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View Full Version : Possible underwater impact? - Better read this! (beware long post)


zone5
08-09-2010, 10:35
Hi everyone, I’ve been a long time off the forum, and do have a bit of a story.

While much of it has been due to incredibly busy personal circumstances, the boat has been out of action for about 4 months due to (your gunna love this Doug) failure of the gearbox on my 50 hp Etec after about 47 hours. It’s a long story so I’ll try to be concise.

In March we were cruising along on Lake Lyell at about 4500 rpm when we noticed an unusual metallic banging from the engine. There was enough time for a look between the missus and me, and then down the back at the engine when all drive stopped and the motor ran free (still running fine). No forward, no reverse, nix, nada, nothing. Fortunately only 400m from the ramp so easy paddle to retrieve. Sat morning so call dealer, they initially thought prop hub, but I was already having doubts about that, boat was out of water, prop secure but graunching when turned by hand. Agreed to drop it off for warranty claim, was pretty obvious gearbox failure.

Now, step back in time when I bought the Solas Saturn prop. At the time I removed the OEM Viper prop I remember thinking “isn’t it odd the way the way BRP put a curve in the spline at the fwd end of the shaft – must be part of the prop location process” and the great shame in all of this was that for someone who studied aero engineering I didn’t take the thought processes a step further and think “it can’t be machined like that, you idiot…” doh Anyway, Saturn prop went on for most of a season, then put the Viper back on, not because I like it better (I don’t) it’s just that it has less blade area for same diameter and pitch and spins up faster, gets the engine in the mid-range quicker to pull me up on the wakeboard, and amazingly (or not) I still don’t get more curious about that funny shaped spline. pointlaugh

Well, back to the present, the shop pulls it apart, gearbox is trashed, pinion broken in half, shaft has some run out, a real mess but they have some odd questions about the props and how I use the boat. (I’m sure the cleverer amongst you can see where this is leading). Obviously (when they mention it) the curve in the fwd end of the spline is in fact a twist in the shaft, and it looks like an impact. I’m initially pretty indignant because I’d never even considered that and, hey, if I’d had one, no problems, I’d bring it in and get it fixed, but every hour of running on that boat I have either been driving it, in it or behind it, and there had, to my knowledge, never been any kind of impact. (I’ve stalled it once putting it in gear at idle when the prop was actually still in some mud). Also, as they all readily agree, there is not even the tiniest mark on either of the propellers, the motor or the boat, and no sign of the prop bush spinning. (I have spent hours looking for any mark, without success…)

Anyway, warranty claim with photos is submitted, BRP knock it back claiming impact. I have a fair bit of to and fro with them because I’m certain I haven’t had one, though I’m still wracking my brains trying to figure what has happened and have to concede it sure does look like one. Mind you the whole thing is, by now, doing my head in. I ran the sums on the shaft (engineering is always handy) and by my calculations, assuming it’s a typical high strength steel, that shaft can take a steady input at typical rpm of almost 200hp before experiencing plastic deformation – a bit more than it should have experienced. (Of course, if there was an impact, it can be overloaded and twist – but what about the rubber prop bush?) I showed it to two engineers and three fitters, 4 out of 5 said they thought the shaft hadn’t been heat treated properly. After that I investigated having full metallurgical testing, it would be about $500+ for Vickers, Rockwell and a couple of others and still not be definitive unless BRP supplied the relevant MPa values for the steel, which given our dispute they just weren’t going to do.

During this time I did have an interesting conversation with the head of BRP warranty claims, I’ll try to reproduce it here as accurately as possible (posted without further comment):

Me: “What concerns me about rejection of my claim is the implication that I am lying to you, having concealed the prop that had an impact and must have been damaged.”

BRP: “No, we’re not suggesting you are lying at all. We’re simply saying that it is possible to have an impact that you are not aware of, does not damage the boat, motor or propeller, but can still cause gearbox failure at some point in the future.”

That was the big issue for me, any suggestion I was lodging a false claim. Anyway, at about the point of setting a hearing date in the NSW Consumer Trader Tribunal to fight them, the stress was getting too much. My dealer pointed out that all of the evidence pointed to impact, and I was willing to concede that point, even though I kept thinking an impact capable of doing this must have been noticeable. Anyway, I accepted something must have happened that I was unaware of and an insurance claim was lodged, factual in that I had experienced gearbox failure, and everything, including the physical evidence and dealer and manufacturer assessments indicated that it was caused by an impact.

The twisted shaft was the necessary key factor for the assessor and the claim was honoured by Club Marine. The repairs were carried out by John and Drew Geo at Marine Scene Campbelltown. It was a complete gearbox rebuild, after all damaged parts were installed everything seemed fine however Drew noticed that when spinning the prop there was, if the surroundings were quiet, a very slight noise at one point in the rotation. Drew’s words to me were “if it was my boat would I be totally happy?”, and his answer was no, so they tore it all down and started again, this time also replacing the (seemingly undamaged) bearing carriers. All good this time and the prop now spins smooth and free for a long time when pushed with a finger. They tank tested the motor extensively and made sure it was top notch before handing it back to me.

