Speed

[Fenlander]

>>Must admit struggling to see any real problem here.

Despite reaching back into the depths of my Suzuki 20 memory with my above thoughts I reckon this is one of those issues that would need to be experienced to really judge before you could say ah yes....

[Salty Pete]

Did a video on the OB testing Fenlander's advice that the OB is increasing and decreasing speed by itself.

This is the second attempt, I couldn't load it direct before so I'll try through You Tube.

http://youtube.com/watch?v=4qNe25-2Kwn

That's not working either.

[beamishken]

Doesnt seem like any of the previous suggestions work , seems like you have the perfect justification to buy a bigger boat. That'll fix it!
😉👍

[Salty Pete]

Well let's have another go.

http://youtube.com/watch?v=2aSkw4CJC58

Beamishken I'm retired and I think that this will be my final boat. Lotto is my only hope now.

[Steve509926]

Hi Pete, it appears as though you have to move that throttle lever a long way before there is any increase in outboard speed and it's only in the last third of movement that there is any change.
Have you bypassed (disconnected) the throttle cable on the outboard and just used the lever on the outboard to see if there is a smoother increase/decrease in speed.?

[chipko]

Looks fairly normal to me on remotes. Not unusual for no increase in revs for a good 20/30 degrees of throttle movement as the gear selector fully engages.

[Salty Pete]

I see your point Steve. The throttle handle may not be lineal in its operation and may pull the cable faster the further the lever is pushed. I'll check the manual on setting up the throttle control.

Chipco: I do move it a long way after the gear is engaged. No suggestion is a bad suggestion.

Have to mow the lawns tomorrow and the damn lawnmower always starts.
I'll have another go over the weekend.

[Fenlander]

Very interesting. There do seem to be two points (approx 2min 55sec & 3min 16sec on the video) where the revs creep up to a greater degree than the throttle input. Assuming all else is good with the outboard and remotes I would say this is the ECU map and not something an owner could adjust. It is a fair point Steve makes for absolute proof to eliminate the remotes it would be good to disconnect the cable and just work from the throttle lever on the outboard.

Assuming there is no fault and this performance issue is just an unlucky combination of outboard and hull interaction the only thing I could think of is to change the prop pitch to try and move this rev jump away from the speed the hull is keen to pop on the plane. Is your prop spot on at the moment re speed vs revs at WOT?

[Salty Pete]

Fenlander, 'scuse my ignorance here buddy but wot's a WOT.

If it relies on having a rev counter we're out of luck. Don't get Beamishken started or he'll recommend I get a bigger boat with an engine diagnostics screen.

I won't be able to get back to the boat for a couple of days.

About the prop, I thought of that but consider that I would have to increase the pitch too much to get the boat to cruise at 10 knots befor I get to the position where the engine revs increases.

I'll try Steves suggestion first.

Thanks

[Fenlander]

WOT... Wide open throttle.

Ideally your outboard would be making close to maximum revs at WOT. A temporary cheap rev counter with a lead just long enough to view it would be less than £20 in the UK on Ebay. The end of the lead just wraps round one plug lead and they have an integral battery so no other connections.

It would just form part of the picture to know if you are spot on or under/over pitched.

I agree it's worth proving the issue isn't the remotes first though.

[Salty Pete]

I checked the movement between the throttle control lever and the linkages. The movement of the throttle handle before the outboard starts accelerating appears normal.

It takes that length of movement to totally engage the gear. The throttle linkage moves as soon as the gear is engaged.

I have illiminated the throttle handle as a problem as the throttle linkage moves smoothly with the handle. I was expecting a jump of the throttle linkage while I was moving the handle.

I have sent a message to Suzuki to see if they can or want to advise where the problem is.

I will report back.

[beamishken]

Originally Posted by Salty Pete

Well let's have another go.

Beamishken I'm retired and I think that this will be my final boat. Lotto is my only hope now.

Thats a shame you have all the ingredients to justify an upgrade , maybe some clever man maths required😉

On a more serious note , tinker sugested early on in the thread to try a hydrofoil/doel fin which might not be a bad idea , it might make the boat plane at low speed without scooting off like a scalded cat. I know they are marmite things but do work in certain circumstances. Could be a cheap easy solution

[Kristoff]

I have a Highfield patrol 600, one of the benefits of the design of these boats is the easy planing aluminium hull. I presume the same applies to your smaller version.

