Scary engine vibration or prop ?

[Jmc1764]

Last September I collected our new boat from near Walton on Haze and motored all the way to Gillingham in Medway. The 1995 Vetus four cylinder diesel hummed all the way with no issues at all and surprisingly economically. Over the winter I decided to fit new glow plugs, change oil and filters , new water pump rubbery thing etc. Just recently as lock down eased I could not wait any longer to take her out. The weather was very windy but we still went along, after a couple of hours trying to sail we gave up and motored back against the tide and wind, If I tried to go over 18oo Rpm there was a lot of vibration and a knocking sound. Very scary in the weather conditions so we crept all the way back to the mooring in fear. Today we have been out and the engine was as smooth as silk, the water was calm and light winds. I could go up to full speed with no noises or vibration at all. Could it have been a lump of weed on the prop ? or is this common in bad weather conditions ? I would have thought if it was something serious it would still be vibrating and knocking ?

 

[RichardS]

The worst vibration I ever had on my boat was caused by a old bit of plastic netting like use in supermarkets for fruit, although the boat kept moving along just as before.

I feared the worse so swam under the stern, removed the small piece of netting and all was back to normal.

It has happened a couple of times since then but all I do is give a short burst in reverse and that fixes it.

Richard

 

[Refueler]

I had some old net on my prop and it was as if someone with a sledge hammer was banging the hull ...
Another time - the fixed part of my rope-cutter Gator sheered its fastenings ... I had to lift boat out to remove ... it was again like someone hammering away !!

 

[Just_sayin']

"Could it have been a lump of weed on the prop ?"

Yes.

 

[peteK]

Thats happened to me,try putting it in reverse and it may clear.

 

[Jmc1764]

Phew, hopefully then it was some weed or net or some other thing caught. I was fearing cutlass bearing or engine mounts or the dreaded Hurth transmission slip. Incidentally I changed the oil in the Hurth as well so this was the first run after "servicing" I have a feathering prop so wondering if going in reverse would help much as it just turns the blades and spin opposite rather than completely reversing the prop. Or maybe these type of prop are more prone to picking up things ?

 

[Refueler]

Here's what caused my banging ....



No amount of astern got rid of it ..... but dried out in Newport - I knocked it with boat hook and it came away ... I did NOT leave it for others ... I fished it out ..

 

[Caer Urfa]

Lucky escape but next time if you can check for any movement in the cutlass bearing also

 

[wilkinsonsails]

Could be a sticking blade on the prop .If it had not opened fully it would make it run unevenly