We tested the boat and the motor now seems even smoother than when new, and pulls another 100 rpm @ WOT compared to when I first got it. 2thumbsup I must stress that this problem was with the gearbox, the actual Etec engine has just kept running sweetly thru the whole drama. Now, that gearbox predates Etecs by many years, I believe it has its origins in Johnson 60 and 70 hp engines from many years ago, with a good reputation.

So what caused the whole problem? Well, on the balance of probabilities it would seem we did hit something, a point I find embarrassing in that I didn’t notice, tho I am slightly mollified by the fact there was absolutely no damage to any part of the boat or motor (prop even checked under magnification!) to notice when on the trailer. What rpm? What speed? Cannot say... The fact that the motor seems even smoother now after the rebuild does occasionally make me wonder about the possibility of some problem ex-factory, but I have no real evidence for that. I’ve thought long and hard about how I feel re BRP and Etec’s (I considered at one point a re-engine with the new 50 EFI Honda) but given that the motor itself never gave us trouble, and that the gearbox has been carefully rebuilt by hand, I still feel confident in the brand, important when you put your family in the boat. I don’t want to move from the Etec, from a user point of view they are great.

Many, many thanks to John and Drew at Marine Scene, when caught in the middle of a difficult situation they gave me maximum support and good advice, and when we finally got on with it they excelled themselves with the care and workmanship they put into my job. 2thumbsup Thanks also to John Box (insurance assessor) and Club Marine, they were thorough and particular (which, as a paying customer I appreciate) and when satisfied that all was correct they did what I pay my insurance for and fixed my problem. They stayed in contact and kept me updated, even checking when it was all over that I was happy. Can’t ask for more than that… Nonetheless I hope not to have to use their services again! Also thanks to Glenn (BigFella) for some good initial advice on processes for dealing with the manufacturer – sorry mate for not getting back to you sooner, but when you get 8 days at home in 8 weeks some things just fall of the list!

Hopefully things are now looking up. “Waterhorse” is back in action (wx permitting), Burrendong Dam has gone from 11% to 80% in a couple of months (that’s twice as much water as Sydney Harbour) and still rising and we have an onsite van up there so looking forward to plenty of use this summer.

Have put this story up just to add to the body of information this site provides, and to acknowledge those that have helped me. Also as a warning to those who have had underwater impacts on any brand of motor, if you think it just hurts the prop beware - it won’t necessarily cause other problems straight away, so get it checked. This was what kept me awake at night, the thought that I might have lost drive (with the family on board) at a more critical moment than when it did occur; tho as I said above, given the work put into the motor, I now think it is as reliable as I felt it was before the incident. (I’m still wondering if stainless props are a good idea, an alloy would probably bend more easily and save the gearbox, as well as indicate what has happened).

Hope this is useful and of interest. I do have a picture of the shaft, but not on this computer (I’m away from home at the moment) so stand by for that.

Sorry for the long post. chrs jc

Dave
08-09-2010, 11:20
wow jc what a bloody nightmare.

Thank goodness its all fixed and working (better) than when new out the box.

Its also great to hear that there are still some companies around that actually 'give a shit' and provide excellent customer service.

I still find it inconceivable that you could impact something, not cause any external visible (or microscopic) damage, and cause such stress injury to the prop shaft. It would have to be a considerable impact force to cause such damage, one which I am sure would have made you exclaim "WHAT the F** was THAT??!!??

Time will only tell whether other similar instances come to light with other owners.

When the bolts on the jet unit on the jetski broke and I asked the mechanic about it he said he had never heard of it before! Maybe somethings, shit does happen?

Well its back and better than before so hopefully this summer will be a great one for the family on the water. :)

zone5
08-09-2010, 11:27
Got it in one Dave - that great unresolved discrepancy - I still sometimes get the bits and look at them and think - how?

Also to support us posting our experiences - was it you that posted a while ago about your less than favourable experiences with another insurance company re the trimaran? That motivated me to shift from them to Club Marine at my renewal, and glad I did...

chrs

Fishmarket
08-09-2010, 11:57
Really goes to show that your Insurance is much more important than the manufacturers warranty. Glad the insurance company came through for you.

Ta
Matt

Doug
08-09-2010, 12:14
There you go - I told you they were shit motors!

Sorry JC, I just couldn't help myself! :D:D

What a bugger. Club Marine has always been good to me, even in the commercial side of things. When someone sank my old tinnie at my jetty they paid up quickly and with the minimum of fuss. They're not the cheapest but worth the extra money.

