Engine movement

CornishAvon · 27 June 2012, 14:02

OK probably a stupid question but I think worth asking just in case..

I was using my new go pro yesterday and filming from different positions on the boat. One position was filming the engine during a blast. During playback today I noticed that the engine during throttling up moved forwards - not a huge amount but definitely moved forwards, then during throttling down to a stop it moved back again. Its not the transom - thats solid - just the engine.

I will try to upload the video to youtube and post a link back in a min so you can see what I'm talking about. Cheers

http://www.youtube.com/watch?v=a0nBd2BxxJY

OK think thats the link. Thanks

jyasaki · 27 June 2012, 16:19

I don't see the engine moving relative to the transom; I suspect you're seeing the entire transom moving forward (a bit of tube deformation) under power. I'd say its pretty normal.

jky

Edit: Or is it a RIB?

CornishAvon · 27 June 2012, 17:03

I wasn't sure it was the transom moving as its well braced etc being a searider. the video does not do it justice in std def. its more noticeable at the end when the motor stalls ( out of petrol). You can see it move forward then.

If you say thats normal then great news as I was not sure and thought it better to ask and look silly on here than out at sea when the motor drops off ;-)

Come to think of it now you mention tube deformation, the tubes were not up to full pressure. Would that make a difference?

Thanks

Hightower · 27 June 2012, 17:50

All looks pretty normal to me!

Don't forget the outboard is held in place by rubber shock absorber mounts, that might account for a little movement, but what I think you're looking at is the leg loading up under thrust and then relaxing when wave hopping or throttling down, this will have the effect of having a tilting action on the outboard.

CornishAvon · 27 June 2012, 17:52

Quote:

Originally Posted by Hightower

All looks pretty normal to me!

Don't forget the outboard is held in place by rubber shock absorber mounts, that might account for a little movement, but what I think you're looking at is the leg loading up under thrust and then relaxing when wave hopping or throttling down, this will have the effect of having a tilting action on the outboard.

Nice one put my mind at ease now. I blame the go pro! Would never had seen it moving if it wasn't for that :-)

Thanks guys

m chappelow · 27 June 2012, 17:57

I would agree with Hightower ,possibly just a bit of flywheel and prop torque too acting on the rubber engine mounts when powering up . i had a Johnson that seemed to do that from new,
some do occasionally wear out .

Boats&Outboards · 27 June 2012, 18:00

Before watching video I thought it would be mounts on a merc 3 pot. Very common. Looking at the video I see the Yam do very unlikely mounts.

I suspect it's the power trim, either low fluid or leaky ram. Try giving it a good yank on the cab plate, trying to tilt it up, see how much movement you have and where from

CornishAvon · 27 June 2012, 20:24

Quote:

Originally Posted by Boats&Outboards

Before watching video I thought it would be mounts on a merc 3 pot. Very common. Looking at the video I see the Yam do very unlikely mounts.

I suspect it's the power trim, either low fluid or leaky ram. Try giving it a good yank on the cab plate, trying to tilt it up, see how much movement you have and where from

I checked the trim fluid level before this trip and it was low. I topped it up before going out.

I will see if I can move the motor as you say by grabbing the cav plate etc. Do you think this amount of movement is not normal then?

Cheers

jyasaki · 27 June 2012, 21:34

Quote:

Originally Posted by CornishAvon

Come to think of it now you mention tube deformation, the tubes were not up to full pressure. Would that make a difference?

Yup.

Though even at the correct pressure, you can expect a bit of flex when the motor comes up on power.

jky

willk · 27 June 2012, 21:39

It's important that tubes are at optimum pressure, especially if they are in contact with the water under way. Low pressure can cause a rippling effect that damages seams and strakes. Don't ask me how I know

Boats&Outboards · 27 June 2012, 21:56

When i first watched it was on iphone so hard to see clearly. Now on larger screen I don't think it's anything to concern yourself with in terms of serious faults. Even if it was slight play in the mounts it'll be expected with a engine circa 10 years old. Like others have said though it may not be the engine itself.

Peter @ Boatsandoutboards4sale ~ askboatsandoutboards4sale@sky.com ~ 07930 421007

CornishAvon · 28 June 2012, 08:18

Great thanks guys. Note to self - must pump up tubes! ;-)

Appreciate the advice :-)

Rokraider · 28 June 2012, 08:36

I suspect part of it is the wide angle of the GoPro lense, if the camera has any sort of movement on the mount, the picture can distort a little. If you watch the whole boat, rather than just the engine in the video, it all seems to flex at the same time. I would expect a bit of movement on the engine mount anywa..

CornishAvon · 28 June 2012, 10:05

Quote:

Originally Posted by Rokraider

I suspect part of it is the wide angle of the GoPro lense, if the camera has any sort of movement on the mount, the picture can distort a little. If you watch the whole boat, rather than just the engine in the video, it all seems to flex at the same time. I would expect a bit of movement on the engine mount anywa..

Yes I see your point. Good spot ;-)