Maximum displacement speed is largely a factor of waterline length, so I would advise against trying to increase the displacement speed. All that will happen is that you push the boat down into its own hole and you put-put along like a plough being dragged through a field using loads of fuel.

What might be an option is reducing the speed which the boat will stay on the plane.

To this end, fitting a hydrofoil to the outboard lower unit and fitting smart tabs to the hull will, I’d be fairly confident, lower the speed at which the boat planes. Whether that speed is low enough for you, probably not. I can’t see you staying on plane at less than around 10 knots.

If you want to motor at 7 or 8 knots, a planning boat is the wrong boat unfortunately. You want a boat with a displacement or semi displacement hull for that.

[Salty Pete]

G'Day Kristoff
You have a 6M Highfield obvious answer to my problem, we swap boats!

I have sent two text messages to two Suzuki dealers with no answer from either. I have got the email address of the guy in charge of one of the dealers so I am hoping for a reply.

To my thinking doing anything to slow the boat down in relation to the revs of the prop is like leaving the handbrake of your car on if it is accelerating too fast. It doesn't solve the problem, just masks the problem and uses more fuel.

It will be interesting to see what the response from Suzuki will be.

I'll keep you posted.

[Salty Pete]

Well, I've sent emails to our Perth agents, only two with no reply so it doesn't look like service is one of Suzuki's strong points.

I guess I'll have to experiment with whatever adjustments I can find.

I certainly won't have a Suzuki on my next boat.

[Fenlander]

Would it be worth booking in for a basic dealer service with diagnostic just in case this threw up something re the revving behaviour? Perhaps even buying the diagnostic yourself which would be cheaper.

[Salty Pete]

Originally Posted by Fenlander

Would it be worth booking in for a basic dealer service with diagnostic just in case this threw up something re the revving behaviour? Perhaps even buying the diagnostic yourself which would be cheaper.

Looks like the way to go. Thanks Fenlander.

But I can see a notice coming up on the screen saying, "Please send this equipment back to the supplier and tell them you are too stupid to use it."

Then of course if I buy a new boat it will have to have a Suzuki because I have the diagnostics for it.

Well here goes I may as well jump into the deep end.

[trevbouy]

I agree with Kristoff here. You will be chasing forever to achieve your goal.
When i bought my rib, during the test I commented we were in the 'hole' at 5 knots.
Trying to get up on plane it rose at 7 then scooted to 10 knots and no amount of trim, throttle input would let it settle to plane at 6 knots, it constantly slowed too far and fell back again with a large bow wave.

I had a long chat with the dealer and he said it's not the engine but the speed/hull combination at that point. It was a common problem for many of the ribs in the harbour trying to achieve the 6 knot speed limit. The engine is fitted with doel fins by previous owner who must have tried to get round it.

[Fenlander]

In truth this situation is true to some extent with all boats that plane and certainly every SIB we've owned re having a speed we rarely use... i.e. between a gentle wash free 5kts and properly on the plane at perhaps 10kts plus.

But from how he describes it Pete's is unusually reactive in this speed range. I'd still like to have him fit a $20 tach and see if his prop is as suitable as it can be.

[Salty Pete]

Originally Posted by Fenlander

In truth this situation is true to some extent with all boats that plane and certainly every SIB we've owned re having a speed we rarely use... i.e. between a gentle wash free 5kts and properly on the plane at perhaps 10kts plus.

But from how he describes it Pete's is unusually reactive in this speed range. I'd still like to have him fit a $20 tach and see if his prop is as suitable as it can be.

Please excuse my ignorance here Fenlander but please explain how a tacho will help me. I know the engine increases revs as I move the throttle handle and I know that the revs starts increasing by itself at a particular point. I can't understand knowing what the revs are, is going to make a difference.

With the diagnostic tool it is possible, so they claim, to change the parameteres of the engine.

Trevbouy - Thanks but that was what I originally thought. If you watch my video you will see that the engine increases speed by itself. If it was just a small window of speed I wouldn't mind but 6 to 15 Knots is a lot for a small boat.