchanger?
Andy
zoidberg
Well-Known Member
Wow!
That JumbleDuck.... the snit he knows!
I have experienced 3 - yes, three - inlet blockages that led to a melted Vetus mixer bottle..... all on the same mate's Rival 34. It became tedious after the second occurrence..... but it did sharpen up the 'coming alongside in a foreign harbour' and 'anchoring under sail' techniques.
That JumbleDuck.... the snit he knows!
I have experienced 3 - yes, three - inlet blockages that led to a melted Vetus mixer bottle..... all on the same mate's Rival 34. It became tedious after the second occurrence..... but it did sharpen up the 'coming alongside in a foreign harbour' and 'anchoring under sail' techniques.
Zagato
Well-Known Member
What comes to mind as the quickest solution would be to drill a couple of holes in the blank part. 5 mins and job done!
JumbleDuck
Well-Known Member
Same thing. Pitot tubes bring the fluid to a stop; the pressure difference between that and the static pressure in the fluid moving past (yes, "static" pressure in a moving fluid ... I didn't invent this stuff) is the stagnation pressure.
"Snit"?
I'm actually near the end - thank goodness - of writing a new university course in fluid dynamics so this stuff is very much in my mind at the moment.
zoidberg
Well-Known Member
Oi! I invented that wurd! Cultural appropriation.... 
I lost track of 'fluid dynamics' way back when the new Junior Pilot on Squadron would be sent up to the Met Office in the Tower, first thing in the morning. The Senior Met Office wallah, in on the joke, would furnish him with with a large Kilner jar, and instructions to go to the approach end of the runway, shake out the previous days stale stuff, and swing the open jar to and fro to capture the fresh..... which he would dutifully bring back, lid closed, to said SMO so as to calculate that day' s 'Bernouilli Count', needed for the Briefings and the morning's METAR signal to all other bases.
I lost track of 'fluid dynamics' way back when the new Junior Pilot on Squadron would be sent up to the Met Office in the Tower, first thing in the morning. The Senior Met Office wallah, in on the joke, would furnish him with with a large Kilner jar, and instructions to go to the approach end of the runway, shake out the previous days stale stuff, and swing the open jar to and fro to capture the fresh..... which he would dutifully bring back, lid closed, to said SMO so as to calculate that day' s 'Bernouilli Count', needed for the Briefings and the morning's METAR signal to all other bases.
rogerthebodger
Well-Known Member
So I do wonder why you ask the question and challenging some of my statements.
Just to let you know I graduated in Mechanical Engineering from University of Aston in Birmingham in 1971 with an second class honours degree upper division.
This degree also included practical experience requirement and also gave full exemption from the IMechE qualification requirements at that time
This may be not the level JD's qualification, but high enough to know my subjects.
What is you level of education, qualifications and in what subjects.?
What type of practical work experience do you have in Engineering subjects.
I don't think I am contravening and rules and regulations just making enquiries.
pvb
Well-Known Member
OK, just thought your calculation seemed much simpler than the formulae in the Bernoulli link.
It's many years since I studied fluid dynamics at university, and I have to say I've forgotten most of it!
rogerthebodger
Well-Known Member
The OP could also take am angle grinder and ut the scoop off completely.
I have already cut the grid off to make the fitting easier to clean any fouling out.
vas
Well-Known Member
fwiw, my yanmar 2GMF inlet has a forward facing scoop.
Following 5 seasons, no problems at all and that's on a mobo with the yanmar typically used when stationed (and not much)
Typical speeds are 8-9kn and an occasional blast at 18-19 (way too rare)
yanmar impeller below w/l
Following 5 seasons, no problems at all and that's on a mobo with the yanmar typically used when stationed (and not much)
Typical speeds are 8-9kn and an occasional blast at 18-19 (way too rare)
yanmar impeller below w/l
pvb
Well-Known Member
They're supposed to face forward on mobos.
doug748
Well-Known Member
I once stuck a hosepipe up the raw water inlet cos I couldn't be arsed. You are rewarded with a good flow of water out of the exhaust.
I would certainly attend to it, but not panic.
.
I would certainly attend to it, but not panic.
.
vas
Well-Known Member
not a main engine, its the generator's engine!
normal main engines have forward facing scoops.
rogerthebodger
Well-Known Member
Just cut the whole scoop off flush with the outside of the hull with an angle grinder would solve any issue if there is an issue in the first place.
JumbleDuck
Well-Known Member
Bernouilli gets quite simple when there is no change of height, one zero velocity and you only need the pressure difference ...
Can I interest you in an economically priced update? No sails, I'm afraid, but it does include wind, weather, tides and waves as well as the usual flow-down-a-pipe and flow-over-a-wing stuff.
pvb
Well-Known Member
A kind offer, but I'll maybe stick with my vague memories!
Moodysailor
Well-Known Member
This is the simplest answer, and will solve most (if not all) concerns. Have done this on yachts a few times, and even on powerboats if we found they had too much positive pressure during commissioning trials.
mikegunn
Well-Known Member
If one were to do that what is to stop the bit inside the hull from falling orf? My scoop is held in place with a single nut on the scoop’s spigot on the inside surface of the hull, which is sandwiched between the inner nut and the flange formed by the scoop.
Mike.