I too find it very hard to believe that you could hit something so hard that you bent bits in the gearbox without damage to prop, boat or motor being visible. Mind you my son once reversed the boat into the end of the carport and bent the shaft. He always claimed (even during waterboarding and drug enhanced interrogation) that he barely touched the wall.

DvrDve
08-09-2010, 13:51
must be that one i dropped when we shipped it

m8 glad the nightmare is over
methinx something happened in transit to this 1

as for S/S vs alloy debate
all the commercial operators up north close to coral swear by alloys -replacing a prop after touching a bommie is easier than keeping a S/S prop and replacing a gearbox
they spin up faster as well -if u need it for ski ing boarding etc

dave almost everytime i break something the mechanic tells me 'never seen /never heard of it' :)

zone5
08-09-2010, 14:00
That's OK Doug - in the small, kind hearted corner of my soul I couldn't deny you the opportunity!

laugh1

zone5
08-09-2010, 14:12
must be that one i dropped when we shipped it

laugh1 shock


they spin up faster as well -if u need it for ski ing boarding etc

that's a good point, tnx...



And yes, I'm a touch paranoid now!

Doug
08-09-2010, 14:58
"the small, kind hearted corner of my soul "

That's the 0.0000000000001 square picometres?

zone5
08-09-2010, 15:04
Just goes to show you ex-military medical types have pretty well sussed out the make up of us ex-military aircrew types... pointlaugh

No secrets then, no secrets now...

chin
08-09-2010, 16:59
That is really something!!!! Not one spelling or grammatical blunder in the entire story!! :)
Sorry jc, just kidding, but it was well written.

I can understand your frustration, knowing you hadn't hit anything, let alone with enough force to twist the spline.
What puzzles me is how hitting anything while underway, could twist the shaft.
Twisting is a result of torque, not impact. I would have thought you could only bend it.
Anyway...all's well that ends well...enjoy your boat mate.

zone5
08-09-2010, 17:06
Hey chin tnx, yeah, the run-out in the shaft is actually a slight bend, I'm guessing that the twist came from prop rotation being resisted at a higher power setting. Now how that doesn't leave a mark on an SS prop (harder than alloy but still a soft material) or get my attention I don't know... I'll post a pic when I get home.

I did flirt with the idea that the shaft might be too soft in manufacture, and twisted under normal use, but according to my back of the envelope calculations it would've had to been deficient to the point of being similar in strength to aluminium, which is clearly not the case, so it was back to the impact hypothesis and head scratching...

chrs jc

BigFella
08-09-2010, 18:15
G'day Zone5,

Great too see your back in the water although your frustrations are well justified!

Water strikes are hard to prove and almost impossible to disprove!

Many years ago in an earlier marine life we had a customer bring one of our inboard ski boats we used to build back with a "warranty" issue!
Now we knew this customer on a personal level and often skied next to his camp with our own ski boat. His problem was a vibration that "appeared" after a long weekend of ski-ing?
We did the usual checks, replaced the shaft several times, tried alternate props, had the shaft and prop balanced still no satisfaction?
The boat had undergone less than 30hrs total running time, so we started looking for alignment and fitting issues? Still no satisfaction?
After thousands of dollars and what seemed like a month of Sundays the problem was finally analyzed and thought to have been caused by suspected "water strike"!
As a last resort we removed the skeg and had it tested, it was twisted, so minute it could only be detected in a lathe with a micrometer!

Now, as outlined we knew this bloke and didn't want to lose him as a customer so we wore the cost's, but to this day he does not and will not admit to having hit anything?
He has absolutely no knowledge of hitting a log or submerged tree or even a bump on the trailer?
Sometimes bumping them into gear whilst inserted in the mud can do it, although you would expect the shafts would be strong enough to withstand such a subtle "bump"?

"Water strikes" are very hard to diagnose, and even harder to explain!

I hope all is good now Zone5, let me know if I can help you out in the future!

zone5
08-09-2010, 18:33
Thanks Bigfella, as you say, hard to disprove!

Pretty certain that shaft, which is way oversize for it's horsepower throughput, should not suffer from engaging gear with a prop in the mud as torque developed at 800 rpm (idle) is pretty minimal compared to full noise, and even the slight movement that soft mud would allow before the engine stops makes a huge difference in the peak torsional load, compared to a dead stop against something hard.

All very frustrating. If you'd not noticed the impact but there was obvious damage, you'd say OK, fair enough, as would be the case if you'd felt it but found nothing after retrieving the boat. But when there is no obvious mark on anything (well, anything external) and you can't recall an event, you start questioning your sanity...

Learjohn
08-09-2010, 20:08
Sounds like out of aligned or badly fitted bearing carriers. Especially if it runs better than new with new ones fitted. Would running slightly out of whack cause a twist to the shaft? Then again you would have felt some form of vibration. Must be just Gremlins. I'll stick to the Yamaha.

