The fool's question bent prop on duuo prop system -

[george unthank]

This must be one of the classical idiot queries here but here goes anyway
I hit rocks yesterday - I was directly in channel etc etc - I was following the chartered course on my GPS- the lake is high at the moment yet I hit this rock in the channel.
I was doing about 7 mph in my Regal 2565 diesel Volvo Penta - 190 hp out drive
I was thrown from my seat , passengers all pretty shook up- a nasty hit.
Checked immediately to see if there was any apparent hull damage - there was none apparent - above water line
I started up again , slowly ,conscious all the time about vibration - I got her past 5 mph without any vibration , but after that when you are just pre-turbo charger kick in phase and when my engine in noisy and vibrates anyway , it did seem to vibrate more than usual.
I probably shouldn't have done this either but I got her on to plane and on up to 17 mpg at about 2000 revs ; again no perceptible vibration
Got to pier and raised skeg as much as I could . I could see there was a fairly uniform bend- twist on each of the blades of the front prop ( its a duo poop ) Props are stainless steel and this is first time I hit anything
The props moves over one another easily and without hindrance with engine off in neutral.
I came home doing about 6 mph . there was no vibration . This '' home journey '' took about 90 mins . No probes registered other than an EVC coming on telling me ''CHECK ENGINE '' followed by an immediate ''ALL CLEAR''
I wonder if the fact that I can run the engine without perceptible vibration will I cause damage to engine
I hear horror stories about seals and gear boxes .
I checked test for any milkiness in the oil - There was none .

I have only 2 weeks left in my boating season .
I wonder if it is safe to run the craft at 6mph without incurring damage . One group in club says no ; the others say Yes .
I'd like to make the most of my remaining holiday time using boat and use it at low revs ONLY it is SAFE to do so.
So what advice can anyone offer me if any -please ? ;
I know the props are bent aid know the safest answer is to take props off and have them straightened and balanced professionally but is this an absolute IMPERATIVE if I use the boat conservatively now for remainder of season - about 4 more trips of 6 hours @ 6 mph return scheduled for remaining
I am getting messages from another forum that unless the skeg in damaged the out drive is built to sustain a substantial impact .
In my case it was substantial- throwing me from my seat - at 7 mph; a passenger smashed a thermos flask - all were shaken as stated above but ok .
So is it safe to use the boat in conservative made ie 6 mph for the next couple of trips as I will be going to Spain in 2 weeks .
If it is. IMPERATIVE that she must have props straightened IMMEDIATLY so be it
But if I can hang on for a few more trips - noting the oil and water - and any sign of ''milkiness ''it would save me a lot of hassle .
Obviously I don't want to risk wrecking engine - but given that the skeg is clear - and there is a turn in 2 of the blades of the outer props and a. dinge in one blade of the inner props - what is the risk of my damaging engine or are there any other things I can look out for to forewarn me of imminent danger OR are there any measures I can take to minimise risk of further damage

 

[jrudge]

Send the props to steel developments and get them repaired.

No oil on the water. No terrible noises probably ok but there is no real way to tell until it is lifted and looked at.

How did you check the oil. As far as I know it is via bung screws in the bottom of the leg. This would require a lift.

 

[spannerman]

Whenever we have a boat in with a prop strike we always check the propshafts with a dial indicator to see if they are bent, there is very little tolerance or non at all on most drives. I guess you have an SX drive, if it is then the max allowable runout is 0.07mm with a max of 0.03mm difference between the inner and outer axle.
If they are slightly out of true it will mean that even if you have new props they will not be running true but slinging around as they rotate, this can ruin the bearings eventually, if the seals don't leak first. Not trying to scare you but if its not checked thoroughly it can cost you more later.

 

[george unthank]

Thank you jr...
There you go.
I was looking at sump oil- just shows how conversant I am with mechanics -
The out drive is where the gear mechanism would be of course - so no I haven't checked . but there is no oil slick or any evidence of pile on water when boat is static in calm water -he says , clutching at straws

 

[jimmy_the_builder]

How did you check the oil. As far as I know it is via bung screws in the bottom of the leg. This would require a lift.

+1 this was my immediate thought as well. I also agree that the props should be repaired before further use. If nothing else I'd be lifting the boat to have a good inspection of the leg.

 

[BruceK]

I've just pulled the boat because I thought she had a dirty bum. Turned out bent props. Been cruising quite a bit since I briefly ground out on sand in the channel which is the only time Im aware of any sort of propstrike. Hadnt noticed anything unusual either except slower than normal hence the lift and wash. I've not only ruined the props but also stripped gears and bent shafts. Unbelievable that they continued to run so smoothly .... almost as unbelievable as the repair bill. I wouldnt chance it. Id pull the boas asap.

 

[rafiki_]

George, you are in insurance claim territory. Call your insurers, and I am sure they will advise you to have the boat lifted, and outdrive inspected and repaired. Could be quite quick if no serious damage.