Am i under propped?

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PhilW

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Hi guys,

Just a quick question.

I have recently got my hands on a CI22 with a mermaid 140 turbo 4 (dorset)
I have a new prop made as the old one had seen better days and would have looked better in the coop with the other cabbages!
The new prop is a 3 bladed 14x13.5 Hyperform which is the same as the one that was removed however the boat is only achieving 14kts max?
unfortunately I don't know what speed the boat was making before as it has spent the last 8/9yrs living in a field..
The engine is having no difficulty making full rpm and beyond 2700rpm with 4 adults 4 kids and a fat dog.
But SWMBO has ideas of shopping trips to the mainland and a couple of extra kts might make things a bit more tolerable.
The only other thing I can think of is slipping clutch plates but there is no significant heat in the gearbox.
Cheers

Phil
 
Is 2700 rpm the max rated if this engine? If so and your comment that it goes beyond this means it revs higher the. That would suggest you may be underpropped. How much under is difficult to say as the governor will come into play to stop the revs going higher at a certain point.
 
LOA 22ft weight I'm guessing about 2600lbs reduction is 1:1
Max rated rpm is 2600 according to the manual but she is achieving 2700 under load if the pump has been tweaked by a previous owner I don't know but there is nothing to suggest this is the case.
I was just wondering if there were any other CI22 owners out there that might have an idea of what size props they are swinging?
 
That does not sound right - weight is low and are you sure it is a 1:1 box? Did you ask your prop supplier to recommend a size?

However 14 knots sounds pretty good and if the engine is making its rated revs then is not far out, although a bit more pitch might bring the revs down within the limit.
 
Certainly sounds like you could increase the pitch a little and still make rated rpm. This should in turn give you a slightly higher top speed, and slightly higher speed for any given rpm.
 
Just a quick reply
My CI with the same engine made 19kts
I will see if I can find the prop specs etc I fitted
Might be a few days but as the Man said
I,ll be back
 
Positive it's a Borg Warner 1:1 box I was guessing at the weight but probably closer to 2500kg as opposed to lbs though
I see no reason to doubt the tacho but will check it next time I get a day off.
Prop was made by Clements and was a like for like of the old prop.
I can live with 14kts flat out and 10kts cruising but lots of people seem to claim their Channel island 22 are between 17 and 19kts.
 
Excellent stuff I was beginning to think I had dreamt it ��
Mines running pretty light as most of the interior is stripped ( it can wait until winter)
 
PhilW said:
Positive it's a Borg Warner 1:1 box I was guessing at the weight but probably closer to 2500kg as opposed to lbs though
I see no reason to doubt the tacho but will check it next time I get a day off.
Prop was made by Clements and was a like for like of the old prop.
I can live with 14kts flat out and 10kts cruising but lots of people seem to claim their Channel island 22 are between 17 and 19kts.
Click to expand...

Working off W/L of 19ft, 2.5 tonnes, Mk1 Mermaid Turbo 4 (Actually 150 hp @ 2,600 rpm), B.W 72C 1:1 according my my calculations 10 knots cruise and 14 knots WOT @ 2,700 slightly out on the droop and clean sounds absolutely spot on.

These engines were a bit under turboed as the the KKK water cooled unit was actually off a smaller Volvo Penta and if you overload these engines EGT goes up like a rocket, do not be tempted to graunch any more pitch on, prop is correct.

Any tacho cannot be relied upon unless you have calibrated it, the Mermaid VDO units are pretty easy.

All looks sweet.
 
Latestarter1 said:
Working off W/L of 19ft, 2.5 tonnes, Mk1 Mermaid Turbo 4 (Actually 150 hp @ 2,600 rpm), B.W 72C 1:1 according my my calculations 10 knots cruise and 14 knots WOT @ 2,700 slightly out on the droop and clean sounds absolutely spot on.

These engines were a bit under turboed as the the KKK water cooled unit was actually off a smaller Volvo Penta and if you overload these engines EGT goes up like a rocket, do not be tempted to graunch any more pitch on, prop is correct.

Any tacho cannot be relied upon unless you have calibrated it, the Mermaid VDO units are pretty easy.

All looks sweet.
Click to expand...

The oracle had spoken believe him and enjoy the boat
 
CLB said:
But how does Kwacka and his 19 knots fit into this?
Click to expand...

I can't remember the reduction or the prop size and pitch
But I do remember the origional Blurb quoting 19kts as flat out
Having read this I set out to make Buccaneer reach said velocity
Bearing in mind folks I totally re - built/ renovated Her
Inc engine out new mountings, gearbox and crank seals , new sump , etc etc and new oil pump, new heat exchanger, the list goes on
Fuel pump re conditioned. new injectors, removed the fuel tank, minted it and re installed with a properly calibrated fuel measurement system
IE A nice piece of oak an inch square with notches on!
New fuel lines, the list goes on
Oh! and a nicely chromed rocker box!
Suffice to say She was bloody mint after 8 years and 10 Grand spent on Her!
I improved the steering by altering the rudder and fitting a steering pump which only gave 4 turns in total, the origional had more turns than an olympic ice skater
The only dam thing I can remember about the prop was that it was an 'Aquapoise' 3 blader
4 blades had been tried by a Pal on his CI 22 and it proved to be no better (speed wise) than a 3 blader
When She was clean underneath I regularly had 19 kts over the ground in slack water
She cruised at 12 to 14 easily depending on the tidal flow at 'cruising' revs. For the life of me I can't accurately remember what those were.
It was 2001 when I sold Her, lots of water under some bridges somewhere since then! Plus numerous boats
What I can remember is a 64 mile trip from the Isle of Man which took roughly 4. 3/4 hours which equated to and average of about 14 kts, yes most of it was assisted by my uncanny ability to work out the tides and superb navigation skills but the last few miles were against the Menai Strait currents were I had to push on a bit!
Whatever I did ref sound proofing, She or Me were never happy at W.O.T, cripes the engine let you know she was there at that velocity!
Most of the time we ran at a more than comfy 12 kts
Dam, it's bugging me now. I WILL return in the not too distant future with the specs for the prop etc
She is still in the vicinity and I will no doubt bump into the current owners (metaphorically speaking) and check how she performs these days
However the owner after me was a bit of a cloth head and terwatted the prop more than once so I don't know what She is swinging now
Dam, I loved that little boat
 
BruceK; are you about Sunday?[/QUOTE said:
Mon/Tue/ saw me in Conwy and up the Strait. Wed in Deganwy and up the Strait, today was just the Strait
Sat/Sun just the Strait, cos thats what the Peeps want and I dont wanna go out the Strait cos its gonna blow.
PM on its way
Click to expand...
 
I've done all the niggly bits had the engine out to change the input seal on the gearbox done the injectors, flushed the coolant, changed all the filters new set of mounts, new gearbox oil cooler, re aligned it as it was massively out. I'm wondering if it's worth swapping the sugar scoop for trim tabs as when she's full of fuel she's quite stern heavy. Swapped the teleflex steering for hydraulic could do with a rudder indicator now.
 
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