Help please Suzuki outboard problem

CobraEcosse · 25 September 2010, 23:47

Hi

I was out on my cobra rib today and travelling at 38 knots in calm waters. Suddenly the revs rose and the boat almost lost all drive. I stopped the boat and inspected the prop and all looks ok. I set off again but could not exceed 6 knots and all that happens is the engine revs rise but no increase in forward motion. I did not ground the boat or knowingly hit anything to cause this.
If it was a car I would think that the clutch was faulty. Hoping it is nothing to serious!

I would welcome any thoughts please.

Thanks

kawasaki · 26 September 2010, 01:41

Quote:

Originally Posted by CobraEcosse

Hi

I was out on my cobra rib today and travelling at 38 knots in calm waters. Suddenly the revs rose and the boat almost lost all drive. I stopped the boat and inspected the prop and all looks ok. I set off again but could not exceed 6 knots and all that happens is the engine revs rise but no increase in forward motion. I did not ground the boat or knowingly hit anything to cause this.
If it was a car I would think that the clutch was faulty. Hoping it is nothing to serious!

I would welcome any thoughts please.

Thanks

Although your prop looks good.
It sounds like the bushing in the centre is duff.
This will give you the symptom you describe

jyasaki · 26 September 2010, 02:50

I agree with Kawa's post.

Could be something like a bad gear in the case, but in that case you probably wouldn't get any thrust at all, hence the prop assessment.

jky

Poly · 26 September 2010, 08:04

If the problem is as the others suggest (and it certainly sounds likely) then the normal way to diagnose it conclusively is: put a line on the prop crossing onto the propshaft (indelible pen / tipex etc); take engine for blast (given how bad you describe you can probably do this without even leaving the harbour) if the mark on the prop and shaft no longer line up then the bush is gone - you need to replace the prop or send the prop away to get repaired (there is a company in Clydebank who have a good reputation for prop repairs - if you search the forum you should find a link)

CobraEcosse · 26 September 2010, 18:48

Thanks to you all. You were absolutely right! Will send away to get fixed. Does anyone have an idea what I can expect to pay for a rebush?

SPR · 26 September 2010, 22:48

Quote:

Originally Posted by CobraEcosse

Thanks to you all. You were absolutely right! Will send away to get fixed. Does anyone have an idea what I can expect to pay for a rebush?

The last time i needed a prop for my Yamaha I was told, better paying the extra few quid and buy the new one.

This of course only holds up if the prop is not a nice shiny new stainless steel one.

It also gave me the chance to buy a different size / pitch of prop. (opens another can of worms). Which made a big big difference to out of hole performance...

but...http://www.steeldevelopments.co.uk/ is a company that does them, never used them though.

regards

S.

simsy · 27 September 2010, 10:13

I bet you were happy to find this quick bolt on solution.... I did not know this could happen. Is there any check you can do to predict that this will happen soon. (marker pen / more perminent mark on the prop and centre sounds like a good idea for all props in this case, to see if it has ever slipped).... Do they normally slip a little bit anyway, I guess not ?

Will my 20hp 2 smoke yam have the power needed to get this phenomanon, lol...?

kawasaki · 27 September 2010, 14:07

Quote:

Originally Posted by simsy

Do they normally slip a little bit anyway, I guess not ?

Will my 20hp 2 smoke yam have the power needed to get this phenomanon, lol...?

No, they don't normally slip!
The 'bushing' is there to save the drive train
IE , if the prop gets terwatted the bush fails and that saves the rest of the gearbox etc.
Same thing with a shear pin on smaller engines/props.

I would imagine your 20hp will be' bushed' if so, it too will behave just like a bigger un.

Theory is-- it's cheaper , easier an quicker to fettle a prop and its innards than a gearbox etc!

Poly · 27 September 2010, 16:35

Quote:

Originally Posted by kawasaki

I would imagine your 20hp will be' bushed' if so, it too will behave just like a bigger un

Yes your 20HP Yam prop has a bush. No way to predict failure (that I am aware of) other than likely to be associated with a prop strike of some sort. Given that its remarkably easy to "ding" a prop a spare prop is a good idea anyway.

gotchiguy · 01 October 2010, 20:43

As I understand it, on the most modern engines the bush will melt almost instantly if the propeller's motion is prevented, I think then once the prop has cleared the obstacle and given a few minutes, the (now liquid) rubber will re-form around the splines and return to normal operation. Obviously if this happened, limiting your speed/revs until the its replacement would be highly advisible.

Kernow Buoy · 01 October 2010, 20:47

Quote:

Originally Posted by CobraEcosse

Thanks to you all. You were absolutely right! Will send away to get fixed. Does anyone have an idea what I can expect to pay for a rebush?

I paid £80 inc p+p for a rebush on a 21" stainless from http://www.castlemarine.co.uk/ used them before good service.

stepheneyre · 02 October 2010, 20:41

hi

try

streemline props
they are very helpfuul if u phone them up

STREAMLINED PROPELLER REPAIRS on ebay its cheeper than the web site

http://www.streamlinedpropellers.co.uk/

Address:
Streamlined Propellers
Unit 17
Cavendish Mews,
Off Grosvenor Rd,
Aldershot
HANTS
GU11 3EH

Tel/Fax:
+44 (0) 1252 316412

Mobile:
07776 014285

Email:
streamlined@ukgateway.net

i bought a s/s prop for my suzuki 150.. at £140.00 new a few years ago
so cheep i bought a spare

thanks

steve