Does prop damage= shaft damage?

[stunod12]

HI,<br /><br />In the past (with my I/O) I've hit bottom a few times. Mostly over mud sandy bottoms. The blades of the prop were bent at the tips mostly. No damage to the outdrive.<br /><br />Question: After looking under Inboards I notice that there's a LONG NARROW SHAFT connecting to the prop. So, If an Inboard hit that same sandy bottom, would there be shaft damage also or would the shaft withstand the impact?<br /><br />Just Thinking out loud,<br />Lou

 

[Solittle]

Re: Does prop damage= shaft damage?

Generally no. Of course that all depends on what you hit and how hard. The neat thing about outboards is that when you hit something your outboard will tilt up - hopefully.

 

[Jack Shellac]

Re: Does prop damage= shaft damage?

Yeah, the driveshaft is generally much stronger than the prop. Like anything, it can be damaged if all the conditions for it are right. The usual thing is for it to get bent by hitting something.

 

[magster65]

Re: Does prop damage= shaft damage?

I think your prop has rubber between the shaft and the blades. That should spin before anything breaks (in theory).

 

[stunod12]

Re: Does prop damage= shaft damage?

Hi Guys,<br /><br />Thanks for the input.<br /> Not that now I'll go out looking for bottoms to hit but at least I feel alittle better.<br /><br /> It's just that when you peak under an inboard boat, it doesn't look so strong. It looks actually very cheap & wimpy. <br /><br />Now, tell me if this hypothecial question can really happen:<br /><br />Your driving along at a cruising speed of 20 and your prop hits a large rock. The force, rips out the shaft completely and water start to rush in from where the shaft was once sitting. Your engine compartment fills quickly. You head back to land with the other engine but your taking on 60 gals of water a minute and your RULE PUMP only pumps out 20gpm. Your boat sinks and you drown. <br /><br />Any truth to that???

 

[Solittle]

Re: Does prop damage= shaft damage?

Yup!

 

[Graywolf]

Re: Does prop damage= shaft damage?

That's why they have life jackets....<br />On the prop qustion. I just had my OB serviced. I have a stainless prop. 75 horse Merc. My service man told me Stainless is about the best, but if I hit something the prop will not bend or break and will take out the gearbox.

 

[largewake]

Re: Does prop damage= shaft damage?

this seems a rather nasty subject, but i am interested in the bit about the outboard that goes up on the tilt at impact, would anyone like to expand on that for me as i have not heard this one before?

 

[codyandamber]

Re: Does prop damage= shaft damage?

Flooding is a large amount of water that exceeds the capacity of your drain pump. The quick definition is if you see the amount of water and you say holy cow!!! I assume you really want to know about the first part (the shaft being knocked out and water rushing in). If I understand you correctly, yes this could happen...

 

[cotterman]

Re: Does prop damage= shaft damage?

doesn't every prop have some kind of shear pin designed to break long before any other damage occurs???

 

[Solittle]

Re: Does prop damage= shaft damage?

cotterman - Shear pins were common many years ago but now most motors have through hub exhausts. The protection for the gearcase is provided by the prop itself. The hub of the prop is seperated from the prop itself by rubber so that when you hit something real hard the rubber gives. Over time the rubber will harden and it will break loose easier than when new and can even break loose from the torque of the driveshaft on hard acceleration. When this happens you take the prop to a shop and they rehub the prop. What that means is they seperate the prop and hub and put new rubber in and it is back to like new.<br /><br />This works well and you don't have to carry shear pins in your tool box - - or even worse - need one and find that you don't have one.

 

[magster65]

Re: Does prop damage= shaft damage?

I saw a tip in a magazine, it says to always have a potato on board. The reason; in case you lose a valve or through hull fitting(maybe a drive shaft) you can quickly work a potato into the hole... it's a lot easier than trying to stuff rags or whatever in.

 

[cotterman]

Re: Does prop damage= shaft damage?

thanks for the info SoLittle<br /><br />so my 1982 9.9 chrysler is a little behind the times???LOL

 

[flashback]

Re: Does prop damage= shaft damage?

stunod12, your hypothetical question about the inboard brought something to mind. several years ago while up at the lake playing we heard a guy come over the radio hollering mayday and said he was sinking. turns out he was about a quarter of a mile away, so we buzzed over to him and discovered that he had water coming in from the stuffing box where the shaft was supposed to be.(this was an inboard, carver i think). I told him to take his T shirt off and wad it up and stuff it in the hole. he looked at me like I was crazy, but went ahead and did it anyway. we then pulled him back to the lift and got his boat on a cradle. Turns out the mechanic that had changed out a bent shaft had not secured it into the coupler. anyway this has much to do about nothing. look at the time. now you know what i do when i can't sleep..........

 

[gss036]

Re: Does prop damage= shaft damage?

Largewake, to touch on your subject of an outboard tipping up. The 5-10 HP models will tip easy enough if you hit something(log)in the water. They are designed that way. On the other hand, I had a friend who likes to run like, flat out WOT! He was running an Evenrude V-8 outboard on a 24' Whaler and went over a semi-submerged log at about 45 mph and completely took off the lower unit.<br />Another guy I know went over rocks on the way out at high tide (from an unfamilar ramp)and came screaming back in as the tide was going out, good thing he was just 200-300 yards from shore, when his I/O hit the rocks, he tore out the entire transom, his insurance company was not very happy. He and his friend had to swim ashore.

 

[golfer]

Re: Does prop damage= shaft damage?

If you are not extremely concerned about the gains in performance in a stainless steel blade, buy aluminum. Safety over performance. The aluminum will bend or break, where as a stainless may in fact strip your shaft. They do not give!!!I live on the edge and stick with stainless steel and try not to get myself into a striking an object situation. Not sure how an outboard compares to an i/o in respect to a prop strike taking out the shaft. But in i/o's, I have seen many, heard many, and had a couple of my own couplers go even without impact, merely fast take off with worn teeth on the coupler to shaft connection.

 

[cpasseno03]

Re: Does prop damage= shaft damage?

You seem to be a little safety conscious of inboards... I have always favored them over and O.B. or I/O, I find them to be more heavy duty, and easier to work on. And best of all, you can put a nice full skeg on there, and depending on how well its constructed, you can run right up on a rocky shore at full speed if you so desire and not hurt anything but that expensive bottom paint Out boards tilt up when trailering or not in use, when in forward they tend to push themselves down. My reverse locks on all the motors I have had have been quite woosy, perhaps that is so when you hit stuff it will kick up a little bit..?<br />Craig

 

[largewake]

Re: Does prop damage= shaft damage?

thanks, out of curriosity,how do you post a piccy on here with an email?

 

[gaffer1]

Re: Does prop damage= shaft damage?

I am 8 years late to this thread, but for those who may read this.
I note in the hypothetical the poster talks about racing back to shore with his other engine.
I once launched my boat and after parking my vehicle came back to find my 14' runabout inundated with a considerable amount of water. (I had forgotten to put the plug in) I immediately put the plug in to stop the flood. I once heard that if you run WOT and pull the plug the water will run out as fast as it ran in.
I moved everything (battery, gas tank etc) as far forward as possible and throttled up to wide open.
My passenger then pulled the plug (ready to reinstall just in case) and sure enough the water rushed out as fast as it had earlier rushed in.
On another point. I once hit a stump and my 40hp outboard did tilt up when it hit with no apparent damage.