look how bad I destroyed my prop

[massimofinance]

cruising my normal waters at around 16 knots, and BAM!. stopped and surveyed the damage. Any advice on what type of prop I should get? SS saltwater? the odd thing is I have an engine guard mounted...

 

[Bt Doctur]

An aluminum is your best choice

 

[achris]

Nah, that'll buff out...

If you can afford it, go Merc genuine stainless steel...

(Cue the 'stainless steel will damage your gears' peanut gallery)

No it will not! A stainless steel propeller is better for holding its shape, has thinner blades for better efficiency, and is less prone to destructive damage, like in your photo... You can bend a blade and it can easily be straightened out.

I have no idea where this stupid theory about gear damage came from, but after running my own boat shop for years and continuing to maintain friends and relatives boats, I can say there is absolutely no evidence to support it... I have seen shafts sheared, gears chipped and crack with both Ali and SS props. I've also seen a SS Prop with 2 blade folded hard against the hub with the drive line completely untouched. The extent of gear and shaft damage has no correlation with the material the propeller is made of!

The only 'advantage' of an aluminium prop is that it's cheaper...

Chris....

 

[jimmbo]

Stick with aluminium, and consider it a Sacrificial Lamb. With a SS if the prop doesn’t bend, the Driveshaft certainly will

 

[achris]

Stick with aluminium, and consider it a Sacrificial Lamb. With a SS if the prop doesn’t bend, the Driveshaft certainly will

Complete BS! Read above!

 

[Bt Doctur]

achris, for your viewing pleasure , from a Black Max wide open with a Hi-Five prop. Prop was reduced to the size of a grapefruit , once removed here was the shaft. Lower unit exploded , crankshaft end broken off the crankshaft. His friend who hit the same boulder sheared off his lower outboard unit completely. Would have aluminum props saved them, probably not
click to enlarge

 

[achris]

.... Would have aluminum props saved them, probably not

Thank you. That's my point exactly!

 

[massimofinance]

Thanks guys. While I consider SS and Alum., should I be worried I caused internal damage at all? Anyway to check that. Also, I’ve been having issue getting on plane, should I consider a 4-fin prop?

 

[Scott Danforth]

Thanks guys. While I consider SS and Alum., should I be worried I caused internal damage at all? Anyway to check that. Also, I’ve been having issue getting on plane, should I consider a 4-fin prop?

that little prop damage most likely didnt do any internal damage.

 

[achris]

Thanks guys. While I consider SS and Alum., should I be worried I caused internal damage at all? Anyway to check that. Also, I’ve been having issue getting on plane, should I consider a 4-fin prop?

Agree with Scott, that sort of damage is unlikely to have done anything bad inside.

As for trouble planing, What RPM were you getting with the old prop? (at wide open). It should be in the top half of the rev range. In your case, and I had to trawl through your previous posts, 4600-4800rpm. Please, in future include the engine description in your initial post. Trying to help with problems without knowing what it is makes it a tad difficult (crystal ball is out at the polishers at the moment. )....

Chris.......

 

[cptbill]

Stick with aluminium, and consider it a Sacrificial Lamb. With a SS if the prop doesn’t bend, the Driveshaft certainly will

That's true if you run in an area where you likely hit again it's a lot less expensive to repair or replace aluminum. I run stainless but I'm in salt water but I did ding one once and man that was costly

 

[massimofinance]

Thanks Chris. I have a mercury mercruiser 5.0L with the alphaone outdrive. The motor won’t go above 3k rpm. 19 knots is where I’m stuck at. A few weeks ago I was cruising at 19 and something suddenly popped and it started going at 26knots. Couldn’t replicate that again unfortunately. Might need new plugs? What about the four fin props? Thx.

 

[Bondo]

A few weeks ago I was cruising at 19 and something suddenly popped and it started going at 26knots.
Couldn’t replicate that again unfortunately.

Ayuh,..... I suggest you fix yer motor, before worrin' about the prop,......

 

[massimofinance]

Ayuh,..... I suggest you fix yer motor, before worrin' about the prop,......

You’re right! Problem is I don’t know what else to do; haven’t been able to find anyone to tell me why my top end has been cut in half (the bottom is clean, I changed both fuel filters, sprayed cleaner into the carb) and that one time, when cruising at 14 knots it suddenly popped to 26 knots. I really don’t want to take it to the mechanic because for one, hes super busy, and two, every time I go there is a $3k bill... thanks team...

 

[QBhoy]

Nah, that'll buff out...

If you can afford it, go Merc genuine stainless steel...

(Cue the 'stainless steel will damage your gears' peanut gallery)

No it will not! A stainless steel propeller is better for holding its shape, has thinner blades for better efficiency, and is less prone to destructive damage, like in your photo... You can bend a blade and it can easily be straightened out.

I have no idea where this stupid theory about gear damage came from, but after running my own boat shop for years and continuing to maintain friends and relatives boats, I can say there is absolutely no evidence to support it... I have seen shafts sheared, gears chipped and crack with both Ali and SS props. I've also seen a SS Prop with 2 blade folded hard against the hub with the drive line completely untouched. The extent of gear and shaft damage has no correlation with the material the propeller is made of!

The only 'advantage' of an aluminium prop is that it's cheaper...

Chris....

At last. Someone with sense and the same opinion as me on stainless and the old rubbish theory about them damaging gears and shafts.
I know where it came from but it isn’t an issue these days at all. It goes back to when stainless props were hard splined onto the shaft. This isn’t usually a things these days generally. They all come with s sacrificial hub that is designed to take the load or shock of any encounter with the bottom.
There just isn’t a real good reason not to have one these days...unless the owner simply doesn’t care for efficiency, performance and a range of other things.

 

[jimmbo]

First impact(rocks) I had with the SS on my VP(10 hrs on it) bent and tore the blades of the prop and bent the Shaft. The prop was a Raker which had a Rubber Hub

 

[QBhoy]

First impact(rocks) I had with the SS on my VP(10 hrs on it) bent and tore the blades of the prop and bent the Shaft. The prop was a Raker which had a Rubber Hub

Sounds horrible and very unfortunate.
I sold my old bayliner 2255 to a newbie owner years ago. It had a high 5 merc prop on it with flo torq hub.
Within a week of owning it...he ran it completely up the shore on a rocky beach on Loch Tay at about 25 mph.
It soon after turned up back at my marina. The local dealer bought it off the owner and insurance company. The drivetrain was fine. The prop was more like a hi 2 haha. The hull was a mess.

 

[jimmbo]

It was a ridge of rocks/slate and there were at least 5 or 6 very solid wallops. The skeg made it through almost undamaged.
Prop was wobbling and the front of the Hub was scraping/machining the end of gearcase behind the bearing carrier. Did a pencil in the centre of the Propshaft while running and it was wobbling. Was going to take a week or so for a new shaft to be delivered, so the Dealer had a mechanic pull the propshaft from a new boat in the showroom and I was on the water 2 days later.