800rpm missing!!!

[chorscroft]

Well before we went down to view the boat we had a marine architect down to look at it and take it out for a spin. Everything seemed reasonably good... until they put it in the sea... 22knots at WOT and very slow acceleration - so slow it probably wouldn't get on the plane in the rough. He said it was also only getting 3200 rpm when it should be at about 4000.
The estimates for speed have all been over 30 knots at least.
How much of a speed difference will 800rpm on each engine make?
I'm guessing the props are too big so properly propping it should increase acceleration too?
Just incase you forgot it's an 8.5m redbay with twin steyr 144hp engines.

Thanks in Advance (again)

Conor

[Chris]

Originally Posted by chorscroft

I'm guessing the props are too big so properly propping it should increase acceleration too?Conor

Since this is a second hand boat would the previous owner not have already been through getting the right props? It seems a bit odd to me, are you sure the engines are not knackered?

[chorscroft]

The owners seemed to not really know what they are doing.
What do you mean by knackered? The engines both have less than 200 hours on them.
The naval architect that looked at the boat also thought that someone might have changed some settings or electrical control for the engines - how would you find this out and reset it.

Regards

Conor

[Chris]

Originally Posted by chorscroft

The owners seemed to not really know what they are doing.
What do you mean by knackered? The engines both have less than 200 hours on them.
The naval architect that looked at the boat also thought that someone might have changed some settings or electrical control for the engines - how would you find this out and reset it.

Conor

To be honest I have no idea why the engines may not be pulling full RPM I guess if it were me I would want this sorted before I parted with the money. Can't the owner confirm if the boat used to perform ok in which case the props are probably not at fault?

[codprawn]

800rpm will make a big difference. If BOTH engines are acting the same it's unlikely to be any sort of normal fault. Either the props are totally wrong for the boat/engines or someone has meddled with things they shouldn't.

Find out what props they are if you can. Very slow acceleration could mean someone has tried to do what you want - fitted 5th gear type props to try to get a high top speed.

It could be a great way of getting a big drop in price................

[chorscroft]

Can you give me an idea of what would be a reasonable prop size for this boat and engines so I can compare it to what is fitted when I look at the boat on monday? Are there any sort of things I would be looking for that would tell me it's the props and not the engines or will the propellers be so big it will be straightforward?

Regards

Conor

[bedajim]

Originally Posted by chorscroft

Can you give me an idea of what would be a reasonable prop size for this boat and engines so I can compare it to what is fitted when I look at the boat on monday? Are there any sort of things I would be looking for that would tell me it's the props and not the engines or will the propellers be so big it will be straightforward?

Regards

Conor

Can't you talk to Redbay ref props they would fit,(read what is stamped on the props) and a local steyr engine dealer pay for them to check it over then offer less the costs if it's ok
When was it last serviced and who did it ask for a bill and go and talk to the people who serviced it

How many owners has it had ask for details of the last one and talk to them

Between the lines is this right rib for you,
reading the posts from day one it's not going to be fast enough
The owner seems to be vague to say the least are they hiding something, if it was all ok and I wanted to sell it I'd know how fast it went, WOT revs, what the switches were for on the console etc etc, the more you post on this boat the more I would steer clear it just does not feel good to me

my 2 pence worth

James

[chorscroft]

I will look at what is stamped on the props when I look at the boat on monday but, unfortunately there are no steyr dealers in Ireland.
It was last serviced 2 years ago and it hasn't been used since apart from test drives.
It has had 2 owners. The current owner received the boat as a part exchange for a mercedes and I'm fairly sure he doesn't have a clue about ribs or boats in general.
I still think it is a great boat if I can get the engine sorted. Although I would like to go faster as long as it can do 32 knots I'm happy enough - I just wanted to explore all the possibilities.
And as codprawn says, if it turns out it's only the props that are the problem I can use that to my advantage as a bargaining tool.

Regards

Conor

[Pete7]

Conor, I would definately have a chat to Redbay once you know what size the props are. If the boat has only 200 hours and the props are not original they you might want to investigate further and find out why they needed changing, but as you say it's a bargining tool and wouldn't put me off the boat. Wrong props and a very slow speed might be the reason she was px'd and a little bit of work could soon have her sorted and running properly.

Nice trailer btw, if you do go ahead I have a brand new spare wheel that would fit her sat in my garage looking for a new home.

Pete

[Searider]

Might be worth speaking with Mermaid regarding the Steyrs. They are the UK agents.

http://www.mermaid-marine.co.uk/HTML/SteyrSummary.htm

[Andy Gee]

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

[chorscroft]

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

[chorscroft]

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