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Old 09 May 2008, 05:35   #11
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Country: UK - Scotland
Town: Inverkip
Make: Redbay 11m Cabin
Length: 10m +
Engine: 2 x Yamaha422Sti 275
Join Date: Feb 2003
Posts: 567
Dont think it will be the props, unless she has had an accident that required 2 new ones and they were the wrong pitch.
Going by what you say I would be looking at:
1. Fuel problems- dirty filters/seperators not allowing enough fuel through
2. Check the air filters
3. Are the Turbos coming on line- could be that the dump valves are stuck or passing
4. May be a throttle sensor is not working
5. ECU problems (if fitted)

Personally I would go along the fuel route first. On twin inboard engines, especially the smaller HP ones if one engine is down on power then at times the other engine cannot pick up the pace and get enough revs to allow the turbo to come in.

With blocked filters on an inboard it is common to loose top end revs/power as the filters get blocked. The engines will rev freely to WoT with no load but will fail to achieve WoT with load due to fuel restriction, the worse the blockage the less power through the range until it stops. I dont really know much about the Steyr engine, but from what I can remember they are fitted with various sensors that can affect the operation.
HTH
Andy
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Old 09 May 2008, 11:39   #12
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Country: UK - N Ireland
Town: Cushendall
Boat name: JanJack /
Make: RedbayBoats / Brig
Length: 8m +
Engine: Yanmar 300 / etec 50
Join Date: Mar 2008
Posts: 81
I sent an email off to mermaidmarine and they said the same thing as you Andy.

"A variety of factors could affect the engine performance, including :-
a) Over sized propellers
b) Restricted fuel flow [both to and from the engine, typically 260 litres per hour]
c) Blocked fuel filters , primary and engine mounted
d) Restricted Air Flow [Fire flaps or air intakes shut ]
e) Engine Fault Code restricting power through ECU"

I will take down all the propeller info. I can.
I think I know how to check the filter as we had to on our yanmar once - is a seperator just another name for a filter?
Where is the air filter and how do I check it?
Is it possible to check the dump valves if so how?
How would I check the throttle sensor?
Mermaid marine told me that; "The operating parameters forthe ECU cannot be changed by anyone other than the factory, these are protected.
There are Fault Codes which the ECU will display, some of which can be reset, deleted or over ridden and these can have a direct bearing on engine performance." - probably not the ECU then?

Regards

Conor
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Old 09 May 2008, 12:29   #13
Member
 
Country: UK - N Ireland
Town: Cushendall
Boat name: JanJack /
Make: RedbayBoats / Brig
Length: 8m +
Engine: Yanmar 300 / etec 50
Join Date: Mar 2008
Posts: 81
Just got a reasonably detailed email back from Joe who was down looking at the boat;
He said:

I didn't check the size of the props before going into the water and unfortunately they left the boat in the water so wasn't able to see afterwards. However the fact that the boat is up on the plane and seems to be reving freely I don't think prop size is the problem! By downsizing pitch of the props to get more rpm generally doesn't improve speed much as the distance traveled on each turn of the prop is less.
If the rpm was increased to 3800 you would be increasing rpm by approx 25% which would be about 6 knots of an increase in speed! What would worry me is that the people at the yard are quite sure that this is the speed that the boat has been doing all along! (ie 22 knots)
I think part of the problem could be with the turbos as the valves don't seem to be opening freely. This could be down to lack of use and there is a possibility that these could be freed up which may or may not improve things.

How hard a job is freeing up the valves on the turbo and is there a good possibility this would solve it?

Regards

Conor
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