John

Waxski
08-09-2010, 22:33
Sounds like me stewing over things. Sometimes in the end you just give up knowing that life isn't fair and there isn't much justice in the world....like when the boat dealer in Cleveland sold my boat (and about 10 others) went into liquidation, didn't put the money into the trust account and used it to prop up his failing business, which unfortunately meant that the liquidators didn't view us as secured creditors and used up the $120,000 from the sale of assets fighting our class action. I don't know who was worse, the Director or the liquidators. The no justice in the world comes from the fact that he didn't do jail time - got off on technicality - and he works at a local dealer still with boats. The only consolation is that my boat was worth about $7,000 and he sold a guys boat worth $21,000 the week before....there is always someone with a worse situation I guess.

So off my soap box (your story reminded me of this experience and bought all the bad memories flooding back) I'm glad it worked out for you though.

So with my mates Signature 1800S with a Yam Pro V 200hp we were wakeboarding up and Burrinjuck with all the submerged hidden trees I hit a submerged log flat out with a big thud. Checked everything and it was all fine - thought I'd killed the box for sure. Interestingly a couple of months later I didn't even feel the tree that took the skeg off....I was banking through the turn hard and heard the tinkle, tilted up motor and oh no....no skeg (side point - it is scary in the mountain dams to be skiing over a section of river you know so well and a week later be skiing over the same spot and hitting the top of a tree that was just under the surface - very scary). So again Club Marine were awesome and had a new skeg rebuilt and welded on. Now months later after the repair heard a big thud when boarding the Molonglo. On the lap back up the river there was a massive dead carp in the same spot. Now that was the culprit. So a couple of months later and we are boarding again and the prop hub let go. Now I wonder if there was a connection from the original Burrinjuck incidents and the final prop hub letting go (this wasn't part of an insurance claim). I think maybe these things can accumulate and cause problems later down the track. Hitting fish and not hearing them can happen - and if a big enough fish just catches the prop I guess it can cause damage without you even realising - no real impact marks given the soft flesh - but hard enough to send a shock through the shaft - we were running a stainless prop too - they really don't give and inch - they look hot though. Just a theory that I have thought about many a time given the series of events.

Anyways my point - well I have run a Propulse on my ski boat and I am about to put one on my current boat. People say they have too much flex, but I think the sharper 4 blade set up does bit better that a 3 blade alloy - just my thought. And if you hit something it can just sheer a blade hopefully without major gearbox damage. I also saw these Pirahna Props too. These sites make for some interesting reading.

http://www.olds.com.au/marine/propellers/propulse/propulse_swedish.html

http://www.boatpropellersaustralia.com.au

We all know the benefits of poly, plastics etc and most of us are poly tragics afterall, but does anyone else out there run a composite (plastic) prop and what are your thoughts?!?!

Dave
08-09-2010, 23:51
Also to support us posting our experiences - was it you that posted a while ago about your less than favourable experiences with another insurance company re the trimaran? That motivated me to shift from them to Club Marine at my renewal, and glad I did...
chrs

Glad that you changed over then. They were assholes to deal with, finally paid up but wore me out doing it...

zone5
09-09-2010, 05:30
Thanks Waxski, that's a good post and a good point. I had at times wondered if the culprit might have been a softer, submerged, waterlogged "log" or piece of timber that was only hit by the prop and provided enough mass to twist the shaft without marking anything... (Yes, almost all of our use is in freshwater dams...) I have to admit though, I never quite took the idea further to a big fish, but your description of the possible mechanism is very plausible...

doh

"They were assholes to deal with..."

Honestly Dave, you need to stop beating around bush and say what you really mean!

DvrDve
09-09-2010, 12:54
zone 5 its been known that dave's and david's keep their feelings/emotions pent up
it come s with the name

tried a plastic prop on my 175 while ago -got rid of it same day - lots of flex slow out the hole etc
though it was same dia /pitch as my alloy it was like spinning chewing gum, being (adjustable i took the pitch as course as it would go -almost a 30 degree increment and it was still sheit

however on small boats a lot of the 2-15hp s now come out from factory with plastic props
i v e got a lil 3.3 with one, hit a log broke the sheer pin -with no damage to the prop though- so they may be tough -but they do seem to flex

zone5
09-09-2010, 13:29
Yeah, that's the problem, the Solas New Saturn I've got is sweet for our use, don't really want to compromise on the performance. The OEM Viper is alright too. Both SS. Just have to be careful, I s'pose...

DvrDve
09-09-2010, 22:24
we were carefull and now we have 12 kids!

zone5
10-09-2010, 19:10
Clearly not using plastic! :eek:

zone5
11-09-2010, 09:32
Well, here is the pic, posted with some embarrassment as the shaft looked like that when I swapped a prop over and in my eagerness I didn't investigate further... doh